Question:
How do the various options for the nodal mesh refinement differ?
Answer:
For the circular type, you need to define the size of the circular compression area via a radius on one hand, and the inner and the outer target length on the other hand. The outer FE length usually corresponds to the global mesh size.
In the case of a rectangular type, specify the "Side Length" of the cube-shaped compression area as well as the "Inner Target FE Length".
For circular refinements, you can use the "FE length arrangement" to control how the mesh size of the FE mesh expands from the inside to the outside.