dt.assign(np.min([fenics_dt, precice_dt]))
# Compute solution u^n+1, use bcs u_D^n+1, u^n and coupling bcs
solve(a == L, u_np1, bcs)
# Write data to preCICE according to which problem is being solved
if problem is ProblemType.DIRICHLET:
# Dirichlet problem reads temperature and writes flux on boundary to Neumann problem
determine_gradient(V_g, u_np1, flux)
precice.write_data(flux)
elif problem is ProblemType.NEUMANN:
# Neumann problem reads flux and writes temperature on boundary to Dirichlet problem
precice.write_data(u_np1)
precice_dt = precice.advance(dt(0))
if precice.is_action_required(precice.action_read_iteration_checkpoint()): # roll back to checkpoint
u_cp, t_cp, n_cp = precice.retrieve_checkpoint()
u_n.assign(u_cp)
t = t_cp
n = n_cp
else: # update solution
u_n.assign(u_np1)
t += float(dt)
n += 1
if precice.is_time_window_complete():
u_ref = interpolate(u_D, V)
u_ref.rename("reference", " ")
error, error_pointwise = compute_errors(u_n, u_ref, V, total_error_tol=error_tol)
# Define boundary condition on left and right boundary
u0 = Constant(0.0)
bc = DirichletBC(V, u0, boundary)
# Define variational problem, simply copied from FEniCS demo
u = TrialFunction(V)
v = TestFunction(V)
f = Expression("10*exp(-(pow(x[0] - 0.5, 2) + pow(x[1] - 0.5, 2)) / 0.02)",
degree=2)
g = Expression("sin(5*x[0])", degree=2)
a = inner(grad(u), grad(v)) * dx
L = f * v * dx + g * v * ds
while precice.is_coupling_ongoing(
): # potential time loop, currently only one timestep is done
# Compute solution
u = Function(V)
solve(a == L, u, bc)
# Save solution in VTK format
file = File("poisson.pvd")
file << u
# write data to preCICE and advance coupling
precice.write_data(u)
precice.advance(precice_dt)
precice.finalize()
read_data = precice.read_data()
# Update the coupling expression with the new read data
precice.update_coupling_expression(volume_term, read_data)
f.assign(interpolate(volume_term, V))
dt_inv.assign(1 / dt)
# Compute solution u^n+1, use bcs u^n and coupling bcs
a, L = lhs(F), rhs(F)
solve(a == L, u_np1, bc)
# Write data to preCICE according to which problem is being solved
precice.write_data(u_np1)
dt = precice.advance(dt)
# roll back to checkpoint
if precice.is_action_required(precice.action_read_iteration_checkpoint()):
u_cp, t_cp, n_cp = precice.retrieve_checkpoint()
u_n.assign(u_cp)
t = t_cp
n = n_cp
else: # update solution
u_n.assign(u_np1)
t += float(dt)
n += 1
if precice.is_time_window_complete():
solution_out << u_n