[wouterremmerie]

Hi everyone,

please see the attached image - the mesh we get by experimenting with snappy looks very bumpy in some locations.

https://imgur.com/a/re4MTAI

We can get rid of most of the bumps by applying the following settings:
- nSmoothPatch 5
- nSmoothInternal 5
- tolerance 2
- nRelaxIter 5
- maxBoundarySkewness 3
- maxInternalSkewness 2

But then we get quite a lot of errors (a lot is relative - about 2-10 problem cells on a 10 million cell mesh) in our checkMesh, mainly complaining about skewed faces, wrongOrientedFaces, negative volume pyramids. Interestingly, these errors often occur on the same cells, so they are linked - which means we don't exactly know which is the "real" error and what is causing it.

We can reduce the number of problem cells by for example:
- working with the same refinement level on the surface (so 6 6 instead of 5 6), as many bumps occur at the transition from one level to another.
- further reducing the maxBoundarySkewness from 3 to 2 (but then we get a lot of bumps again)

We've tried this on many models and haven't really found a reliable way to get a smooth surface mesh without introducing problem cells. Does anyone have the same experience and perhaps have some tips?