def init_callback(self, boundary_data, **_):
dim = boundary_data.dim
coord_names = ['x', 'y', 'z'][:dim]
pdf_acc = AccessPdfValues(self.stencil, streaming_pattern=self.streaming_pattern,
timestep=self.zeroth_timestep, streaming_dir='out')
def get_boundary_cell_pdfs(f_cell, b_cell, direction):
if self.equilibrium_calculation is not None:
density = self.initial_density(
*b_cell) if callable(self.initial_density) else self.initial_density
velocity = self.initial_velocity(
*b_cell) if callable(self.initial_velocity) else self.initial_velocity
return self.equilibrium_calculation(density, velocity, direction)
else:
return pdf_acc.read_pdf(boundary_data.pdf_array, f_cell, direction)
for entry in boundary_data.index_array:
center = tuple(entry[c] for c in coord_names)
direction = self.stencil[entry["dir"]]
inv_dir = self.stencil.index(inverse_direction(direction))
tangential_offset = tuple(offset - normal for offset, normal in zip(direction, self.normal_direction))
domain_cell = tuple(f + o for f, o in zip(center, tangential_offset))
outflow_cell = tuple(f + o for f, o in zip(center, direction))
# Initial fluid cell PDF values
entry['pdf'] = pdf_acc.read_pdf(boundary_data.pdf_array, domain_cell, inv_dir)
entry['pdf_nd'] = get_boundary_cell_pdfs(domain_cell, outflow_cell, inv_dir)
def read(field, stencil):
res = []
for i, d in enumerate(stencil):
inv_dir = inverse_direction(d)
field_access = field[inv_dir](stencil.index(inv_dir))
res.append(field_access)
return res
def write(field, stencil):
result = []
for direction in stencil:
inv_dir = inverse_direction(direction)
spatial_offset = tuple(max(e, 0) for e in direction)
result.append(field[spatial_offset](stencil.index(inv_dir)))
return result
def read(self, field, stencil):
result = []
for i, d in enumerate(stencil):
pull_direction = inverse_direction(d)
periodic_pull_direction = []
for coord_id, dir_element in enumerate(pull_direction):
if not self._periodicity[coord_id]:
periodic_pull_direction.append(dir_element)
continue
lower_limit = self._ghostLayers
upper_limit = field.spatial_shape[
coord_id] - 1 - self._ghostLayers
limit_diff = upper_limit - lower_limit
loop_counter = LoopOverCoordinate.get_loop_counter_symbol(
coord_id)
if dir_element == 0:
periodic_pull_direction.append(0)
elif dir_element == 1:
new_dir_element = sp.Piecewise(
(dir_element, loop_counter < upper_limit),
(-limit_diff, True))
periodic_pull_direction.append(new_dir_element)
elif dir_element == -1:
new_dir_element = sp.Piecewise(
(dir_element, loop_counter > lower_limit),
(limit_diff, True))
periodic_pull_direction.append(new_dir_element)
else:
raise NotImplementedError(
"This accessor supports only nearest neighbor stencils"
)
result.append(field[tuple(periodic_pull_direction)](i))
return result
def boundary_substitutions(lb_method):
stencil = lb_method.stencil
w = lb_method.weights
replacements = {}
for idx, offset in enumerate(stencil):
symbolic_offset = BoundaryOffsetInfo.offset_from_dir(idx,
dim=lb_method.dim)
for sym, value in zip(symbolic_offset, offset):
replacements[sym] = value
replacements[BoundaryOffsetInfo.inv_dir(idx)] = stencil.index(
inverse_direction(offset))
replacements[LbmWeightInfo.weight_of_direction(idx)] = w[idx]
return replacements
def generate_pack_info_from_kernel(generation_context,
class_name: str,
assignments: Sequence[Assignment],
kind='pull',
**create_kernel_params):
"""Generates a waLBerla GPU PackInfo from a (pull) kernel.
Args:
generation_context: see documentation of `generate_sweep`
class_name: name of the generated class
assignments: list of assignments from the compute kernel - generates PackInfo for "pull" part only
i.e. the kernel is expected to only write to the center
kind:
**create_kernel_params: remaining keyword arguments are passed to `pystencils.create_kernel`
"""
assert kind in ('push', 'pull')
reads = set()
writes = set()
if isinstance(assignments, AssignmentCollection):
assignments = assignments.all_assignments
for a in assignments:
if not isinstance(a, Assignment):
continue
reads.update(a.rhs.atoms(Field.Access))
writes.update(a.lhs.atoms(Field.Access))
spec = defaultdict(set)
if kind == 'pull':
for fa in reads:
assert all(abs(e) <= 1 for e in fa.offsets)
if all(offset == 0 for offset in fa.offsets):
continue
comm_direction = inverse_direction(fa.offsets)
for comm_dir in comm_directions(comm_direction):
spec[(comm_dir, )].add(fa.field.center(*fa.index))
elif kind == 'push':
for fa in writes:
assert all(abs(e) <= 1 for e in fa.offsets)
if all(offset == 0 for offset in fa.offsets):
continue
for comm_dir in comm_directions(fa.offsets):
spec[(comm_dir, )].add(fa)
else:
raise ValueError("Invalid 'kind' parameter")
return generate_pack_info(generation_context, class_name, spec,
**create_kernel_params)
def test_extrapolation_outflow_initialization_by_copy():
stencil = LBStencil(Stencil.D2Q9)
domain_size = (1, 5)
streaming_pattern = 'esotwist'
zeroth_timestep = 'even'
pdf_acc = AccessPdfValues(stencil,
streaming_pattern=streaming_pattern,
timestep=zeroth_timestep,
streaming_dir='out')
dh = create_data_handling(domain_size, default_target=Target.CPU)
lb_method = create_lb_method(stencil=stencil)
pdf_field = dh.add_array('f', values_per_cell=stencil.Q)
dh.fill(pdf_field.name, np.nan, ghost_layers=True)
pdf_arr = dh.cpu_arrays[pdf_field.name]
bh = LatticeBoltzmannBoundaryHandling(lb_method,
dh,
pdf_field.name,
streaming_pattern=streaming_pattern,
target=Target.CPU)
for y in range(1, 6):
for j in range(stencil.Q):
pdf_acc.write_pdf(pdf_arr, (1, y), j, j)
normal_dir = (1, 0)
outflow = ExtrapolationOutflow(normal_dir,
lb_method,
streaming_pattern=streaming_pattern,
zeroth_timestep=zeroth_timestep)
boundary_slice = get_ghost_region_slice(normal_dir)
bh.set_boundary(outflow, boundary_slice)
bh.prepare()
blocks = list(dh.iterate())
index_list = blocks[0][
bh._index_array_name].boundary_object_to_index_list[outflow]
assert len(index_list) == 13
for entry in index_list:
direction = stencil[entry["dir"]]
inv_dir = stencil.index(inverse_direction(direction))
assert entry[f'pdf'] == inv_dir
assert entry[f'pdf_nd'] == inv_dir
def _force_on_boundary(self, boundary_obj, prev_timestep):
dh = self._data_handling
ff_ghost_layers = dh.ghost_layers_of_field(
self.flag_interface.flag_field_name)
method = self._lb_method
stencil = np.array(method.stencil)
inv_direction = np.array([
method.stencil.index(inverse_direction(d)) for d in method.stencil
])
result = np.zeros(self.dim)
for b in dh.iterate(ghost_layers=ff_ghost_layers):
obj_to_ind_list = b[
self._index_array_name].boundary_object_to_index_list
pdf_array = b[self._field_name]
if boundary_obj in obj_to_ind_list:
ind_arr = obj_to_ind_list[boundary_obj]
inverse_ind_arr = ind_arr.copy()
inverse_ind_arr['dir'] = inv_direction[inverse_ind_arr['dir']]
acc_out = AccessPdfValues(
self._lb_method.stencil,
streaming_pattern=self._streaming_pattern,
timestep=prev_timestep,
streaming_dir='out')
acc_in = AccessPdfValues(
self._lb_method.stencil,
streaming_pattern=self._streaming_pattern,
timestep=prev_timestep.next(),
streaming_dir='in')
acc_fluid = acc_out if boundary_obj.inner_or_boundary else acc_in
acc_boundary = acc_in if boundary_obj.inner_or_boundary else acc_out
fluid_values = acc_fluid.collect_from_index_list(
pdf_array, ind_arr)
boundary_values = acc_boundary.collect_from_index_list(
pdf_array, inverse_ind_arr)
values = fluid_values + boundary_values
forces = stencil[ind_arr['dir']] * values[:, np.newaxis]
result += forces.sum(axis=0)
return dh.reduce_float_sequence(list(result), 'sum')
def test_extrapolation_outflow_initialization_by_callback():
stencil = LBStencil(Stencil.D2Q9)
domain_size = (1, 5)
streaming_pattern = 'esotwist'
zeroth_timestep = 'even'
dh = create_data_handling(domain_size, default_target=Target.CPU)
lb_method = create_lb_method(stencil=stencil)
pdf_field = dh.add_array('f', values_per_cell=stencil.Q)
dh.fill(pdf_field.name, np.nan, ghost_layers=True)
bh = LatticeBoltzmannBoundaryHandling(lb_method,
dh,
pdf_field.name,
streaming_pattern=streaming_pattern,
target=Target.CPU)
normal_dir = (1, 0)
outflow = ExtrapolationOutflow(normal_direction=normal_dir,
lb_method=lb_method,
streaming_pattern=streaming_pattern,
zeroth_timestep=zeroth_timestep,
initial_density=lambda x, y: 1,
initial_velocity=lambda x, y: (0, 0))
boundary_slice = get_ghost_region_slice(normal_dir)
bh.set_boundary(outflow, boundary_slice)
bh.prepare()
weights = [w.evalf() for w in lb_method.weights]
blocks = list(dh.iterate())
index_list = blocks[0][
bh._index_array_name].boundary_object_to_index_list[outflow]
assert len(index_list) == 13
for entry in index_list:
direction = stencil[entry["dir"]]
inv_dir = stencil.index(inverse_direction(direction))
assert entry[f'pdf_nd'] == weights[inv_dir]
def init_callback(self, boundary_data, **_):
if len(boundary_data.index_array) > 1e6:
warn(f"The calculation of the normal direction for each cell might take a long time, because "
f"{len(boundary_data.index_array)} cells are marked as Free Slip boundary cells. Consider specifying "
f" the normal direction beforehand, which is possible if it is equal for all cells (e.g. at a wall)")
dim = boundary_data.dim
coords = [coord for coord, _ in zip(['x', 'y', 'z'], range(dim))]
boundary_cells = set()
# get a set containing all boundary cells
for cell in boundary_data.index_array:
fluid_cell = tuple([cell[coord] for coord in coords])
direction = self.stencil[cell['dir']]
boundary_cell = tuple([i + d for i, d in zip(fluid_cell, direction)])
boundary_cells.add(boundary_cell)
for cell in boundary_data.index_array:
fluid_cell = tuple([cell[coord] for coord in coords])
direction = self.stencil[cell['dir']]
ref_direction = direction
normal_direction = [0] * dim
for i in range(dim):
sub_direction = [0] * dim
sub_direction[i] = direction[i]
test_cell = tuple([x + y for x, y in zip(fluid_cell, sub_direction)])
if test_cell in boundary_cells:
normal_direction[i] = direction[i]
ref_direction = MirroredStencilDirections.mirror_stencil(ref_direction, i)
ref_direction = inverse_direction(ref_direction)
for i, cell_name in zip(range(dim), self.additional_data):
cell[cell_name[0]] = -normal_direction[i]
cell['ref_dir'] = self.stencil.index(ref_direction)
def test_free_slip_index_list():
stencil = LBStencil(Stencil.D2Q9)
dh = create_data_handling(domain_size=(4, 4), periodicity=(False, False))
src = dh.add_array('src', values_per_cell=len(stencil), alignment=True)
dh.fill('src', 0.0, ghost_layers=True)
lbm_config = LBMConfig(stencil=stencil,
method=Method.SRT,
relaxation_rate=1.8)
method = create_lb_method(lbm_config=lbm_config)
bh = LatticeBoltzmannBoundaryHandling(method, dh, 'src', name="bh")
free_slip = FreeSlip(stencil=stencil)
add_box_boundary(bh, free_slip)
bh.prepare()
for b in dh.iterate():
for b_obj, idx_arr in b[
bh._index_array_name].boundary_object_to_index_list.items():
index_array = idx_arr
# normal directions
normal_west = (1, 0)
normal_east = (-1, 0)
normal_south = (0, 1)
normal_north = (0, -1)
normal_south_west = (1, 1)
normal_north_west = (1, -1)
normal_south_east = (-1, 1)
normal_north_east = (-1, -1)
for cell in index_array:
direction = stencil[cell[2]]
inv_dir = inverse_direction(direction)
boundary_cell = (cell[0] + direction[0], cell[1] + direction[1])
normal = (cell[3], cell[4])
# the data is written on the inverse direction of the fluid cell near the boundary
# the data is read from the mirrored direction of the inverse direction where the mirror axis is the normal
assert cell[5] == stencil.index(mirror_stencil(list(inv_dir), normal))
if boundary_cell[0] == 0 and 0 < boundary_cell[1] < 5:
assert normal == normal_west
if boundary_cell[0] == 5 and 0 < boundary_cell[1] < 5:
assert normal == normal_east
if 0 < boundary_cell[0] < 5 and boundary_cell[1] == 0:
assert normal == normal_south
if 0 < boundary_cell[0] < 5 and boundary_cell[1] == 5:
assert normal == normal_north
if boundary_cell == (0, 0):
assert cell[2] == cell[5]
assert normal == normal_south_west
if boundary_cell == (5, 0):
assert cell[2] == cell[5]
assert normal == normal_south_east
if boundary_cell == (0, 5):
assert cell[2] == cell[5]
assert normal == normal_north_west
if boundary_cell == (5, 5):
assert cell[2] == cell[5]
assert normal == normal_north_east
def read(field, stencil):
return [field[inverse_direction(d)](i) for i, d in enumerate(stencil)]
def write(field, stencil):
return [field(stencil.index(inverse_direction(d))) for d in stencil]
def generate_mpidtype_info_from_kernel(
generation_context,
class_name: str,
assignments: Sequence[Assignment],
kind='pull',
namespace='pystencils',
):
assert kind in ('push', 'pull')
reads = set()
writes = set()
if isinstance(assignments, AssignmentCollection):
assignments = assignments.all_assignments
for a in assignments:
if not isinstance(a, Assignment):
continue
reads.update(a.rhs.atoms(Field.Access))
writes.update(a.lhs.atoms(Field.Access))
spec = defaultdict(set)
if kind == 'pull':
read_fields = set(fa.field for fa in reads)
assert len(
read_fields
) == 1, "Only scenarios where one fields neighbors are accessed"
field = read_fields.pop()
for fa in reads:
assert all(abs(e) <= 1 for e in fa.offsets)
if all(offset == 0 for offset in fa.offsets):
continue
comm_direction = inverse_direction(fa.offsets)
for comm_dir in comm_directions(comm_direction):
assert len(
fa.index
) == 1, "Supports only fields with a single index dimension"
spec[(offset_to_direction_string(comm_dir), )].add(fa.index[0])
elif kind == 'push':
written_fields = set(fa.field for fa in writes)
assert len(
written_fields
) == 1, "Only scenarios where one fields neighbors are accessed"
field = written_fields.pop()
for fa in writes:
assert all(abs(e) <= 1 for e in fa.offsets)
if all(offset == 0 for offset in fa.offsets):
continue
for comm_dir in comm_directions(fa.offsets):
assert len(
fa.index
) == 1, "Supports only fields with a single index dimension"
spec[(offset_to_direction_string(comm_dir), )].add(fa.index[0])
else:
raise ValueError("Invalid 'kind' parameter")
jinja_context = {
'class_name': class_name,
'namespace': namespace,
'kind': kind,
'field_name': field.name,
'f_size': field.index_shape[0],
'spec': spec,
}
env = Environment(loader=PackageLoader('pystencils_walberla'),
undefined=StrictUndefined)
header = env.get_template("MpiDtypeInfo.tmpl.h").render(**jinja_context)
generation_context.write_file("{}.h".format(class_name), header)