def test_exotic_boundaries():
step = LatticeBoltzmannStep((50, 50),
relaxation_rate=1.8,
compressible=False,
periodicity=False)
add_box_boundary(step.boundary_handling, NeumannByCopy())
step.boundary_handling.set_boundary(StreamInConstant(0), make_slice[0, :])
step.run(100)
assert np.max(step.velocity[:, :, :]) < 1e-13
def rod_simulation(stencil_name,
diameter,
parallel=False,
entropic=False,
re=150,
time_to_simulate=17.0,
eval_interval=0.5,
write_vtk=True,
write_numpy=True):
if stencil_name == 'D3Q19_new':
stencil = Stencil.D3Q19
maxwellian_moments = True
elif stencil_name == 'D3Q19_old':
stencil = Stencil.D3Q19
maxwellian_moments = False
elif stencil_name == 'D3Q27':
stencil = Stencil.D3Q27
maxwellian_moments = False
else:
raise ValueError("Unknown stencil name " + stencil_name)
d = diameter
length = 16 * d
u_max_at_throat = 0.07
u_max_at_inflow = 0.07 / (3**2)
# Geometry parameters
inflow_area = int(1.5 * d)
constriction_length = int(1.8904 * d)
throat_length = int(10 / 3 * d)
constriction_diameter = int(d / 3)
u_mean_at_throat = u_max_at_throat / 2
lattice_viscosity = u_mean_at_throat * constriction_diameter / re
omega = relaxation_rate_from_lattice_viscosity(lattice_viscosity)
lbm_config = LBMConfig(stencil=LBStencil(stencil),
compressible=True,
method=Method.SRT,
relaxation_rate=omega,
entropic=entropic,
maxwellian_moments=maxwellian_moments)
kernel_params = {}
print("ω=", omega)
dh = create_data_handling(domain_size=(length, d, d), parallel=parallel)
sc = LatticeBoltzmannStep(data_handling=dh,
kernel_params=kernel_params,
name=stencil_name,
lbm_config=lbm_config)
# ----------------- Boundary Setup --------------------------------
def pipe_geometry(x, *_):
# initialize with full diameter everywhere
result = np.ones_like(x) * d
# constriction
constriction_begin = inflow_area
constriction_end = constriction_begin + constriction_length
c_x = np.linspace(0, 1, constriction_length)
result[constriction_begin:constriction_end] = d * (
1 - c_x) + constriction_diameter * c_x
# throat
throat_start = constriction_end
throat_end = throat_start + throat_length
result[throat_start:throat_end] = constriction_diameter
return result
bh = sc.boundary_handling
add_pipe_inflow_boundary(bh, u_max_at_inflow, make_slice[0, :, :])
outflow = FixedDensity(1.0)
bh.set_boundary(outflow, slice_from_direction('E', 3))
wall = NoSlip()
add_pipe_walls(bh, pipe_geometry, wall)
# ----------------- Run --------------------------------------------
scenario_name = stencil_name
if not os.path.exists(scenario_name):
os.mkdir(scenario_name)
def to_time_steps(non_dimensional_time):
return int(diameter / (u_max_at_inflow / 2) * non_dimensional_time)
time_steps = to_time_steps(time_to_simulate)
eval_interval = to_time_steps(eval_interval)
print("Total number of time steps", time_steps)
for i in range(time_steps // eval_interval):
sc.run(eval_interval)
if write_vtk:
sc.write_vtk()
vel = sc.velocity[:, :, :, :]
max_vel = np.max(vel)
print("Time steps:", sc.time_steps_run, "/", time_steps,
"Max velocity: ", max_vel)
if np.isnan(max_vel):
raise ValueError("Simulation went unstable")
if write_numpy:
np.save(scenario_name + f'/velocity_{sc.time_steps_run}',
sc.velocity_slice().filled(0.0))