def update_cpp(self, dt, velocity):
alpha = get_local(self.alpha_function)
beta = get_local(self.blending_function)
gradient = [
get_local(gi) for gi in self.gradient_reconstructor.gradient
]
velocity = [get_local(vi) for vi in velocity]
g_vecs = numpy.array(gradient, dtype=float)
v_vecs = numpy.array(velocity, dtype=float)
assert g_vecs.shape[0] == g_vecs.shape[0] == self.simulation.ndim
hric_funcs = {2: self.cpp_mod.hric_2D, 3: self.cpp_mod.hric_3D}
hric_func = hric_funcs[self.simulation.ndim]
Co_max = hric_func(self.cpp_inp, self.mesh, alpha, g_vecs, v_vecs,
beta, dt, self.variant)
set_local(self.blending_function, beta, apply='insert')
return Co_max
def crossing_points_and_cells(simulation, field, value, preprocessed):
"""
Find cells that contain the value iso surface. This is done by
connecting cell midpoints across facets and seing if the level set
crosses this line. If it does, the point where it crosses, the cell
containing the free surface crossing point and the vector from the low
value cell to the high value cell is stored.
The direction vector is made into a unit vector and then scaled by the
value difference between the two cells. The vectors are computed in
this way so that they can be averaged (for a cell with multiple
crossing points) to get an approximate direction of increasing value
(typically increasing density, meaning they point into the fluid in a
water/air simulation). This is used such that the high value and the
low value sides of the field can be approximately determined.
The field is assumed to be piecewice constant (DG0)
"""
facet_data, cell_dofs, is_ghost_cell = preprocessed
all_values = get_local(field)
# We define acronym LCCM: line connecting cell midpoints
# - We restrinct ourselves to LCCMs that cross only ONE facet
# - We number LLCMs by the index of the crossed facet
# Find the crossing points where the contour crosses a LCCM
crossing_points = {}
for fid, fdata in facet_data.items():
# Get preprocessed data
cid0, cid1, coords0, coords1, uvec = fdata
# Check for level crossing
v0 = all_values[cell_dofs[cid0]]
v1 = all_values[cell_dofs[cid1]]
b1, b2 = v0 < value, v1 < value
if (b1 and b2) or not (b1 or b2):
# LCCM not crossed by contour
continue
# Find the location where the contour line crosses the LCCM
fac = (v0 - value) / (v0 - v1)
crossing_point = tuple((1 - fac) * coords0 + fac * coords1)
# Scaled direction vector
direction = uvec * (v0 - v1)
# Find the cell containing the contour line
surf_cid = cid0 if fac <= 0.5 else cid1
is_ghost = is_ghost_cell[cid0] if fac <= 0.5 else is_ghost_cell[cid1]
if not is_ghost:
# Store the point and direction towards the high value cell
crossing_points.setdefault(surf_cid, []).append(
(crossing_point, direction))
return crossing_points
def _reconstruct_gradient(
alpha_function,
num_neighbours,
neighbours,
lstsq_matrices,
lstsq_inv_matrices,
gradient,
):
"""
Reconstruct the gradient, Python version of the code
This function used to have a more Pythonic implementation
that was most likely also faster. See old commits for that
code. This code is here to verify the C++ version that is
much faster than this (and the old Pythonic version)
"""
a_cell_vec = get_local(alpha_function)
mesh = alpha_function.function_space().mesh()
V = alpha_function.function_space()
assert V == gradient[0].function_space()
cell_dofs = cell_dofmap(V)
np_gradient = [gi.vector().get_local() for gi in gradient]
# Reshape arrays. The C++ version needs flatt arrays
# (limitation in Instant/Dolfin) and we have the same
# interface for both versions of the code
ncells = len(num_neighbours)
ndim = mesh.topology().dim()
num_cells_owned, num_neighbours_max = neighbours.shape
assert ncells == num_cells_owned
lstsq_matrices = lstsq_matrices.reshape((ncells, ndim, num_neighbours_max))
lstsq_inv_matrices = lstsq_inv_matrices.reshape((ncells, ndim, ndim))
for icell in range(num_cells_owned):
cdof = cell_dofs[icell]
Nnbs = num_neighbours[icell]
nbs = neighbours[icell, :Nnbs]
# Get the matrices
AT = lstsq_matrices[icell, :, :Nnbs]
ATAI = lstsq_inv_matrices[icell]
a0 = a_cell_vec[cdof]
b = [(a_cell_vec[cell_dofs[ni]] - a0) for ni in nbs]
b = numpy.array(b, float)
# Calculate the and store the gradient
g = numpy.dot(ATAI, numpy.dot(AT, b))
for d in range(ndim):
np_gradient[d][cdof] = g[d]
for i, np_grad in enumerate(np_gradient):
set_local(gradient[i], np_grad, apply='insert')
def update_level_set_view(simulation, level_set_view, crossings, cache):
"""
Create a level set CG1 scalar function where the value is 0 at the
given crossing point locations and approximately the distance to the
nearest crossing point by following the edges of the mesh away from
the crossing points and keeping track of the closest such point
"""
dofs_x, dof_dist, cell_dofs, dof_cells = cache
values = level_set_view.vector().get_local()
values[:] = 1e100
Nlocal = len(values)
# For MPI ranks that contain the free surface we first fill out the
# distance values starting at the free surface
if crossings:
# Mark distances in cells with a free surface
for cid, cross in crossings.items():
for crossing_point, direction in cross:
for dof in cell_dofs[cid]:
if dof < Nlocal:
dpos = dofs_x[dof]
vec = dpos - crossing_point
dist = (vec[0]**2 + vec[1]**2 + vec[2]**2)**0.5
# Make the level set function a signed distance function
# if vec.dot(direction) < 0:
# dist = -dist
if abs(dist) < abs(values[dof]):
values[dof] = dist
# Breadth-first search to populate all of the local domain
queue = deque()
for cid in crossings:
queue.extend([d for d in cell_dofs[cid] if d < Nlocal])
bfs(queue, values, cell_dofs, dof_cells, dof_dist)
# Update ghost cell values
level_set_view.vector().set_local(values)
level_set_view.vector().apply('insert')
# Breadth first search from ghost dofs
values2 = get_local(level_set_view)
queue = deque(range(Nlocal, len(values2)))
bfs(queue, values2, cell_dofs, dof_cells, dof_dist)
level_set_view.vector().set_local(values2[:Nlocal])
level_set_view.vector().apply('insert')
def test_get_set_local_with_ghosts():
comm = dolfin.MPI.comm_world
rank = dolfin.MPI.rank(comm)
dolfin.parameters['ghost_mode'] = 'shared_vertex'
mesh = dolfin.UnitSquareMesh(comm, 4, 4)
V = dolfin.FunctionSpace(mesh, 'DG', 0)
u = dolfin.Function(V)
dm = V.dofmap()
im = dm.index_map()
# Write global dof number into array for all dofs
start, end = u.vector().local_range()
arr = u.vector().get_local()
arr[:] = numpy.arange(start, end)
u.vector().set_local(arr)
u.vector().apply('insert')
# Get local + ghost values
arr2 = get_local(u.vector(), V)
# Get ghost global indices and some sizes
global_ghost_dofs = im.local_to_global_unowned()
Nall = im.size(im.MapSize.ALL)
Nghost = global_ghost_dofs.size
Nown = im.size(im.MapSize.OWNED)
assert Nown + Nghost == Nall
# Produce the expected answer
dofs = numpy.arange(start, end + Nghost)
dofs[Nown:] = global_ghost_dofs
# Check the results
assert dofs.shape == arr2.shape
diff = abs(dofs - arr2).max()
print
print(rank, start, end, global_ghost_dofs)
print(rank, numpy.array(arr2, dtype=numpy.intc), '\n ', dofs, diff)
assert diff == 0
def run(self, use_weak_bcs=None):
"""
Perform slope limiting of DG Lagrange functions
"""
# No limiter needed for piecewice constant functions
if self.degree == 0:
return
timer = df.Timer('Ocellaris HierarchalTaylorSlopeLimiter')
# Update the Taylor function with the current Lagrange values
lagrange_to_taylor(self.phi, self.taylor)
taylor_arr = get_local(self.taylor)
alpha_arrs = [alpha.vector().get_local() for alpha in self.alpha_funcs]
# Get global bounds, see SlopeLimiterBase.set_initial_field()
global_min, global_max = self.global_bounds
# Update previous field values Taylor functions
if self.phi_old is not None:
lagrange_to_taylor(self.phi_old, self.taylor_old)
taylor_arr_old = get_local(self.taylor_old)
else:
taylor_arr_old = taylor_arr
# Get updated boundary conditions
weak_vals = None
use_weak_bcs = self.use_weak_bcs if use_weak_bcs is None else use_weak_bcs
if use_weak_bcs:
weak_vals = self.phi.vector().get_local()
boundary_dof_type, boundary_dof_value = self.boundary_conditions.get_bcs(
weak_vals)
# Run the limiter implementation
if self.use_cpp:
self._run_cpp(
taylor_arr,
taylor_arr_old,
alpha_arrs,
global_min,
global_max,
boundary_dof_type,
boundary_dof_value,
)
elif self.degree == 1 and self.ndim == 2:
self._run_dg1(
taylor_arr,
taylor_arr_old,
alpha_arrs[0],
global_min,
global_max,
boundary_dof_type,
boundary_dof_value,
)
elif self.degree == 2 and self.ndim == 2:
self._run_dg2(
taylor_arr,
taylor_arr_old,
alpha_arrs[0],
alpha_arrs[1],
global_min,
global_max,
boundary_dof_type,
boundary_dof_value,
)
else:
raise OcellarisError(
'Unsupported dimension for Python version of the HierarchalTaylor limiter',
'Only 2D is supported',
)
# Update the Lagrange function with the limited Taylor values
set_local(self.taylor, taylor_arr, apply='insert')
taylor_to_lagrange(self.taylor, self.phi)
# Enforce boundary conditions
if self.enforce_boundary_conditions:
has_dbc = boundary_dof_type == self.boundary_conditions.BC_TYPE_DIRICHLET
vals = self.phi.vector().get_local()
vals[has_dbc] = boundary_dof_value[has_dbc]
self.phi.vector().set_local(vals)
self.phi.vector().apply('insert')
# Update the secondary output arrays, alphas
for alpha, alpha_arr in zip(self.alpha_funcs, alpha_arrs):
alpha.vector().set_local(alpha_arr)
alpha.vector().apply('insert')
timer.stop()
def _run_dg1(
self,
taylor_arr,
taylor_arr_old,
alpha_arr,
global_min,
global_max,
boundary_dof_type,
boundary_dof_value,
):
"""
Perform slope limiting of a DG1 function
"""
inp = self.input
lagrange_arr = get_local(self.phi)
for icell in range(self.num_cells_owned):
dofs = inp.cell_dofs_V[icell]
center_value = taylor_arr[dofs[0]]
skip_this_cell = self.limit_cell[icell] == 0
# Find the minimum slope limiter coefficient alpha
alpha = 1.0
if not skip_this_cell:
for i in range(3):
dof = dofs[i]
nn = inp.num_neighbours[dof]
if nn == 0:
skip_this_cell = True
break
# Find vertex neighbours minimum and maximum values
minval = maxval = center_value
for nb in inp.neighbours[dof, :nn]:
nb_center_val_dof = inp.cell_dofs_V[nb][0]
nb_val = taylor_arr[nb_center_val_dof]
minval = min(minval, nb_val)
maxval = max(maxval, nb_val)
nb_val = taylor_arr_old[nb_center_val_dof]
minval = min(minval, nb_val)
maxval = max(maxval, nb_val)
# Modify local bounds to incorporate the global bounds
minval = max(minval, global_min)
maxval = min(maxval, global_max)
center_value = max(center_value, global_min)
center_value = min(center_value, global_max)
vertex_value = lagrange_arr[dof]
if vertex_value > center_value:
alpha = min(alpha, (maxval - center_value) /
(vertex_value - center_value))
elif vertex_value < center_value:
alpha = min(alpha, (minval - center_value) /
(vertex_value - center_value))
if skip_this_cell:
alpha = 1.0
alpha_arr[inp.cell_dofs_V0[icell]] = alpha
taylor_arr[dofs[0]] = center_value
taylor_arr[dofs[1]] *= alpha
taylor_arr[dofs[2]] *= alpha
def gather_vtk_info(mesh, funcs):
"""
Gather the necessary information to write a legacy VTK output file
on the root process
"""
# The code below assumes that the first function is DG2 (u0)
assert funcs[0].function_space().ufl_element().family() in (
'Discontinuous Lagrange',
'Lagrange',
)
assert funcs[0].function_space().ufl_element().degree() == 2
# The code is currently 3D only
gdim = mesh.geometry().dim()
dofs_x = funcs[0].function_space().tabulate_dof_coordinates().reshape(
(-1, gdim))
assert gdim in (
2, 3), 'VTK output currently only supported for 2D and 3D meshes'
# Collect information about the functions
func_names = []
all_vals = []
dofmaps = []
for u in funcs:
func_names.append(u.name())
all_vals.append(get_local(u))
dofmaps.append(u.function_space().dofmap())
# Collect local data
local_res = _collect_3D(mesh, gdim, dofs_x, func_names, all_vals, dofmaps)
# MPI communication to get all data on root process
comm = mesh.mpi_comm()
all_results = comm.gather(local_res)
if all_results is None:
return None
# Assemble information from all processes
coords, connectivity, cell_types = [], [], []
func_vals = {n: [] for n in func_names}
for coords_i, connectivity_i, cell_types_i, func_vals_i in all_results:
K = len(coords)
coords.extend(coords_i)
for conn in connectivity_i:
connectivity.append(conn[:1] + [c + K for c in conn[1:]])
cell_types.extend(cell_types_i)
for n in func_names:
func_vals[n].extend(func_vals_i[n])
# Convert to numpy arrays
coords = numpy.array(coords, dtype=numpy.float32)
connectivity = numpy.array(connectivity, dtype=numpy.intc)
cell_types = numpy.array(cell_types, dtype=numpy.intc)
for n in func_names:
func_vals[n] = numpy.array(func_vals[n], dtype=numpy.float32)
# Check that the data is appropriate for output
Nverts = len(coords)
Ncells = len(connectivity)
assert coords.shape == (Nverts, 3)
assert connectivity.shape == (Ncells, 11 if gdim == 3 else 7)
assert cell_types.shape == (Ncells, )
for n in func_names:
assert func_vals[n].shape == (Nverts, )
return coords, connectivity, cell_types, func_vals
def update_python(self, dt, velocity):
alpha_arr = get_local(self.alpha_function)
beta_arr = get_local(self.blending_function)
cell_dofs = self.cpp_inp.cell_dofmap
facet_dofs = self.cpp_inp.facet_dofmap
polydeg = self.alpha_function.ufl_element().degree()
conFC = self.simulation.data['connectivity_FC']
facet_info = self.simulation.data['facet_info']
cell_info = self.simulation.data['cell_info']
# Get the numpy arrays of the input functions
gradient = self.gradient_reconstructor.gradient
gradient_arrs = [get_local(gi) for gi in gradient]
velocity_arrs = [get_local(vi) for vi in velocity]
EPS = 1e-6
Co_max = 0
for facet in dolfin.facets(self.mesh, 'regular'):
fidx = facet.index()
fdof = facet_dofs[fidx]
finfo = facet_info[fidx]
# Find the local cells (the two cells sharing this face)
connected_cells = conFC(fidx)
if len(connected_cells) != 2:
# This should be an exterior facet (on ds)
assert facet.exterior()
beta_arr[fdof] = 0.0
continue
# Indices of the two local cells
ic0, ic1 = connected_cells
# Velocity at the facet
ump = [vi[fdof] for vi in velocity_arrs]
# Midpoint of local cells
cell0_mp = cell_info[ic0].midpoint
cell1_mp = cell_info[ic1].midpoint
mp_dist = cell1_mp - cell0_mp
# Normal pointing out of cell 0
normal = finfo.normal
# Find indices of downstream ("D") cell and central ("C") cell
uf = numpy.dot(normal, ump)
if uf > 0:
iaC = ic0
iaD = ic1
vec_to_downstream = mp_dist
# nminC, nmaxC = nmin0, nmax0
else:
iaC = ic1
iaD = ic0
vec_to_downstream = -mp_dist
# nminC, nmaxC = nmin1, nmax1
# Find alpha in D and C cells
if polydeg == 0:
aD = alpha_arr[cell_dofs[iaD]]
aC = alpha_arr[cell_dofs[iaC]]
elif polydeg == 1:
aD, aC = numpy.zeros(1), numpy.zeros(1)
self.alpha_function.eval(aD, cell_info[iaD].midpoint)
self.alpha_function.eval(aC, cell_info[iaC].midpoint)
aD, aC = aD[0], aC[0]
if abs(aC - aD) < EPS:
# No change in this area, use upstream value
beta_arr[fdof] = 0.0
continue
# Gradient of alpha in the central cell
gC = [gi[cell_dofs[iaC]] for gi in gradient_arrs]
len_gC2 = numpy.dot(gC, gC)
if len_gC2 == 0:
# No change in this area, use upstream value
beta_arr[fdof] = 0.0
continue
# Upstream value
# See Ubbink's PhD (1997) equations 4.21 and 4.22
aU = aD - 2 * numpy.dot(gC, vec_to_downstream)
aU = min(max(aU, 0.0), 1.0)
# Calculate the facet Courant number
Co = abs(uf) * dt * finfo.area / cell_info[iaC].volume
Co_max = max(Co_max, Co)
if abs(aU - aD) < EPS:
# No change in this area, use upstream value
beta_arr[fdof] = 0.0
continue
# Angle between face normal and surface normal
len_normal2 = numpy.dot(normal, normal)
cos_theta = numpy.dot(normal, gC) / (len_normal2 * len_gC2)**0.5
# Introduce normalized variables
tilde_aC = (aC - aU) / (aD - aU)
if tilde_aC <= 0 or tilde_aC >= 1:
# Only upwind is stable
beta_arr[fdof] = 0.0
continue
if self.variant == 'HRIC':
# Compressive scheme
tilde_aF = 2 * tilde_aC if 0 <= tilde_aC <= 0.5 else 1
# Correct tilde_aF to avoid aligning with interfaces
t = abs(cos_theta)**0.5
tilde_aF_star = tilde_aF * t + tilde_aC * (1 - t)
# Correct tilde_af_star for high Courant numbers
if Co < 0.4:
tilde_aF_final = tilde_aF_star
elif Co < 0.75:
tilde_aF_final = tilde_aC + (tilde_aF_star - tilde_aC) * (
0.75 - Co) / (0.75 - 0.4)
else:
tilde_aF_final = tilde_aC
elif self.variant == 'MHRIC':
# Compressive scheme
tilde_aF = 2 * tilde_aC if 0 <= tilde_aC <= 0.5 else 1
# Less compressive scheme
tilde_aF_ultimate_quickest = min((6 * tilde_aC + 3) / 8,
tilde_aF)
# Correct tilde_aF to avoid aligning with interfaces
t = abs(cos_theta)**0.5
tilde_aF_final = tilde_aF * t + tilde_aF_ultimate_quickest * (
1 - t)
elif self.variant == 'RHRIC':
# Compressive scheme
tilde_aF_hyperc = min(tilde_aC / Co, 1)
# Less compressive scheme
tilde_aF_hric = min(tilde_aC * Co + 2 * tilde_aC * (1 - Co),
tilde_aF_hyperc)
# Correct tilde_aF to avoid aligning with interfaces
t = cos_theta**4
tilde_aF_final = tilde_aF_hyperc * t + tilde_aF_hric * (1 - t)
# Avoid tilde_aF being slightly lower that tilde_aC due to
# floating point errors, it must be greater or equal
if tilde_aC - EPS < tilde_aF_final < tilde_aC:
tilde_aF_final = tilde_aC
# Calculate the downstream blending factor (0=upstream, 1=downstream)
tilde_beta = (tilde_aF_final - tilde_aC) / (1 - tilde_aC)
if not (0.0 <= tilde_beta <= 1.0):
print('ERROR, tilde_beta %r is out of range [0, 1]' %
tilde_beta)
print(' face normal: %r' % normal)
print(' surface gradient: %r' % gC)
print(' cos(theta): %r' % cos_theta)
print(' sqrt(abs(cos(theta))) %r' % t)
print(' tilde_aF_final %r' % tilde_aF_final)
print(' tilde_aC %r' % tilde_aC)
print(' aU %r, aC %r, aD %r' % (aU, aC, aD))
assert 0.0 <= tilde_beta <= 1.0
beta_arr[fdof] = tilde_beta
set_local(self.blending_function, beta_arr, apply='insert')
return Co_max
