Is it reasonable for a FEM and FVM code to converge to slightly different solutions for the same physical problem (identical BCs, geometry, properties, etc...), provided stability constraints are satisfied? Or even, is it possible for different FEM methods to converge to different solutions?
This is supposed to be more of a general question, but it is inspired by a specific example that I tested a few weeks ago.
A few weeks ago, I tried modeling a simple thermal expansion problem in Abaqus, ANSYS, and a FVM solver, all of which operates under linear elasticity. I'm pretty sure the conditions are specified identically in all 3 solvers, but it appears that the 3 solvers converge to slightly different results with about a 10-20% difference (the difference exists for Abaqus vs. ANSYS as well, 2 FEM solvers).
I wrote the FVM solver myself, and I've verified that the linear elasticity equations are solved correctly and I assume established solvers like ANSYS and Abaqus are solving their equations correctly as well. It puzzles me how the 3 solvers can each converge to different solutions, and I can't intuitively think of how this can be possible, numerically?