예제 #1
0
파일: tools.py 프로젝트: ra2003/pyrticle
    def __init__(self, t0, y0, dt):
        self.t = [t0]
        self.y = [y0]
        self.dt = dt

        from hedge.timestep.runge_kutta import LSRK4TimeStepper
        self.forward_stepper = LSRK4TimeStepper()
        self.backward_stepper = LSRK4TimeStepper()
예제 #2
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    def __init__(self,
                 order,
                 startup_stepper=None,
                 dtype=numpy.float64,
                 rcon=None):
        self.f_history = []

        from pytools import match_precision
        self.dtype = numpy.dtype(dtype)
        self.scalar_dtype = match_precision(numpy.dtype(numpy.float64),
                                            self.dtype)
        self.coefficients = numpy.asarray(make_ab_coefficients(order),
                                          dtype=self.scalar_dtype)

        if startup_stepper is not None:
            self.startup_stepper = startup_stepper
        else:
            from hedge.timestep.runge_kutta import LSRK4TimeStepper
            self.startup_stepper = LSRK4TimeStepper(self.dtype)

        from pytools.log import IntervalTimer, EventCounter
        timer_factory = IntervalTimer
        if rcon is not None:
            timer_factory = rcon.make_timer

        self.timer = timer_factory(
            "t_ab", "Time spent doing algebra in Adams-Bashforth")
        self.flop_counter = EventCounter(
            "n_flops_ab", "Floating point operations performed in AB")
예제 #3
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    def __init__(self,
                 method,
                 large_dt,
                 substep_count,
                 order,
                 order_f2f=None,
                 order_s2f=None,
                 order_f2s=None,
                 order_s2s=None,
                 startup_stepper=None):

        if isinstance(method, str):
            from hedge.timestep.multirate_ab.methods import methods
            self.method_name = method
            method = methods[method]
        else:
            self.method_name = None

        self.method = method

        self.large_dt = large_dt
        self.small_dt = large_dt / substep_count
        self.substep_count = substep_count

        from hedge.timestep.multirate_ab.methods import \
                HIST_F2F, HIST_S2F, HIST_F2S, HIST_S2S

        self.orders = {
            HIST_F2F: order_f2f,
            HIST_S2F: order_s2f,
            HIST_F2S: order_f2s,
            HIST_S2S: order_s2s,
        }

        for hn in HIST_NAMES:
            if self.orders[hn] is None:
                self.orders[hn] = order

        self.max_order = max(self.orders.values())

        # histories of rhs evaluations
        self.histories = dict((hn, []) for hn in HIST_NAMES)

        if startup_stepper is not None:
            self.startup_stepper = startup_stepper
        else:
            self.startup_stepper = LSRK4TimeStepper()

        self.startup_history = []

        self.hist_is_fast = {
            HIST_F2F: True,
            HIST_S2F: self.method.s2f_hist_is_fast,
            HIST_S2S: False,
            HIST_F2S: False
        }
예제 #4
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def run_setup(units, casename, setup, discr, pusher, visualize=False):
    from hedge.timestep.runge_kutta import LSRK4TimeStepper
    from hedge.visualization import SiloVisualizer
    from hedge.models.em import MaxwellOperator

    vis = SiloVisualizer(discr)

    from pyrticle.cloud import PicMethod
    from pyrticle.deposition.shape import ShapeFunctionDepositor
    method = PicMethod(discr,
                       units,
                       ShapeFunctionDepositor(),
                       pusher(),
                       3,
                       3,
                       debug=set(["verbose_vis"]))

    e, h = setup.fields(discr)
    b = units.MU0 * h

    init_positions = setup.positions(0)
    init_velocities = setup.velocities(0)

    nparticles = len(init_positions)

    state = method.make_state()
    method.add_particles(
        state,
        zip(
            init_positions,
            init_velocities,
            nparticles * [setup.charge],
            nparticles * [units.EL_MASS],
        ), nparticles)

    final_time = setup.final_time()
    nsteps = setup.nsteps()
    dt = final_time / nsteps

    # timestepping ------------------------------------------------------------
    from hedge.models.em import MaxwellOperator
    max_op = MaxwellOperator(epsilon=units.EPSILON0, mu=units.MU0, flux_type=1)

    fields = max_op.assemble_eh(e, h)

    from pyrticle.cloud import \
            FieldToParticleRhsCalculator, \
            ParticleRhsCalculator
    p_rhs_calculator = ParticleRhsCalculator(method, max_op)
    f2p_rhs_calculator = FieldToParticleRhsCalculator(method, max_op)

    def rhs(t, ts_state):
        return (p_rhs_calculator(t, lambda: fields, lambda: ts_state.state) +
                f2p_rhs_calculator(t, lambda: fields, lambda: ts_state.state))

    stepper = LSRK4TimeStepper()
    t = 0

    bbox = discr.mesh.bounding_box()
    z_period = bbox[1][2] - bbox[0][2]

    def check_result():
        from hedge.tools import cross

        deriv_dt = 1e-12

        dim = discr.dimensions
        true_x = setup.positions(t)
        true_v = setup.velocities(t)
        true_f = [(p2 - p1) / (2 * deriv_dt) for p1, p2 in zip(
            setup.momenta(t - deriv_dt), setup.momenta(t + deriv_dt))]

        state = ts_state.state

        from pyrticle.tools import NumberShiftableVector
        vis_info = state.vis_listener.particle_vis_map
        sim_x = state.positions
        sim_v = method.velocities(state)
        sim_f = NumberShiftableVector.unwrap(vis_info["mag_force"] +
                                             vis_info["el_force"])
        sim_el_f = NumberShiftableVector.unwrap(vis_info["el_force"])
        sim_mag_f = NumberShiftableVector.unwrap(vis_info["mag_force"])

        local_e = setup.e()
        local_b = units.MU0 * setup.h()

        x_err = 0
        v_err = 0
        f_err = 0

        for i in range(len(state)):
            #real_f = numpy.array(cross(sim_v, setup.charge*local_b)) + setup.charge*local_e

            my_true_x = true_x[i]
            my_true_x[2] = my_true_x[2] % z_period
            if False and i == 0:
                #print "particle %d" % i
                print "pos:", la.norm(true_x[i] - sim_x[i]) / la.norm(
                    true_x[i])
                #print "vel:", la.norm(true_v[i]-sim_v[i])/la.norm(true_v[i])
                #print "force:", la.norm(true_f[i]-sim_f[i])/la.norm(true_f[i])
                print "pos:", true_x[i], sim_x[i]
                #print "vel:", true_v[i], sim_v[i]
                #print "force:", true_f[i], sim_f[i]
                #print "forces%d:..." % i, sim_el_f[i], sim_mag_f[i]
                #print "acc%d:" % i, la.norm(a-sim_a)
                #u = numpy.vstack((v, sim_v, f, sim_f, real_f))
                #print "acc%d:\n%s" % (i, u)
                #raw_input()

            def rel_err(sim, true):
                return la.norm(true - sim) / la.norm(true)

            x_err = max(x_err, rel_err(sim_x[i], my_true_x))
            v_err = max(v_err, rel_err(sim_v[i], true_v[i]))
            f_err = max(f_err, rel_err(sim_f[i], true_f[i]))

        return x_err, v_err, f_err

    # make sure verbose-vis fields are filled
    from pyrticle.cloud import TimesteppablePicState
    ts_state = TimesteppablePicState(method, state)
    del state

    rhs(t, ts_state)

    errors = (0, 0, 0)

    for step in xrange(nsteps):
        if step % int(setup.nsteps() / 300) == 0:
            errors = tuple(
                max(old_err, new_err)
                for old_err, new_err in zip(errors, check_result()))

            if visualize:
                visf = vis.make_file("%s-%04d" % (casename, step))

                method.add_to_vis(vis, visf, ts_state.state, time=t, step=step)

                if True:
                    vis.add_data(visf, [
                        ("e", e),
                        ("h", h),
                    ],
                                 time=t,
                                 step=step)
                else:
                    vis.add_data(visf, [], time=t, step=step)
                visf.close()

        method.upkeep(ts_state.state)

        ts_state = stepper(ts_state, t, dt, rhs)

        t += dt

    assert errors[0] < 2e-12, casename + "-pos"
    assert errors[1] < 2e-13, casename + "-vel"
    assert errors[2] < 2e-4, casename + "-acc"

    vis.close()
예제 #5
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def main(write_output=True,
         dir_tag=TAG_NONE,
         neu_tag=TAG_NONE,
         rad_tag=TAG_ALL,
         flux_type_arg="upwind"):
    from math import sin, cos, pi, exp, sqrt  # noqa

    from hedge.backends import guess_run_context
    rcon = guess_run_context()

    dim = 2

    if dim == 1:
        if rcon.is_head_rank:
            from hedge.mesh.generator import make_uniform_1d_mesh
            mesh = make_uniform_1d_mesh(-10, 10, 500)
    elif dim == 2:
        from hedge.mesh.generator import make_rect_mesh
        if rcon.is_head_rank:
            mesh = make_rect_mesh(a=(-1, -1), b=(1, 1), max_area=0.003)
    elif dim == 3:
        if rcon.is_head_rank:
            from hedge.mesh.generator import make_ball_mesh
            mesh = make_ball_mesh(max_volume=0.0005)
    else:
        raise RuntimeError("bad number of dimensions")

    if rcon.is_head_rank:
        print "%d elements" % len(mesh.elements)
        mesh_data = rcon.distribute_mesh(mesh)
    else:
        mesh_data = rcon.receive_mesh()

    discr = rcon.make_discretization(mesh_data, order=4)

    from hedge.timestep.runge_kutta import LSRK4TimeStepper
    stepper = LSRK4TimeStepper()

    from hedge.visualization import VtkVisualizer
    if write_output:
        vis = VtkVisualizer(discr, rcon, "fld")

    source_center = np.array([0.7, 0.4])
    source_width = 1 / 16
    source_omega = 3

    import hedge.optemplate as sym
    sym_x = sym.nodes(2)
    sym_source_center_dist = sym_x - source_center

    from hedge.models.wave import VariableVelocityStrongWaveOperator
    op = VariableVelocityStrongWaveOperator(
        c=sym.If(sym.Comparison(np.dot(sym_x, sym_x), "<", 0.4**2), 1, 0.5),
        dimensions=discr.dimensions,
        source=sym.CFunction("sin")(source_omega * sym.ScalarParameter("t")) *
        sym.CFunction("exp")(
            -np.dot(sym_source_center_dist, sym_source_center_dist) /
            source_width**2),
        dirichlet_tag=dir_tag,
        neumann_tag=neu_tag,
        radiation_tag=rad_tag,
        flux_type=flux_type_arg)

    from hedge.tools import join_fields
    fields = join_fields(
        discr.volume_zeros(),
        [discr.volume_zeros() for i in range(discr.dimensions)])

    # {{{ diagnostics setup

    from pytools.log import LogManager, \
            add_general_quantities, \
            add_simulation_quantities, \
            add_run_info

    if write_output:
        log_file_name = "wave.dat"
    else:
        log_file_name = None

    logmgr = LogManager(log_file_name, "w", rcon.communicator)
    add_run_info(logmgr)
    add_general_quantities(logmgr)
    add_simulation_quantities(logmgr)
    discr.add_instrumentation(logmgr)

    from pytools.log import IntervalTimer
    vis_timer = IntervalTimer("t_vis", "Time spent visualizing")
    logmgr.add_quantity(vis_timer)
    stepper.add_instrumentation(logmgr)

    from hedge.log import LpNorm
    u_getter = lambda: fields[0]
    logmgr.add_quantity(LpNorm(u_getter, discr, 1, name="l1_u"))
    logmgr.add_quantity(LpNorm(u_getter, discr, name="l2_u"))

    logmgr.add_watches(["step.max", "t_sim.max", "l2_u", "t_step.max"])

    # }}}

    # {{{ timestep loop

    rhs = op.bind(discr)
    try:
        from hedge.timestep.stability import \
                approximate_rk4_relative_imag_stability_region
        max_dt = (1 / discr.compile(op.max_eigenvalue_expr())() *
                  discr.dt_non_geometric_factor() *
                  discr.dt_geometric_factor() *
                  approximate_rk4_relative_imag_stability_region(stepper))
        if flux_type_arg == "central":
            max_dt *= 0.25

        from hedge.timestep import times_and_steps
        step_it = times_and_steps(final_time=3,
                                  logmgr=logmgr,
                                  max_dt_getter=lambda t: max_dt)

        for step, t, dt in step_it:
            if step % 10 == 0 and write_output:
                visf = vis.make_file("fld-%04d" % step)

                vis.add_data(visf, [
                    ("u", fields[0]),
                    ("v", fields[1:]),
                ],
                             time=t,
                             step=step)
                visf.close()

            fields = stepper(fields, t, dt, rhs)

        assert discr.norm(fields) < 1
    finally:
        if write_output:
            vis.close()

        logmgr.close()
        discr.close()
예제 #6
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def main(write_output=True):
    from math import sin, exp, sqrt  # noqa

    from hedge.mesh.generator import make_rect_mesh
    mesh = make_rect_mesh(a=(-0.5, -0.5), b=(0.5, 0.5), max_area=0.008)

    from hedge.backends.jit import Discretization

    discr = Discretization(mesh, order=4)

    from hedge.visualization import VtkVisualizer
    vis = VtkVisualizer(discr, None, "fld")

    source_center = np.array([0.1, 0.22])
    source_width = 0.05
    source_omega = 3

    import hedge.optemplate as sym
    sym_x = sym.nodes(2)
    sym_source_center_dist = sym_x - source_center

    from hedge.models.wave import StrongWaveOperator
    from hedge.mesh import TAG_ALL, TAG_NONE
    op = StrongWaveOperator(
        -0.1,
        discr.dimensions,
        source_f=sym.CFunction("sin")(
            source_omega * sym.ScalarParameter("t")) * sym.CFunction("exp")(
                -np.dot(sym_source_center_dist, sym_source_center_dist) /
                source_width**2),
        dirichlet_tag=TAG_NONE,
        neumann_tag=TAG_NONE,
        radiation_tag=TAG_ALL,
        flux_type="upwind")

    from hedge.tools import join_fields
    fields = join_fields(
        discr.volume_zeros(),
        [discr.volume_zeros() for i in range(discr.dimensions)])

    from hedge.timestep.runge_kutta import LSRK4TimeStepper
    stepper = LSRK4TimeStepper()
    dt = op.estimate_timestep(discr, stepper=stepper, fields=fields)

    nsteps = int(10 / dt)
    print "dt=%g nsteps=%d" % (dt, nsteps)

    rhs = op.bind(discr)
    for step in range(nsteps):
        t = step * dt

        if step % 10 == 0 and write_output:
            print step, t, discr.norm(fields[0])
            visf = vis.make_file("fld-%04d" % step)

            vis.add_data(visf, [
                ("u", fields[0]),
                ("v", fields[1:]),
            ],
                         time=t,
                         step=step)
            visf.close()

        fields = stepper(fields, t, dt, rhs)

    vis.close()
예제 #7
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def main(write_output=True):
    from math import sin, cos, pi, exp, sqrt
    from hedge.data import TimeConstantGivenFunction, \
            ConstantGivenFunction

    from hedge.backends import guess_run_context
    rcon = guess_run_context()

    dim = 2

    def boundary_tagger(fvi, el, fn, all_v):
        if el.face_normals[fn][0] > 0:
            return ["dirichlet"]
        else:
            return ["neumann"]

    if dim == 2:
        if rcon.is_head_rank:
            from hedge.mesh.generator import make_disk_mesh
            mesh = make_disk_mesh(r=0.5, boundary_tagger=boundary_tagger)
    elif dim == 3:
        if rcon.is_head_rank:
            from hedge.mesh.generator import make_ball_mesh
            mesh = make_ball_mesh(max_volume=0.001)
    else:
        raise RuntimeError, "bad number of dimensions"

    if rcon.is_head_rank:
        print "%d elements" % len(mesh.elements)
        mesh_data = rcon.distribute_mesh(mesh)
    else:
        mesh_data = rcon.receive_mesh()

    discr = rcon.make_discretization(mesh_data,
                                     order=3,
                                     debug=["cuda_no_plan"],
                                     default_scalar_type=numpy.float64)

    if write_output:
        from hedge.visualization import VtkVisualizer
        vis = VtkVisualizer(discr, rcon, "fld")

    def u0(x, el):
        if la.norm(x) < 0.2:
            return 1
        else:
            return 0

    def coeff(x, el):
        if x[0] < 0:
            return 0.25
        else:
            return 1

    def dirichlet_bc(t, x):
        return 0

    def neumann_bc(t, x):
        return 2

    from hedge.models.diffusion import DiffusionOperator
    op = DiffusionOperator(
        discr.dimensions,
        #coeff=coeff,
        dirichlet_tag="dirichlet",
        dirichlet_bc=TimeConstantGivenFunction(ConstantGivenFunction(0)),
        neumann_tag="neumann",
        neumann_bc=TimeConstantGivenFunction(ConstantGivenFunction(1)))
    u = discr.interpolate_volume_function(u0)

    # diagnostics setup -------------------------------------------------------
    from pytools.log import LogManager, \
            add_general_quantities, \
            add_simulation_quantities, \
            add_run_info

    if write_output:
        log_file_name = "heat.dat"
    else:
        log_file_name = None

    logmgr = LogManager(log_file_name, "w", rcon.communicator)
    add_run_info(logmgr)
    add_general_quantities(logmgr)
    add_simulation_quantities(logmgr)
    discr.add_instrumentation(logmgr)

    from hedge.log import LpNorm
    u_getter = lambda: u
    logmgr.add_quantity(LpNorm(u_getter, discr, 1, name="l1_u"))
    logmgr.add_quantity(LpNorm(u_getter, discr, name="l2_u"))

    logmgr.add_watches(["step.max", "t_sim.max", "l2_u", "t_step.max"])

    # timestep loop -----------------------------------------------------------
    from hedge.timestep.runge_kutta import LSRK4TimeStepper, ODE45TimeStepper
    from hedge.timestep.dumka3 import Dumka3TimeStepper
    #stepper = LSRK4TimeStepper()
    stepper = Dumka3TimeStepper(
        3,
        rtol=1e-6,
        rcon=rcon,
        vector_primitive_factory=discr.get_vector_primitive_factory(),
        dtype=discr.default_scalar_type)
    #stepper = ODE45TimeStepper(rtol=1e-6, rcon=rcon,
    #vector_primitive_factory=discr.get_vector_primitive_factory(),
    #dtype=discr.default_scalar_type)
    stepper.add_instrumentation(logmgr)

    rhs = op.bind(discr)
    try:
        next_dt = op.estimate_timestep(discr,
                                       stepper=LSRK4TimeStepper(),
                                       t=0,
                                       fields=u)

        from hedge.timestep import times_and_steps
        step_it = times_and_steps(final_time=0.1,
                                  logmgr=logmgr,
                                  max_dt_getter=lambda t: next_dt,
                                  taken_dt_getter=lambda: taken_dt)

        for step, t, dt in step_it:
            if step % 10 == 0 and write_output:
                visf = vis.make_file("fld-%04d" % step)
                vis.add_data(visf, [
                    ("u", discr.convert_volume(u, kind="numpy")),
                ],
                             time=t,
                             step=step)
                visf.close()

            u, t, taken_dt, next_dt = stepper(u, t, next_dt, rhs)
            #u = stepper(u, t, dt, rhs)

        assert discr.norm(u) < 1
    finally:
        if write_output:
            vis.close()

        logmgr.close()
        discr.close()
예제 #8
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def main(write_output=True,
         dir_tag=TAG_NONE,
         neu_tag=TAG_NONE,
         rad_tag=TAG_ALL,
         flux_type_arg="upwind",
         dtype=np.float64,
         debug=[]):
    from math import sin, cos, pi, exp, sqrt  # noqa

    from hedge.backends import guess_run_context
    rcon = guess_run_context()

    dim = 2

    if dim == 1:
        if rcon.is_head_rank:
            from hedge.mesh.generator import make_uniform_1d_mesh
            mesh = make_uniform_1d_mesh(-10, 10, 500)
    elif dim == 2:
        from hedge.mesh.generator import make_rect_mesh
        if rcon.is_head_rank:
            mesh = make_rect_mesh(a=(-0.5, -0.5), b=(0.5, 0.5), max_area=0.008)
    elif dim == 3:
        if rcon.is_head_rank:
            from hedge.mesh.generator import make_ball_mesh
            mesh = make_ball_mesh(max_volume=0.0005)
    else:
        raise RuntimeError("bad number of dimensions")

    if rcon.is_head_rank:
        print "%d elements" % len(mesh.elements)
        mesh_data = rcon.distribute_mesh(mesh)
    else:
        mesh_data = rcon.receive_mesh()

    from hedge.timestep.runge_kutta import LSRK4TimeStepper
    stepper = LSRK4TimeStepper(dtype=dtype)

    from hedge.models.wave import StrongWaveOperator
    from hedge.mesh import TAG_ALL, TAG_NONE  # noqa

    source_center = np.array([0.1, 0.22])
    source_width = 0.05
    source_omega = 3

    import hedge.optemplate as sym
    sym_x = sym.nodes(2)
    sym_source_center_dist = sym_x - source_center

    op = StrongWaveOperator(
        -1,
        dim,
        source_f=sym.CFunction("sin")(
            source_omega * sym.ScalarParameter("t")) * sym.CFunction("exp")(
                -np.dot(sym_source_center_dist, sym_source_center_dist) /
                source_width**2),
        dirichlet_tag=dir_tag,
        neumann_tag=neu_tag,
        radiation_tag=rad_tag,
        flux_type=flux_type_arg)

    discr = rcon.make_discretization(mesh_data,
                                     order=4,
                                     debug=debug,
                                     default_scalar_type=dtype,
                                     tune_for=op.op_template())

    from hedge.visualization import VtkVisualizer
    if write_output:
        vis = VtkVisualizer(discr, rcon, "fld")

    from hedge.tools import join_fields
    fields = join_fields(
        discr.volume_zeros(dtype=dtype),
        [discr.volume_zeros(dtype=dtype) for i in range(discr.dimensions)])

    # {{{ diagnostics setup

    from pytools.log import LogManager, \
            add_general_quantities, \
            add_simulation_quantities, \
            add_run_info

    if write_output:
        log_file_name = "wave.dat"
    else:
        log_file_name = None

    logmgr = LogManager(log_file_name, "w", rcon.communicator)
    add_run_info(logmgr)
    add_general_quantities(logmgr)
    add_simulation_quantities(logmgr)
    discr.add_instrumentation(logmgr)

    from pytools.log import IntervalTimer
    vis_timer = IntervalTimer("t_vis", "Time spent visualizing")
    logmgr.add_quantity(vis_timer)
    stepper.add_instrumentation(logmgr)

    from hedge.log import LpNorm
    u_getter = lambda: fields[0]
    logmgr.add_quantity(LpNorm(u_getter, discr, 1, name="l1_u"))
    logmgr.add_quantity(LpNorm(u_getter, discr, name="l2_u"))

    logmgr.add_watches(["step.max", "t_sim.max", "l2_u", "t_step.max"])

    # }}}

    # {{{ timestep loop

    rhs = op.bind(discr)
    try:
        from hedge.timestep import times_and_steps
        step_it = times_and_steps(
            final_time=4,
            logmgr=logmgr,
            max_dt_getter=lambda t: op.estimate_timestep(
                discr, stepper=stepper, t=t, fields=fields))

        for step, t, dt in step_it:
            if step % 10 == 0 and write_output:
                visf = vis.make_file("fld-%04d" % step)

                vis.add_data(visf, [
                    ("u", discr.convert_volume(fields[0], kind="numpy")),
                    ("v", discr.convert_volume(fields[1:], kind="numpy")),
                ],
                             time=t,
                             step=step)
                visf.close()

            fields = stepper(fields, t, dt, rhs)

        assert discr.norm(fields) < 1
        assert fields[0].dtype == dtype

    finally:
        if write_output:
            vis.close()

        logmgr.close()
        discr.close()
예제 #9
0
def main(write_output=True,
         allow_features=None,
         flux_type_arg=1,
         bdry_flux_type_arg=None,
         extra_discr_args={}):
    from hedge.mesh.generator import make_cylinder_mesh, make_box_mesh
    from hedge.tools import EOCRecorder, to_obj_array
    from math import sqrt, pi  # noqa
    from analytic_solutions import (  # noqa
        RealPartAdapter, SplitComplexAdapter, CylindricalFieldAdapter,
        CylindricalCavityMode, RectangularWaveguideMode, RectangularCavityMode)
    from hedge.models.em import MaxwellOperator

    logging.basicConfig(level=logging.DEBUG)

    from hedge.backends import guess_run_context
    rcon = guess_run_context(allow_features)

    epsilon0 = 8.8541878176e-12  # C**2 / (N m**2)
    mu0 = 4 * pi * 1e-7  # N/A**2.
    epsilon = 1 * epsilon0
    mu = 1 * mu0

    eoc_rec = EOCRecorder()

    cylindrical = False
    periodic = False

    if cylindrical:
        R = 1
        d = 2
        mode = CylindricalCavityMode(m=1,
                                     n=1,
                                     p=1,
                                     radius=R,
                                     height=d,
                                     epsilon=epsilon,
                                     mu=mu)
        # r_sol = CylindricalFieldAdapter(RealPartAdapter(mode))
        # c_sol = SplitComplexAdapter(CylindricalFieldAdapter(mode))

        if rcon.is_head_rank:
            mesh = make_cylinder_mesh(radius=R, height=d, max_volume=0.01)
    else:
        if periodic:
            mode = RectangularWaveguideMode(epsilon, mu, (3, 2, 1))
            periodicity = (False, False, True)
        else:
            periodicity = None
        mode = RectangularCavityMode(epsilon, mu, (1, 2, 2))

        if rcon.is_head_rank:
            mesh = make_box_mesh(max_volume=0.001, periodicity=periodicity)

    if rcon.is_head_rank:
        mesh_data = rcon.distribute_mesh(mesh)
    else:
        mesh_data = rcon.receive_mesh()

    for order in [4, 5, 6]:
        #for order in [1,2,3,4,5,6]:
        extra_discr_args.setdefault("debug", []).extend(
            ["cuda_no_plan", "cuda_dump_kernels"])

        op = MaxwellOperator(epsilon,
                             mu,
                             flux_type=flux_type_arg,
                             bdry_flux_type=bdry_flux_type_arg)

        discr = rcon.make_discretization(mesh_data,
                                         order=order,
                                         tune_for=op.op_template(),
                                         **extra_discr_args)

        from hedge.visualization import VtkVisualizer
        if write_output:
            vis = VtkVisualizer(discr, rcon, "em-%d" % order)

        mode.set_time(0)

        def get_true_field():
            return discr.convert_volume(to_obj_array(
                mode(discr).real.astype(discr.default_scalar_type).copy()),
                                        kind=discr.compute_kind)

        fields = get_true_field()

        if rcon.is_head_rank:
            print "---------------------------------------------"
            print "order %d" % order
            print "---------------------------------------------"
            print "#elements=", len(mesh.elements)

        from hedge.timestep.runge_kutta import LSRK4TimeStepper
        stepper = LSRK4TimeStepper(dtype=discr.default_scalar_type, rcon=rcon)
        #from hedge.timestep.dumka3 import Dumka3TimeStepper
        #stepper = Dumka3TimeStepper(3, dtype=discr.default_scalar_type, rcon=rcon)

        # {{{ diagnostics setup

        from pytools.log import LogManager, add_general_quantities, \
                add_simulation_quantities, add_run_info

        if write_output:
            log_file_name = "maxwell-%d.dat" % order
        else:
            log_file_name = None

        logmgr = LogManager(log_file_name, "w", rcon.communicator)

        add_run_info(logmgr)
        add_general_quantities(logmgr)
        add_simulation_quantities(logmgr)
        discr.add_instrumentation(logmgr)
        stepper.add_instrumentation(logmgr)

        from pytools.log import IntervalTimer
        vis_timer = IntervalTimer("t_vis", "Time spent visualizing")
        logmgr.add_quantity(vis_timer)

        from hedge.log import EMFieldGetter, add_em_quantities
        field_getter = EMFieldGetter(discr, op, lambda: fields)
        add_em_quantities(logmgr, op, field_getter)

        logmgr.add_watches(
            ["step.max", "t_sim.max", ("W_field", "W_el+W_mag"), "t_step.max"])

        # }}}

        # {{{ timestep loop

        rhs = op.bind(discr)
        final_time = 0.5e-9

        try:
            from hedge.timestep import times_and_steps
            step_it = times_and_steps(
                final_time=final_time,
                logmgr=logmgr,
                max_dt_getter=lambda t: op.estimate_timestep(
                    discr, stepper=stepper, t=t, fields=fields))

            for step, t, dt in step_it:
                if step % 50 == 0 and write_output:
                    sub_timer = vis_timer.start_sub_timer()
                    e, h = op.split_eh(fields)
                    visf = vis.make_file("em-%d-%04d" % (order, step))
                    vis.add_data(visf, [
                        ("e", discr.convert_volume(e, kind="numpy")),
                        ("h", discr.convert_volume(h, kind="numpy")),
                    ],
                                 time=t,
                                 step=step)
                    visf.close()
                    sub_timer.stop().submit()

                fields = stepper(fields, t, dt, rhs)

            mode.set_time(final_time)

            eoc_rec.add_data_point(order,
                                   discr.norm(fields - get_true_field()))

        finally:
            if write_output:
                vis.close()

            logmgr.close()
            discr.close()

        if rcon.is_head_rank:
            print
            print eoc_rec.pretty_print("P.Deg.", "L2 Error")

        # }}}

    assert eoc_rec.estimate_order_of_convergence()[0, 1] > 6
예제 #10
0
def main(write_output=True):
    from hedge.timestep.runge_kutta import LSRK4TimeStepper
    from math import sqrt, pi, exp

    from hedge.backends import guess_run_context
    rcon = guess_run_context()

    epsilon0 = 8.8541878176e-12  # C**2 / (N m**2)
    mu0 = 4 * pi * 1e-7  # N/A**2.
    epsilon = 1 * epsilon0
    mu = 1 * mu0

    c = 1 / sqrt(mu * epsilon)

    pml_width = 0.5
    #mesh = make_mesh(a=np.array((-1,-1,-1)), b=np.array((1,1,1)),
    #mesh = make_mesh(a=np.array((-3,-3)), b=np.array((3,3)),
    mesh = make_mesh(
        a=np.array((-1, -1)),
        b=np.array((1, 1)),
        #mesh = make_mesh(a=np.array((-2,-2)), b=np.array((2,2)),
        pml_width=pml_width,
        max_volume=0.01)

    if rcon.is_head_rank:
        mesh_data = rcon.distribute_mesh(mesh)
    else:
        mesh_data = rcon.receive_mesh()

    class Current:
        def volume_interpolant(self, t, discr):
            from hedge.tools import make_obj_array

            result = discr.volume_zeros(kind="numpy", dtype=np.float64)

            omega = 6 * c
            if omega * t > 2 * pi:
                return make_obj_array([result, result, result])

            x = make_obj_array(discr.nodes.T)
            r = np.sqrt(np.dot(x, x))

            idx = r < 0.3
            result[idx] = (1+np.cos(pi*r/0.3))[idx] \
                    *np.sin(omega*t)**3

            result = discr.convert_volume(result,
                                          kind=discr.compute_kind,
                                          dtype=discr.default_scalar_type)
            return make_obj_array([-result, result, result])

    order = 3
    discr = rcon.make_discretization(mesh_data,
                                     order=order,
                                     debug=["cuda_no_plan"])

    from hedge.visualization import VtkVisualizer
    if write_output:
        vis = VtkVisualizer(discr, rcon, "em-%d" % order)

    from hedge.mesh import TAG_ALL, TAG_NONE
    from hedge.data import GivenFunction, TimeHarmonicGivenFunction, TimeIntervalGivenFunction
    from hedge.models.em import MaxwellOperator
    from hedge.models.pml import \
            AbarbanelGottliebPMLMaxwellOperator, \
            AbarbanelGottliebPMLTMMaxwellOperator, \
            AbarbanelGottliebPMLTEMaxwellOperator

    op = AbarbanelGottliebPMLTEMaxwellOperator(epsilon,
                                               mu,
                                               flux_type=1,
                                               current=Current(),
                                               pec_tag=TAG_ALL,
                                               absorb_tag=TAG_NONE,
                                               add_decay=True)

    fields = op.assemble_ehpq(discr=discr)

    stepper = LSRK4TimeStepper()

    if rcon.is_head_rank:
        print "order %d" % order
        print "#elements=", len(mesh.elements)

    # diagnostics setup ---------------------------------------------------
    from pytools.log import LogManager, add_general_quantities, \
            add_simulation_quantities, add_run_info

    if write_output:
        log_file_name = "maxwell-%d.dat" % order
    else:
        log_file_name = None

    logmgr = LogManager(log_file_name, "w", rcon.communicator)
    add_run_info(logmgr)
    add_general_quantities(logmgr)
    add_simulation_quantities(logmgr)
    discr.add_instrumentation(logmgr)
    stepper.add_instrumentation(logmgr)

    from pytools.log import IntervalTimer
    vis_timer = IntervalTimer("t_vis", "Time spent visualizing")
    logmgr.add_quantity(vis_timer)

    from hedge.log import EMFieldGetter, add_em_quantities
    field_getter = EMFieldGetter(discr, op, lambda: fields)
    add_em_quantities(logmgr, op, field_getter)

    logmgr.add_watches(
        ["step.max", "t_sim.max", ("W_field", "W_el+W_mag"), "t_step.max"])

    from hedge.log import LpNorm

    class FieldIdxGetter:
        def __init__(self, whole_getter, idx):
            self.whole_getter = whole_getter
            self.idx = idx

        def __call__(self):
            return self.whole_getter()[self.idx]

    # timestep loop -------------------------------------------------------

    t = 0
    pml_coeff = op.coefficients_from_width(discr, width=pml_width)
    rhs = op.bind(discr, pml_coeff)

    try:
        from hedge.timestep import times_and_steps
        step_it = times_and_steps(
            final_time=4 / c,
            logmgr=logmgr,
            max_dt_getter=lambda t: op.estimate_timestep(
                discr, stepper=stepper, t=t, fields=fields))

        for step, t, dt in step_it:
            if step % 10 == 0 and write_output:
                e, h, p, q = op.split_ehpq(fields)
                visf = vis.make_file("em-%d-%04d" % (order, step))
                #pml_rhs_e, pml_rhs_h, pml_rhs_p, pml_rhs_q = \
                #op.split_ehpq(rhs(t, fields))
                j = Current().volume_interpolant(t, discr)
                vis.add_data(
                    visf,
                    [
                        ("e", discr.convert_volume(e, "numpy")),
                        ("h", discr.convert_volume(h, "numpy")),
                        ("p", discr.convert_volume(p, "numpy")),
                        ("q", discr.convert_volume(q, "numpy")),
                        ("j", discr.convert_volume(j, "numpy")),
                        #("pml_rhs_e", pml_rhs_e),
                        #("pml_rhs_h", pml_rhs_h),
                        #("pml_rhs_p", pml_rhs_p),
                        #("pml_rhs_q", pml_rhs_q),
                        #("max_rhs_e", max_rhs_e),
                        #("max_rhs_h", max_rhs_h),
                        #("max_rhs_p", max_rhs_p),
                        #("max_rhs_q", max_rhs_q),
                    ],
                    time=t,
                    step=step)
                visf.close()

            fields = stepper(fields, t, dt, rhs)

        _, _, energies_data = logmgr.get_expr_dataset("W_el+W_mag")
        energies = [value for tick_nbr, value in energies_data]

        assert energies[-1] < max(energies) * 1e-2

    finally:
        logmgr.close()

        if write_output:
            vis.close()
예제 #11
0
def main(write_output=True,
         flux_type_arg="upwind",
         dtype=np.float64,
         debug=[]):
    from math import sin, cos, pi, exp, sqrt  # noqa

    from hedge.backends import guess_run_context
    rcon = guess_run_context()

    if rcon.is_head_rank:
        from hedge.mesh.reader.gmsh import generate_gmsh
        mesh = generate_gmsh(GEOMETRY,
                             2,
                             allow_internal_boundaries=True,
                             force_dimension=2)

        print "%d elements" % len(mesh.elements)
        mesh_data = rcon.distribute_mesh(mesh)
    else:
        mesh_data = rcon.receive_mesh()

    discr = rcon.make_discretization(mesh_data,
                                     order=4,
                                     debug=debug,
                                     default_scalar_type=dtype)
    from hedge.timestep.runge_kutta import LSRK4TimeStepper
    stepper = LSRK4TimeStepper(dtype=dtype)

    from hedge.visualization import VtkVisualizer
    if write_output:
        vis = VtkVisualizer(discr, rcon, "fld")

    source_center = 0
    source_width = 0.05
    source_omega = 3

    import hedge.optemplate as sym
    sym_x = sym.nodes(2)
    sym_source_center_dist = sym_x - source_center

    from hedge.models.wave import StrongWaveOperator
    op = StrongWaveOperator(
        -1,
        discr.dimensions,
        source_f=sym.CFunction("sin")(
            source_omega * sym.ScalarParameter("t")) * sym.CFunction("exp")(
                -np.dot(sym_source_center_dist, sym_source_center_dist) /
                source_width**2),
        dirichlet_tag="boundary",
        neumann_tag=TAG_NONE,
        radiation_tag=TAG_NONE,
        flux_type=flux_type_arg)

    from hedge.tools import join_fields
    fields = join_fields(
        discr.volume_zeros(dtype=dtype),
        [discr.volume_zeros(dtype=dtype) for i in range(discr.dimensions)])

    # diagnostics setup -------------------------------------------------------
    from pytools.log import LogManager, \
            add_general_quantities, \
            add_simulation_quantities, \
            add_run_info

    if write_output:
        log_file_name = "wiggly.dat"
    else:
        log_file_name = None

    logmgr = LogManager(log_file_name, "w", rcon.communicator)
    add_run_info(logmgr)
    add_general_quantities(logmgr)
    add_simulation_quantities(logmgr)
    discr.add_instrumentation(logmgr)

    stepper.add_instrumentation(logmgr)

    logmgr.add_watches(["step.max", "t_sim.max", "t_step.max"])

    # timestep loop -----------------------------------------------------------
    rhs = op.bind(discr)
    try:
        from hedge.timestep import times_and_steps
        step_it = times_and_steps(
            final_time=4,
            logmgr=logmgr,
            max_dt_getter=lambda t: op.estimate_timestep(
                discr, stepper=stepper, t=t, fields=fields))

        for step, t, dt in step_it:
            if step % 10 == 0 and write_output:
                visf = vis.make_file("fld-%04d" % step)

                vis.add_data(visf, [
                    ("u", fields[0]),
                    ("v", fields[1:]),
                ],
                             time=t,
                             step=step)
                visf.close()

            fields = stepper(fields, t, dt, rhs)

        assert discr.norm(fields) < 1
        assert fields[0].dtype == dtype

    finally:
        if write_output:
            vis.close()

        logmgr.close()
        discr.close()
예제 #12
0
def main(write_output=True,
         flux_type_arg="central",
         use_quadrature=True,
         final_time=20):
    from math import sin, cos, pi, sqrt

    from hedge.backends import guess_run_context
    rcon = guess_run_context()

    # mesh setup --------------------------------------------------------------
    if rcon.is_head_rank:
        #from hedge.mesh.generator import make_disk_mesh
        #mesh = make_disk_mesh()
        from hedge.mesh.generator import make_rect_mesh
        mesh = make_rect_mesh(a=(-1, -1), b=(1, 1), max_area=0.008)

    if rcon.is_head_rank:
        mesh_data = rcon.distribute_mesh(mesh)
    else:
        mesh_data = rcon.receive_mesh()

    # space-time-dependent-velocity-field -------------------------------------
    # simple vortex
    class TimeDependentVField:
        """ `TimeDependentVField` is a callable expecting `(x, t)` representing space and time

        `x` is of the length of the spatial dimension and `t` is the time."""
        shape = (2, )

        def __call__(self, pt, el, t):
            x, y = pt
            # Correction-Factor to make the speed zero on the on the boundary
            #fac = (1-x**2)*(1-y**2)
            fac = 1.
            return numpy.array([-y * fac, x * fac]) * cos(pi * t)

    class VField:
        """ `VField` is a callable expecting `(x)` representing space

        `x` is of the length of the spatial dimension."""
        shape = (2, )

        def __call__(self, pt, el):
            x, y = pt
            # Correction-Factor to make the speed zero on the on the boundary
            #fac = (1-x**2)*(1-y**2)
            fac = 1.
            return numpy.array([-y * fac, x * fac])

    # space-time-dependent State BC (optional)-----------------------------------
    class TimeDependentBc_u:
        """ space and time dependent BC for state u"""
        def __call__(self, pt, el, t):
            x, y = pt
            if t <= 0.5:
                if x > 0:
                    return 1
                else:
                    return 0
            else:
                return 0

    class Bc_u:
        """ Only space dependent BC for state u"""
        def __call__(seld, pt, el):
            x, y = pt
            if x > 0:
                return 1
            else:
                return 0

    # operator setup ----------------------------------------------------------
    # In the operator setup it is possible to switch between a only space
    # dependent velocity field `VField` or a time and space dependent
    # `TimeDependentVField`.
    # For `TimeDependentVField`: advec_v=TimeDependentGivenFunction(VField())
    # For `VField`: advec_v=TimeConstantGivenFunction(GivenFunction(VField()))
    # Same for the Bc_u Function! If you don't define Bc_u then the BC for u = 0.

    from hedge.data import \
            ConstantGivenFunction, \
            TimeConstantGivenFunction, \
            TimeDependentGivenFunction, \
            GivenFunction
    from hedge.models.advection import VariableCoefficientAdvectionOperator
    op = VariableCoefficientAdvectionOperator(
        mesh.dimensions,
        #advec_v=TimeDependentGivenFunction(
        #    TimeDependentVField()),
        advec_v=TimeConstantGivenFunction(GivenFunction(VField())),
        #bc_u_f=TimeDependentGivenFunction(
        #    TimeDependentBc_u()),
        bc_u_f=TimeConstantGivenFunction(GivenFunction(Bc_u())),
        flux_type=flux_type_arg)

    # discretization setup ----------------------------------------------------
    order = 5
    if use_quadrature:
        quad_min_degrees = {"quad": 3 * order}
    else:
        quad_min_degrees = {}

    discr = rcon.make_discretization(
        mesh_data,
        order=order,
        default_scalar_type=numpy.float64,
        debug=["cuda_no_plan"],
        quad_min_degrees=quad_min_degrees,
        tune_for=op.op_template(),
    )
    vis_discr = discr

    # visualization setup -----------------------------------------------------
    from hedge.visualization import VtkVisualizer
    if write_output:
        vis = VtkVisualizer(vis_discr, rcon, "fld")

    # initial condition -------------------------------------------------------
    if True:

        def initial(pt, el):
            # Gauss pulse
            from math import exp
            x = (pt - numpy.array([0.3, 0.5])) * 8
            return exp(-numpy.dot(x, x))
    else:

        def initial(pt, el):
            # Rectangle
            x, y = pt
            if abs(x) < 0.5 and abs(y) < 0.2:
                return 2
            else:
                return 1

    u = discr.interpolate_volume_function(initial)

    # timestep setup ----------------------------------------------------------
    from hedge.timestep.runge_kutta import LSRK4TimeStepper
    stepper = LSRK4TimeStepper(
        vector_primitive_factory=discr.get_vector_primitive_factory())

    if rcon.is_head_rank:
        print "%d elements" % len(discr.mesh.elements)

    # filter setup-------------------------------------------------------------
    from hedge.discretization import ExponentialFilterResponseFunction
    from hedge.optemplate.operators import FilterOperator
    mode_filter = FilterOperator(
            ExponentialFilterResponseFunction(min_amplification=0.9,order=4))\
                    .bind(discr)

    # diagnostics setup -------------------------------------------------------
    from pytools.log import LogManager, \
            add_general_quantities, \
            add_simulation_quantities, \
            add_run_info

    if write_output:
        log_file_name = "space-dep.dat"
    else:
        log_file_name = None

    logmgr = LogManager(log_file_name, "w", rcon.communicator)
    add_run_info(logmgr)
    add_general_quantities(logmgr)
    add_simulation_quantities(logmgr)
    discr.add_instrumentation(logmgr)

    stepper.add_instrumentation(logmgr)

    from hedge.log import Integral, LpNorm
    u_getter = lambda: u
    logmgr.add_quantity(Integral(u_getter, discr, name="int_u"))
    logmgr.add_quantity(LpNorm(u_getter, discr, p=1, name="l1_u"))
    logmgr.add_quantity(LpNorm(u_getter, discr, name="l2_u"))

    logmgr.add_watches(["step.max", "t_sim.max", "l2_u", "t_step.max"])

    # Initialize v for data output:
    v = op.advec_v.volume_interpolant(0, discr)

    # timestep loop -----------------------------------------------------------
    rhs = op.bind(discr)
    try:
        from hedge.timestep import times_and_steps
        step_it = times_and_steps(final_time=final_time,
                                  logmgr=logmgr,
                                  max_dt_getter=lambda t: op.estimate_timestep(
                                      discr, stepper=stepper, t=t, fields=u))

        for step, t, dt in step_it:
            if step % 10 == 0 and write_output:
                visf = vis.make_file("fld-%04d" % step)
                vis.add_data(visf,
                             [("u", discr.convert_volume(u, kind="numpy")),
                              ("v", discr.convert_volume(v, kind="numpy"))],
                             time=t,
                             step=step)
                visf.close()

            u = stepper(u, t, dt, rhs)

            # We're feeding in a discontinuity through the BCs.
            # Quadrature does not help with shock capturing--
            # therefore we do need to filter here, regardless
            # of whether quadrature is enabled.
            u = mode_filter(u)

        assert discr.norm(u) < 10

    finally:
        if write_output:
            vis.close()

        logmgr.close()
        discr.close()
예제 #13
0
def main(write_output=True, flux_type_arg="upwind"):
    from hedge.tools import mem_checkpoint
    from math import sin, cos, pi, sqrt
    from math import floor

    from hedge.backends import guess_run_context
    rcon = guess_run_context()

    def f(x):
        return sin(pi * x)

    def u_analytic(x, el, t):
        return f((-numpy.dot(v, x) / norm_v + t * norm_v))

    def boundary_tagger(vertices, el, face_nr, all_v):
        if numpy.dot(el.face_normals[face_nr], v) < 0:
            return ["inflow"]
        else:
            return ["outflow"]

    dim = 2

    if dim == 1:
        v = numpy.array([1])
        if rcon.is_head_rank:
            from hedge.mesh.generator import make_uniform_1d_mesh
            mesh = make_uniform_1d_mesh(0, 2, 10, periodic=True)
    elif dim == 2:
        v = numpy.array([2, 0])
        if rcon.is_head_rank:
            from hedge.mesh.generator import make_disk_mesh
            mesh = make_disk_mesh(boundary_tagger=boundary_tagger)
    elif dim == 3:
        v = numpy.array([0, 0, 1])
        if rcon.is_head_rank:
            from hedge.mesh.generator import make_cylinder_mesh, make_ball_mesh, make_box_mesh

            mesh = make_cylinder_mesh(max_volume=0.04,
                                      height=2,
                                      boundary_tagger=boundary_tagger,
                                      periodic=False,
                                      radial_subdivisions=32)
    else:
        raise RuntimeError, "bad number of dimensions"

    norm_v = la.norm(v)

    if rcon.is_head_rank:
        mesh_data = rcon.distribute_mesh(mesh)
    else:
        mesh_data = rcon.receive_mesh()

    if dim != 1:
        mesh_data = mesh_data.reordered_by("cuthill")

    discr = rcon.make_discretization(mesh_data, order=4)
    vis_discr = discr

    from hedge.visualization import VtkVisualizer
    if write_output:
        vis = VtkVisualizer(vis_discr, rcon, "fld")

    # operator setup ----------------------------------------------------------
    from hedge.data import \
            ConstantGivenFunction, \
            TimeConstantGivenFunction, \
            TimeDependentGivenFunction
    from hedge.models.advection import StrongAdvectionOperator, WeakAdvectionOperator
    op = WeakAdvectionOperator(v,
                               inflow_u=TimeDependentGivenFunction(u_analytic),
                               flux_type=flux_type_arg)

    u = discr.interpolate_volume_function(lambda x, el: u_analytic(x, el, 0))

    # timestep setup ----------------------------------------------------------
    from hedge.timestep.runge_kutta import LSRK4TimeStepper
    stepper = LSRK4TimeStepper()

    if rcon.is_head_rank:
        print "%d elements" % len(discr.mesh.elements)

    # diagnostics setup -------------------------------------------------------
    from pytools.log import LogManager, \
            add_general_quantities, \
            add_simulation_quantities, \
            add_run_info

    if write_output:
        log_file_name = "advection.dat"
    else:
        log_file_name = None

    logmgr = LogManager(log_file_name, "w", rcon.communicator)
    add_run_info(logmgr)
    add_general_quantities(logmgr)
    add_simulation_quantities(logmgr)
    discr.add_instrumentation(logmgr)

    stepper.add_instrumentation(logmgr)

    from hedge.log import Integral, LpNorm
    u_getter = lambda: u
    logmgr.add_quantity(Integral(u_getter, discr, name="int_u"))
    logmgr.add_quantity(LpNorm(u_getter, discr, p=1, name="l1_u"))
    logmgr.add_quantity(LpNorm(u_getter, discr, name="l2_u"))

    logmgr.add_watches(["step.max", "t_sim.max", "l2_u", "t_step.max"])

    # timestep loop -----------------------------------------------------------
    rhs = op.bind(discr)

    try:
        from hedge.timestep import times_and_steps
        step_it = times_and_steps(final_time=3,
                                  logmgr=logmgr,
                                  max_dt_getter=lambda t: op.estimate_timestep(
                                      discr, stepper=stepper, t=t, fields=u))

        for step, t, dt in step_it:
            if step % 5 == 0 and write_output:
                visf = vis.make_file("fld-%04d" % step)
                vis.add_data(visf, [
                    ("u", discr.convert_volume(u, kind="numpy")),
                ],
                             time=t,
                             step=step)
                visf.close()

            u = stepper(u, t, dt, rhs)

        true_u = discr.interpolate_volume_function(
            lambda x, el: u_analytic(x, el, t))
        print discr.norm(u - true_u)
        assert discr.norm(u - true_u) < 1e-2
    finally:
        if write_output:
            vis.close()

        logmgr.close()
        discr.close()
예제 #14
0
    def __init__(self, units):
        from pyrticle.deposition.shape import \
                ShapeFunctionDepositor, \
                NormalizedShapeFunctionDepositor
        from pyrticle.deposition.advective import \
                AdvectiveDepositor
        from pyrticle.deposition.grid import \
                GridDepositor
        from pyrticle.deposition.grid_find import \
                GridFindDepositor
        from pyrticle.deposition.grid_base import \
                SingleBrickGenerator, \
                FineCoreBrickGenerator

        from pyrticle.pusher import \
                MonomialParticlePusher, \
                AverageParticlePusher

        import pyrticle.geometry
        import pyrticle.distribution

        constants = {
            "numpy": numpy,
            "la": numpy.linalg,
            "units": units,
            "pyrticle": pyrticle,
            "DepShape": ShapeFunctionDepositor,
            "DepNormShape": NormalizedShapeFunctionDepositor,
            "DepAdv": AdvectiveDepositor,
            "DepGrid": GridDepositor,
            "DepGridFind": GridFindDepositor,
            "SingleBrickGenerator": SingleBrickGenerator,
            "FineCoreBrickGenerator": FineCoreBrickGenerator,
            "PushMonomial": MonomialParticlePusher,
            "PushAverage": AverageParticlePusher,
        }

        import hedge.data

        from hedge.timestep.runge_kutta import LSRK4TimeStepper

        variables = {
            "pusher":
            None,
            "depositor":
            None,
            "mesh":
            None,
            "dimensions_pos":
            None,
            "dimensions_velocity":
            None,
            "beam_axis":
            None,
            "beam_diag_axis":
            None,
            "tube_length":
            None,
            "element_order":
            None,
            "maxwell_flux_type":
            "lf",
            "maxwell_bdry_flux_type":
            1,
            "shape_exponent":
            2,
            "shape_bandwidth":
            "optimize",
            "chi":
            None,
            "phi_decay":
            0,
            "phi_filter":
            None,
            "potential_bc":
            hedge.data.ConstantGivenFunction(),
            "final_time":
            None,
            "nparticles":
            20000,
            "distribution":
            None,
            "vis_interval":
            100,
            "vis_pattern":
            "pic-%04d",
            "vis_order":
            None,
            "output_path":
            ".",
            "debug":
            set(["ic", "poisson", "shape_bw"]),
            "dg_debug":
            set(),
            "profile_output_filename":
            None,
            "watch_vars": [
                "step", "t_sim", ("W_field", "W_el+W_mag"), "t_step", "t_eta",
                "n_part"
            ],
            "hook_startup":
            lambda runner: None,
            "hook_after_step":
            lambda runner, state: None,
            "hook_when_done":
            lambda runner: None,
            "hook_vis_quantities":
            lambda observer: [
                ("e", observer.e),
                ("h", observer.h),
                ("j", observer.method.deposit_j(observer.state)),
            ],
            "hook_visualize":
            lambda runner, vis, visf, observer: None,
            "timestepper_maker":
            lambda dt: LSRK4TimeStepper(),
            "dt_scale":
            1,
        }

        doc = {
            "chi":
            "relative speed of hyp. cleaning (None for no cleaning)",
            "nparticles":
            "how many particles",
            "vis_interval":
            "how often a visualization of the fields is written",
            "max_volume_inner":
            "max. tet volume in inner mesh [m^3]",
            "max_volume_outer":
            "max. tet volume in outer mesh [m^3]",
            "shape_bandwidth":
            "either 'optimize', 'guess' or a positive real number",
            "phi_filter":
            "a tuple (min_amp, order) or None, describing the filtering applied to phi in hypclean mode",
        }

        pytools.CPyUserInterface.__init__(self, variables, constants, doc)
예제 #15
0
    stepper.add_instrumentation(logmgr)

    try:
        from hedge.timestep import times_and_steps
        # for visc=0.01
        #stab_fac = 0.1 # RK4
        #stab_fac = 1.6 # dumka3(3), central
        #stab_fac = 3 # dumka3(4), central

        #stab_fac = 0.01 # RK4
        stab_fac = 0.2  # dumka3(3), central
        #stab_fac = 3 # dumka3(4), central

        dt = stab_fac * op.estimate_timestep(
            discr, stepper=LSRK4TimeStepper(), t=0, fields=u)

        step_it = times_and_steps(final_time=case.final_time,
                                  logmgr=logmgr,
                                  max_dt_getter=lambda t: dt)
        from hedge.optemplate import InverseVandermondeOperator
        inv_vdm = InverseVandermondeOperator().bind(discr)

        for step, t, dt in step_it:
            if step % 3 == 0 and write_output:
                if hasattr(case, "u_exact"):
                    extra_fields = [("u_exact",
                                     discr.interpolate_volume_function(
                                         lambda x, el: case.u_exact(x[0], t)))]
                else:
                    extra_fields = []
예제 #16
0
def main(write_output=True, dtype=np.float32):
    from hedge.backends import guess_run_context
    rcon = guess_run_context()

    from hedge.mesh.generator import make_rect_mesh
    if rcon.is_head_rank:
        h_fac = 1
        mesh = make_rect_mesh(a=(0, 0),
                              b=(1, 1),
                              max_area=h_fac**2 * 1e-4,
                              periodicity=(True, True),
                              subdivisions=(int(70 / h_fac), int(70 / h_fac)))

    from hedge.models.gas_dynamics.lbm import \
            D2Q9LBMMethod, LatticeBoltzmannOperator

    op = LatticeBoltzmannOperator(D2Q9LBMMethod(), lbm_delta_t=0.001, nu=1e-4)

    if rcon.is_head_rank:
        print "%d elements" % len(mesh.elements)
        mesh_data = rcon.distribute_mesh(mesh)
    else:
        mesh_data = rcon.receive_mesh()

    discr = rcon.make_discretization(mesh_data,
                                     order=3,
                                     default_scalar_type=dtype,
                                     debug=["cuda_no_plan"])
    from hedge.timestep.runge_kutta import LSRK4TimeStepper
    stepper = LSRK4TimeStepper(
        dtype=dtype,
        #vector_primitive_factory=discr.get_vector_primitive_factory()
    )

    from hedge.visualization import VtkVisualizer
    if write_output:
        vis = VtkVisualizer(discr, rcon, "fld")

    from hedge.data import CompiledExpressionData

    def ic_expr(t, x, fields):
        from hedge.optemplate import CFunction
        from pymbolic.primitives import IfPositive
        from pytools.obj_array import make_obj_array

        tanh = CFunction("tanh")
        sin = CFunction("sin")

        rho = 1
        u0 = 0.05
        w = 0.05
        delta = 0.05

        from hedge.optemplate.primitives import make_common_subexpression as cse
        u = cse(
            make_obj_array([
                IfPositive(x[1] - 1 / 2, u0 * tanh(4 * (3 / 4 - x[1]) / w),
                           u0 * tanh(4 * (x[1] - 1 / 4) / w)),
                u0 * delta * sin(2 * np.pi * (x[0] + 1 / 4))
            ]), "u")

        return make_obj_array([
            op.method.f_equilibrium(rho, alpha, u)
            for alpha in range(len(op.method))
        ])

    # timestep loop -----------------------------------------------------------
    stream_rhs = op.bind_rhs(discr)
    collision_update = op.bind(discr, op.collision_update)
    get_rho = op.bind(discr, op.rho)
    get_rho_u = op.bind(discr, op.rho_u)

    f_bar = CompiledExpressionData(ic_expr).volume_interpolant(0, discr)

    from hedge.discretization import ExponentialFilterResponseFunction
    from hedge.optemplate.operators import FilterOperator
    mode_filter = FilterOperator(
            ExponentialFilterResponseFunction(min_amplification=0.9, order=4))\
                    .bind(discr)

    final_time = 1000
    try:
        lbm_dt = op.lbm_delta_t
        dg_dt = op.estimate_timestep(discr, stepper=stepper)
        print dg_dt

        dg_steps_per_lbm_step = int(np.ceil(lbm_dt / dg_dt))
        dg_dt = lbm_dt / dg_steps_per_lbm_step

        lbm_steps = int(final_time // op.lbm_delta_t)
        for step in xrange(lbm_steps):
            t = step * lbm_dt

            if step % 100 == 0 and write_output:
                visf = vis.make_file("fld-%04d" % step)

                rho = get_rho(f_bar)
                rho_u = get_rho_u(f_bar)
                vis.add_data(
                    visf,
                    [("fbar%d" % i, discr.convert_volume(f_bar_i, "numpy"))
                     for i, f_bar_i in enumerate(f_bar)] + [
                         ("rho", discr.convert_volume(rho, "numpy")),
                         ("rho_u", discr.convert_volume(rho_u, "numpy")),
                     ],
                    time=t,
                    step=step)
                visf.close()

            print "step=%d, t=%f" % (step, t)

            f_bar = collision_update(f_bar)

            for substep in range(dg_steps_per_lbm_step):
                f_bar = stepper(f_bar, t + substep * dg_dt, dg_dt, stream_rhs)

            #f_bar = mode_filter(f_bar)

    finally:
        if write_output:
            vis.close()

        discr.close()
예제 #17
0
def main(write_output=True, allow_features=None, flux_type_arg=1,
        bdry_flux_type_arg=None, extra_discr_args={}):
    from math import sqrt, pi
    from hedge.models.em import TEMaxwellOperator

    from hedge.backends import guess_run_context
    rcon = guess_run_context(allow_features)

    epsilon0 = 8.8541878176e-12 # C**2 / (N m**2)
    mu0 = 4*pi*1e-7 # N/A**2.
    c = 1/sqrt(mu0*epsilon0)

    materials = {"vacuum" : (epsilon0, mu0),
                 "dielectric" : (2*epsilon0, mu0)}

    output_dir = "2d_cavity"

    import os
    if not os.access(output_dir, os.F_OK):
        os.makedirs(output_dir)

    # should no tag raise an error or default to free space?
    def eps_val(x, el):
        for key in materials.keys():
            if el in material_elements[key]:
                return materials[key][0]
        raise ValueError, "Element does not belong to any material"

    def mu_val(x, el):
        for key in materials.keys():
            if el in material_elements[key]:
                return materials[key][1]
        raise ValueError, "Element does not belong to any material"

    # geometry of cavity
    d = 100e-3
    a = 150e-3

    # analytical frequency and transverse wavenumbers of resonance
    f0 = 9.0335649907522321e8
    h = 2*pi*f0/c
    l = -h*sqrt(2)

    # substitute the following and change materials for a homogeneous cavity
    #h = pi/a
    #l =-h

    def initial_val(discr):
        # the initial solution for the TE_10-like mode
        def initial_Hz(x, el):
            from math import cos, sin
            if el in material_elements["vacuum"]:
                return h*cos(h*x[0])
            else:
                return -l*sin(h*d)/sin(l*(a-d))*cos(l*(a-x[0]))

        from hedge.tools import make_obj_array
        result_zero = discr.volume_zeros(kind="numpy", dtype=numpy.float64)
        H_z = make_tdep_given(initial_Hz).volume_interpolant(0, discr)
        return make_obj_array([result_zero, result_zero, H_z])

    if rcon.is_head_rank:
        from hedge.mesh.reader.gmsh import generate_gmsh
        mesh = generate_gmsh(CAVITY_GEOMETRY, 2, force_dimension=2)
        mesh_data = rcon.distribute_mesh(mesh)
    else:
        mesh_data = rcon.receive_mesh()

    # Work out which elements belong to each material
    material_elements = {}
    for key in materials.keys():
        material_elements[key] = set(mesh_data.tag_to_elements[key])

    order = 3
    #extra_discr_args.setdefault("debug", []).append("cuda_no_plan")
    #extra_discr_args.setdefault("debug", []).append("dump_optemplate_stages")

    from hedge.data import make_tdep_given
    from hedge.mesh import TAG_ALL

    op = TEMaxwellOperator(epsilon=make_tdep_given(eps_val), mu=make_tdep_given(mu_val), \
            flux_type=flux_type_arg, \
            bdry_flux_type=bdry_flux_type_arg, dimensions=2, pec_tag=TAG_ALL)
    # op = TEMaxwellOperator(epsilon=epsilon0, mu=mu0,
            # flux_type=flux_type_arg, \
            # bdry_flux_type=bdry_flux_type_arg, dimensions=2, pec_tag=TAG_ALL)

    discr = rcon.make_discretization(mesh_data, order=order,
            tune_for=op.op_template(),
            **extra_discr_args)

    # create the initial solution
    fields = initial_val(discr)

    from hedge.visualization import VtkVisualizer
    if write_output:
        from os.path import join
        vis = VtkVisualizer(discr, rcon, join(output_dir, "cav-%d" % order))

    # monitor the solution at a point to find the resonant frequency
    try:
        point_getter = discr.get_point_evaluator(numpy.array([75e-3, 25e-3, 0])) #[0.25, 0.25, 0.25]))
    except RuntimeError:
        point_getter = None

    if rcon.is_head_rank:
        print "---------------------------------------------"
        print "order %d" % order
        print "---------------------------------------------"
        print "#elements=", len(mesh.elements)

    from hedge.timestep.runge_kutta import LSRK4TimeStepper
    stepper = LSRK4TimeStepper(dtype=discr.default_scalar_type, rcon=rcon)
    #from hedge.timestep.dumka3 import Dumka3TimeStepper
    #stepper = Dumka3TimeStepper(3, dtype=discr.default_scalar_type, rcon=rcon)

    # diagnostics setup ---------------------------------------------------
    from pytools.log import LogManager, add_general_quantities, \
            add_simulation_quantities, add_run_info

    if write_output:
        from os.path import join
        log_file_name = join(output_dir, "cavity-%d.dat" % order)
    else:
        log_file_name = None

    logmgr = LogManager(log_file_name, "w", rcon.communicator)

    add_run_info(logmgr)
    add_general_quantities(logmgr)
    add_simulation_quantities(logmgr)
    discr.add_instrumentation(logmgr)
    stepper.add_instrumentation(logmgr)

    from pytools.log import IntervalTimer
    vis_timer = IntervalTimer("t_vis", "Time spent visualizing")
    logmgr.add_quantity(vis_timer)

    #from hedge.log import EMFieldGetter, add_em_quantities
    #field_getter = EMFieldGetter(discr, op, lambda: fields)
    #add_em_quantities(logmgr, op, field_getter)

    logmgr.add_watches(
            ["step.max", "t_sim.max",
                #("W_field", "W_el+W_mag"),
                "t_step.max"]
            )

    # timestep loop -------------------------------------------------------
    rhs = op.bind(discr)
    final_time = 10e-9

    if point_getter is not None:
        from os.path import join
        pointfile = open(join(output_dir, "point.txt"), "wt")
        done_dt = False
    try:
        from hedge.timestep import times_and_steps
        from os.path import join
        step_it = times_and_steps(
                final_time=final_time, logmgr=logmgr,
                max_dt_getter=lambda t: op.estimate_timestep(discr,
                    stepper=stepper, t=t, fields=fields))

        for step, t, dt in step_it:
            if step % 10 == 0 and write_output:
                sub_timer = vis_timer.start_sub_timer()
                e, h = op.split_eh(fields)
                visf = vis.make_file(join(output_dir, "cav-%d-%04d") % (order, step))
                vis.add_data(visf,
                        [
                            ("e",
                                discr.convert_volume(e, kind="numpy")),
                            ("h",
                                discr.convert_volume(h, kind="numpy")),],
                        time=t, step=step
                        )
                visf.close()
                sub_timer.stop().submit()

            fields = stepper(fields, t, dt, rhs)
            if point_getter is not None:
                val = point_getter(fields)
                #print val
                if not done_dt:
                    pointfile.write("#%g\n" % dt)
                    done_dt = True
                pointfile.write("%g\n" %val[0])

    finally:
        if write_output:
            vis.close()

        logmgr.close()
        discr.close()

        if point_getter is not None:
            pointfile.close()
예제 #18
0
def test_kv_with_no_charge():
    from random import seed
    seed(0)

    from pyrticle.units import SIUnitsWithNaturalConstants
    units = SIUnitsWithNaturalConstants()

    # discretization setup ----------------------------------------------------
    from hedge.mesh import make_cylinder_mesh
    from hedge.backends import guess_run_context

    rcon = guess_run_context([])

    tube_length = 100 * units.MM
    mesh = make_cylinder_mesh(radius=25 * units.MM,
                              height=tube_length,
                              periodic=True)

    discr = rcon.make_discretization(mesh, order=3)

    dt = discr.dt_factor(units.VACUUM_LIGHT_SPEED()) / 2
    final_time = 1 * units.M / units.VACUUM_LIGHT_SPEED()
    nsteps = int(final_time / dt) + 1
    dt = final_time / nsteps

    # particles setup ---------------------------------------------------------
    from pyrticle.cloud import PicMethod
    from pyrticle.deposition.shape import ShapeFunctionDepositor
    from pyrticle.pusher import MonomialParticlePusher

    method = PicMethod(discr, units, ShapeFunctionDepositor(),
                       MonomialParticlePusher(), 3, 3)

    nparticles = 10000
    cloud_charge = 1e-9 * units.C
    electrons_per_particle = cloud_charge / nparticles / units.EL_CHARGE

    el_energy = 5.2e6 * units.EV
    gamma = el_energy / units.EL_REST_ENERGY()
    beta = (1 - 1 / gamma**2)**0.5

    from pyrticle.distribution import KVZIntervalBeam
    beam = KVZIntervalBeam(units,
                           total_charge=0,
                           p_charge=0,
                           p_mass=electrons_per_particle * units.EL_MASS,
                           radii=2 * [2.5 * units.MM],
                           emittances=2 * [5 * units.MM * units.MRAD],
                           z_length=5 * units.MM,
                           z_pos=10 * units.MM,
                           beta=beta)

    state = method.make_state()
    method.add_particles(state, beam.generate_particles(), nparticles)

    # diagnostics setup -------------------------------------------------------
    from pytools.log import LogManager
    from pyrticle.log import add_beam_quantities, StateObserver
    observer = StateObserver(method, None)
    logmgr = LogManager(mode="w")
    add_beam_quantities(logmgr, observer, axis=0, beam_axis=2)

    from pyrticle.distribution import KVPredictedRadius
    logmgr.add_quantity(
        KVPredictedRadius(dt,
                          beam_v=beta * units.VACUUM_LIGHT_SPEED(),
                          predictor=beam.get_rms_predictor(axis=0),
                          suffix="x_rms"))
    logmgr.add_quantity(
        KVPredictedRadius(dt,
                          beam_v=beta * units.VACUUM_LIGHT_SPEED(),
                          predictor=beam.get_total_predictor(axis=0),
                          suffix="x_total"))

    # timestep loop -----------------------------------------------------------
    vel = method.velocities(state)
    from hedge.tools import join_fields

    def rhs(t, y):
        return join_fields([
            vel,
            0 * vel,
            0,  # drecon
        ])

    from hedge.timestep.runge_kutta import LSRK4TimeStepper
    stepper = LSRK4TimeStepper()
    t = 0

    from pyrticle.cloud import TimesteppablePicState
    ts_state = TimesteppablePicState(method, state)

    for step in xrange(nsteps):
        observer.set_fields_and_state(None, ts_state.state)

        logmgr.tick()

        ts_state = stepper(ts_state, t, dt, rhs)
        method.upkeep(ts_state.state)

        t += dt

    logmgr.tick()

    _, _, err_table = logmgr.get_expr_dataset(
        "(rx_rms-rx_rms_theory)/rx_rms_theory")
    rel_max_rms_error = max(err for step, err in err_table)
    assert rel_max_rms_error < 0.01
예제 #19
0
def main():
    import logging
    logging.basicConfig(level=logging.INFO)

    from hedge.backends import guess_run_context
    rcon = guess_run_context()

    if rcon.is_head_rank:
        if True:
            mesh = make_squaremesh()
        else:
            from hedge.mesh import make_rect_mesh
            mesh = make_rect_mesh(
                boundary_tagger=lambda fvi, el, fn, all_v: ["inflow"],
                max_area=0.1)

        mesh_data = rcon.distribute_mesh(mesh)
    else:
        mesh_data = rcon.receive_mesh()

    from pytools import add_python_path_relative_to_script
    add_python_path_relative_to_script(".")

    for order in [3]:
        from gas_dynamics_initials import UniformMachFlow
        square = UniformMachFlow(gaussian_pulse_at=numpy.array([-2, 2]),
                                 pulse_magnitude=0.003)

        from hedge.models.gas_dynamics import (GasDynamicsOperator,
                                               GammaLawEOS)

        op = GasDynamicsOperator(dimensions=2,
                                 equation_of_state=GammaLawEOS(square.gamma),
                                 mu=square.mu,
                                 prandtl=square.prandtl,
                                 spec_gas_const=square.spec_gas_const,
                                 bc_inflow=square,
                                 bc_outflow=square,
                                 bc_noslip=square,
                                 inflow_tag="inflow",
                                 outflow_tag="outflow",
                                 noslip_tag="noslip")

        discr = rcon.make_discretization(
            mesh_data,
            order=order,
            debug=[
                "cuda_no_plan",
                "cuda_dump_kernels",
                #"dump_dataflow_graph",
                #"dump_optemplate_stages",
                #"dump_dataflow_graph",
                #"dump_op_code"
                #"cuda_no_plan_el_local"
            ],
            default_scalar_type=numpy.float64,
            tune_for=op.op_template(),
            quad_min_degrees={
                "gasdyn_vol": 3 * order,
                "gasdyn_face": 3 * order,
            })

        from hedge.visualization import SiloVisualizer, VtkVisualizer
        #vis = VtkVisualizer(discr, rcon, "shearflow-%d" % order)
        vis = SiloVisualizer(discr, rcon)

        from hedge.timestep.runge_kutta import (LSRK4TimeStepper,
                                                ODE23TimeStepper,
                                                ODE45TimeStepper)
        from hedge.timestep.dumka3 import Dumka3TimeStepper
        #stepper = LSRK4TimeStepper(dtype=discr.default_scalar_type,
        #vector_primitive_factory=discr.get_vector_primitive_factory())

        stepper = ODE23TimeStepper(
            dtype=discr.default_scalar_type,
            rtol=1e-6,
            vector_primitive_factory=discr.get_vector_primitive_factory())
        # Dumka works kind of poorly
        #stepper = Dumka3TimeStepper(dtype=discr.default_scalar_type,
        #rtol=1e-7, pol_index=2,
        #vector_primitive_factory=discr.get_vector_primitive_factory())

        #from hedge.timestep.dumka3 import Dumka3TimeStepper
        #stepper = Dumka3TimeStepper(3, rtol=1e-7)

        # diagnostics setup ---------------------------------------------------
        from pytools.log import LogManager, add_general_quantities, \
                add_simulation_quantities, add_run_info

        logmgr = LogManager("cns-square-sp-%d.dat" % order, "w",
                            rcon.communicator)

        add_run_info(logmgr)
        add_general_quantities(logmgr)
        discr.add_instrumentation(logmgr)
        stepper.add_instrumentation(logmgr)

        from pytools.log import LogQuantity

        class ChangeSinceLastStep(LogQuantity):
            """Records the change of a variable between a time step and the previous
               one"""
            def __init__(self, name="change"):
                LogQuantity.__init__(self, name, "1",
                                     "Change since last time step")

                self.old_fields = 0

            def __call__(self):
                result = discr.norm(fields - self.old_fields)
                self.old_fields = fields
                return result

        #logmgr.add_quantity(ChangeSinceLastStep())

        add_simulation_quantities(logmgr)
        logmgr.add_watches(["step.max", "t_sim.max", "t_step.max"])

        # filter setup ------------------------------------------------------------
        from hedge.discretization import Filter, ExponentialFilterResponseFunction
        mode_filter = Filter(
            discr,
            ExponentialFilterResponseFunction(min_amplification=0.95, order=6))

        # timestep loop -------------------------------------------------------
        fields = square.volume_interpolant(0, discr)

        navierstokes_ex = op.bind(discr)

        max_eigval = [0]

        def rhs(t, q):
            ode_rhs, speed = navierstokes_ex(t, q)
            max_eigval[0] = speed
            return ode_rhs

        rhs(0, fields)

        if rcon.is_head_rank:
            print "---------------------------------------------"
            print "order %d" % order
            print "---------------------------------------------"
            print "#elements=", len(mesh.elements)

        try:
            from hedge.timestep import times_and_steps
            step_it = times_and_steps(
                final_time=1000,
                #max_steps=500,
                logmgr=logmgr,
                max_dt_getter=lambda t: next_dt,
                taken_dt_getter=lambda: taken_dt)

            model_stepper = LSRK4TimeStepper()
            next_dt = op.estimate_timestep(discr,
                                           stepper=model_stepper,
                                           t=0,
                                           max_eigenvalue=max_eigval[0])

            for step, t, dt in step_it:
                #if (step % 10000 == 0): #and step < 950000) or (step % 500 == 0 and step > 950000):
                #if False:
                if step % 5 == 0:
                    visf = vis.make_file("square-%d-%06d" % (order, step))

                    #from pyvisfile.silo import DB_VARTYPE_VECTOR
                    vis.add_data(visf, [
                        ("rho",
                         discr.convert_volume(op.rho(fields), kind="numpy")),
                        ("e", discr.convert_volume(op.e(fields),
                                                   kind="numpy")),
                        ("rho_u",
                         discr.convert_volume(op.rho_u(fields), kind="numpy")),
                        ("u", discr.convert_volume(op.u(fields),
                                                   kind="numpy")),
                    ],
                                 expressions=[
                                     ("p", "(0.4)*(e- 0.5*(rho_u*u))"),
                                 ],
                                 time=t,
                                 step=step)
                    visf.close()

                if stepper.adaptive:
                    fields, t, taken_dt, next_dt = stepper(fields, t, dt, rhs)
                else:
                    taken_dt = dt
                    fields = stepper(fields, t, dt, rhs)
                    dt = op.estimate_timestep(discr,
                                              stepper=model_stepper,
                                              t=0,
                                              max_eigenvalue=max_eigval[0])

                #fields = mode_filter(fields)

        finally:
            vis.close()
            logmgr.save()
            discr.close()