def get_viscous_timestep(discr, state):
"""Routine returns the the node-local maximum stable viscous timestep.
Parameters
----------
discr: grudge.eager.EagerDGDiscretization
the discretization to use
state: :class:`~mirgecom.gas_model.FluidState`
Full fluid conserved and thermal state
Returns
-------
:class:`~meshmode.dof_array.DOFArray`
The maximum stable timestep at each node.
"""
from grudge.dt_utils import characteristic_lengthscales
length_scales = characteristic_lengthscales(state.array_context, discr)
mu = 0
d_alpha_max = 0
if state.is_viscous:
mu = state.viscosity
d_alpha_max = \
get_local_max_species_diffusivity(
state.array_context,
state.species_diffusivity
)
return (length_scales / (state.wavespeed +
((mu + d_alpha_max) / length_scales)))
def get_viscous_timestep(discr, eos, cv):
"""Routine returns the the node-local maximum stable viscous timestep.
Parameters
----------
discr: grudge.eager.EagerDGDiscretization
the discretization to use
eos: :class:`~mirgecom.eos.GasEOS`
A gas equation of state
cv: :class:`~mirgecom.fluid.ConservedVars`
Fluid solution
Returns
-------
:class:`~meshmode.dof_array.DOFArray`
The maximum stable timestep at each node.
"""
from grudge.dt_utils import characteristic_lengthscales
from mirgecom.fluid import compute_wavespeed
length_scales = characteristic_lengthscales(cv.array_context, discr)
mu = 0
d_alpha_max = 0
transport = eos.transport_model()
if transport:
mu = transport.viscosity(eos, cv)
d_alpha_max = \
get_local_max_species_diffusivity(
cv.array_context, discr,
transport.species_diffusivity(eos, cv)
)
return (length_scales / (compute_wavespeed(eos, cv) +
((mu + d_alpha_max) / length_scales)))
def test_viscous_timestep(actx_factory, dim, mu, vel):
"""Test timestep size."""
actx = actx_factory()
nel_1d = 4
from meshmode.mesh.generation import generate_regular_rect_mesh
mesh = generate_regular_rect_mesh(a=(1.0, ) * dim,
b=(2.0, ) * dim,
nelements_per_axis=(nel_1d, ) * dim)
order = 1
discr = EagerDGDiscretization(actx, mesh, order=order)
zeros = discr.zeros(actx)
ones = zeros + 1.0
velocity = make_obj_array([zeros + vel for _ in range(dim)])
massval = 1
mass = massval * ones
# I *think* this energy should yield c=1.0
energy = zeros + 1.0 / (1.4 * .4)
mom = mass * velocity
species_mass = None
cv = make_conserved(dim,
mass=mass,
energy=energy,
momentum=mom,
species_mass=species_mass)
from grudge.dt_utils import characteristic_lengthscales
chlen = characteristic_lengthscales(actx, discr)
from grudge.op import nodal_min
chlen_min = nodal_min(discr, "vol", chlen)
mu = mu * chlen_min
if mu < 0:
mu = 0
tv_model = None
else:
tv_model = SimpleTransport(viscosity=mu)
eos = IdealSingleGas()
gas_model = GasModel(eos=eos, transport=tv_model)
fluid_state = make_fluid_state(cv, gas_model)
from mirgecom.viscous import get_viscous_timestep
dt_field = get_viscous_timestep(discr, fluid_state)
speed_total = fluid_state.wavespeed
dt_expected = chlen / (speed_total + (mu / chlen))
error = (dt_expected - dt_field) / dt_expected
assert actx.to_numpy(discr.norm(error, np.inf)) == 0
def estimate_rk4_timestep(self, actx, dcoll, **kwargs):
r"""Estimate the largest stable timestep for an RK4 method.
:arg actx: a :class:`arraycontext.ArrayContext`.
:arg dcoll: a :class:`grudge.discretization.DiscretizationCollection`.
:arg \**kwargs: Optional keyword arguments for determining the
max characteristic velocity of the operator. These are passed
to :meth:`max_characteristic_velocity`.
"""
from grudge.dt_utils import characteristic_lengthscales
import grudge.op as op
wavespeeds = self.max_characteristic_velocity(actx, **kwargs)
local_timesteps = (characteristic_lengthscales(actx, dcoll) /
wavespeeds)
return op.nodal_min(dcoll, "vol", local_timesteps)
def get_inviscid_timestep(discr, eos, cv):
"""Return node-local stable timestep estimate for an inviscid fluid.
The maximum stable timestep is computed from the acoustic wavespeed.
Parameters
----------
discr: grudge.eager.EagerDGDiscretization
the discretization to use
eos: mirgecom.eos.GasEOS
Implementing the pressure and temperature functions for
returning pressure and temperature as a function of the state q.
cv: :class:`~mirgecom.fluid.ConservedVars`
Fluid solution
Returns
-------
class:`~meshmode.dof_array.DOFArray`
The maximum stable timestep at each node.
"""
from grudge.dt_utils import characteristic_lengthscales
from mirgecom.fluid import compute_wavespeed
return (characteristic_lengthscales(cv.array_context, discr) /
compute_wavespeed(eos, cv))
def get_inviscid_timestep(discr, state):
"""Return node-local stable timestep estimate for an inviscid fluid.
The maximum stable timestep is computed from the acoustic wavespeed.
Parameters
----------
discr: grudge.eager.EagerDGDiscretization
the discretization to use
state: :class:`~mirgecom.gas_model.FluidState`
Full fluid conserved and thermal state
Returns
-------
class:`~meshmode.dof_array.DOFArray`
The maximum stable timestep at each node.
"""
from grudge.dt_utils import characteristic_lengthscales
return (characteristic_lengthscales(state.array_context, discr) /
state.wavespeed)
def estimate_rk4_timestep(actx, dcoll, c):
from grudge.dt_utils import characteristic_lengthscales
local_dts = characteristic_lengthscales(actx, dcoll) / c
return op.nodal_min(dcoll, "vol", local_dts)
def main(use_profiling=False, use_logmgr=False, lazy_eval: bool = False):
"""Drive the example."""
cl_ctx = cl.create_some_context()
logmgr = initialize_logmgr(use_logmgr, filename="wave.sqlite", mode="wu")
if use_profiling:
if lazy_eval:
raise RuntimeError("Cannot run lazy with profiling.")
queue = cl.CommandQueue(
cl_ctx, properties=cl.command_queue_properties.PROFILING_ENABLE)
actx = PyOpenCLProfilingArrayContext(
queue,
allocator=cl_tools.MemoryPool(cl_tools.ImmediateAllocator(queue)))
else:
queue = cl.CommandQueue(cl_ctx)
if lazy_eval:
actx = PytatoPyOpenCLArrayContext(queue)
else:
actx = PyOpenCLArrayContext(
queue,
allocator=cl_tools.MemoryPool(
cl_tools.ImmediateAllocator(queue)))
dim = 2
nel_1d = 16
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)
current_cfl = 0.485
wave_speed = 1.0
from grudge.dt_utils import characteristic_lengthscales
nodal_dt = characteristic_lengthscales(actx, discr) / wave_speed
from grudge.op import nodal_min
dt = actx.to_numpy(current_cfl * nodal_min(discr, "vol", nodal_dt))[()]
print("%d elements" % mesh.nelements)
fields = flat_obj_array(bump(actx, discr),
[discr.zeros(actx) for i in range(discr.dim)])
if logmgr:
logmgr_add_cl_device_info(logmgr, queue)
logmgr_add_device_memory_usage(logmgr, queue)
logmgr.add_watches(["step.max", "t_step.max", "t_log.max"])
try:
logmgr.add_watches(
["memory_usage_python.max", "memory_usage_gpu.max"])
except KeyError:
pass
if use_profiling:
logmgr.add_watches(["multiply_time.max"])
vis_timer = IntervalTimer("t_vis", "Time spent visualizing")
logmgr.add_quantity(vis_timer)
vis = make_visualizer(discr)
def rhs(t, w):
return wave_operator(discr, c=wave_speed, w=w)
compiled_rhs = actx.compile(rhs)
t = 0
t_final = 1
istep = 0
while t < t_final:
if logmgr:
logmgr.tick_before()
fields = thaw(freeze(fields, actx), actx)
fields = rk4_step(fields, t, dt, compiled_rhs)
if istep % 10 == 0:
if use_profiling:
print(actx.tabulate_profiling_data())
print(istep, t, actx.to_numpy(discr.norm(fields[0], np.inf)))
vis.write_vtk_file("fld-wave-%04d.vtu" % istep, [
("u", fields[0]),
("v", fields[1:]),
],
overwrite=True)
t += dt
istep += 1
if logmgr:
set_dt(logmgr, dt)
logmgr.tick_after()
def main(snapshot_pattern="wave-mpi-{step:04d}-{rank:04d}.pkl", restart_step=None,
use_profiling=False, use_logmgr=False, actx_class=PyOpenCLArrayContext):
"""Drive the example."""
cl_ctx = cl.create_some_context()
queue = cl.CommandQueue(cl_ctx)
from mpi4py import MPI
comm = MPI.COMM_WORLD
rank = comm.Get_rank()
num_parts = comm.Get_size()
logmgr = initialize_logmgr(use_logmgr,
filename="wave-mpi.sqlite", mode="wu", mpi_comm=comm)
if use_profiling:
queue = cl.CommandQueue(cl_ctx,
properties=cl.command_queue_properties.PROFILING_ENABLE)
actx = actx_class(queue,
allocator=cl_tools.MemoryPool(cl_tools.ImmediateAllocator(queue)),
logmgr=logmgr)
else:
queue = cl.CommandQueue(cl_ctx)
actx = actx_class(queue,
allocator=cl_tools.MemoryPool(cl_tools.ImmediateAllocator(queue)))
if restart_step is None:
from meshmode.distributed import MPIMeshDistributor, get_partition_by_pymetis
mesh_dist = MPIMeshDistributor(comm)
dim = 2
nel_1d = 16
if mesh_dist.is_mananger_rank():
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)
print("%d elements" % mesh.nelements)
part_per_element = get_partition_by_pymetis(mesh, num_parts)
local_mesh = mesh_dist.send_mesh_parts(mesh, part_per_element, num_parts)
del mesh
else:
local_mesh = mesh_dist.receive_mesh_part()
fields = None
else:
from mirgecom.restart import read_restart_data
restart_data = read_restart_data(
actx, snapshot_pattern.format(step=restart_step, rank=rank)
)
local_mesh = restart_data["local_mesh"]
nel_1d = restart_data["nel_1d"]
assert comm.Get_size() == restart_data["num_parts"]
order = 3
discr = EagerDGDiscretization(actx, local_mesh, order=order,
mpi_communicator=comm)
current_cfl = 0.485
wave_speed = 1.0
from grudge.dt_utils import characteristic_lengthscales
dt = current_cfl * characteristic_lengthscales(actx, discr) / wave_speed
from grudge.op import nodal_min
dt = nodal_min(discr, "vol", dt)
t_final = 1
if restart_step is None:
t = 0
istep = 0
fields = flat_obj_array(
bump(actx, discr),
[discr.zeros(actx) for i in range(discr.dim)]
)
else:
t = restart_data["t"]
istep = restart_step
assert istep == restart_step
restart_fields = restart_data["fields"]
old_order = restart_data["order"]
if old_order != order:
old_discr = EagerDGDiscretization(actx, local_mesh, order=old_order,
mpi_communicator=comm)
from meshmode.discretization.connection import make_same_mesh_connection
connection = make_same_mesh_connection(actx, discr.discr_from_dd("vol"),
old_discr.discr_from_dd("vol"))
fields = connection(restart_fields)
else:
fields = restart_fields
if logmgr:
logmgr_add_cl_device_info(logmgr, queue)
logmgr_add_device_memory_usage(logmgr, queue)
logmgr.add_watches(["step.max", "t_step.max", "t_log.max"])
try:
logmgr.add_watches(["memory_usage_python.max", "memory_usage_gpu.max"])
except KeyError:
pass
if use_profiling:
logmgr.add_watches(["multiply_time.max"])
vis_timer = IntervalTimer("t_vis", "Time spent visualizing")
logmgr.add_quantity(vis_timer)
vis = make_visualizer(discr)
def rhs(t, w):
return wave_operator(discr, c=wave_speed, w=w)
compiled_rhs = actx.compile(rhs)
while t < t_final:
if logmgr:
logmgr.tick_before()
# restart must happen at beginning of step
if istep % 100 == 0 and (
# Do not overwrite the restart file that we just read.
istep != restart_step):
from mirgecom.restart import write_restart_file
write_restart_file(
actx, restart_data={
"local_mesh": local_mesh,
"order": order,
"fields": fields,
"t": t,
"step": istep,
"nel_1d": nel_1d,
"num_parts": num_parts},
filename=snapshot_pattern.format(step=istep, rank=rank),
comm=comm
)
if istep % 10 == 0:
print(istep, t, discr.norm(fields[0]))
vis.write_parallel_vtk_file(
comm,
"fld-wave-mpi-%03d-%04d.vtu" % (rank, istep),
[
("u", fields[0]),
("v", fields[1:]),
], overwrite=True
)
fields = thaw(freeze(fields, actx), actx)
fields = rk4_step(fields, t, dt, compiled_rhs)
t += dt
istep += 1
if logmgr:
set_dt(logmgr, dt)
logmgr.tick_after()
final_soln = discr.norm(fields[0])
assert np.abs(final_soln - 0.04409852463947439) < 1e-14
