bcs = [DirichletBC(V, coupling_expression, coupling_boundary), DirichletBC(V, u_D, bottom_boundary)]
a, L = lhs(F), rhs(F)
# Time-stepping
u_np1 = Function(V)
F_known_u = u_np1 * v / dt * dx + alpha * dot(grad(u_np1), grad(v)) * dx - u_n * v / dt * dx
t = 0
u_D.t = t + dt
file_out = File("Solid/VTK/%s.pvd" % precice.get_participant_name())
n = 0
while precice.is_coupling_ongoing():
if precice.is_action_required(precice.action_write_iteration_checkpoint()): # write checkpoint
precice.store_checkpoint(u_n, t, n)
read_data = precice.read_data()
# Update the coupling expression with the new read data
precice.update_coupling_expression(coupling_expression, read_data)
dt.assign(np.min([fenics_dt, precice_dt]))
# Compute solution
solve(a == L, u_np1, bcs)
# Dirichlet problem obtains flux from solution and sends flux on boundary to Neumann problem
fluxes = fluxes_from_temperature_full_domain(F_known_u, V, k)
precice.write_data(fluxes)
error_total, error_pointwise = compute_errors(u_n, u_ref, V)
error_out << error_pointwise
# set t_1 = t_0 + dt, this gives u_D^1
u_D.t = t + dt(
0) # call dt(0) to evaluate FEniCS Constant. Todo: is there a better way?
f.t = t + dt(0)
flux = Function(V_g)
flux.rename("Flux", "")
while precice.is_coupling_ongoing():
if precice.is_action_required(
precice.action_write_iteration_checkpoint()): # write checkpoint
precice.store_checkpoint(u_n, t, n)
read_data = precice.read_data()
# Update the coupling expression with the new read data
precice.update_coupling_expression(coupling_expression, read_data)
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