コード例 #1
0
ファイル: models.py プロジェクト: elma16/SeaIceSim
    def __init__(self, mesh, conditions, timestepping, params, output, solver_params):
        super().__init__(mesh, conditions, timestepping, params, output, solver_params)

        self.u0 = Function(self.V)
        self.u1 = Function(self.V)

        self.sigma0 = Function(self.S)
        self.sigma1 = Function(self.S)

        theta = conditions.theta
        uh = (1-theta) * self.u0 + theta * self.u1

        a = Function(self.U)
        h = Function(self.U)
        
        p = TestFunction(self.V)
        q = TestFunction(self.S)

        self.initial_condition((self.u0, conditions.ic['u']), (a, conditions.ic['a']), (h, conditions.ic['h']))
        
        ep_dot = self.strain(grad(uh))
        zeta = self.zeta(h, a, self.delta(uh))
        eta = zeta * params.e ** (-2)
        rheology = 2 * eta * ep_dot + (zeta - eta) * tr(ep_dot) * Identity(2) - 0.5 * self.Ice_Strength(h, a) * Identity(2)

        self.initial_condition((self.sigma0, rheology),(self.sigma1, self.sigma0))

        def sigma_next(timestep, zeta, ep_dot, sigma, P):
            A = 1 + 0.25 * (timestep * params.e ** 2) / params.T
            B = timestep * 0.125 * (1 - params.e ** 2) / params.T
            rhs = (1 - (timestep * params.e ** 2) / (4 * params.T)) * sigma - timestep / params.T * (
                    0.125 * (1 - params.e ** 2) * tr(sigma) * Identity(2) - 0.25 * P * Identity(2) + zeta * ep_dot)
            C = (rhs[0, 0] - rhs[1, 1]) / A
            D = (rhs[0, 0] + rhs[1, 1]) / (A + 2 * B)
            sigma00 = 0.5 * (C + D)
            sigma11 = 0.5 * (D - C)
            sigma01 = rhs[0, 1]
            sigma = as_matrix([[sigma00, sigma01], [sigma01, sigma11]])

            return sigma

        s = sigma_next(self.timestep, zeta, ep_dot, self.sigma0, self.Ice_Strength(h, a))

        sh = (1-theta) * s + theta * self.sigma0

        eqn = self.momentum_equation(h, self.u1, self.u0, p, sh, params.rho, uh, conditions.ocean_curr,
                                params.rho_a, params.C_a, params.rho_w, params.C_w, conditions.geo_wind, params.cor, self.timestep, ind=self.ind)

        tensor_eqn = inner(self.sigma1-s, q) * dx

        if conditions.stabilised['state']:
            alpha = conditions.stabilised['alpha']
            eqn += stabilisation_term(alpha=alpha, zeta=avg(zeta), mesh=mesh, v=uh, test=p)

        bcs = DirichletBC(self.V, conditions.bc['u'], "on_boundary")

        uprob = NonlinearVariationalProblem(eqn, self.u1, bcs)
        self.usolver = NonlinearVariationalSolver(uprob, solver_parameters=solver_params.bt_params)
        sprob = NonlinearVariationalProblem(tensor_eqn, self.sigma1)
        self.ssolver = NonlinearVariationalSolver(sprob, solver_parameters=solver_params.bt_params)
コード例 #2
0
ファイル: solving_utils.py プロジェクト: tlroy/firedrake
    def split(self, fields):
        from ufl import as_vector, replace
        from firedrake import NonlinearVariationalProblem as NLVP, FunctionSpace
        splits = self._splits.get(tuple(fields))
        if splits is not None:
            return splits

        splits = []
        problem = self._problem
        splitter = ExtractSubBlock()
        for field in fields:
            try:
                if len(field) > 1:
                    raise NotImplementedError("Can't split into subblock")
            except TypeError:
                # Just a single field, we can handle that
                pass
            F = splitter.split(problem.F, argument_indices=(field, ))
            J = splitter.split(problem.J, argument_indices=(field, field))
            us = problem.u.split()
            subu = us[field]
            vec = []
            for i, u in enumerate(us):
                for idx in numpy.ndindex(u.ufl_shape):
                    vec.append(u[idx])
            u = as_vector(vec)
            F = replace(F, {problem.u: u})
            J = replace(J, {problem.u: u})
            if problem.Jp is not None:
                Jp = splitter.split(problem.Jp,
                                    argument_indices=(field, field))
                Jp = replace(Jp, {problem.u: u})
            else:
                Jp = None
            bcs = []
            for bc in problem.bcs:
                if bc.function_space().index == field:
                    V = FunctionSpace(subu.ufl_domain(), subu.ufl_element())
                    bcs.append(
                        type(bc)(V,
                                 bc.function_arg,
                                 bc.sub_domain,
                                 method=bc.method))
            new_problem = NLVP(
                F,
                subu,
                bcs=bcs,
                J=J,
                Jp=None,
                form_compiler_parameters=problem.form_compiler_parameters)
            new_problem._constant_jacobian = problem._constant_jacobian
            splits.append(
                type(self)(new_problem,
                           mat_type=self.mat_type,
                           pmat_type=self.pmat_type,
                           appctx=self.appctx))
        return self._splits.setdefault(tuple(fields), splits)
コード例 #3
0
    def __init__(self,
                 F,
                 butcher_tableau,
                 t,
                 dt,
                 u0,
                 bcs=None,
                 solver_parameters=None,
                 update_solver_parameters=None,
                 splitting=AI,
                 nullspace=None,
                 appctx=None):
        self.u0 = u0
        self.t = t
        self.dt = dt
        self.num_fields = len(u0.function_space())
        self.num_stages = len(butcher_tableau.b)
        self.butcher_tableau = butcher_tableau

        Fbig, update_stuff, UU, bigBCs, gblah, nsp = getFormStage(
            F, butcher_tableau, u0, t, dt, bcs, splitting=splitting)

        self.UU = UU
        self.bigBCs = bigBCs
        self.bcdat = gblah
        self.update_stuff = update_stuff

        self.prob = NonlinearVariationalProblem(Fbig, UU, bigBCs)

        appctx_irksome = {
            "F": F,
            "butcher_tableau": butcher_tableau,
            "t": t,
            "dt": dt,
            "u0": u0,
            "bcs": bcs,
            "nullspace": nullspace
        }
        if appctx is None:
            appctx = appctx_irksome
        else:
            appctx = {**appctx, **appctx_irksome}

        self.solver = NonlinearVariationalSolver(
            self.prob,
            appctx=appctx,
            nullspace=nsp,
            solver_parameters=solver_parameters)

        unew, Fupdate, update_bcs, update_bcs_gblah = self.update_stuff
        self.update_problem = NonlinearVariationalProblem(
            Fupdate, unew, update_bcs)

        self.update_solver = NonlinearVariationalSolver(
            self.update_problem, solver_parameters=update_solver_parameters)

        self._update = self._update_general
コード例 #4
0
ファイル: solving_utils.py プロジェクト: kalogirou/firedrake
    def split(self, fields):
        from ufl import as_vector, replace
        from firedrake import NonlinearVariationalProblem as NLVP, FunctionSpace
        splits = self._splits.get(tuple(fields))
        if splits is not None:
            return splits

        splits = []
        problem = self._problem
        splitter = ExtractSubBlock()
        for field in fields:
            try:
                if len(field) > 1:
                    raise NotImplementedError("Can't split into subblock")
            except TypeError:
                # Just a single field, we can handle that
                pass
            F = splitter.split(problem.F, argument_indices=(field, ))
            J = splitter.split(problem.J, argument_indices=(field, field))
            us = problem.u.split()
            subu = us[field]
            vec = []
            for i, u in enumerate(us):
                for idx in numpy.ndindex(u.ufl_shape):
                    vec.append(u[idx])
            u = as_vector(vec)
            F = replace(F, {problem.u: u})
            J = replace(J, {problem.u: u})
            if problem.Jp is not None:
                Jp = splitter.split(problem.Jp, argument_indices=(field, field))
                Jp = replace(Jp, {problem.u: u})
            else:
                Jp = None
            bcs = []
            for bc in problem.bcs:
                if bc.function_space().index == field:
                    V = FunctionSpace(subu.ufl_domain(), subu.ufl_element())
                    bcs.append(type(bc)(V,
                                        bc.function_arg,
                                        bc.sub_domain,
                                        method=bc.method))
            new_problem = NLVP(F, subu, bcs=bcs, J=J, Jp=None,
                               form_compiler_parameters=problem.form_compiler_parameters)
            new_problem._constant_jacobian = problem._constant_jacobian
            splits.append(type(self)(new_problem, mat_type=self.mat_type, pmat_type=self.pmat_type,
                                     appctx=self.appctx))
        return self._splits.setdefault(tuple(fields), splits)
コード例 #5
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    def setup_solver(self, up_init=None):
        """ Setup the solvers
        """
        self.up0 = Function(self.W)
        if up_init is not None:
            chk_in = checkpointing.HDF5File(up_init, file_mode='r')
            chk_in.read(self.up0, "/up")
            chk_in.close()
        self.u0, self.p0 = split(self.up0)

        self.up = Function(self.W)
        if up_init is not None:
            chk_in = checkpointing.HDF5File(up_init, file_mode='r')
            chk_in.read(self.up, "/up")
            chk_in.close()
        self.u1, self.p1 = split(self.up)

        self.up.sub(0).rename("velocity")
        self.up.sub(1).rename("pressure")

        v, q = TestFunctions(self.W)

        h = CellVolume(self.mesh)
        u_norm = sqrt(dot(self.u0, self.u0))

        if self.has_nullspace:
            nullspace = MixedVectorSpaceBasis(
                self.W,
                [self.W.sub(0), VectorSpaceBasis(constant=True)])
        else:
            nullspace = None

        tau = ((2.0 / self.dt)**2 + (2.0 * u_norm / h)**2 +
               (4.0 * self.nu / h**2)**2)**(-0.5)

        # temporal discretization
        F = (1.0 / self.dt) * inner(self.u1 - self.u0, v) * dx

        # weak form
        F += (+inner(dot(self.u0, nabla_grad(self.u1)), v) * dx +
              self.nu * inner(grad(self.u1), grad(v)) * dx -
              (1.0 / self.rho) * self.p1 * div(v) * dx +
              div(self.u1) * q * dx - inner(self.forcing, v) * dx)

        # residual form
        R = (+(1.0 / self.dt) * (self.u1 - self.u0) +
             dot(self.u0, nabla_grad(self.u1)) - self.nu * div(grad(self.u1)) +
             (1.0 / self.rho) * grad(self.p1) - self.forcing)

        # GLS
        F += tau * inner(
            +dot(self.u0, nabla_grad(v)) - self.nu * div(grad(v)) +
            (1.0 / self.rho) * grad(q), R) * dx

        self.problem = NonlinearVariationalProblem(F, self.up, self.bcs)
        self.solver = NonlinearVariationalSolver(
            self.problem,
            nullspace=nullspace,
            solver_parameters=self.solver_parameters)
コード例 #6
0
ファイル: solver.py プロジェクト: AndrewLister-STFC/TTiP
    def solve(self, file_path='ttip_result/solution.pvd'):
        """
        Setup and solve the nonlinear problem.
        Save value to file given.
        Any additional keyword arguments are passed to the iteration method.

        Args:
            file_path (string, optional):
                The path to save the pvd file to.
                vtk files will be generated in the same directory as the pvd.
                It is recommended that this is a separate drectory per run.
                Defaults to 'TTiP_result/solution.pvd'.
        """
        F = self.problem.a - self.problem.L
        steady_state = self.is_steady_state()

        if isinstance(self.problem, BoundaryMixin):
            var_prob = NonlinearVariationalProblem(F,
                                                   self.u,
                                                   bcs=self.problem.bcs)
        else:
            var_prob = NonlinearVariationalProblem(F, self.u)
        solver = NonlinearVariationalSolver(problem=var_prob,
                                            solver_parameters=self.params)

        outfile = File(file_path)
        outfile.write(self.u, target_degree=1, target_continuity=H1)

        if steady_state:
            solver.solve()
            outfile.write(self.u, target_degree=1, target_continuity=H1)
        else:
            self.problem.T_.assign(self.u)
            last_perc = 0
            for i in range(self.problem.steps):
                solver.solve()

                perc = int(100 * (i + 1) / self.problem.steps)
                if perc > last_perc:
                    print(f'{perc}%')
                    last_perc = perc

                self.problem.T_.assign(self.u)
                outfile.write(self.u, target_degree=1, target_continuity=H1)
コード例 #7
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    def _ad_problem_clone(self, problem, dependencies):
        """Replaces every coefficient in the residual and jacobian with a deepcopy to return
        a clone of the original NonlinearVariationalProblem instance. We'll be modifying the
        numerical values of the coefficients in the residual and jacobian, so in order not to
        affect the user-defined self._ad_problem.F, self._ad_problem.J and self._ad_problem.u
        expressions, we'll instead create clones of them.
        """
        from firedrake import NonlinearVariationalProblem
        F_replace_map = {}
        J_replace_map = {}

        F_coefficients = problem.F.coefficients()
        J_coefficients = problem.J.coefficients()

        _ad_count_map = {}
        for block_variable in dependencies:
            coeff = block_variable.output
            if coeff in F_coefficients and coeff not in F_replace_map:
                if isinstance(coeff, Constant):
                    F_replace_map[coeff] = copy.deepcopy(coeff)
                else:
                    F_replace_map[coeff] = coeff.copy(deepcopy=True)
                _ad_count_map[F_replace_map[coeff]] = coeff.count()

            if coeff in J_coefficients and coeff not in J_replace_map:
                if coeff in F_replace_map:
                    J_replace_map[coeff] = F_replace_map[coeff]
                elif isinstance(coeff, Constant):
                    J_replace_map[coeff] = copy.deepcopy(coeff)
                else:
                    J_replace_map[coeff] = coeff.copy()
                _ad_count_map[J_replace_map[coeff]] = coeff.count()

        nlvp = NonlinearVariationalProblem(replace(problem.F, F_replace_map),
                                           F_replace_map[problem.u],
                                           bcs=problem.bcs,
                                           J=replace(problem.J, J_replace_map))
        nlvp._ad_count_map_update(_ad_count_map)
        return nlvp
コード例 #8
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ファイル: models.py プロジェクト: elma16/SeaIceSim
    def __init__(self, mesh, conditions, timestepping, params, output, solver_params):
        super().__init__(mesh, conditions, timestepping, params, output, solver_params)

        self.w0 = Function(self.W3)
        self.w1 = Function(self.W3)

        u0, s0, h0, a0 = self.w0.split()

        p, q, r, m = TestFunctions(self.W3)

        self.initial_condition((u0, conditions.ic['u']), (s0, conditions.ic['s']),
                               (a0, conditions.ic['a']), (h0, conditions.ic['h']))

        self.w1.assign(self.w0)

        u1, s1, h1, a1 = split(self.w1)
        u0, s0, h0, a0 = split(self.w0)

        theta = conditions.theta
        uh = (1-theta) * u0 + theta * u1
        sh = (1-theta) * s0 + theta * s1
        hh = (1-theta) * h0 + theta * h1
        ah = (1-theta) * a0 + theta * a1

        ep_dot = self.strain(grad(uh))
        zeta = self.zeta(hh, ah, self.delta(uh))

        rheology = params.e ** 2 * sh + Identity(2) * 0.5 * ((1 - params.e ** 2) * tr(sh) + self.Ice_Strength(hh, ah))
        
        eqn = self.momentum_equation(hh, u1, u0, p, sh, params.rho, uh, conditions.ocean_curr, params.rho_a,
                                params.C_a, params.rho_w, params.C_w, conditions.geo_wind, params.cor, self.timestep, ind=self.ind)
        eqn += self.transport_equation(uh, hh, ah, h1, h0, a1, a0, r, m, self.n, self.timestep)
        eqn += inner(self.ind * (s1 - s0) + 0.5 * self.timestep * rheology / params.T, q) * dx
        eqn -= inner(q * zeta * self.timestep / params.T, ep_dot) * dx

        if conditions.stabilised['state']:
            alpha = conditions.stabilised['alpha']
            eqn += self.stabilisation_term(alpha=alpha, zeta=avg(zeta), mesh=mesh, v=uh, test=p)

        bcs = DirichletBC(self.W3.sub(0), conditions.bc['u'], "on_boundary")

        uprob = NonlinearVariationalProblem(eqn, self.w1, bcs)
        self.usolver = NonlinearVariationalSolver(uprob, solver_parameters=solver_params.bt_params)

        self.u1, self.s0, self.h1, self.a1 = self.w1.split()
コード例 #9
0
ファイル: models.py プロジェクト: elma16/SeaIceSim
    def __init__(self, mesh, conditions, timestepping, params, output, solver_params):
        super().__init__(mesh, conditions, timestepping, params, output, solver_params)

        self.w0 = Function(self.W2)
        self.w1 = Function(self.W2)

        u0, h0, a0 = self.w0.split()

        p, q, r = TestFunctions(self.W2)

        self.initial_condition((u0, conditions.ic['u']), (h0, conditions.ic['h']),
                               (a0, conditions.ic['a']))

        self.w1.assign(self.w0)
        u1, h1, a1 = split(self.w1)
        u0, h0, a0 = split(self.w0)

        theta = conditions.theta
        uh = (1-theta) * u0 + theta * u1
        ah = (1-theta) * a0 + theta * a1
        hh = (1-theta) * h0 + theta * h1

        ep_dot = self.strain(grad(uh))
        zeta = self.zeta(hh, ah, self.delta(uh))
        eta = zeta * params.e ** (-2)
        sigma = 2 * eta * ep_dot + (zeta - eta) * tr(ep_dot) * Identity(2) - self.Ice_Strength(hh, ah) * 0.5 * Identity(
            2)

        eqn = self.momentum_equation(hh, u1, u0, p, sigma, params.rho, uh, conditions.ocean_curr, params.rho_a,
                                params.C_a, params.rho_w, params.C_w, conditions.geo_wind, params.cor, self.timestep)
        eqn += self.transport_equation(uh, hh, ah, h1, h0, a1, a0, q, r, self.n, self.timestep)

        if conditions.stabilised['state']:
            alpha = conditions.stabilised['alpha']
            eqn += self.stabilisation_term(alpha=alpha, zeta=avg(zeta), mesh=mesh, v=uh, test=p)

        bcs = DirichletBC(self.W2.sub(0), conditions.bc['u'], "on_boundary")

        uprob = NonlinearVariationalProblem(eqn, self.w1, bcs)
        self.usolver = NonlinearVariationalSolver(uprob, solver_parameters=solver_params.bt_params)

        self.u1, self.h1, self.a1 = self.w1.split()
コード例 #10
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def run(steady=False):
    """
    solve CdT/dt = S + div(k*grad(T))
    => C*v*(dT/dt)/k*dx - S*v/k*dx + grad(v)*grad(T)*dx = v*dot(grad(T), n)*ds
    """
    steps = 250
    dt = 1e-10
    timescale = (0, steps * dt)
    if steady:
        print('Running steady state.')
    else:
        print(f'Running with time step {dt:.2g}s on time interval: '
              f'{timescale[0]:.2g}s - {timescale[1]:.2g}s')
    dt_invc = Constant(1 / dt)
    extent = [40e-6, 40e-6, 40e-6]
    mesh = BoxMesh(20, 20, 20, *extent)

    V = FunctionSpace(mesh, 'CG', 1)
    print(V.dim())

    T = Function(V)  # temperature at time i+1 (electron for now)
    T_ = Function(V)  # temperature at time i
    v = TestFunction(V)  # test function

    S = create_S(mesh, V, extent)
    C = create_heat_capacity(mesh, V, extent)
    k = create_conductivity(mesh, V, T)

    set_initial_value(mesh, T_, extent)

    # Mass matrix section
    M = C * T * dt_invc * v * dx
    M_ = C * T_ * dt_invc * v * dx
    # Stiffness matrix section
    A = k * dot(grad(T), grad(v)) * dx
    # function section
    f = S * v * dx
    # boundaries
    bcs, R, b = create_dirichlet_bounds(mesh,
                                        V,
                                        T,
                                        v,
                                        k,
                                        g=100,
                                        boundary=[1, 2, 3, 4, 5, 6])
    # bcs += create_dirichlet_bounds(mesh, V, T, v, k, 500, [6])[0]
    # bcs, R, b = create_robin_bounds(mesh, T, v, k, 1e8/(100), 1e8)

    if steady:
        steps = 1
        a = A + R
        L = f + b
    else:
        a = M + A + R
        L = M_ + f + b

    prob = NonlinearVariationalProblem(a - L, T, bcs=bcs)
    solver = NonlinearVariationalSolver(prob, solver_parameters=SOLVE_PARAMS)

    T.assign(T_)

    timestamp = datetime.now().strftime("%d-%b-%Y-%H-%M-%S")
    outfile = File(f'{timestamp}/first_output.pvd')
    outfile.write(T_, target_degree=1, target_continuity=H1)
    last_perc = 0
    for i in range(steps):
        solver.solve()

        perc = int(100 * (i + 1) / steps)
        if perc > last_perc:
            print(f'{perc}%')
            last_perc = perc

        T_.assign(T)
        outfile.write(T_, target_degree=1, target_continuity=H1)
コード例 #11
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    def split(self, fields):
        from firedrake import replace, as_vector, split
        from firedrake import NonlinearVariationalProblem as NLVP
        fields = tuple(tuple(f) for f in fields)
        splits = self._splits.get(tuple(fields))
        if splits is not None:
            return splits

        splits = []
        problem = self._problem
        splitter = ExtractSubBlock()
        for field in fields:
            F = splitter.split(problem.F, argument_indices=(field, ))
            J = splitter.split(problem.J, argument_indices=(field, field))
            us = problem.u.split()
            V = F.arguments()[0].function_space()
            # Exposition:
            # We are going to make a new solution Function on the sub
            # mixed space defined by the relevant fields.
            # But the form may refer to the rest of the solution
            # anyway.
            # So we pull it apart and will make a new function on the
            # subspace that shares data.
            pieces = [us[i].dat for i in field]
            if len(pieces) == 1:
                val, = pieces
                subu = function.Function(V, val=val)
                subsplit = (subu, )
            else:
                val = op2.MixedDat(pieces)
                subu = function.Function(V, val=val)
                # Split it apart to shove in the form.
                subsplit = split(subu)
            # Permutation from field indexing to indexing of pieces
            field_renumbering = dict([f, i] for i, f in enumerate(field))
            vec = []
            for i, u in enumerate(us):
                if i in field:
                    # If this is a field we're keeping, get it from
                    # the new function. Otherwise just point to the
                    # old data.
                    u = subsplit[field_renumbering[i]]
                if u.ufl_shape == ():
                    vec.append(u)
                else:
                    for idx in numpy.ndindex(u.ufl_shape):
                        vec.append(u[idx])

            # So now we have a new representation for the solution
            # vector in the old problem. For the fields we're going
            # to solve for, it points to a new Function (which wraps
            # the original pieces). For the rest, it points to the
            # pieces from the original Function.
            # IOW, we've reinterpreted our original mixed solution
            # function as being made up of some spaces we're still
            # solving for, and some spaces that have just become
            # coefficients in the new form.
            u = as_vector(vec)
            F = replace(F, {problem.u: u})
            J = replace(J, {problem.u: u})
            if problem.Jp is not None:
                Jp = splitter.split(problem.Jp, argument_indices=(field, field))
                Jp = replace(Jp, {problem.u: u})
            else:
                Jp = None
            bcs = []
            for bc in problem.bcs:
                Vbc = bc.function_space()
                if Vbc.parent is not None and isinstance(Vbc.parent.ufl_element(), VectorElement):
                    index = Vbc.parent.index
                else:
                    index = Vbc.index
                cmpt = Vbc.component
                # TODO: need to test this logic
                if index in field:
                    if len(field) == 1:
                        W = V
                    else:
                        W = V.sub(field_renumbering[index])
                    if cmpt is not None:
                        W = W.sub(cmpt)
                    bcs.append(type(bc)(W,
                                        bc.function_arg,
                                        bc.sub_domain,
                                        method=bc.method))
            new_problem = NLVP(F, subu, bcs=bcs, J=J, Jp=Jp,
                               form_compiler_parameters=problem.form_compiler_parameters)
            new_problem._constant_jacobian = problem._constant_jacobian
            splits.append(type(self)(new_problem, mat_type=self.mat_type, pmat_type=self.pmat_type,
                                     appctx=self.appctx))
        return self._splits.setdefault(tuple(fields), splits)
コード例 #12
0
def build_initial_conditions(prognostic_variables, simulation_parameters):
    """
    Initialises the prognostic variables based on the
    initial condition string.

    :arg prognostic_variables: a PrognosticVariables object.
    :arg simulation_parameters: a dictionary containing the simulation parameters.
    """

    mesh = simulation_parameters['mesh'][-1]
    ic = simulation_parameters['ic'][-1]
    alphasq = simulation_parameters['alphasq'][-1]
    c0 = simulation_parameters['c0'][-1]
    gamma = simulation_parameters['gamma'][-1]
    x, = SpatialCoordinate(mesh)
    Ld = simulation_parameters['Ld'][-1]
    deltax = Ld / simulation_parameters['resolution'][-1]
    w = simulation_parameters['peak_width'][-1]
    epsilon = 1

    ic_dict = {
        'two_peaks':
        (0.2 * 2 /
         (exp(x - 403. / 15. * 40. / Ld) + exp(-x + 403. / 15. * 40. / Ld)) +
         0.5 * 2 /
         (exp(x - 203. / 15. * 40. / Ld) + exp(-x + 203. / 15. * 40. / Ld))),
        'gaussian':
        0.5 * exp(-((x - 10.) / 2.)**2),
        'gaussian_narrow':
        0.5 * exp(-((x - 10.) / 1.)**2),
        'gaussian_wide':
        0.5 * exp(-((x - 10.) / 3.)**2),
        'peakon':
        conditional(x < Ld / 2., exp((x - Ld / 2) / sqrt(alphasq)),
                    exp(-(x - Ld / 2) / sqrt(alphasq))),
        'one_peak':
        0.5 * 2 /
        (exp(x - 203. / 15. * 40. / Ld) + exp(-x + 203. / 15. * 40. / Ld)),
        'proper_peak':
        0.5 * 2 / (exp(x - Ld / 4) + exp(-x + Ld / 4)),
        'new_peak':
        0.5 * 2 / (exp((x - Ld / 4) / w) + exp((-x + Ld / 4) / w)),
        'flat':
        Constant(2 * pi**2 / (9 * 40**2)),
        'fast_flat':
        Constant(0.1),
        'coshes':
        Constant(2000) * cosh((2000**0.5 / 2) * (x - 0.75))**(-2) +
        Constant(1000) * cosh(1000**0.5 / 2 * (x - 0.25))**(-2),
        'd_peakon':
        exp(-sqrt((x - Ld / 2)**2 + epsilon * deltax**2) / sqrt(alphasq)),
        'zero':
        Constant(0.0),
        'two_peakons':
        conditional(
            x < Ld / 4,
            exp((x - Ld / 4) / sqrt(alphasq)) -
            exp(-(x + Ld / 4) / sqrt(alphasq)),
            conditional(
                x < 3 * Ld / 4,
                exp(-(x - Ld / 4) / sqrt(alphasq)) - exp(
                    (x - 3 * Ld / 4) / sqrt(alphasq)),
                exp((x - 5 * Ld / 4) / sqrt(alphasq)) -
                exp(-(x - 3 * Ld / 4) / sqrt(alphasq)))),
        'twin_peakons':
        conditional(
            x < Ld / 4,
            exp((x - Ld / 4) / sqrt(alphasq)) + 0.5 * exp(
                (x - Ld / 2) / sqrt(alphasq)),
            conditional(
                x < Ld / 2,
                exp(-(x - Ld / 4) / sqrt(alphasq)) + 0.5 * exp(
                    (x - Ld / 2) / sqrt(alphasq)),
                conditional(
                    x < 3 * Ld / 4,
                    exp(-(x - Ld / 4) / sqrt(alphasq)) +
                    0.5 * exp(-(x - Ld / 2) / sqrt(alphasq)),
                    exp((x - 5 * Ld / 4) / sqrt(alphasq)) +
                    0.5 * exp(-(x - Ld / 2) / sqrt(alphasq))))),
        'periodic_peakon': (conditional(
            x < Ld / 2, 0.5 / (1 - exp(-Ld / sqrt(alphasq))) *
            (exp((x - Ld / 2) / sqrt(alphasq)) +
             exp(-Ld / sqrt(alphasq)) * exp(-(x - Ld / 2) / sqrt(alphasq))),
            0.5 / (1 - exp(-Ld / sqrt(alphasq))) *
            (exp(-(x - Ld / 2) / sqrt(alphasq)) +
             exp(-Ld / sqrt(alphasq)) * exp((x - Ld / 2) / sqrt(alphasq))))),
        'cos_bell':
        conditional(x < Ld / 4, (cos(pi * (x - Ld / 8) / (2 * Ld / 8)))**2,
                    0.0),
        'antisymmetric':
        1 / (exp((x - Ld / 4) / Ld) + exp((-x + Ld / 4) / Ld)) - 1 / (exp(
            (Ld - x - Ld / 4) / Ld) + exp((Ld + x + Ld / 4) / Ld))
    }

    ic_expr = ic_dict[ic]

    if prognostic_variables.scheme in ['upwind', 'LASCH']:

        VCG5 = FunctionSpace(mesh, "CG", 5)
        smooth_condition = Function(VCG5).interpolate(ic_expr)
        prognostic_variables.u.project(as_vector([smooth_condition]))

        # need to find initial m by solving helmholtz problem
        CG1 = FunctionSpace(mesh, "CG", 1)
        u0 = prognostic_variables.u
        p = TestFunction(CG1)
        m_CG = Function(CG1)
        ones = Function(prognostic_variables.Vu).project(
            as_vector([Constant(1.)]))

        Lm = (p * m_CG - p * dot(ones, u0) -
              alphasq * p.dx(0) * dot(ones, u0.dx(0))) * dx
        mprob0 = NonlinearVariationalProblem(Lm, m_CG)
        msolver0 = NonlinearVariationalSolver(mprob0,
                                              solver_parameters={
                                                  'ksp_type': 'preonly',
                                                  'pc_type': 'lu'
                                              })
        msolver0.solve()
        prognostic_variables.m.interpolate(m_CG)

        if prognostic_variables.scheme == 'LASCH':
            prognostic_variables.Eu.assign(prognostic_variables.u)
            prognostic_variables.Em.assign(prognostic_variables.m)

    elif prognostic_variables.scheme in ('conforming', 'hydrodynamic', 'test',
                                         'LASCH_hydrodynamic',
                                         'LASCH_hydrodynamic_m',
                                         'no_gradient'):
        if ic == 'peakon':
            Vu = prognostic_variables.Vu
            # delta = Function(Vu)
            # middle_index = int(len(delta.dat.data[:]) / 2)
            # delta.dat.data[middle_index] = 1
            # u0 = prognostic_variables.u
            # phi = TestFunction(Vu)
            #
            # eqn = phi * u0 * dx + alphasq * phi.dx(0) * u0.dx(0) * dx - phi * delta * dx
            # prob = NonlinearVariationalProblem(eqn, u0)
            # solver = NonlinearVariationalSolver(prob)
            # solver.solve()
            # W = MixedFunctionSpace((Vu, Vu))
            # psi, phi = TestFunctions(W)
            # w = Function(W)
            # u, F = w.split()
            # u.interpolate(ic_expr)
            # u, F = split(w)
            #
            # eqn = (psi * u * dx - psi * (0.5 * u * u + F) * dx
            #        + phi * F * dx + alphasq * phi.dx(0) * F.dx(0) * dx
            #        - phi * u * u * dx - 0.5 * alphasq * phi * u.dx(0) * u.dx(0) * dx)
            #
            # u, F = w.split()
            #
            # prob = NonlinearVariationalProblem(eqn, w)
            # solver = NonlinearVariationalSolver(prob)
            # solver.solve()
            # prognostic_variables.u.assign(u)
            prognostic_variables.u.project(ic_expr)
            # prognostic_variables.u.interpolate(ic_expr)
        else:
            VCG5 = FunctionSpace(mesh, "CG", 5)
            smooth_condition = Function(VCG5).interpolate(ic_expr)
            prognostic_variables.u.project(smooth_condition)

        if prognostic_variables.scheme in [
                'LASCH_hydrodynamic', 'LASCH_hydrodynamic_m'
        ]:
            prognostic_variables.Eu.assign(prognostic_variables.u)

    else:
        raise NotImplementedError('Other schemes not yet implemented.')
コード例 #13
0
ファイル: equations.py プロジェクト: tommbendall/peakondrake
    def __init__(self, prognostic_variables, simulation_parameters):

        mesh = simulation_parameters['mesh'][-1]
        self.scheme = simulation_parameters['scheme'][-1]
        self.timestepping = simulation_parameters['timestepping'][-1]
        alphasq = simulation_parameters['alphasq'][-1]
        c0 = simulation_parameters['c0'][-1]
        gamma = simulation_parameters['gamma'][-1]
        Dt = Constant(simulation_parameters['dt'][-1])
        self.solvers = []

        if alphasq.values()[0] > 0.0 and gamma.values()[0] == 0.0:
            self.setup = 'ch'
            if self.scheme == 'upwind' and self.timestepping == 'ssprk3':

                Vm = prognostic_variables.Vm
                Vu = prognostic_variables.Vu
                self.m = prognostic_variables.m
                self.u = prognostic_variables.u
                self.Xi = prognostic_variables.dXi
                self.m0 = Function(Vm).assign(self.m)

                # now make problem for the actual problem
                psi = TestFunction(Vm)
                self.m_trial = Function(Vm)
                self.dm = Function(
                    Vm
                )  # introduce this as the advection operator for a single step

                us = Dt * self.u + self.Xi

                nhat = FacetNormal(mesh)
                un = 0.5 * (dot(us, nhat) + abs(dot(us, nhat)))
                ones = Function(Vu).project(as_vector([Constant(1.)]))

                Lm = (psi * self.dm * dx -
                      psi.dx(0) * self.m_trial * dot(ones, us) * dx +
                      psi * self.m_trial * dot(ones, us.dx(0)) * dx +
                      jump(psi) * (un('+') * self.m_trial('+') -
                                   un('-') * self.m_trial('-')) * dS)
                mprob = NonlinearVariationalProblem(Lm, self.dm)
                self.msolver = NonlinearVariationalSolver(mprob,
                                                          solver_parameters={
                                                              'ksp_type':
                                                              'preonly',
                                                              'pc_type':
                                                              'bjacobi',
                                                              'sub_pc_type':
                                                              'ilu'
                                                          })

                phi = TestFunction(Vu)
                Lu = (dot(phi, ones) * self.m * dx - dot(phi, self.u) * dx -
                      alphasq * dot(self.u.dx(0), phi.dx(0)) * dx)
                uprob = NonlinearVariationalProblem(Lu, self.u)
                self.usolver = NonlinearVariationalSolver(uprob,
                                                          solver_parameters={
                                                              'ksp_type':
                                                              'preonly',
                                                              'pc_type': 'lu'
                                                          })

            elif self.scheme == 'hydrodynamic' and self.timestepping == 'midpoint':
                Vu = prognostic_variables.Vu

                self.u = prognostic_variables.u

                W = MixedFunctionSpace((Vu, ) * 3)
                psi, phi, zeta = TestFunctions(W)

                w1 = Function(W)
                self.u1, dFh, dGh = split(w1)

                uh = (self.u1 + self.u) / 2
                dXi = prognostic_variables.dXi
                dXi_x = prognostic_variables.dXi_x
                dXi_xx = prognostic_variables.dXi_xx
                dvh = Dt * uh + dXi

                Lu = (psi * (self.u1 - self.u) * dx +
                      psi * uh.dx(0) * dvh * dx - psi.dx(0) * dFh * dx +
                      psi * dGh * dx + phi * dFh * dx +
                      alphasq * phi.dx(0) * dFh.dx(0) * dx -
                      phi * uh * uh * Dt * dx -
                      0.5 * alphasq * phi * uh.dx(0) * uh.dx(0) * Dt * dx +
                      zeta * dGh * dx + alphasq * zeta.dx(0) * dGh.dx(0) * dx -
                      2 * zeta * uh * dXi_x * dx -
                      alphasq * zeta * uh.dx(0) * dXi_xx * dx)

                self.u1, dFh, dGh = w1.split()

                uprob = NonlinearVariationalProblem(Lu, w1)
                self.usolver = NonlinearVariationalSolver(uprob,
                                                          solver_parameters={
                                                              'mat_type':
                                                              'aij',
                                                              'ksp_type':
                                                              'preonly',
                                                              'pc_type': 'lu'
                                                          })

            elif self.scheme == 'no_gradient' and self.timestepping == 'midpoint':
                # a version of the hydrodynamic form but without exploiting the gradient
                Vu = prognostic_variables.Vu

                self.u = prognostic_variables.u

                W = MixedFunctionSpace((Vu, ) * 3)
                psi, phi, zeta = TestFunctions(W)

                w1 = Function(W)
                self.u1, dFh, dGh = split(w1)

                uh = (self.u1 + self.u) / 2
                dXi = prognostic_variables.dXi
                dXi_x = prognostic_variables.dXi_x
                dXi_xx = prognostic_variables.dXi_xx
                dvh = Dt * uh + dXi

                Lu = (psi * (self.u1 - self.u) * dx +
                      psi * uh.dx(0) * dvh * dx + psi * dFh.dx(0) * dx +
                      psi * dGh * dx + phi * dFh * dx +
                      alphasq * phi.dx(0) * dFh.dx(0) * dx -
                      phi * uh * uh * Dt * dx -
                      0.5 * alphasq * phi * uh.dx(0) * uh.dx(0) * Dt * dx +
                      zeta * dGh * dx + alphasq * zeta.dx(0) * dGh.dx(0) * dx -
                      2 * zeta * uh * dXi_x * dx -
                      alphasq * zeta * uh.dx(0) * dXi_xx * dx)

                self.u1, dFh, dGh = w1.split()

                uprob = NonlinearVariationalProblem(Lu, w1)
                self.usolver = NonlinearVariationalSolver(uprob,
                                                          solver_parameters={
                                                              'mat_type':
                                                              'aij',
                                                              'ksp_type':
                                                              'preonly',
                                                              'pc_type': 'lu'
                                                          })

            elif self.scheme == 'test' and self.timestepping == 'midpoint':
                self.u = prognostic_variables.u
                Vu = prognostic_variables.Vu
                psi = TestFunction(Vu)
                self.u1 = Function(Vu)
                uh = (self.u1 + self.u) / 2
                dvh = Dt * uh + prognostic_variables.dXi

                eqn = (psi * (self.u1 - self.u) * dx -
                       psi * uh * dvh.dx(0) * dx)
                prob = NonlinearVariationalProblem(eqn, self.u1)
                self.usolver = NonlinearVariationalSolver(prob,
                                                          solver_parameters={
                                                              'mat_type':
                                                              'aij',
                                                              'ksp_type':
                                                              'preonly',
                                                              'pc_type': 'lu'
                                                          })

            else:
                raise ValueError(
                    'Scheme %s and timestepping %s either not compatible or not recognised.'
                    % (self.scheme, self.timestepping))

        elif alphasq.values()[0] == 0.0 and gamma.values()[0] > 0.0:
            self.setup = 'kdv'
            if self.scheme == 'upwind' and self.timestepping == 'ssprk3':
                raise NotImplementedError(
                    'Scheme %s and timestepping %s not yet implemented.' %
                    (self.scheme, self.timestepping))

            elif self.scheme == 'upwind' and self.timestepping == 'midpoint':
                raise NotImplementedError(
                    'Scheme %s and timestepping %s not yet implemented.' %
                    (self.scheme, self.timestepping))

            elif self.scheme == 'hydrodynamic' and self.timestepping == 'midpoint':
                raise NotImplementedError(
                    'Scheme %s and timestepping %s not yet implemented.' %
                    (self.scheme, self.timestepping))

            else:
                raise ValueError(
                    'Scheme %s and timestepping %s either not compatible or not recognised.'
                    % (self.scheme, self.timestepping))

        else:
            raise NotImplementedError(
                'Schemes for your values of alpha squared %.3f and gamma %.3f are not yet implemented.'
                % (alphasq, gamma))
コード例 #14
0
def compressible_hydrostatic_balance(state,
                                     theta0,
                                     rho0,
                                     exner0=None,
                                     top=False,
                                     exner_boundary=Constant(1.0),
                                     mr_t=None,
                                     solve_for_rho=False,
                                     params=None):
    """
    Compute a hydrostatically balanced density given a potential temperature
    profile. By default, this uses a vertically-oriented hybridization
    procedure for solving the resulting discrete systems.

    :arg state: The :class:`State` object.
    :arg theta0: :class:`.Function`containing the potential temperature.
    :arg rho0: :class:`.Function` to write the initial density into.
    :arg top: If True, set a boundary condition at the top. Otherwise, set
    it at the bottom.
    :arg exner_boundary: a field or expression to use as boundary data for exner
    on the top or bottom as specified.
    :arg mr_t: the initial total water mixing ratio field.
    """

    # Calculate hydrostatic Pi
    VDG = state.spaces("DG")
    Vu = state.spaces("HDiv")
    Vv = FunctionSpace(state.mesh, Vu.ufl_element()._elements[-1])
    W = MixedFunctionSpace((Vv, VDG))
    v, exner = TrialFunctions(W)
    dv, dexner = TestFunctions(W)

    n = FacetNormal(state.mesh)

    cp = state.parameters.cp

    # add effect of density of water upon theta
    theta = theta0

    if mr_t is not None:
        theta = theta0 / (1 + mr_t)

    alhs = ((cp * inner(v, dv) - cp * div(dv * theta) * exner) * dx +
            dexner * div(theta * v) * dx)

    if top:
        bmeasure = ds_t
        bstring = "bottom"
    else:
        bmeasure = ds_b
        bstring = "top"

    arhs = -cp * inner(dv, n) * theta * exner_boundary * bmeasure

    # Possibly make g vary with spatial coordinates?
    g = state.parameters.g

    arhs -= g * inner(dv, state.k) * dx

    bcs = [DirichletBC(W.sub(0), zero(), bstring)]

    w = Function(W)
    exner_problem = LinearVariationalProblem(alhs, arhs, w, bcs=bcs)

    if params is None:
        params = {
            'ksp_type': 'preonly',
            'pc_type': 'python',
            'mat_type': 'matfree',
            'pc_python_type': 'gusto.VerticalHybridizationPC',
            # Vertical trace system is only coupled vertically in columns
            # block ILU is a direct solver!
            'vert_hybridization': {
                'ksp_type': 'preonly',
                'pc_type': 'bjacobi',
                'sub_pc_type': 'ilu'
            }
        }

    exner_solver = LinearVariationalSolver(exner_problem,
                                           solver_parameters=params,
                                           options_prefix="exner_solver")

    exner_solver.solve()
    v, exner = w.split()
    if exner0 is not None:
        exner0.assign(exner)

    if solve_for_rho:
        w1 = Function(W)
        v, rho = w1.split()
        rho.interpolate(thermodynamics.rho(state.parameters, theta0, exner))
        v, rho = split(w1)
        dv, dexner = TestFunctions(W)
        exner = thermodynamics.exner_pressure(state.parameters, rho, theta0)
        F = ((cp * inner(v, dv) - cp * div(dv * theta) * exner) * dx +
             dexner * div(theta0 * v) * dx +
             cp * inner(dv, n) * theta * exner_boundary * bmeasure)
        F += g * inner(dv, state.k) * dx
        rhoproblem = NonlinearVariationalProblem(F, w1, bcs=bcs)
        rhosolver = NonlinearVariationalSolver(rhoproblem,
                                               solver_parameters=params,
                                               options_prefix="rhosolver")
        rhosolver.solve()
        v, rho_ = w1.split()
        rho0.assign(rho_)
    else:
        rho0.interpolate(thermodynamics.rho(state.parameters, theta0, exner))
コード例 #15
0
    def __init__(self, prognostic_variables, simulation_parameters):

        mesh = simulation_parameters['mesh'][-1]
        x, = SpatialCoordinate(mesh)
        Ld = simulation_parameters['Ld'][-1]
        self.scheme = simulation_parameters['scheme'][-1]

        self.dt = simulation_parameters['dt'][-1]
        self.num_Xis = simulation_parameters['num_Xis'][-1]
        self.Xi_family = simulation_parameters['Xi_family'][-1]
        self.dXi = prognostic_variables.dXi
        self.dWs = [Constant(0.0) for dw in range(self.num_Xis)]
        self.dW_nums = prognostic_variables.dW_nums
        self.Xi_functions = []
        self.nXi_updates = simulation_parameters['nXi_updates'][-1]
        self.smooth_t = simulation_parameters['smooth_t'][-1]
        self.fixed_dW = simulation_parameters['fixed_dW'][-1]

        if self.smooth_t is not None and self.nXi_updates > 1:
            raise ValueError('Prescribing forcing and including multiple Xi updates are not compatible.')

        if self.smooth_t is not None or self.fixed_dW is not None:
            print('WARNING: Remember to change sigma to sigma * sqrt(dt) with the prescribed forcing option or the fixed_dW option.')


        seed = simulation_parameters['seed'][-1]
        np.random.seed(seed)

        # make sure sigma is a Constant
        if self.num_Xis != 0:
            if isinstance(simulation_parameters['sigma'][-1], Constant):
                self.sigma = simulation_parameters['sigma'][-1]
            else:
                self.sigma = Constant(simulation_parameters['sigma'][-1])
        else:
            self.sigma = Constant(0.0)

        self.pure_xi_list = prognostic_variables.pure_xi_list
        self.pure_xi_x_list = prognostic_variables.pure_xi_x_list
        self.pure_xi_xx_list = prognostic_variables.pure_xi_xx_list
        self.pure_xi_xxx_list = prognostic_variables.pure_xi_xxx_list
        self.pure_xi_xxxx_list = prognostic_variables.pure_xi_xxxx_list
        for xi in range(self.num_Xis):
            self.pure_xi_list.append(Function(self.dXi.function_space()))
            self.pure_xi_x_list.append(Function(self.dXi.function_space()))
            self.pure_xi_xx_list.append(Function(self.dXi.function_space()))
            self.pure_xi_xxx_list.append(Function(self.dXi.function_space()))
            self.pure_xi_xxxx_list.append(Function(self.dXi.function_space()))


        if self.Xi_family == 'sines':
            for n in range(self.num_Xis):
                if (n+1) % 2 == 1:
                    self.Xi_functions.append(self.sigma * sin(2*(n+1)*pi*x/Ld))
                else:
                    self.Xi_functions.append(self.sigma * cos(2*(n+1)*pi*x/Ld))

        elif self.Xi_family == 'double_sines':
            for n in range(self.num_Xis):
                if (n+1) % 2 == 1:
                    self.Xi_functions.append(self.sigma * sin(4*(n+1)*pi*x/Ld))
                else:
                    self.Xi_functions.append(self.sigma * cos(4*(n+1)*pi*x/Ld))

        elif self.Xi_family == 'high_freq_sines':
            for n in range(self.num_Xis):
                if (n+1) % 2 == 1:
                    self.Xi_functions.append(self.sigma * sin((2*(n+1)+10)*pi*x/Ld))
                else:
                    self.Xi_functions.append(self.sigma * cos((2*(n+1)+10)*pi*x/Ld))

        elif self.Xi_family == 'gaussians':
            for n in range(self.num_Xis):
                self.Xi_functions.append(self.sigma * 0.5*self.num_Xis*exp(-((x-Ld*(n+1)/(self.num_Xis +1.0))/2.)**2))

        elif self.Xi_family == 'quadratic':
            if self.num_Xis > 1:
                raise NotImplementedError('Quadratic Xi not yet implemented for more than one Xi')
            else:
                self.Xi_functions.append(32/(Ld*Ld)*conditional(x > Ld/4,
                                                     conditional(x > 3*Ld/8,
                                                                 conditional(x > 5*Ld/8,
                                                                             conditional(x < 3*Ld/4,
                                                                                         self.sigma * (x - 3*Ld/4)**2,
                                                                                         0.0),
                                                                             (x-Ld/2)**2+Ld**2/32),
                                                                 (x-Ld/4)**2),
                                                     0.0))
        elif self.Xi_family == 'proper_peak':
            if self.num_Xis > 1:
                raise NotImplementedError('Quadratic Xi not yet implemented for more than one Xi')
            else:
                self.Xi_functions.append(self.sigma * 0.5*2/(exp(x-Ld/2)+exp(-x+Ld/2)))

        elif self.Xi_family == 'constant':
            if self.num_Xis > 1:
                raise NotImplementedError('Constant Xi not yet implemented for more than one Xi')
            else:
                self.Xi_functions.append(self.sigma * (sin(0*pi*x/Ld)+1))


        else:
            raise NotImplementedError('Xi_family %s not implemented' % self.Xi_family)

        # make lists of functions for xi_x, xi_xx and xi_xxx
        if self.scheme in ['hydrodynamic', 'LASCH_hydrodynamic']:
            self.dXi_x = prognostic_variables.dXi_x
            self.dXi_xx = prognostic_variables.dXi_xx

            self.Xi_x_functions = []
            self.Xi_xx_functions = []

            for Xi_expr in self.Xi_functions:
                Xi_x_function = Function(self.dXi_x.function_space())
                Xi_xx_function = Function(self.dXi_xx.function_space())

                phi_x = TestFunction(self.dXi_x.function_space())
                phi_xx = TestFunction(self.dXi_xx.function_space())

                Xi_x_eqn = phi_x * Xi_x_function * dx + phi_x.dx(0) * Xi_expr * dx
                Xi_xx_eqn = phi_xx * Xi_xx_function * dx + phi_xx.dx(0) * Xi_x_function * dx

                Xi_x_problem = NonlinearVariationalProblem(Xi_x_eqn, Xi_x_function)
                Xi_xx_problem = NonlinearVariationalProblem(Xi_xx_eqn, Xi_xx_function)

                Xi_x_solver = NonlinearVariationalSolver(Xi_x_problem)
                Xi_xx_solver = NonlinearVariationalSolver(Xi_xx_problem)

                # for some reason these solvers don't work for constant Xi functions
                # so just manually make the derivatives be zero
                if self.Xi_family == 'constant':
                    Xi_x_function.interpolate(0.0*x)
                    Xi_xx_function.interpolate(0.0*x)
                else:
                    Xi_x_solver.solve()
                    Xi_xx_solver.solve()

                self.Xi_x_functions.append(Xi_x_function)
                self.Xi_xx_functions.append(Xi_xx_function)

        # now make a master xi
        Xi_expr = 0.0*x

        for dW, Xi_function, pure_xi, pure_xi_x, pure_xi_xx, pure_xi_xxx, pure_xi_xxxx in zip(self.dWs, self.Xi_functions, self.pure_xi_list, self.pure_xi_x_list, self.pure_xi_xx_list, self.pure_xi_xxx_list, self.pure_xi_xxxx_list):
            Xi_expr += dW * Xi_function
            if self.scheme in ['upwind', 'LASCH']:
                pure_xi.interpolate(as_vector([Xi_function]))
                pure_xi_x.project(as_vector([Xi_function.dx(0)]))

                CG1 = FunctionSpace(mesh, "CG", 1)
                psi =  TestFunction(CG1)
                xixx_scalar = Function(CG1)
                xixx_eqn = psi * xixx_scalar * dx + psi.dx(0) * Xi_function.dx(0) * dx
                prob = NonlinearVariationalProblem(xixx_eqn, xixx_scalar)
                solver = NonlinearVariationalSolver(prob)
                solver.solve()
                pure_xi_xx.interpolate(as_vector([xixx_scalar]))

            else:
                pure_xi.interpolate(Xi_function)

                # I guess we can't take the gradient of constants
                if self.Xi_family != 'constant':
                    pure_xi_x.project(Xi_function.dx(0))
                    pure_xi_xx.project(pure_xi_x.dx(0))
                    pure_xi_xxx.project(pure_xi_xx.dx(0))
                    pure_xi_xxxx.project(pure_xi_xxx.dx(0))

        if self.scheme in ['upwind', 'LASCH']:
            self.dXi_interpolator = Interpolator(as_vector([Xi_expr]), self.dXi)
        else:
            self.dXi_interpolator = Interpolator(Xi_expr, self.dXi)

        if self.scheme in ['hydrodynamic', 'LASCH_hydrodynamic']:

            # initialise blank expressions
            Xi_x_expr = 0.0*x
            Xi_xx_expr = 0.0*x

            # make full expressions by adding all dW * Xi_xs
            for dW, Xi_x_function, Xi_xx_function in zip(self.dWs, self.Xi_x_functions, self.Xi_xx_functions):
                Xi_x_expr += dW * Xi_x_function
                Xi_xx_expr += dW * Xi_xx_function

            self.dXi_x_interpolator = Interpolator(Xi_x_expr, self.dXi_x)
            self.dXi_xx_interpolator = Interpolator(Xi_xx_expr, self.dXi_xx)
コード例 #16
0
def moist_hydrostatic_balance(state, theta_e, water_t, pi_boundary=Constant(1.0)):
    """
    Given a wet equivalent potential temperature, theta_e, and the total moisture
    content, water_t, compute a hydrostatically balance virtual potential temperature,
    dry density and water vapour profile.
    :arg state: The :class:`State` object.
    :arg theta_e: The initial wet equivalent potential temperature profile.
    :arg water_t: The total water pseudo-mixing ratio profile.
    :arg pi_boundary: the value of pi on the lower boundary of the domain.
    """

    theta0 = state.fields('theta')
    rho0 = state.fields('rho')
    water_v0 = state.fields('water_v')

    # Calculate hydrostatic Pi
    Vt = theta0.function_space()
    Vr = rho0.function_space()
    Vv = state.fields('u').function_space()
    n = FacetNormal(state.mesh)
    g = state.parameters.g
    cp = state.parameters.cp
    R_d = state.parameters.R_d
    p_0 = state.parameters.p_0

    VDG = state.spaces("DG")
    if any(deg > 2 for deg in VDG.ufl_element().degree()):
        state.logger.warning("default quadrature degree most likely not sufficient for this degree element")
    quadrature_degree = (5, 5)

    params = {'ksp_type': 'preonly',
              'ksp_monitor_true_residual': True,
              'ksp_converged_reason': True,
              'snes_converged_reason': True,
              'ksp_max_it': 100,
              'mat_type': 'aij',
              'pc_type': 'lu',
              'pc_factor_mat_solver_type': 'mumps'}

    theta0.interpolate(theta_e)
    water_v0.interpolate(water_t)
    Pi = Function(Vr)
    epsilon = 0.9  # relaxation constant

    # set up mixed space
    Z = MixedFunctionSpace((Vt, Vt))
    z = Function(Z)

    gamma, phi = TestFunctions(Z)

    theta_v, w_v = z.split()

    # give first guesses for trial functions
    theta_v.assign(theta0)
    w_v.assign(water_v0)

    theta_v, w_v = split(z)

    # define variables
    T = thermodynamics.T(state.parameters, theta_v, Pi, r_v=w_v)
    p = thermodynamics.p(state.parameters, Pi)
    w_sat = thermodynamics.r_sat(state.parameters, T, p)

    dxp = dx(degree=(quadrature_degree))

    # set up weak form of theta_e and w_sat equations
    F = (-gamma * theta_e * dxp
         + gamma * thermodynamics.theta_e(state.parameters, T, p, w_v, water_t) * dxp
         - phi * w_v * dxp
         + phi * w_sat * dxp)

    problem = NonlinearVariationalProblem(F, z)
    solver = NonlinearVariationalSolver(problem, solver_parameters=params)

    theta_v, w_v = z.split()

    Pi_h = Function(Vr).interpolate((p / p_0) ** (R_d / cp))

    # solve for Pi with theta_v and w_v constant
    # then solve for theta_v and w_v with Pi constant
    for i in range(5):
        compressible_hydrostatic_balance(state, theta0, rho0, pi0=Pi_h, water_t=water_t)
        Pi.assign(Pi * (1 - epsilon) + epsilon * Pi_h)
        solver.solve()
        theta0.assign(theta0 * (1 - epsilon) + epsilon * theta_v)
        water_v0.assign(water_v0 * (1 - epsilon) + epsilon * w_v)

    # now begin on Newton solver, setup up new mixed space
    Z = MixedFunctionSpace((Vt, Vt, Vr, Vv))
    z = Function(Z)

    gamma, phi, psi, w = TestFunctions(Z)

    theta_v, w_v, pi, v = z.split()

    # use previous values as first guesses for newton solver
    theta_v.assign(theta0)
    w_v.assign(water_v0)
    pi.assign(Pi)

    theta_v, w_v, pi, v = split(z)

    # define variables
    T = thermodynamics.T(state.parameters, theta_v, pi, r_v=w_v)
    p = thermodynamics.p(state.parameters, pi)
    w_sat = thermodynamics.r_sat(state.parameters, T, p)

    F = (-gamma * theta_e * dxp
         + gamma * thermodynamics.theta_e(state.parameters, T, p, w_v, water_t) * dxp
         - phi * w_v * dxp
         + phi * w_sat * dxp
         + cp * inner(v, w) * dxp
         - cp * div(w * theta_v / (1.0 + water_t)) * pi * dxp
         + psi * div(theta_v * v / (1.0 + water_t)) * dxp
         + cp * inner(w, n) * pi_boundary * theta_v / (1.0 + water_t) * ds_b
         + g * inner(w, state.k) * dxp)

    bcs = [DirichletBC(Z.sub(3), 0.0, "top")]

    problem = NonlinearVariationalProblem(F, z, bcs=bcs)
    solver = NonlinearVariationalSolver(problem, solver_parameters=params)

    solver.solve()

    theta_v, w_v, pi, v = z.split()

    # assign final values
    theta0.assign(theta_v)
    water_v0.assign(w_v)

    # find rho
    compressible_hydrostatic_balance(state, theta0, rho0, water_t=water_t, solve_for_rho=True)
コード例 #17
0
 def solver(self):
     # setup solver using lhs and rhs defined in derived class
     problem = NonlinearVariationalProblem(self.lhs-self.rhs, self.dq, bcs=self.bcs)
     solver_name = self.field_name+self.__class__.__name__
     return NonlinearVariationalSolver(problem, solver_parameters=self.solver_parameters, options_prefix=solver_name)
コード例 #18
0
ファイル: models.py プロジェクト: elma16/SeaIceSim
 def assemble(self, eqn, func, bcs, params):
     uprob = NonlinearVariationalProblem(eqn, func, bcs)
     self.usolver = NonlinearVariationalSolver(uprob, solver_parameters=params)
コード例 #19
0
def compressible_hydrostatic_balance(state, theta0, rho0, pi0=None,
                                     top=False, pi_boundary=Constant(1.0),
                                     water_t=None,
                                     solve_for_rho=False,
                                     params=None):
    """
    Compute a hydrostatically balanced density given a potential temperature
    profile.

    :arg state: The :class:`State` object.
    :arg theta0: :class:`.Function`containing the potential temperature.
    :arg rho0: :class:`.Function` to write the initial density into.
    :arg top: If True, set a boundary condition at the top. Otherwise, set
    it at the bottom.
    :arg pi_boundary: a field or expression to use as boundary data for pi on
    the top or bottom as specified.
    :arg water_t: the initial total water mixing ratio field.
    """

    # Calculate hydrostatic Pi
    VDG = state.spaces("DG")
    Vv = state.spaces("Vv")
    W = MixedFunctionSpace((Vv, VDG))
    v, pi = TrialFunctions(W)
    dv, dpi = TestFunctions(W)

    n = FacetNormal(state.mesh)

    cp = state.parameters.cp

    # add effect of density of water upon theta
    theta = theta0

    if water_t is not None:
        theta = theta0 / (1 + water_t)

    alhs = (
        (cp*inner(v, dv) - cp*div(dv*theta)*pi)*dx
        + dpi*div(theta*v)*dx
    )

    if top:
        bmeasure = ds_t
        bstring = "bottom"
    else:
        bmeasure = ds_b
        bstring = "top"

    arhs = -cp*inner(dv, n)*theta*pi_boundary*bmeasure
    g = state.parameters.g
    arhs -= g*inner(dv, state.k)*dx

    bcs = [DirichletBC(W.sub(0), 0.0, bstring)]

    w = Function(W)
    PiProblem = LinearVariationalProblem(alhs, arhs, w, bcs=bcs)

    if params is None:
        params = {'pc_type': 'fieldsplit',
                  'pc_fieldsplit_type': 'schur',
                  'ksp_type': 'gmres',
                  'ksp_monitor_true_residual': True,
                  'ksp_max_it': 100,
                  'ksp_gmres_restart': 50,
                  'pc_fieldsplit_schur_fact_type': 'FULL',
                  'pc_fieldsplit_schur_precondition': 'selfp',
                  'fieldsplit_0_ksp_type': 'richardson',
                  'fieldsplit_0_ksp_max_it': 5,
                  'fieldsplit_0_pc_type': 'gamg',
                  'fieldsplit_1_pc_gamg_sym_graph': True,
                  'fieldsplit_1_mg_levels_ksp_type': 'chebyshev',
                  'fieldsplit_1_mg_levels_ksp_chebyshev_esteig': True,
                  'fieldsplit_1_mg_levels_ksp_max_it': 5,
                  'fieldsplit_1_mg_levels_pc_type': 'bjacobi',
                  'fieldsplit_1_mg_levels_sub_pc_type': 'ilu'}

    PiSolver = LinearVariationalSolver(PiProblem,
                                       solver_parameters=params)

    PiSolver.solve()
    v, Pi = w.split()
    if pi0 is not None:
        pi0.assign(Pi)

    if solve_for_rho:
        w1 = Function(W)
        v, rho = w1.split()
        rho.interpolate(thermodynamics.rho(state.parameters, theta0, Pi))
        v, rho = split(w1)
        dv, dpi = TestFunctions(W)
        pi = thermodynamics.pi(state.parameters, rho, theta0)
        F = (
            (cp*inner(v, dv) - cp*div(dv*theta)*pi)*dx
            + dpi*div(theta0*v)*dx
            + cp*inner(dv, n)*theta*pi_boundary*bmeasure
        )
        F += g*inner(dv, state.k)*dx
        rhoproblem = NonlinearVariationalProblem(F, w1, bcs=bcs)
        rhosolver = NonlinearVariationalSolver(rhoproblem, solver_parameters=params)
        rhosolver.solve()
        v, rho_ = w1.split()
        rho0.assign(rho_)
    else:
        rho0.interpolate(thermodynamics.rho(state.parameters, theta0, Pi))
コード例 #20
0
phi = TestFunction(Vt)
rho_averaged = Function(Vt)
rho_recoverer = Recoverer(rho0,
                          rho_averaged,
                          VDG=FunctionSpace(mesh,
                                            BrokenElement(Vt.ufl_element())),
                          boundary_method=physics_boundary_method)
rho_recoverer.project()

exner = thermodynamics.exner_pressure(state.parameters, rho_averaged, theta0)
p = thermodynamics.p(state.parameters, exner)
T = thermodynamics.T(state.parameters, theta0, exner, r_v=w_v)
w_sat = thermodynamics.r_sat(state.parameters, T, p)

w_functional = (phi * w_v * dxp - phi * w_sat * dxp)
w_problem = NonlinearVariationalProblem(w_functional, w_v)
w_solver = NonlinearVariationalSolver(w_problem)
w_solver.solve()

water_v0.assign(w_v)
water_c0.assign(water_t - water_v0)

state.set_reference_profiles([('rho', rho_b), ('theta', theta_b),
                              ('vapour_mixing_ratio', water_vb)])

rho_opts = None
theta_opts = EmbeddedDGOptions()
u_transport = ImplicitMidpoint(state, "u")

transported_fields = [
    SSPRK3(state, "rho", options=rho_opts),
コード例 #21
0
    def __init__(self, diagnostic_variables, prognostic_variables, outputting,
                 simulation_parameters):

        self.diagnostic_variables = diagnostic_variables
        self.prognostic_variables = prognostic_variables
        self.outputting = outputting
        self.simulation_parameters = simulation_parameters
        Dt = Constant(simulation_parameters['dt'][-1])
        Ld = simulation_parameters['Ld'][-1]
        u = self.prognostic_variables.u
        Xi = self.prognostic_variables.dXi
        Vu = u.function_space()
        vector_u = True if Vu.ufl_element() == VectorElement else False
        ones = Function(
            VectorFunctionSpace(self.prognostic_variables.mesh, "CG",
                                1)).project(as_vector([Constant(1.0)]))
        self.to_update_constants = False
        self.interpolators = []
        self.projectors = []
        self.solvers = []

        mesh = u.function_space().mesh()
        x, = SpatialCoordinate(mesh)
        alphasq = simulation_parameters['alphasq'][-1]
        periodic = simulation_parameters['periodic'][-1]

        # do peakon data checks here
        true_peakon_data = simulation_parameters['true_peakon_data'][-1]
        if true_peakon_data is not None:
            self.true_peakon_file = Dataset(
                'results/' + true_peakon_data + '/data.nc', 'r')
            # check length of file is correct
            ndump = simulation_parameters['ndump'][-1]
            tmax = simulation_parameters['tmax'][-1]
            dt = simulation_parameters['dt'][-1]
            if len(self.true_peakon_file['time'][:]) != int(tmax /
                                                            (ndump * dt)) + 1:
                raise ValueError(
                    'If reading in true peakon data, the dump frequency must be the same as that used for the true peakon data.'
                    +
                    ' Length of true peakon data as %i, but proposed length is %i'
                    % (len(self.true_peakon_file['time'][:]),
                       int(tmax / (ndump * dt)) + 1))
            if self.true_peakon_file['p'][:].shape != (int(tmax /
                                                           (ndump * dt)) +
                                                       1, ):
                raise ValueError(
                    'True peakon data shape %i must be the same shape as proposed data %i'
                    % ((int(tmax / (ndump * dt)) + 1, ),
                       self.true_peakon_file['p'][:].shape))

        # do peakon data checks here
        true_mean_peakon_data = simulation_parameters['true_mean_peakon_data'][
            -1]
        if true_mean_peakon_data is not None:
            self.true_mean_peakon_file = Dataset(
                'results/' + true_mean_peakon_data + '/data.nc', 'r')
            # check length of file is correct
            ndump = simulation_parameters['ndump'][-1]
            tmax = simulation_parameters['tmax'][-1]
            dt = simulation_parameters['dt'][-1]
            if len(self.true_mean_peakon_file['time'][:]) != int(tmax /
                                                                 (ndump * dt)):
                raise ValueError(
                    'If reading in true peakon data, the dump frequency must be the same as that used for the true peakon data.'
                )
            if self.true_mean_peakon_file['p'][:].shape != (int(
                    tmax / (ndump * dt)), ):
                raise ValueError(
                    'True peakon data must have same shape as proposed data!')

        for key, value in self.diagnostic_variables.fields.items():

            if key == 'uscalar':
                uscalar = self.diagnostic_variables.fields['uscalar']
                u_interpolator = Interpolator(dot(ones, u), uscalar)
                self.interpolators.append(u_interpolator)

            elif key == 'Euscalar':
                Eu = self.prognostic_variables.Eu
                Euscalar = self.diagnostic_variables.fields['Euscalar']
                Eu_interpolator = Interpolator(dot(ones, Eu), Euscalar)
                self.interpolators.append(Eu_interpolator)

            elif key == 'Xiscalar':
                Xi = self.prognostic_variables.dXi
                Xiscalar = self.diagnostic_variables.fields['Xiscalar']
                Xi_interpolator = Interpolator(dot(ones, Xi), Xiscalar)
                self.interpolators.append(Xi_interpolator)

            elif key == 'du':
                if type(u.function_space().ufl_element()) == VectorElement:
                    u_to_project = self.diagnostic_variables.fields['uscalar']
                else:
                    u_to_project = u
                du = self.diagnostic_variables.fields['du']
                du_projector = Projector(u_to_project.dx(0), du)
                self.projectors.append(du_projector)

            elif key == 'jump_du':
                du = self.diagnostic_variables.fields['du']
                jump_du = self.diagnostic_variables.fields['jump_du']
                V = jump_du.function_space()
                jtrial = TrialFunction(V)
                psi = TestFunction(V)
                Lj = psi('+') * abs(jump(du)) * dS
                aj = psi('+') * jtrial('+') * dS
                jprob = LinearVariationalProblem(aj, Lj, jump_du)
                jsolver = LinearVariationalSolver(jprob)
                self.solvers.append(jsolver)

            elif key == 'du_smooth':
                du = self.diagnostic_variables.fields['du']
                du_smooth = self.diagnostic_variables.fields['du_smooth']
                projector = Projector(du, du_smooth)
                self.projectors.append(projector)

            elif key == 'u2_flux':
                gamma = simulation_parameters['gamma'][-1]
                u2_flux = self.diagnostic_variables.fields['u2_flux']
                xis = self.prognostic_variables.pure_xi_list
                xis_x = []
                xis_xxx = []
                CG1 = FunctionSpace(mesh, "CG", 1)
                psi = TestFunction(CG1)
                for xi in xis:
                    xis_x.append(Function(CG1).project(xi.dx(0)))
                for xi_x in xis_x:
                    xi_xxx = Function(CG1)
                    form = (psi * xi_xxx + psi.dx(0) * xi_x.dx(0)) * dx
                    prob = NonlinearVariationalProblem(form, xi_xxx)
                    solver = NonlinearVariationalSolver(prob)
                    solver.solve()
                    xis_xxx.append(xi_xxx)

                flux_expr = 0.0 * x
                for xi, xi_x, xi_xxx in zip(xis, xis_x, xis_xxx):
                    flux_expr += (6 * u.dx(0) * xi + 12 * u * xi_x + gamma *
                                  xi_xxx) * (6 * u.dx(0) * xi + 24 * u * xi_x +
                                             gamma * xi_xxx)
                projector = Projector(flux_expr, u2_flux)
                self.projectors.append(projector)

            elif key == 'a':
                # find  6 * u_x * Xi + gamma * Xi_xxx
                mesh = u.function_space().mesh()
                gamma = simulation_parameters['gamma'][-1]
                a_flux = self.diagnostic_variables.fields['a']
                xis = self.prognostic_variables.pure_xis
                xis_x = []
                xis_xxx = []
                CG1 = FunctionSpace(mesh, "CG", 1)
                psi = TestFunction(CG1)
                for xi in xis:
                    xis_x.append(Function(CG1).project(xi.dx(0)))
                for xi_x in xis_x:
                    xi_xxx = Function(CG1)
                    form = (psi * xi_xxx + psi.dx(0) * xi_x.dx(0)) * dx
                    prob = NonlinearVariationalProblem(form, xi_xxx)
                    solver = NonlinearVariationalSolver(prob)
                    solver.solve()
                    xis_xxx.append(xi_xxx)

                x, = SpatialCoordinate(mesh)
                a_expr = 0.0 * x
                for xi, xi_x, xi_xxx in zip(xis, xis_x, xis_xxx):
                    a_expr += 6 * u.dx(0) * xi + gamma * xi_xxx
                projector = Projector(a_expr, a_flux)
                self.projectors.append(projector)

            elif key == 'b':
                # find 12 * u * Xi_x
                mesh = u.function_space().mesh()
                gamma = simulation_parameters['gamma'][-1]
                b_flux = self.diagnostic_variables.fields['b']
                xis = self.prognostic_variables.pure_xis

                x, = SpatialCoordinate(mesh)
                b_expr = 0.0 * x
                for xi, xi_x, xi_xxx in zip(xis, xis_x, xis_xxx):
                    b_expr += 12 * u * xi.dx(0)
                projector = Projector(b_expr, b_flux)
                self.projectors.append(projector)

            elif key == 'kdv_1':
                # find the first part of the kdv form
                u0 = prognostic_variables.u0
                uh = (u + u0) / 2
                us = Dt * uh + sqrt(Dt) * Xi
                psi = TestFunction(Vu)
                du_1 = self.diagnostic_variables.fields['kdv_1']

                eqn = psi * du_1 * dx - 6 * psi.dx(0) * uh * us * dx
                prob = NonlinearVariationalProblem(eqn, du_1)
                solver = NonlinearVariationalSolver(prob)
                self.solvers.append(solver)

            elif key == 'kdv_2':
                # find the second part of the kdv form
                u0 = prognostic_variables.u0
                uh = (u + u0) / 2
                us = Dt * uh + sqrt(Dt) * Xi
                psi = TestFunction(Vu)
                du_2 = self.diagnostic_variables.fields['kdv_2']

                eqn = psi * du_2 * dx + 6 * psi * uh * us.dx(0) * dx
                prob = NonlinearVariationalProblem(eqn, du_2)
                solver = NonlinearVariationalSolver(prob)
                self.solvers.append(solver)

            elif key == 'kdv_3':
                # find the third part of the kdv form
                u0 = prognostic_variables.u0
                uh = (u + u0) / 2
                us = Dt * uh + sqrt(Dt) * Xi
                du_3 = self.diagnostic_variables.fields['kdv_3']
                gamma = simulation_parameters['gamma'][-1]

                phi = TestFunction(Vu)
                F = Function(Vu)

                eqn = (phi * F * dx + phi.dx(0) * us.dx(0) * dx)
                prob = NonlinearVariationalProblem(eqn, F)
                solver = NonlinearVariationalSolver(prob)
                self.solvers.append(solver)

                self.projectors.append(Projector(-gamma * F.dx(0), du_3))

                # nu = TestFunction(Vu)
                # back_eqn = nu * du_3 * dx - gamma * nu.dx(0) * F * dx
                # back_prob = NonlinearVariationalProblem(back_eqn, du_3)
                # back_solver = NonlinearVariationalSolver(back_prob)
                # self.solvers.append(solver)

            elif key == 'm':

                m = self.diagnostic_variables.fields['m']
                phi = TestFunction(Vu)
                eqn = phi * m * dx - phi * u * dx - alphasq * phi.dx(0) * u.dx(
                    0) * dx
                prob = NonlinearVariationalProblem(eqn, m)
                solver = NonlinearVariationalSolver(prob)
                self.solvers.append(solver)

            elif key == 'u_xx':

                u_xx = self.diagnostic_variables.fields['u_xx']
                phi = TestFunction(Vu)
                eqn = phi * u_xx * dx + phi.dx(0) * u_xx.dx(0) * dx
                prob = NonlinearVariationalProblem(eqn, u_xx)
                solver = NonlinearVariationalSolver(prob)
                self.solvers.append(solver)

            elif key == 'u_sde':
                self.to_update_constants = True
                self.Ld = Ld
                self.alphasq = alphasq
                self.p = Constant(1.0 * 0.5 * (1 + exp(-Ld / sqrt(alphasq))) /
                                  (1 - exp(-Ld / sqrt(alphasq))))
                self.q = Constant(Ld / 2)

                u_sde = self.diagnostic_variables.fields['u_sde']
                if periodic:
                    expr = conditional(
                        x < self.q - Ld / 2,
                        self.p * ((exp(-(x - self.q + Ld) / sqrt(alphasq)) +
                                   exp(-Ld / sqrt(alphasq)) * exp(
                                       (x - self.q + Ld) / sqrt(alphasq))) /
                                  (1 - exp(-Ld / sqrt(alphasq)))),
                        conditional(
                            x < self.q + Ld / 2,
                            self.p * ((exp(-sqrt((self.q - x)**2 / alphasq)) +
                                       exp(-Ld / sqrt(alphasq)) *
                                       exp(sqrt((self.q - x)**2 / alphasq))) /
                                      (1 - exp(-Ld / sqrt(alphasq)))),
                            self.p *
                            ((exp(-(self.q + Ld - x) / sqrt(alphasq)) +
                              exp(-Ld / sqrt(alphasq) * exp(
                                  (self.q + Ld - x) / sqrt(alphasq)))) /
                             (1 - exp(-Ld / sqrt(alphasq))))))
                else:
                    expr = conditional(
                        x < self.q - Ld / 2,
                        self.p * exp(-(x - self.q + Ld) / sqrt(alphasq)),
                        conditional(
                            x < self.q + Ld / 2,
                            self.p * exp(-sqrt((self.q - x)**2 / alphasq)),
                            self.p * exp(-(self.q + Ld - x) / sqrt(alphasq))))

                self.interpolators.append(Interpolator(expr, u_sde))

            elif key == 'u_sde_weak':
                u_sde = self.diagnostic_variables.fields['u_sde']
                u_sde_weak = self.diagnostic_variables.fields['u_sde_weak']
                psi = TestFunction(Vu)

                eqn = psi * u_sde_weak * dx - psi * (u - u_sde) * dx
                prob = NonlinearVariationalProblem(eqn, u_sde_weak)
                solver = NonlinearVariationalSolver(prob)
                self.solvers.append(solver)

            elif key == 'u_sde_mean':
                self.to_update_constants = True
                self.p = Constant(1.0)
                self.q = Constant(Ld / 2)

                if periodic:
                    raise NotImplementedError(
                        'u_sde_mean not yet implemented for periodic peakon')

                u_sde = self.diagnostic_variables.fields['u_sde_mean']
                expr = conditional(
                    x < self.q - Ld / 2,
                    self.p * exp(-(x - self.q + Ld) / sqrt(alphasq)),
                    conditional(
                        x < self.q + Ld / 2,
                        self.p * exp(-sqrt((self.q - x)**2 / alphasq)),
                        self.p * exp(-(self.q + Ld - x) / sqrt(alphasq))))
                self.interpolators.append(Interpolator(expr, u_sde))

            elif key == 'u_sde_weak_mean':
                u_sde = self.diagnostic_variables.fields['u_sde_mean']
                u_sde_weak = self.diagnostic_variables.fields[
                    'u_sde_weak_mean']
                psi = TestFunction(Vu)

                eqn = psi * u_sde_weak * dx - psi * (u - u_sde) * dx
                prob = NonlinearVariationalProblem(eqn, u_sde_weak)
                solver = NonlinearVariationalSolver(prob)
                self.solvers.append(solver)

            elif key == 'pure_xi':
                pure_xi = 0.0 * x
                for xi in self.prognostic_variables.pure_xi_list:
                    if vector_u:
                        pure_xi += dot(ones, xi)
                    else:
                        pure_xi += xi
                Xiscalar = self.diagnostic_variables.fields['pure_xi']
                Xi_interpolator = Interpolator(pure_xi, Xiscalar)
                self.interpolators.append(Xi_interpolator)

            elif key == 'pure_xi_x':
                pure_xi_x = 0.0 * x
                for xix in self.prognostic_variables.pure_xi_x_list:
                    if vector_u:
                        pure_xi_x += dot(ones, xix)
                    else:
                        pure_xi_x += xix
                Xiscalar = self.diagnostic_variables.fields['pure_xi_x']
                Xi_interpolator = Interpolator(pure_xi_x, Xiscalar)
                self.interpolators.append(Xi_interpolator)

            elif key == 'pure_xi_xx':
                pure_xi_xx = 0.0 * x
                for xixx in self.prognostic_variables.pure_xi_xx_list:
                    if vector_u:
                        pure_xi_xx += dot(ones, xixx)
                    else:
                        pure_xi_xx += xixx
                Xiscalar = self.diagnostic_variables.fields['pure_xi_xx']
                Xi_interpolator = Interpolator(pure_xi_xx, Xiscalar)
                self.interpolators.append(Xi_interpolator)

            elif key == 'pure_xi_xxx':
                pure_xi_xxx = 0.0 * x
                for xixxx in self.prognostic_variables.pure_xi_xxx_list:
                    if vector_u:
                        pure_xi_xxx += dot(ones, xixxx)
                    else:
                        pure_xi_xxx += xixxx
                Xiscalar = self.diagnostic_variables.fields['pure_xi_xxx']
                Xi_interpolator = Interpolator(pure_xi_xxx, Xiscalar)
                self.interpolators.append(Xi_interpolator)

            elif key == 'pure_xi_xxxx':
                pure_xi_xxxx = 0.0 * x
                for xixxxx in self.prognostic_variables.pure_xi_xx_list:
                    if vector_u:
                        pure_xi_xxxx += dot(ones, xixxxx)
                    else:
                        pure_xi_xxxx += xixxxx
                Xiscalar = self.diagnostic_variables.fields['pure_xi_xxxx']
                Xi_interpolator = Interpolator(pure_xi_xxxx, Xiscalar)
                self.interpolators.append(Xi_interpolator)

            else:
                raise NotImplementedError('Diagnostic %s not yet implemented' %
                                          key)