Hi, I am working on FEM methods as a part of my senior year project and I have written a poisson solver for the same purpose. The solver works pretty well on the simple problems that I have designed as of now and seems to give correct answer (i.e. the data matches the theoretical prediction) 1. Parallel Plate Capacitor 2. Potential inside and outside a hollow sphere of charge 3. Parallel Plate Capacitor with rough surfaces (In this case, I have obtained a good co-relation between the calculations in my advisors pulblished paper and my paper.) However, I have not yet designed any real life problem as of now. So before I design it, I would like to ask if there is any such gold standard for such a thing (a standard problem which is complex enough to demand good convergence requirements from the solver but not so complex as the solution to be contentious) and is there a place where I can get data so that I can verify my own results by running actual error calculations and such stuff rather than just checking the shapes of the graphs. P.S. My solver is a 3D solver so I would like to have a 3D problem for the same.