Ejemplo n.º 1
0
def test_lump_rhs(actx_factory, dim, order):
    """Test the inviscid rhs using the non-trivial mass lump case.

    The case is tested against the analytic expressions of the RHS.
    Checks several different orders and refinement levels to check error behavior.
    """
    actx = actx_factory()

    tolerance = 1e-10
    maxxerr = 0.0

    from pytools.convergence import EOCRecorder

    eoc_rec = EOCRecorder()

    for nel_1d in [4, 8, 12]:
        from meshmode.mesh.generation import (
            generate_regular_rect_mesh, )

        mesh = generate_regular_rect_mesh(
            a=(-5, ) * dim,
            b=(5, ) * dim,
            nelements_per_axis=(nel_1d, ) * dim,
        )

        logger.info(f"Number of elements: {mesh.nelements}")

        discr = EagerDGDiscretization(actx, mesh, order=order)
        nodes = thaw(actx, discr.nodes())

        # Init soln with Lump and expected RHS = 0
        center = np.zeros(shape=(dim, ))
        velocity = np.zeros(shape=(dim, ))
        lump = Lump(dim=dim, center=center, velocity=velocity)
        lump_soln = lump(nodes)
        boundaries = {
            BTAG_ALL: PrescribedInviscidBoundary(fluid_solution_func=lump)
        }
        inviscid_rhs = euler_operator(discr,
                                      eos=IdealSingleGas(),
                                      boundaries=boundaries,
                                      cv=lump_soln,
                                      time=0.0)
        expected_rhs = lump.exact_rhs(discr, cv=lump_soln, time=0)

        err_max = discr.norm((inviscid_rhs - expected_rhs).join(), np.inf)
        if err_max > maxxerr:
            maxxerr = err_max

        eoc_rec.add_data_point(1.0 / nel_1d, err_max)
    logger.info(f"Max error: {maxxerr}")

    logger.info(f"Error for (dim,order) = ({dim},{order}):\n" f"{eoc_rec}")

    assert (eoc_rec.order_estimate() >= order - 0.5
            or eoc_rec.max_error() < tolerance)
Ejemplo n.º 2
0
def test_idealsingle_lump(ctx_factory):
    """Test EOS with mass lump.

    Tests that the IdealSingleGas EOS returns
    the correct (uniform) pressure for the Lump
    solution field.
    """
    cl_ctx = ctx_factory()
    queue = cl.CommandQueue(cl_ctx)
    actx = PyOpenCLArrayContext(queue)

    dim = 2
    nel_1d = 4

    from meshmode.mesh.generation import generate_regular_rect_mesh

    mesh = generate_regular_rect_mesh(a=[(0.0, ), (-5.0, )],
                                      b=[(10.0, ), (5.0, )],
                                      n=(nel_1d, ) * dim)

    order = 3
    logger.info(f"Number of elements {mesh.nelements}")

    discr = EagerDGDiscretization(actx, mesh, order=order)
    nodes = thaw(actx, discr.nodes())

    # Init soln with Vortex
    center = np.zeros(shape=(dim, ))
    velocity = np.zeros(shape=(dim, ))
    center[0] = 5
    velocity[0] = 1
    lump = Lump(center=center, velocity=velocity)
    eos = IdealSingleGas()
    lump_soln = lump(0, nodes)

    cv = split_conserved(dim, lump_soln)
    p = eos.pressure(cv)
    exp_p = 1.0
    errmax = discr.norm(p - exp_p, np.inf)

    exp_ke = 0.5 * cv.mass
    ke = eos.kinetic_energy(cv)
    kerr = discr.norm(ke - exp_ke, np.inf)

    te = eos.total_energy(cv, p)
    terr = discr.norm(te - cv.energy, np.inf)

    logger.info(f"lump_soln = {lump_soln}")
    logger.info(f"pressure = {p}")

    assert errmax < 1e-15
    assert kerr < 1e-15
    assert terr < 1e-15
Ejemplo n.º 3
0
def test_idealsingle_lump(ctx_factory, dim):
    """Test IdealSingle EOS with mass lump.

    Tests that the IdealSingleGas EOS returns the correct (uniform) pressure for the
    Lump solution field.
    """
    cl_ctx = ctx_factory()
    queue = cl.CommandQueue(cl_ctx)
    actx = PyOpenCLArrayContext(queue)

    nel_1d = 4

    from meshmode.mesh.generation import generate_regular_rect_mesh

    mesh = generate_regular_rect_mesh(a=(-0.5, ) * dim,
                                      b=(0.5, ) * dim,
                                      nelements_per_axis=(nel_1d, ) * dim)

    order = 3
    logger.info(f"Number of elements {mesh.nelements}")

    discr = EagerDGDiscretization(actx, mesh, order=order)
    from meshmode.dof_array import thaw
    nodes = thaw(actx, discr.nodes())

    # Init soln with Vortex
    center = np.zeros(shape=(dim, ))
    velocity = np.zeros(shape=(dim, ))
    velocity[0] = 1
    lump = Lump(dim=dim, center=center, velocity=velocity)
    eos = IdealSingleGas()
    cv = lump(nodes)

    def inf_norm(x):
        return actx.to_numpy(discr.norm(x, np.inf))

    p = eos.pressure(cv)
    exp_p = 1.0
    errmax = inf_norm(p - exp_p)

    exp_ke = 0.5 * cv.mass
    ke = eos.kinetic_energy(cv)
    kerr = inf_norm(ke - exp_ke)

    te = eos.total_energy(cv, p)
    terr = inf_norm(te - cv.energy)

    logger.info(f"lump_soln = {cv}")
    logger.info(f"pressure = {p}")

    assert errmax < 1e-15
    assert kerr < 1e-15
    assert terr < 1e-15
Ejemplo n.º 4
0
def test_lump_init(ctx_factory):
    """
    Simple test to check that Lump initializer
    creates the expected solution field.
    """
    cl_ctx = ctx_factory()
    queue = cl.CommandQueue(cl_ctx)
    actx = PyOpenCLArrayContext(queue)
    dim = 2
    nel_1d = 4

    from meshmode.mesh.generation import generate_regular_rect_mesh

    mesh = generate_regular_rect_mesh(a=[(0.0, ), (-5.0, )],
                                      b=[(10.0, ), (5.0, )],
                                      n=(nel_1d, ) * dim)

    order = 3
    logger.info(f"Number of elements: {mesh.nelements}")

    discr = EagerDGDiscretization(actx, mesh, order=order)
    nodes = thaw(actx, discr.nodes())

    # Init soln with Vortex
    center = np.zeros(shape=(dim, ))
    velocity = np.zeros(shape=(dim, ))
    center[0] = 5
    velocity[0] = 1
    lump = Lump(center=center, velocity=velocity)
    lump_soln = lump(0, nodes)

    cv = split_conserved(dim, lump_soln)
    p = 0.4 * (cv.energy - 0.5 * np.dot(cv.momentum, cv.momentum) / cv.mass)
    exp_p = 1.0
    errmax = discr.norm(p - exp_p, np.inf)

    logger.info(f"lump_soln = {lump_soln}")
    logger.info(f"pressure = {p}")

    assert errmax < 1e-15
Ejemplo n.º 5
0
def main(ctx_factory=cl.create_some_context,
         snapshot_pattern="y0euler-{step:06d}-{rank:04d}.pkl",
         restart_step=None,
         use_profiling=False,
         use_logmgr=False):
    """Drive the Y0 example."""

    from mpi4py import MPI
    comm = MPI.COMM_WORLD
    rank = 0
    rank = comm.Get_rank()
    nparts = comm.Get_size()
    """logging and profiling"""
    logmgr = initialize_logmgr(use_logmgr,
                               use_profiling,
                               filename="y0euler.sqlite",
                               mode="wu",
                               mpi_comm=comm)

    cl_ctx = ctx_factory()
    if use_profiling:
        queue = cl.CommandQueue(
            cl_ctx, properties=cl.command_queue_properties.PROFILING_ENABLE)
        actx = PyOpenCLProfilingArrayContext(
            queue,
            allocator=cl_tools.MemoryPool(cl_tools.ImmediateAllocator(queue)),
            logmgr=logmgr)
    else:
        queue = cl.CommandQueue(cl_ctx)
        actx = PyOpenCLArrayContext(queue,
                                    allocator=cl_tools.MemoryPool(
                                        cl_tools.ImmediateAllocator(queue)))

    #nviz = 500
    #nrestart = 500
    nviz = 50
    nrestart = 10000000
    current_dt = 1.0e-7
    #t_final = 5.e-7
    t_final = 3e-4

    dim = 2
    order = 1
    exittol = 10000000  # do never exit when comparing to exact solution
    #t_final = 0.001
    current_cfl = 1.0
    vel_init = np.zeros(shape=(dim, ))
    vel_inflow = np.zeros(shape=(dim, ))
    vel_outflow = np.zeros(shape=(dim, ))
    orig = np.zeros(shape=(dim, ))
    #vel[0] = 340.0
    #vel_inflow[0] = 100.0  # m/s
    current_t = 0
    casename = "y0euler"
    constant_cfl = False
    # no internal euler status messages
    nstatus = 1000000000
    checkpoint_t = current_t
    current_step = 0

    # working gas: CO2 #
    #   gamma = 1.289
    #   MW=44.009  g/mol
    #   cp = 37.135 J/mol-K,
    #   rho= 1.977 kg/m^3 @298K
    gamma_CO2 = 1.289
    R_CO2 = 8314.59 / 44.009

    # background
    #   100 Pa
    #   298 K
    #   rho = 1.77619667e-3 kg/m^3
    #   velocity = 0,0,0
    rho_bkrnd = 1.77619667e-3
    pres_bkrnd = 100
    temp_bkrnd = 298
    c_bkrnd = math.sqrt(gamma_CO2 * pres_bkrnd / rho_bkrnd)

    # isentropic shock relations #
    # lab frame, moving shock
    # state 1 is behind (downstream) the shock, state 2 is in front (upstream) of the shock

    mach = 2.0
    pressure_ratio = (2. * gamma_CO2 * mach * mach -
                      (gamma_CO2 - 1.)) / (gamma_CO2 + 1.)
    density_ratio = (gamma_CO2 + 1.) * mach * mach / (
        (gamma_CO2 - 1.) * mach * mach + 2.)
    mach2 = math.sqrt(((gamma_CO2 - 1.) * mach * mach + 2.) /
                      (2. * gamma_CO2 * mach * mach - (gamma_CO2 - 1.)))

    rho1 = rho_bkrnd
    pressure1 = pres_bkrnd
    rho2 = rho1 * density_ratio
    pressure2 = pressure1 * pressure_ratio
    velocity1 = 0.
    velocity2 = -mach * c_bkrnd * (1 / density_ratio - 1)
    c_shkd = math.sqrt(gamma_CO2 * pressure2 / rho2)

    vel_inflow[0] = velocity2

    timestepper = rk4_step
    eos = IdealSingleGas(gamma=gamma_CO2, gas_const=R_CO2)
    bulk_init = Discontinuity(dim=dim,
                              x0=.05,
                              sigma=0.01,
                              rhol=rho2,
                              rhor=rho1,
                              pl=pressure2,
                              pr=pressure1,
                              ul=vel_inflow[0],
                              ur=0.)
    inflow_init = Lump(dim=dim,
                       rho0=rho2,
                       p0=pressure2,
                       center=orig,
                       velocity=vel_inflow,
                       rhoamp=0.0)
    outflow_init = Lump(dim=dim,
                        rho0=rho1,
                        p0=pressure1,
                        center=orig,
                        velocity=vel_outflow,
                        rhoamp=0.0)

    inflow = PrescribedBoundary(inflow_init)
    outflow = PrescribedBoundary(outflow_init)
    wall = AdiabaticSlipBoundary()
    dummy = DummyBoundary()

    # shock capturing parameters
    # sonic conditions
    density_ratio = (gamma_CO2 + 1.) * 1.0 / ((gamma_CO2 - 1.) + 2.)

    density_star = rho1 * density_ratio
    shock_thickness = 20 * 0.001  # on the order of 3 elements, should match what is in mesh generator
    # alpha is ~h/p (spacing/order)
    #alpha_sc = shock_thickness*abs(velocity1-velocity2)*density_star
    alpha_sc = 0.1
    # sigma is ~p^-4
    sigma_sc = -11.0
    # kappa is empirical ...
    kappa_sc = 0.5
    print(
        f"Shock capturing parameters: alpha {alpha_sc}, s0 {sigma_sc}, kappa {kappa_sc}"
    )

    # timestep estimate
    wave_speed = max(mach2 * c_bkrnd, c_shkd + velocity2)
    char_len = 0.001
    area = char_len * char_len / 2
    perimeter = 2 * char_len + math.sqrt(2 * char_len * char_len)
    h = 2 * area / perimeter

    dt_est = 1 / (wave_speed * order * order / h)
    print(f"Time step estimate {dt_est}\n")

    dt_est_visc = 1 / (wave_speed * order * order / h +
                       alpha_sc * order * order * order * order / h / h)
    print(f"Viscous timestep estimate {dt_est_visc}\n")

    from grudge import sym
    #    boundaries = {BTAG_ALL: DummyBoundary}
    boundaries = {
        sym.DTAG_BOUNDARY("Inflow"): inflow,
        sym.DTAG_BOUNDARY("Outflow"): outflow,
        sym.DTAG_BOUNDARY("Wall"): wall
    }

    #local_mesh, global_nelements = create_parallel_grid(comm,
    #get_pseudo_y0_mesh)
    #
    #local_nelements = local_mesh.nelements

    if restart_step is None:
        local_mesh, global_nelements = create_parallel_grid(comm, get_mesh)
        local_nelements = local_mesh.nelements

    else:  # Restart
        with open(snapshot_pattern.format(step=restart_step, rank=rank),
                  "rb") as f:
            restart_data = pickle.load(f)

        local_mesh = restart_data["local_mesh"]
        local_nelements = local_mesh.nelements
        global_nelements = restart_data["global_nelements"]

        assert comm.Get_size() == restart_data["num_parts"]

    if rank == 0:
        logging.info("Making discretization")
    discr = EagerDGDiscretization(actx,
                                  local_mesh,
                                  order=order,
                                  mpi_communicator=comm)
    nodes = thaw(actx, discr.nodes())

    if restart_step is None:
        if rank == 0:
            logging.info("Initializing soln.")
        current_state = bulk_init(0, nodes, eos=eos)
    else:
        current_t = restart_data["t"]
        current_step = restart_step

        current_state = unflatten(
            actx, discr.discr_from_dd("vol"),
            obj_array_vectorize(actx.from_numpy, restart_data["state"]))

    vis_timer = None

    if logmgr:
        logmgr_add_device_name(logmgr, queue)
        logmgr_add_discretization_quantities(logmgr, discr, eos, dim)
        #logmgr_add_package_versions(logmgr)

        logmgr.add_watches([
            "step.max", "t_sim.max", "t_step.max", "min_pressure",
            "max_pressure", "min_temperature", "max_temperature"
        ])

        try:
            logmgr.add_watches(["memory_usage.max"])
        except KeyError:
            pass

        if use_profiling:
            logmgr.add_watches(["pyopencl_array_time.max"])

        vis_timer = IntervalTimer("t_vis", "Time spent visualizing")
        logmgr.add_quantity(vis_timer)

    #visualizer = make_visualizer(discr, discr.order + 3
    #if discr.dim == 2 else discr.order)
    visualizer = make_visualizer(discr, discr.order)

    #    initname = initializer.__class__.__name__
    initname = "pseudoY0"
    eosname = eos.__class__.__name__
    init_message = make_init_message(dim=dim,
                                     order=order,
                                     nelements=local_nelements,
                                     global_nelements=global_nelements,
                                     dt=current_dt,
                                     t_final=t_final,
                                     nstatus=nstatus,
                                     nviz=nviz,
                                     cfl=current_cfl,
                                     constant_cfl=constant_cfl,
                                     initname=initname,
                                     eosname=eosname,
                                     casename=casename)
    if rank == 0:
        logger.info(init_message)

    get_timestep = partial(inviscid_sim_timestep,
                           discr=discr,
                           t=current_t,
                           dt=current_dt,
                           cfl=current_cfl,
                           eos=eos,
                           t_final=t_final,
                           constant_cfl=constant_cfl)

    def my_rhs(t, state):
        #return inviscid_operator(discr, eos=eos, boundaries=boundaries, q=state, t=t)
        return (inviscid_operator(
            discr, q=state, t=t, boundaries=boundaries, eos=eos) +
                artificial_viscosity(discr,
                                     t=t,
                                     r=state,
                                     eos=eos,
                                     boundaries=boundaries,
                                     alpha=alpha_sc,
                                     sigma=sigma_sc,
                                     kappa=kappa_sc))

    def my_checkpoint(step, t, dt, state):

        write_restart = (check_step(step, nrestart)
                         if step != restart_step else False)
        if write_restart is True:
            with open(snapshot_pattern.format(step=step, rank=rank),
                      "wb") as f:
                pickle.dump(
                    {
                        "local_mesh": local_mesh,
                        "state": obj_array_vectorize(actx.to_numpy,
                                                     flatten(state)),
                        "t": t,
                        "step": step,
                        "global_nelements": global_nelements,
                        "num_parts": nparts,
                    }, f)

        #x0=f(time)
        exact_soln = Discontinuity(dim=dim,
                                   x0=.05,
                                   sigma=0.00001,
                                   rhol=rho2,
                                   rhor=rho1,
                                   pl=pressure2,
                                   pr=pressure1,
                                   ul=vel_inflow[0],
                                   ur=0.,
                                   uc=mach * c_bkrnd)

        return sim_checkpoint(discr=discr,
                              visualizer=visualizer,
                              eos=eos,
                              q=state,
                              vizname=casename,
                              step=step,
                              t=t,
                              dt=dt,
                              nstatus=nstatus,
                              nviz=nviz,
                              exittol=exittol,
                              constant_cfl=constant_cfl,
                              comm=comm,
                              vis_timer=vis_timer,
                              overwrite=True,
                              exact_soln=exact_soln,
                              sigma=sigma_sc,
                              kappa=kappa_sc)

    if rank == 0:
        logging.info("Stepping.")

    (current_step, current_t, current_state) = \
        advance_state(rhs=my_rhs, timestepper=timestepper,
                      checkpoint=my_checkpoint,
                      get_timestep=get_timestep, state=current_state,
                      t_final=t_final, t=current_t, istep=current_step,
                      logmgr=logmgr,eos=eos,dim=dim)

    if rank == 0:
        logger.info("Checkpointing final state ...")

    my_checkpoint(current_step,
                  t=current_t,
                  dt=(current_t - checkpoint_t),
                  state=current_state)

    if current_t - t_final < 0:
        raise ValueError("Simulation exited abnormally")

    if logmgr:
        logmgr.close()
    elif use_profiling:
        print(actx.tabulate_profiling_data())
Ejemplo n.º 6
0
def main(ctx_factory=cl.create_some_context):
    cl_ctx = ctx_factory()
    queue = cl.CommandQueue(cl_ctx)
    actx = PyOpenCLArrayContext(queue,
                                allocator=cl_tools.MemoryPool(
                                    cl_tools.ImmediateAllocator(queue)))

    dim = 3
    nel_1d = 16
    order = 3
    exittol = .09
    t_final = 0.01
    current_cfl = 1.0
    vel = np.zeros(shape=(dim, ))
    orig = np.zeros(shape=(dim, ))
    vel[:dim] = 1.0
    current_dt = .001
    current_t = 0
    eos = IdealSingleGas()
    initializer = Lump(numdim=dim, center=orig, velocity=vel)
    casename = "lump"
    boundaries = {BTAG_ALL: PrescribedBoundary(initializer)}
    constant_cfl = False
    nstatus = 1
    nviz = 1
    rank = 0
    checkpoint_t = current_t
    current_step = 0
    timestepper = rk4_step
    box_ll = -5.0
    box_ur = 5.0

    comm = MPI.COMM_WORLD
    rank = comm.Get_rank()

    from meshmode.mesh.generation import generate_regular_rect_mesh
    generate_grid = partial(generate_regular_rect_mesh,
                            a=(box_ll, ) * dim,
                            b=(box_ur, ) * dim,
                            n=(nel_1d, ) * dim)
    local_mesh, global_nelements = create_parallel_grid(comm, generate_grid)
    local_nelements = local_mesh.nelements

    discr = EagerDGDiscretization(actx,
                                  local_mesh,
                                  order=order,
                                  mpi_communicator=comm)
    nodes = thaw(actx, discr.nodes())
    current_state = initializer(0, nodes)

    visualizer = make_visualizer(
        discr, discr.order + 3 if discr.dim == 2 else discr.order)
    initname = initializer.__class__.__name__
    eosname = eos.__class__.__name__
    init_message = make_init_message(dim=dim,
                                     order=order,
                                     nelements=local_nelements,
                                     global_nelements=global_nelements,
                                     dt=current_dt,
                                     t_final=t_final,
                                     nstatus=nstatus,
                                     nviz=nviz,
                                     cfl=current_cfl,
                                     constant_cfl=constant_cfl,
                                     initname=initname,
                                     eosname=eosname,
                                     casename=casename)
    if rank == 0:
        logger.info(init_message)

    get_timestep = partial(inviscid_sim_timestep,
                           discr=discr,
                           t=current_t,
                           dt=current_dt,
                           cfl=current_cfl,
                           eos=eos,
                           t_final=t_final,
                           constant_cfl=constant_cfl)

    def my_rhs(t, state):
        return inviscid_operator(discr,
                                 q=state,
                                 t=t,
                                 boundaries=boundaries,
                                 eos=eos)

    def my_checkpoint(step, t, dt, state):
        return sim_checkpoint(discr,
                              visualizer,
                              eos,
                              q=state,
                              exact_soln=initializer,
                              vizname=casename,
                              step=step,
                              t=t,
                              dt=dt,
                              nstatus=nstatus,
                              nviz=nviz,
                              exittol=exittol,
                              constant_cfl=constant_cfl,
                              comm=comm)

    try:
        (current_step, current_t, current_state) = \
            advance_state(rhs=my_rhs, timestepper=timestepper,
                          checkpoint=my_checkpoint,
                          get_timestep=get_timestep, state=current_state,
                          t=current_t, t_final=t_final)
    except ExactSolutionMismatch as ex:
        current_step = ex.step
        current_t = ex.t
        current_state = ex.state

    #    if current_t != checkpoint_t:
    if rank == 0:
        logger.info("Checkpointing final state ...")
        my_checkpoint(current_step,
                      t=current_t,
                      dt=(current_t - checkpoint_t),
                      state=current_state)

    if current_t - t_final < 0:
        raise ValueError("Simulation exited abnormally")
Ejemplo n.º 7
0
def main(ctx_factory=cl.create_some_context, use_logmgr=True,
         use_overintegration=False,
         use_leap=False, use_profiling=False, casename=None,
         rst_filename=None, actx_class=PyOpenCLArrayContext):
    """Drive the example."""
    cl_ctx = ctx_factory()

    if casename is None:
        casename = "mirgecom"

    from mpi4py import MPI
    comm = MPI.COMM_WORLD
    rank = comm.Get_rank()
    num_parts = comm.Get_size()

    from mirgecom.simutil import global_reduce as _global_reduce
    global_reduce = partial(_global_reduce, comm=comm)

    logmgr = initialize_logmgr(use_logmgr,
        filename=f"{casename}.sqlite", mode="wu", mpi_comm=comm)

    if use_profiling:
        queue = cl.CommandQueue(
            cl_ctx, properties=cl.command_queue_properties.PROFILING_ENABLE)
    else:
        queue = cl.CommandQueue(cl_ctx)

    actx = actx_class(
        queue,
        allocator=cl_tools.MemoryPool(cl_tools.ImmediateAllocator(queue)))

    # timestepping control
    current_step = 0
    if use_leap:
        from leap.rk import RK4MethodBuilder
        timestepper = RK4MethodBuilder("state")
    else:
        timestepper = rk4_step
    t_final = 0.1
    current_cfl = 1.0
    current_dt = .01
    current_t = 0
    constant_cfl = False

    # some i/o frequencies
    nstatus = 1
    nrestart = 5
    nviz = 10
    nhealth = 1

    dim = 3
    rst_path = "restart_data/"
    rst_pattern = (
        rst_path + "{cname}-{step:04d}-{rank:04d}.pkl"
    )
    if rst_filename:  # read the grid from restart data
        rst_filename = f"{rst_filename}-{rank:04d}.pkl"
        from mirgecom.restart import read_restart_data
        restart_data = read_restart_data(actx, rst_filename)
        local_mesh = restart_data["local_mesh"]
        local_nelements = local_mesh.nelements
        global_nelements = restart_data["global_nelements"]
        assert restart_data["num_parts"] == num_parts
    else:  # generate the grid from scratch
        from meshmode.mesh.generation import generate_regular_rect_mesh
        box_ll = -1
        box_ur = 1
        nel_1d = 16
        generate_mesh = partial(generate_regular_rect_mesh, a=(box_ll,)*dim,
                                b=(box_ur,) * dim, nelements_per_axis=(nel_1d,)*dim)
        local_mesh, global_nelements = generate_and_distribute_mesh(comm,
                                                                    generate_mesh)
        local_nelements = local_mesh.nelements

    from grudge.dof_desc import DISCR_TAG_BASE, DISCR_TAG_QUAD
    from meshmode.discretization.poly_element import \
        default_simplex_group_factory, QuadratureSimplexGroupFactory

    order = 1
    discr = EagerDGDiscretization(
        actx, local_mesh,
        discr_tag_to_group_factory={
            DISCR_TAG_BASE: default_simplex_group_factory(
                base_dim=local_mesh.dim, order=order),
            DISCR_TAG_QUAD: QuadratureSimplexGroupFactory(2*order + 1)
        },
        mpi_communicator=comm
    )
    nodes = thaw(discr.nodes(), actx)

    if use_overintegration:
        quadrature_tag = DISCR_TAG_QUAD
    else:
        quadrature_tag = None

    vis_timer = None

    if logmgr:
        logmgr_add_cl_device_info(logmgr, queue)
        logmgr_add_device_memory_usage(logmgr, queue)
        logmgr_add_many_discretization_quantities(logmgr, discr, dim,
                             extract_vars_for_logging, units_for_logging)

        vis_timer = IntervalTimer("t_vis", "Time spent visualizing")
        logmgr.add_quantity(vis_timer)

        logmgr.add_watches([
            ("step.max", "step = {value}, "),
            ("t_sim.max", "sim time: {value:1.6e} s\n"),
            ("min_pressure", "------- P (min, max) (Pa) = ({value:1.9e}, "),
            ("max_pressure",    "{value:1.9e})\n"),
            ("t_step.max", "------- step walltime: {value:6g} s, "),
            ("t_log.max", "log walltime: {value:6g} s")
        ])

    eos = IdealSingleGas()
    gas_model = GasModel(eos=eos)
    vel = np.zeros(shape=(dim,))
    orig = np.zeros(shape=(dim,))
    initializer = Lump(dim=dim, center=orig, velocity=vel, rhoamp=0.0)
    wall = AdiabaticSlipBoundary()
    boundaries = {BTAG_ALL: wall}
    uniform_state = initializer(nodes)
    acoustic_pulse = AcousticPulse(dim=dim, amplitude=1.0, width=.1,
                                   center=orig)
    if rst_filename:
        current_t = restart_data["t"]
        current_step = restart_data["step"]
        current_cv = restart_data["cv"]
        if logmgr:
            from mirgecom.logging_quantities import logmgr_set_time
            logmgr_set_time(logmgr, current_step, current_t)
    else:
        # Set the current state from time 0
        current_cv = acoustic_pulse(x_vec=nodes, cv=uniform_state, eos=eos)

    current_state = make_fluid_state(current_cv, gas_model)

    visualizer = make_visualizer(discr)

    initname = "pulse"
    eosname = eos.__class__.__name__
    init_message = make_init_message(dim=dim, order=order,
                                     nelements=local_nelements,
                                     global_nelements=global_nelements,
                                     dt=current_dt, t_final=t_final, nstatus=nstatus,
                                     nviz=nviz, cfl=current_cfl,
                                     constant_cfl=constant_cfl, initname=initname,
                                     eosname=eosname, casename=casename)
    if rank == 0:
        logger.info(init_message)

    def my_write_viz(step, t, state, dv=None):
        if dv is None:
            dv = eos.dependent_vars(state)
        viz_fields = [("cv", state),
                      ("dv", dv)]
        from mirgecom.simutil import write_visfile
        write_visfile(discr, viz_fields, visualizer, vizname=casename,
                      step=step, t=t, overwrite=True, vis_timer=vis_timer)

    def my_write_restart(step, t, state):
        rst_fname = rst_pattern.format(cname=casename, step=step, rank=rank)
        if rst_fname != rst_filename:
            rst_data = {
                "local_mesh": local_mesh,
                "cv": state,
                "t": t,
                "step": step,
                "order": order,
                "global_nelements": global_nelements,
                "num_parts": num_parts
            }
            from mirgecom.restart import write_restart_file
            write_restart_file(actx, rst_data, rst_fname, comm)

    def my_health_check(pressure):
        health_error = False
        from mirgecom.simutil import check_naninf_local, check_range_local
        if check_naninf_local(discr, "vol", pressure) \
           or check_range_local(discr, "vol", pressure, .8, 1.5):
            health_error = True
            logger.info(f"{rank=}: Invalid pressure data found.")
        return health_error

    def my_pre_step(step, t, dt, state):
        fluid_state = make_fluid_state(state, gas_model)
        dv = fluid_state.dv

        try:

            if logmgr:
                logmgr.tick_before()

            from mirgecom.simutil import check_step
            do_viz = check_step(step=step, interval=nviz)
            do_restart = check_step(step=step, interval=nrestart)
            do_health = check_step(step=step, interval=nhealth)

            if do_health:
                health_errors = global_reduce(my_health_check(dv.pressure), op="lor")
                if health_errors:
                    if rank == 0:
                        logger.info("Fluid solution failed health check.")
                    raise MyRuntimeError("Failed simulation health check.")

            if do_restart:
                my_write_restart(step=step, t=t, state=state)

            if do_viz:
                my_write_viz(step=step, t=t, state=state, dv=dv)

        except MyRuntimeError:
            if rank == 0:
                logger.info("Errors detected; attempting graceful exit.")
            my_write_viz(step=step, t=t, state=state)
            my_write_restart(step=step, t=t, state=state)
            raise

        dt = get_sim_timestep(discr, fluid_state, t, dt, current_cfl, t_final,
                              constant_cfl)
        return state, dt

    def my_post_step(step, t, dt, state):
        # Logmgr needs to know about EOS, dt, dim?
        # imo this is a design/scope flaw
        if logmgr:
            set_dt(logmgr, dt)
            set_sim_state(logmgr, dim, state, eos)
            logmgr.tick_after()
        return state, dt

    def my_rhs(t, state):
        fluid_state = make_fluid_state(cv=state, gas_model=gas_model)
        return euler_operator(discr, state=fluid_state, time=t,
                              boundaries=boundaries,
                              gas_model=gas_model,
                              quadrature_tag=quadrature_tag)

    current_dt = get_sim_timestep(discr, current_state, current_t, current_dt,
                                  current_cfl, t_final, constant_cfl)

    current_step, current_t, current_cv = \
        advance_state(rhs=my_rhs, timestepper=timestepper,
                      pre_step_callback=my_pre_step,
                      post_step_callback=my_post_step, dt=current_dt,
                      state=current_cv, t=current_t, t_final=t_final)

    # Dump the final data
    if rank == 0:
        logger.info("Checkpointing final state ...")
    final_state = make_fluid_state(current_cv, gas_model)
    final_dv = final_state.dv

    my_write_viz(step=current_step, t=current_t, state=current_cv, dv=final_dv)
    my_write_restart(step=current_step, t=current_t, state=current_cv)

    if logmgr:
        logmgr.close()
    elif use_profiling:
        print(actx.tabulate_profiling_data())

    finish_tol = 1e-16
    assert np.abs(current_t - t_final) < finish_tol
Ejemplo n.º 8
0
def main(ctx_factory=cl.create_some_context,
         use_logmgr=True,
         use_leap=False,
         use_profiling=False,
         casename=None,
         rst_filename=None,
         actx_class=PyOpenCLArrayContext):
    """Drive example."""
    cl_ctx = ctx_factory()

    if casename is None:
        casename = "mirgecom"

    from mpi4py import MPI
    comm = MPI.COMM_WORLD
    rank = comm.Get_rank()
    nparts = comm.Get_size()

    from mirgecom.simutil import global_reduce as _global_reduce
    global_reduce = partial(_global_reduce, comm=comm)

    logmgr = initialize_logmgr(use_logmgr,
                               filename=f"{casename}.sqlite",
                               mode="wu",
                               mpi_comm=comm)

    if use_profiling:
        queue = cl.CommandQueue(
            cl_ctx, properties=cl.command_queue_properties.PROFILING_ENABLE)
    else:
        queue = cl.CommandQueue(cl_ctx)

    actx = actx_class(queue,
                      allocator=cl_tools.MemoryPool(
                          cl_tools.ImmediateAllocator(queue)))

    # timestepping control
    if use_leap:
        from leap.rk import RK4MethodBuilder
        timestepper = RK4MethodBuilder("state")
    else:
        timestepper = rk4_step
    t_final = 0.01
    current_cfl = 1.0
    current_dt = .001
    current_t = 0
    current_step = 0
    constant_cfl = False

    # some i/o frequencies
    nstatus = 1
    nhealth = 1
    nrestart = 10
    nviz = 1

    dim = 2

    rst_path = "restart_data/"
    rst_pattern = (rst_path + "{cname}-{step:04d}-{rank:04d}.pkl")
    if rst_filename:  # read the grid from restart data
        rst_filename = f"{rst_filename}-{rank:04d}.pkl"

        from mirgecom.restart import read_restart_data
        restart_data = read_restart_data(actx, rst_filename)
        local_mesh = restart_data["local_mesh"]
        local_nelements = local_mesh.nelements
        global_nelements = restart_data["global_nelements"]
        assert restart_data["num_parts"] == nparts
    else:  # generate the grid from scratch
        box_ll = -5.0
        box_ur = 5.0
        nel_1d = 16
        from meshmode.mesh.generation import generate_regular_rect_mesh
        generate_mesh = partial(generate_regular_rect_mesh,
                                a=(box_ll, ) * dim,
                                b=(box_ur, ) * dim,
                                nelements_per_axis=(nel_1d, ) * dim)
        local_mesh, global_nelements = generate_and_distribute_mesh(
            comm, generate_mesh)
        local_nelements = local_mesh.nelements

    order = 3
    discr = EagerDGDiscretization(actx,
                                  local_mesh,
                                  order=order,
                                  mpi_communicator=comm)
    nodes = thaw(discr.nodes(), actx)

    vis_timer = None

    if logmgr:
        logmgr_add_device_name(logmgr, queue)
        logmgr_add_device_memory_usage(logmgr, queue)
        logmgr_add_many_discretization_quantities(logmgr, discr, dim,
                                                  extract_vars_for_logging,
                                                  units_for_logging)

        vis_timer = IntervalTimer("t_vis", "Time spent visualizing")
        logmgr.add_quantity(vis_timer)

        logmgr.add_watches([
            ("step.max", "step = {value}, "),
            ("t_sim.max", "sim time: {value:1.6e} s\n"),
            ("min_pressure", "------- P (min, max) (Pa) = ({value:1.9e}, "),
            ("max_pressure", "{value:1.9e})\n"),
            ("t_step.max", "------- step walltime: {value:6g} s, "),
            ("t_log.max", "log walltime: {value:6g} s")
        ])

    # soln setup, init
    eos = IdealSingleGas()
    vel = np.zeros(shape=(dim, ))
    orig = np.zeros(shape=(dim, ))
    vel[:dim] = 1.0
    initializer = Lump(dim=dim, center=orig, velocity=vel)
    from mirgecom.gas_model import GasModel, make_fluid_state
    gas_model = GasModel(eos=eos)

    def boundary_solution(discr, btag, gas_model, state_minus, **kwargs):
        actx = state_minus.array_context
        bnd_discr = discr.discr_from_dd(btag)
        nodes = thaw(bnd_discr.nodes(), actx)
        return make_fluid_state(
            initializer(x_vec=nodes, eos=gas_model.eos, **kwargs), gas_model)

    boundaries = {
        BTAG_ALL:
        PrescribedFluidBoundary(boundary_state_func=boundary_solution)
    }

    if rst_filename:
        current_t = restart_data["t"]
        current_step = restart_data["step"]
        current_cv = restart_data["cv"]
        if logmgr:
            from mirgecom.logging_quantities import logmgr_set_time
            logmgr_set_time(logmgr, current_step, current_t)
    else:
        # Set the current state from time 0
        current_cv = initializer(nodes)
    current_state = make_fluid_state(current_cv, gas_model)

    visualizer = make_visualizer(discr)
    initname = initializer.__class__.__name__
    eosname = eos.__class__.__name__
    init_message = make_init_message(dim=dim,
                                     order=order,
                                     nelements=local_nelements,
                                     global_nelements=global_nelements,
                                     dt=current_dt,
                                     t_final=t_final,
                                     nstatus=nstatus,
                                     nviz=nviz,
                                     cfl=current_cfl,
                                     constant_cfl=constant_cfl,
                                     initname=initname,
                                     eosname=eosname,
                                     casename=casename)
    if rank == 0:
        logger.info(init_message)

    def my_write_viz(step, t, state, dv=None, exact=None, resid=None):
        if dv is None:
            dv = eos.dependent_vars(state)
        if exact is None:
            exact = initializer(x_vec=nodes, eos=eos, time=t)
        if resid is None:
            resid = state - exact
        viz_fields = [("cv", state), ("dv", dv), ("exact", exact),
                      ("residual", resid)]
        from mirgecom.simutil import write_visfile
        write_visfile(discr,
                      viz_fields,
                      visualizer,
                      vizname=casename,
                      step=step,
                      t=t,
                      overwrite=True,
                      vis_timer=vis_timer)

    def my_write_restart(state, step, t):
        rst_fname = rst_pattern.format(cname=casename, step=step, rank=rank)
        if rst_fname != rst_filename:
            rst_data = {
                "local_mesh": local_mesh,
                "state": state,
                "t": t,
                "step": step,
                "order": order,
                "global_nelements": global_nelements,
                "num_parts": nparts
            }
            from mirgecom.restart import write_restart_file
            write_restart_file(actx, rst_data, rst_fname, comm)

    def my_health_check(dv, state, exact):
        health_error = False
        from mirgecom.simutil import check_naninf_local, check_range_local
        if check_naninf_local(discr, "vol", dv.pressure) \
           or check_range_local(discr, "vol", dv.pressure, .9999999999, 1.00000001):
            health_error = True
            logger.info(f"{rank=}: Invalid pressure data found.")

        from mirgecom.simutil import compare_fluid_solutions
        component_errors = compare_fluid_solutions(discr, state, exact)
        exittol = .09
        if max(component_errors) > exittol:
            health_error = True
            if rank == 0:
                logger.info("Solution diverged from exact soln.")

        return health_error

    def my_pre_step(step, t, dt, state):
        fluid_state = make_fluid_state(state, gas_model)
        dv = fluid_state.dv
        try:
            exact = None

            if logmgr:
                logmgr.tick_before()

            from mirgecom.simutil import check_step
            do_viz = check_step(step=step, interval=nviz)
            do_restart = check_step(step=step, interval=nrestart)
            do_health = check_step(step=step, interval=nhealth)
            do_status = check_step(step=step, interval=nstatus)

            if do_health:
                exact = initializer(x_vec=nodes, eos=eos, time=t)
                health_errors = global_reduce(my_health_check(dv=dv,
                                                              state=state,
                                                              exact=exact),
                                              op="lor")
                if health_errors:
                    if rank == 0:
                        logger.info("Fluid solution failed health check.")
                    raise MyRuntimeError("Failed solution health check.")

            if do_restart:
                my_write_restart(step=step, t=t, state=state)

            if do_viz:
                if exact is None:
                    exact = initializer(x_vec=nodes, eos=eos, time=t)
                resid = state - exact
                my_write_viz(step=step,
                             t=t,
                             dv=dv,
                             state=state,
                             exact=exact,
                             resid=resid)

            if do_status:
                if exact is None:
                    exact = initializer(x_vec=nodes, eos=eos, time=t)
                from mirgecom.simutil import compare_fluid_solutions
                component_errors = compare_fluid_solutions(discr, state, exact)
                status_msg = ("------- errors=" +
                              ", ".join("%.3g" % en
                                        for en in component_errors))
                if rank == 0:
                    logger.info(status_msg)

        except MyRuntimeError:
            if rank == 0:
                logger.info("Errors detected; attempting graceful exit.")
            my_write_viz(step=step, t=t, state=state)
            my_write_restart(step=step, t=t, state=state)
            raise

        dt = get_sim_timestep(discr, fluid_state, t, dt, current_cfl, t_final,
                              constant_cfl)
        return state, dt

    def my_post_step(step, t, dt, state):
        # Logmgr needs to know about EOS, dt, dim?
        # imo this is a design/scope flaw
        if logmgr:
            set_dt(logmgr, dt)
            set_sim_state(logmgr, dim, state, eos)
            logmgr.tick_after()
        return state, dt

    def my_rhs(t, state):
        fluid_state = make_fluid_state(state, gas_model)
        return euler_operator(discr,
                              state=fluid_state,
                              time=t,
                              boundaries=boundaries,
                              gas_model=gas_model)

    current_dt = get_sim_timestep(discr, current_state, current_t, current_dt,
                                  current_cfl, t_final, constant_cfl)

    current_step, current_t, current_cv = \
        advance_state(rhs=my_rhs, timestepper=timestepper,
                      pre_step_callback=my_pre_step,
                      post_step_callback=my_post_step, dt=current_dt,
                      state=current_state.cv, t=current_t, t_final=t_final)

    # Dump the final data
    if rank == 0:
        logger.info("Checkpointing final state ...")

    current_state = make_fluid_state(current_cv, gas_model)
    final_dv = current_state.dv
    final_exact = initializer(x_vec=nodes, eos=eos, time=current_t)
    final_resid = current_state.cv - final_exact
    my_write_viz(step=current_step,
                 t=current_t,
                 state=current_state.cv,
                 dv=final_dv,
                 exact=final_exact,
                 resid=final_resid)
    my_write_restart(step=current_step, t=current_t, state=current_state.cv)

    if logmgr:
        logmgr.close()
    elif use_profiling:
        print(actx.tabulate_profiling_data())

    finish_tol = 1e-16
    time_err = current_t - t_final
    if np.abs(time_err) > finish_tol:
        raise ValueError(
            f"Simulation did not finish at expected time {time_err=}.")
Ejemplo n.º 9
0
def test_slipwall_identity(actx_factory, dim):
    """Identity test - check for the expected boundary solution.

    Checks that the slipwall implements the expected boundary solution:
    rho_plus = rho_minus
    v_plus = v_minus - 2 * (n_hat . v_minus) * n_hat
    mom_plus = rho_plus * v_plus
    E_plus = E_minus
    """
    actx = actx_factory()

    nel_1d = 4

    from meshmode.mesh.generation import generate_regular_rect_mesh

    mesh = generate_regular_rect_mesh(a=(-0.5, ) * dim,
                                      b=(0.5, ) * dim,
                                      nelements_per_axis=(nel_1d, ) * dim)

    order = 3
    discr = EagerDGDiscretization(actx, mesh, order=order)
    nodes = thaw(actx, discr.nodes())
    eos = IdealSingleGas()
    orig = np.zeros(shape=(dim, ))
    nhat = thaw(actx, discr.normal(BTAG_ALL))

    logger.info(f"Number of {dim}d elems: {mesh.nelements}")

    # for velocity going along each direction
    for vdir in range(dim):
        vel = np.zeros(shape=(dim, ))
        # for velocity directions +1, and -1
        for parity in [1.0, -1.0]:
            vel[vdir] = parity  # Check incoming normal
            initializer = Lump(dim=dim, center=orig, velocity=vel, rhoamp=0.0)
            wall = AdiabaticSlipBoundary()

            uniform_state = initializer(nodes)
            from functools import partial
            bnd_norm = partial(discr.norm, p=np.inf, dd=BTAG_ALL)

            bnd_pair = wall.boundary_pair(discr,
                                          btag=BTAG_ALL,
                                          eos=eos,
                                          cv=uniform_state)

            # check that mass and energy are preserved
            mass_resid = bnd_pair.int.mass - bnd_pair.ext.mass
            mass_err = bnd_norm(mass_resid)
            assert mass_err == 0.0

            energy_resid = bnd_pair.int.energy - bnd_pair.ext.energy
            energy_err = bnd_norm(energy_resid)
            assert energy_err == 0.0

            # check that exterior momentum term is mom_interior - 2 * mom_normal
            mom_norm_comp = np.dot(bnd_pair.int.momentum, nhat)
            mom_norm = nhat * mom_norm_comp
            expected_mom_ext = bnd_pair.int.momentum - 2.0 * mom_norm
            mom_resid = bnd_pair.ext.momentum - expected_mom_ext
            mom_err = bnd_norm(mom_resid)

            assert mom_err == 0.0
Ejemplo n.º 10
0
def test_lump_rhs(actx_factory, dim, order, use_overintegration):
    """Test the inviscid rhs using the non-trivial mass lump case.

    The case is tested against the analytic expressions of the RHS.
    Checks several different orders and refinement levels to check error behavior.
    """
    actx = actx_factory()

    tolerance = 1e-10
    maxxerr = 0.0

    from pytools.convergence import EOCRecorder

    eoc_rec = EOCRecorder()

    for nel_1d in [4, 8, 12]:
        from meshmode.mesh.generation import (
            generate_regular_rect_mesh,
        )

        mesh = generate_regular_rect_mesh(
            a=(-5,) * dim, b=(5,) * dim, nelements_per_axis=(nel_1d,) * dim,
        )

        logger.info(f"Number of elements: {mesh.nelements}")

        from grudge.dof_desc import DISCR_TAG_BASE, DISCR_TAG_QUAD
        from meshmode.discretization.poly_element import \
            default_simplex_group_factory, QuadratureSimplexGroupFactory

        discr = EagerDGDiscretization(
            actx, mesh,
            discr_tag_to_group_factory={
                DISCR_TAG_BASE: default_simplex_group_factory(
                    base_dim=dim, order=order),
                DISCR_TAG_QUAD: QuadratureSimplexGroupFactory(2*order + 1)
            }
        )

        if use_overintegration:
            quadrature_tag = DISCR_TAG_QUAD
        else:
            quadrature_tag = None

        nodes = thaw(discr.nodes(), actx)

        # Init soln with Lump and expected RHS = 0
        center = np.zeros(shape=(dim,))
        velocity = np.zeros(shape=(dim,))
        lump = Lump(dim=dim, center=center, velocity=velocity)
        lump_soln = lump(nodes)
        gas_model = GasModel(eos=IdealSingleGas())
        fluid_state = make_fluid_state(lump_soln, gas_model)

        def _lump_boundary(discr, btag, gas_model, state_minus, **kwargs):
            actx = state_minus.array_context
            bnd_discr = discr.discr_from_dd(btag)
            nodes = thaw(bnd_discr.nodes(), actx)
            return make_fluid_state(lump(x_vec=nodes, cv=state_minus, **kwargs),
                                    gas_model)

        boundaries = {
            BTAG_ALL: PrescribedFluidBoundary(boundary_state_func=_lump_boundary)
        }

        inviscid_rhs = euler_operator(
            discr, state=fluid_state, gas_model=gas_model, boundaries=boundaries,
            time=0.0, quadrature_tag=quadrature_tag
        )
        expected_rhs = lump.exact_rhs(discr, cv=lump_soln, time=0)

        err_max = max_component_norm(discr, inviscid_rhs-expected_rhs, np.inf)
        if err_max > maxxerr:
            maxxerr = err_max

        eoc_rec.add_data_point(1.0 / nel_1d, err_max)
    logger.info(f"Max error: {maxxerr}")

    logger.info(
        f"Error for (dim,order) = ({dim},{order}):\n"
        f"{eoc_rec}"
    )

    assert (
        eoc_rec.order_estimate() >= order - 0.5
        or eoc_rec.max_error() < tolerance
    )
Ejemplo n.º 11
0
def main(ctx_factory=cl.create_some_context, use_leap=False):
    """Drive the example."""
    cl_ctx = ctx_factory()
    queue = cl.CommandQueue(cl_ctx)
    actx = PyOpenCLArrayContext(queue,
                                allocator=cl_tools.MemoryPool(
                                    cl_tools.ImmediateAllocator(queue)))

    logger = logging.getLogger(__name__)

    dim = 2
    nel_1d = 16
    order = 1
    exittol = 2e-2
    exittol = 100.0
    t_final = 0.1
    current_cfl = 1.0
    vel = np.zeros(shape=(dim, ))
    orig = np.zeros(shape=(dim, ))
    #    vel[:dim] = 1.0
    current_dt = .01
    current_t = 0
    eos = IdealSingleGas()
    initializer = Lump(dim=dim, center=orig, velocity=vel, rhoamp=0.0)
    casename = "pulse"
    boundaries = {BTAG_ALL: PrescribedBoundary(initializer)}
    wall = AdiabaticSlipBoundary()
    boundaries = {BTAG_ALL: wall}
    constant_cfl = False
    nstatus = 10
    nviz = 10
    rank = 0
    checkpoint_t = current_t
    current_step = 0
    if use_leap:
        from leap.rk import RK4MethodBuilder
        timestepper = RK4MethodBuilder("state")
    else:
        timestepper = rk4_step
    box_ll = -0.5
    box_ur = 0.5

    from mpi4py import MPI
    comm = MPI.COMM_WORLD
    nproc = comm.Get_size()
    rank = comm.Get_rank()
    num_parts = nproc

    from meshmode.mesh.generation import generate_regular_rect_mesh
    if num_parts > 1:
        generate_mesh = partial(generate_regular_rect_mesh,
                                a=(box_ll, ) * dim,
                                b=(box_ur, ) * dim,
                                nelements_per_axis=(nel_1d, ) * dim)
        local_mesh, global_nelements = generate_and_distribute_mesh(
            comm, generate_mesh)
    else:
        local_mesh = generate_regular_rect_mesh(a=(box_ll, ) * dim,
                                                b=(box_ur, ) * dim,
                                                nelements_per_axis=(nel_1d, ) *
                                                dim)
        global_nelements = local_mesh.nelements
    local_nelements = local_mesh.nelements

    discr = EagerDGDiscretization(actx,
                                  local_mesh,
                                  order=order,
                                  mpi_communicator=comm)
    nodes = thaw(actx, discr.nodes())
    uniform_state = initializer(nodes)
    acoustic_pulse = AcousticPulse(dim=dim,
                                   amplitude=1.0,
                                   width=.1,
                                   center=orig)
    current_state = acoustic_pulse(x_vec=nodes, cv=uniform_state, eos=eos)

    visualizer = make_visualizer(discr)

    initname = "pulse"
    eosname = eos.__class__.__name__
    init_message = make_init_message(dim=dim,
                                     order=order,
                                     nelements=local_nelements,
                                     global_nelements=global_nelements,
                                     dt=current_dt,
                                     t_final=t_final,
                                     nstatus=nstatus,
                                     nviz=nviz,
                                     cfl=current_cfl,
                                     constant_cfl=constant_cfl,
                                     initname=initname,
                                     eosname=eosname,
                                     casename=casename)
    if rank == 0:
        logger.info(init_message)

    get_timestep = partial(inviscid_sim_timestep,
                           discr=discr,
                           t=current_t,
                           dt=current_dt,
                           cfl=current_cfl,
                           eos=eos,
                           t_final=t_final,
                           constant_cfl=constant_cfl)

    def my_rhs(t, state):
        return euler_operator(discr,
                              cv=state,
                              t=t,
                              boundaries=boundaries,
                              eos=eos)

    def my_checkpoint(step, t, dt, state):
        return sim_checkpoint(discr,
                              visualizer,
                              eos,
                              cv=state,
                              vizname=casename,
                              step=step,
                              t=t,
                              dt=dt,
                              nstatus=nstatus,
                              nviz=nviz,
                              exittol=exittol,
                              constant_cfl=constant_cfl,
                              comm=comm)

    try:
        (current_step, current_t, current_state) = \
            advance_state(rhs=my_rhs, timestepper=timestepper,
                checkpoint=my_checkpoint,
                get_timestep=get_timestep, state=current_state,
                t=current_t, t_final=t_final)
    except ExactSolutionMismatch as ex:
        current_step = ex.step
        current_t = ex.t
        current_state = ex.state

    #    if current_t != checkpoint_t:
    if rank == 0:
        logger.info("Checkpointing final state ...")
    my_checkpoint(current_step,
                  t=current_t,
                  dt=(current_t - checkpoint_t),
                  state=current_state)

    if current_t - t_final < 0:
        raise ValueError("Simulation exited abnormally")