Fix ill-posed problem by providing additional data. (#144)

See precice/fenics-adapter#113 for details.

Author: BenjaminRodenberg

HT/partitioned-heat/fenics-fenics/heat.py

@@ -29,7 +29,7 @@
     File, solve, lhs, rhs, grad, inner, dot, dx, ds, interpolate, VectorFunctionSpace, MeshFunction, MPI
 from fenicsprecice import Adapter
 from errorcomputation import compute_errors
-from my_enums import ProblemType, Subcycling
+from my_enums import ProblemType, Subcycling, DomainPart
 import argparse
 import numpy as np
 from problem_setup import get_geometry, get_problem_setup
@@ -211,6 +211,10 @@ def determine_gradient(V_g, u, flux):
         precice.store_checkpoint(u_n, t, n)
 
     read_data = precice.read_data()
+    if problem is ProblemType.DIRICHLET and (domain_part is DomainPart.CIRCULAR or domain_part is DomainPart.RECTANGLE):
+        # We have to data for an arbitrary point that is not on the circle, to obtain exact solution.
+        # See https://github.com/precice/fenics-adapter/issues/113 for details.
+        read_data[(0, 0)] = u_D(0, 0)
 
     # Update the coupling expression with the new read data
     precice.update_coupling_expression(coupling_expression, read_data)