Federico Alzamora Previtali

You can find some information in the user Guide here: 46.9. Dynamic Mesh Task Page (ansys.com)

Basically, the Unified Remeshing method (default) should work well on triangular/tetrahedral cells, while the Methods-based method should be applied for other cell types.

Negative volume cells can also occur if your time step is too large relative to the moving zones.