def update(self):
if not self.active:
return
with Timer('Ocellaris update hydrostatic pressure'):
A = self.tensor_lhs
b = assemble(self.form_rhs)
if self.null_space is None:
# Create vector that spans the null space, and normalize
null_space_vector = b.copy()
null_space_vector[:] = sqrt(1.0 / null_space_vector.size())
# Create null space basis object and attach to PETSc matrix
self.null_space = VectorSpaceBasis([null_space_vector])
as_backend_type(A).set_nullspace(self.null_space)
self.null_space.orthogonalize(b)
self.solver.solve(A, self.func.vector(), b)
if not self.every_timestep:
# Give initial values for p, but do not continuously compute p_hydrostatic
sim = self.simulation
p = sim.data['p']
if p.vector().max() == p.vector().min() == 0.0:
sim.log.info(
'Initial pressure field is identically zero, initializing to hydrostatic'
)
p.interpolate(self.func)
# Disable further hydrostatic pressure calculations
self.func.vector().zero()
del sim.data['p_hydrostatic']
del self.func
self.active = False
def build_pressure_null_space(self):
# Prepare function used to correct pressure values
null_fcn = Function(self.subspace("p"))
null_fcn.vector()[:] = 1.0
# Create vector that spans the null space and normalize
null_vec = Vector(null_fcn.vector())
null_vec *= 1.0 / null_vec.norm("l2")
# FIXME: Check what are relevant norms for different Krylov methods
# Create null space basis object
null_space = VectorSpaceBasis([null_vec])
return (null_space, null_fcn)
def build_pressure_null_space(self):
# Prepare function used to correct pressure values
W_ns = self.function_spaces()[1]
# NOTE: The following works only for nodal elements
# null_fcn = Function(W_ns)
# W_ns.sub(1).dofmap().set(null_fcn.vector(), 1.0)
null_fcn = self._get_constant_pressure(W_ns)
# Create vector that spans the null space and normalize
null_vec = Vector(null_fcn.vector())
null_vec *= 1.0 / null_vec.norm("l2")
# FIXME: Check what are relevant norms for different Krylov methods
# Create null space basis object
null_space = VectorSpaceBasis([null_vec])
return (null_space, null_fcn)
class HydrostaticPressure:
def __init__(self, simulation, every_timestep):
"""
Calculate the hydrostatic pressure
"""
self.simulation = simulation
self.active = True
self.every_timestep = every_timestep
rho = simulation.data['rho']
g = simulation.data['g']
ph = simulation.data['p_hydrostatic']
# Define the weak form
Vp = ph.function_space()
p = TrialFunction(Vp)
q = TestFunction(Vp)
a = dot(grad(p), grad(q)) * dx
L = rho * dot(g, grad(q)) * dx
self.func = ph
self.tensor_lhs = assemble(a)
self.form_rhs = Form(L)
self.null_space = None
self.solver = linear_solver_from_input(
simulation,
'solver/p_hydrostatic',
default_parameters=DEFAULT_SOLVER_CONFIGURATION,
)
def update(self):
if not self.active:
return
with Timer('Ocellaris update hydrostatic pressure'):
A = self.tensor_lhs
b = assemble(self.form_rhs)
if self.null_space is None:
# Create vector that spans the null space, and normalize
null_space_vector = b.copy()
null_space_vector[:] = sqrt(1.0 / null_space_vector.size())
# Create null space basis object and attach to PETSc matrix
self.null_space = VectorSpaceBasis([null_space_vector])
as_backend_type(A).set_nullspace(self.null_space)
self.null_space.orthogonalize(b)
self.solver.solve(A, self.func.vector(), b)
if not self.every_timestep:
# Give initial values for p, but do not continuously compute p_hydrostatic
sim = self.simulation
p = sim.data['p']
if p.vector().max() == p.vector().min() == 0.0:
sim.log.info(
'Initial pressure field is identically zero, initializing to hydrostatic'
)
p.interpolate(self.func)
# Disable further hydrostatic pressure calculations
self.func.vector().zero()
del sim.data['p_hydrostatic']
del self.func
self.active = False