示例#1
0
def main():
    import logging
    logging.basicConfig(level=logging.INFO)

    from grudge.backends import guess_run_context
    rcon = guess_run_context()

    if rcon.is_head_rank:
        if True:
            mesh = make_squaremesh()
        else:
            from grudge.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 grudge.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.sym_operator(),
            quad_min_degrees={
                "gasdyn_vol": 3 * order,
                "gasdyn_face": 3 * order,
            })

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

        from grudge.timestep.runge_kutta import (LSRK4TimeStepper,
                                                 ODE23TimeStepper,
                                                 ODE45TimeStepper)
        from grudge.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 grudge.timestep.dumka3 import Dumka3TimeStepper
        #stepper = Dumka3TimeStepper(3, rtol=1e-7)

        # diagnostics setup ---------------------------------------------------
        from logpyle 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 logpyle 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 grudge.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 grudge.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()
示例#2
0
                    extra_fields = []

                visf = vis.make_file("fld-%04d" % step)
                vis.add_data(visf, [
                    ("u", u),
                ] + extra_fields,
                             time=t,
                             step=step)
                visf.close()

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

        if isinstance(case, ExactTestCase):
            assert discr.norm(u, 1) < 50

    finally:
        if write_output:
            vis.close()

        logmgr.save()


if __name__ == "__main__":
    main()


# entry points for py.test ----------------------------------------------------
@mark_test.long
def test_stability():
    main(write_output=False)
示例#3
0
def main():
    from grudge.backends import guess_run_context
    rcon = guess_run_context(
        #["cuda"]
    )

    from grudge.tools import EOCRecorder, to_obj_array
    eoc_rec = EOCRecorder()

    def boundary_tagger(vertices, el, face_nr, all_v):
        return ["inflow"]

    if rcon.is_head_rank:
        from grudge.mesh import make_rect_mesh, \
                               make_centered_regular_rect_mesh
        #mesh = make_rect_mesh((0,0), (10,1), max_area=0.01)
        refine = 1
        mesh = make_centered_regular_rect_mesh(
            (0, 0),
            (10, 1),
            n=(20, 4),
            #periodicity=(True, False),
            post_refine_factor=refine,
            boundary_tagger=boundary_tagger)
        mesh_data = rcon.distribute_mesh(mesh)
    else:
        mesh_data = rcon.receive_mesh()

    for order in [3]:
        discr = rcon.make_discretization(mesh_data,
                                         order=order,
                                         default_scalar_type=numpy.float64)

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

        shearflow = SteadyShearFlow()
        fields = shearflow.volume_interpolant(0, discr)
        gamma, mu, prandtl, spec_gas_const = shearflow.properties()

        from grudge.models.gas_dynamics import GasDynamicsOperator
        op = GasDynamicsOperator(dimensions=2,
                                 gamma=gamma,
                                 mu=mu,
                                 prandtl=prandtl,
                                 spec_gas_const=spec_gas_const,
                                 bc_inflow=shearflow,
                                 bc_outflow=shearflow,
                                 bc_noslip=shearflow,
                                 inflow_tag="inflow",
                                 outflow_tag="outflow",
                                 noslip_tag="noslip")

        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

        # needed to get first estimate of maximum eigenvalue
        rhs(0, fields)

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

        from grudge.timestep import RK4TimeStepper
        stepper = RK4TimeStepper()

        # diagnostics setup ---------------------------------------------------
        from logpyle import LogManager, add_general_quantities, \
                add_simulation_quantities, add_run_info

        logmgr = LogManager("navierstokes-cpu-%d-%d.dat" % (order, refine),
                            "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 -------------------------------------------------------
        try:
            from grudge.timestep import times_and_steps
            step_it = times_and_steps(
                final_time=0.3,
                #max_steps=500,
                logmgr=logmgr,
                max_dt_getter=lambda t: op.estimate_timestep(
                    discr, stepper=stepper, t=t, max_eigenvalue=max_eigval[0]))

            for step, t, dt in step_it:
                if step % 10 == 0:
                    #if False:
                    visf = vis.make_file("shearflow-%d-%04d" % (order, step))

                    #true_fields = shearflow.volume_interpolant(t, discr)

                    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")),

                            #("true_rho", discr.convert_volume(op.rho(true_fields), kind="numpy")),
                            #("true_e", discr.convert_volume(op.e(true_fields), kind="numpy")),
                            #("true_rho_u", discr.convert_volume(op.rho_u(true_fields), kind="numpy")),
                            #("true_u", discr.convert_volume(op.u(true_fields), kind="numpy")),
                        ],
                        expressions=[
                            #("diff_rho", "rho-true_rho"),
                            #("diff_e", "e-true_e"),
                            #("diff_rho_u", "rho_u-true_rho_u", DB_VARTYPE_VECTOR),
                            ("p", "0.4*(e- 0.5*(rho_u*u))"),
                        ],
                        time=t,
                        step=step)
                    visf.close()

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

            true_fields = shearflow.volume_interpolant(t, discr)
            l2_error = discr.norm(op.u(fields) - op.u(true_fields))
            eoc_rec.add_data_point(order, l2_error)
            print()
            print(eoc_rec.pretty_print("P.Deg.", "L2 Error"))

            logmgr.set_constant("l2_error", l2_error)

        finally:
            vis.close()
            logmgr.save()
            discr.close()
示例#4
0
def main():
    from grudge.backends import guess_run_context
    rcon = guess_run_context()

    if rcon.is_head_rank:
        mesh = make_nacamesh()
        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 [4]:
        from gas_dynamics_initials import UniformMachFlow
        uniform_flow = UniformMachFlow()

        from grudge.models.gas_dynamics import GasDynamicsOperator, GammaLawEOS
        op = GasDynamicsOperator(dimensions=2,
                                 equation_of_state=GammaLawEOS(
                                     uniform_flow.gamma),
                                 prandtl=uniform_flow.prandtl,
                                 spec_gas_const=uniform_flow.spec_gas_const,
                                 mu=uniform_flow.mu,
                                 bc_inflow=uniform_flow,
                                 bc_outflow=uniform_flow,
                                 bc_noslip=uniform_flow,
                                 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_optemplate_stages",
                #"dump_dataflow_graph",
                #"print_op_code"
            ],
            default_scalar_type=numpy.float32,
            tune_for=op.sym_operator())

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

        fields = uniform_flow.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))

        from grudge.timestep.runge_kutta import \
                ODE23TimeStepper, LSRK4TimeStepper
        stepper = ODE23TimeStepper(
            dtype=discr.default_scalar_type,
            rtol=1e-6,
            vector_primitive_factory=discr.get_vector_primitive_factory())
        #stepper = LSRK4TimeStepper(dtype=discr.default_scalar_type)

        # diagnostics setup ---------------------------------------------------
        from logpyle import LogManager, add_general_quantities, \
                add_simulation_quantities, add_run_info

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

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

        from logpyle 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())

        # filter setup-------------------------------------------------------------
        from grudge.discretization import Filter, ExponentialFilterResponseFunction
        mode_filter = Filter(
            discr,
            ExponentialFilterResponseFunction(min_amplification=0.9, order=4))
        # timestep loop -------------------------------------------------------

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

        try:
            from grudge.timestep import times_and_steps
            step_it = times_and_steps(
                final_time=200,
                #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 % 10 == 0:
                    visf = vis.make_file("naca-%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")),

                            #("true_rho", op.rho(true_fields)),
                            #("true_e", op.e(true_fields)),
                            #("true_rho_u", op.rho_u(true_fields)),
                            #("true_u", op.u(true_fields)),

                            #("rhs_rho", discr.convert_volume(op.rho(rhs_fields), kind="numpy")),
                            #("rhs_e", discr.convert_volume(op.e(rhs_fields), kind="numpy")),
                            #("rhs_rho_u", discr.convert_volume(op.rho_u(rhs_fields), kind="numpy")),
                        ],
                        expressions=[
                            #("diff_rho", "rho-true_rho"),
                            #("diff_e", "e-true_e"),
                            #("diff_rho_u", "rho_u-true_rho_u", DB_VARTYPE_VECTOR),
                            ("p", "(0.4)*(e- 0.5*(rho_u*u))"),
                        ],
                        time=t,
                        step=step)
                    visf.close()

                fields, t, taken_dt, next_dt = stepper(fields, t, dt, rhs)
                fields = mode_filter(fields)

        finally:
            vis.close()
            logmgr.save()
            discr.close()
示例#5
0
def main():
    from grudge.backends import guess_run_context
    rcon = guess_run_context(["cuda", "mpi"])

    if rcon.is_head_rank:
        mesh = make_wingmesh()
        #from grudge.mesh import make_rect_mesh
        #mesh = make_rect_mesh(
        #       boundary_tagger=lambda fvi, el, fn, all_v: ["inflow"])
        mesh_data = rcon.distribute_mesh(mesh)
    else:
        mesh_data = rcon.receive_mesh()

    for order in [3]:
        from pytools import add_python_path_relative_to_script
        add_python_path_relative_to_script("..")

        from gas_dynamics_initials import UniformMachFlow
        wing = UniformMachFlow(angle_of_attack=0)

        from grudge.models.gas_dynamics import GasDynamicsOperator
        op = GasDynamicsOperator(dimensions=3,
                                 gamma=wing.gamma,
                                 mu=wing.mu,
                                 prandtl=wing.prandtl,
                                 spec_gas_const=wing.spec_gas_const,
                                 bc_inflow=wing,
                                 bc_outflow=wing,
                                 bc_noslip=wing,
                                 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",
                #"print_op_code"
                "cuda_no_metis",
            ],
            default_scalar_type=numpy.float64,
            tune_for=op.sym_operator())

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

        fields = wing.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))

        from grudge.timestep import RK4TimeStepper
        stepper = RK4TimeStepper()

        # diagnostics setup ---------------------------------------------------
        from logpyle import LogManager, add_general_quantities, \
                add_simulation_quantities, add_run_info

        logmgr = LogManager("navierstokes-%d.dat" % order, "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 -------------------------------------------------------
        try:
            from grudge.timestep import times_and_steps
            step_it = times_and_steps(
                final_time=200,
                #max_steps=500,
                logmgr=logmgr,
                max_dt_getter=lambda t: 0.6 * op.estimate_timestep(
                    discr, stepper=stepper, t=t, max_eigenvalue=max_eigval[0]))

            for step, t, dt in step_it:
                if step % 200 == 0:
                    #if False:
                    visf = vis.make_file("wing-%d-%06d" % (order, step))

                    #rhs_fields = rhs(t, fields)

                    from pyvisfile.silo import DB_VARTYPE_VECTOR
                    from grudge.discretization import ones_on_boundary
                    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")),

                            #("rhs_rho", discr.convert_volume(op.rho(rhs_fields), kind="numpy")),
                            #("rhs_e", discr.convert_volume(op.e(rhs_fields), kind="numpy")),
                            #("rhs_rho_u", discr.convert_volume(op.rho_u(rhs_fields), kind="numpy")),
                        ],
                        expressions=[
                            ("p", "(0.4)*(e- 0.5*(rho_u*u))"),
                        ],
                        time=t,
                        step=step)
                    visf.close()

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

        finally:
            vis.close()
            logmgr.save()
            discr.close()
示例#6
0
def main():
    from grudge.backends import guess_run_context
    rcon = guess_run_context(["cuda"])

    if rcon.is_head_rank:
        mesh = make_boxmesh()
        #from grudge.mesh import make_rect_mesh
        #mesh = make_rect_mesh(
        #       boundary_tagger=lambda fvi, el, fn, all_v: ["inflow"])
        mesh_data = rcon.distribute_mesh(mesh)
    else:
        mesh_data = rcon.receive_mesh()

    for order in [3]:
        from pytools import add_python_path_relative_to_script
        add_python_path_relative_to_script("..")

        from gas_dynamics_initials import UniformMachFlow
        box = UniformMachFlow(angle_of_attack=0)

        from grudge.models.gas_dynamics import GasDynamicsOperator
        op = GasDynamicsOperator(dimensions=3,
                gamma=box.gamma, mu=box.mu,
                prandtl=box.prandtl, spec_gas_const=box.spec_gas_const,
                bc_inflow=box, bc_outflow=box, bc_noslip=box,
                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",
                            #"print_op_code",
                            "cuda_no_plan_el_local",
                            ],
                        default_scalar_type=numpy.float32,
                        tune_for=op.sym_operator())

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

        fields = box.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))

        from grudge.timestep import RK4TimeStepper
        stepper = RK4TimeStepper()

        # diagnostics setup ---------------------------------------------------
        from logpyle import LogManager, add_general_quantities, \
                add_simulation_quantities, add_run_info

        logmgr = LogManager("navierstokes-%d.dat" % order, "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"])

        from logpyle 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())

        # timestep loop -------------------------------------------------------
        try:
            from grudge.timestep import times_and_steps
            step_it = times_and_steps(
                    final_time=200,
                    #max_steps=500,
                    logmgr=logmgr,
                    max_dt_getter=lambda t: op.estimate_timestep(discr,
                        stepper=stepper, t=t, max_eigenvalue=max_eigval[0]))

            for step, t, dt in step_it:
                if step % 200 == 0:
                #if False:
                    visf = vis.make_file("box-%d-%06d" % (order, step))

                    #rhs_fields = rhs(t, fields)

                    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")),

                                # ("rhs_rho", discr.convert_volume(
                                #     op.rho(rhs_fields), kind="numpy")),
                                # ("rhs_e", discr.convert_volume(
                                #     op.e(rhs_fields), kind="numpy")),
                                # ("rhs_rho_u", discr.convert_volume(
                                #     op.rho_u(rhs_fields), kind="numpy")),
                                ],
                            expressions=[
                                ("p", "(0.4)*(e- 0.5*(rho_u*u))"),
                                ],
                            time=t, step=step
                            )
                    visf.close()

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

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