v = TestFunction(V) F = u * v / dt * dx + alpha * dot(grad(u), grad(v)) * dx - u_n * v / dt * dx # apply constant Dirichlet boundary condition at bottom edge # apply Dirichlet boundary condition on coupling interface 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
raise Exception("Boundary markers are not implemented yet") # return dot(coupling_bc_expression, v) * dolfin.dss(boundary_marker) a, L = lhs(F), rhs(F) # Time-stepping u_np1 = Function(V) u_np1.rename("Temperature", "") t = 0 # reference solution at t=0 u_ref = interpolate(u_D, V) u_ref.rename("reference", " ") # Generating output files temperature_out = File("out/%s.pvd" % precice.get_participant_name()) ref_out = File("out/ref%s.pvd" % precice.get_participant_name()) error_out = File("out/error%s.pvd" % precice.get_participant_name()) # output solution and reference solution at t=0, n=0 n = 0 print('output u^%d and u_ref^%d' % (n, n)) temperature_out << u_n ref_out << u_ref 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?