Hi guys, thanks for reporting.
We’re still on it (as a matter of fact - right now). We understand the issue and we can assure you that this is generally harmless: it’s not a bug in the mesher and it should also not impact the results negatively (but please read the caveat below).
What’s happening here is the following:
Because we want good meshes, we are applying relatively strict quality criteria. The mesher is configured so that it refines the mesh in areas where it cannot meet the quality criteria of the mesh. This is what causes the refinements in the first place.
Generally, the meshes with the refinement have better quality than without. However, they also have more cells - and sometimes they have more cells than needed. This is problem number 1.
Problem number 2 is that the variance in mesh fineness also affects the condition of the matrix in the simulation. This means that the behaviour of the solver changes (the meaning of the residuals change) and this is possibly the cause for different results, at least if the simulations aren’t fully converged.
If you observe differences in results, one thing to look out for is to ensure that the result is actually converged. Residuals are one way to check that, however I strongly recommend to use result control items (e.g. probe points, or forces) to judge whether or not a result is converged.
We’re right now working on an improvement for the situation. Probably we will go back to less strict quality metrics, which means that mesh quality will become slightly worse again (and again, that’s not an accident, or a bug, but a conscious design choice motivated by a trade-off between mesh size and quality).
In the meantime - sorry for the inconvenience, guys. We really didn’t want to break things for you.