If a model has not been verified by other means, a convergence test is useful for determining if the mesh density is sufficient. Here you refine the mesh and run the study again, and then check if the solution is converging to a stable value as the mesh is refined. If the solution changes when you refine the mesh, the solution is mesh dependent, so the model requires a finer mesh. You can use adaptive mesh refinement, which adds mesh elements based on an error criterion, to resolve those areas where the error is large. See the “Stresses and Strains in a Wrench” model in the
Introduction to COMSOL Multiphysics book for an example of a convergence test.