Hello,
I made a fully coupled model of two physics (Darcy's law and Heat transfer in porous media) for 2D horizontal geothermal heat exchanger (i.e., coupled heat and moisture transfer in soil under thermal gradient). Once I ran the model, error messages came up regarding convergence issues with time dependent solver (i.e. nonlinear solver did not converge). I studied many resources in COMSOL website and followed the tips that posted (e.g. change method to ease tolerance factor). I've also learned that coarse mesh may cause the convergence issue. I thus set extremely fine mesh, especially near the boundaries between domains. Even the model was running for overnight, I still got same error messeage. Does anyone know the solution to fix this issue? I am looking for a way that I can stay with my normal mesh and run the model without error.