8.1.1. How to Refine a Mesh
You must follow these two steps to refine a mesh:
1.Select the entity (or set of entities) around which refinement will be done.
2.Specify the level of refinement to be done (in other words, the desired size of the elements in the refinement region, relative to the size of the original elements). The refined elements will always be smaller than the original elements; the local mesh refinement process does not provide mesh coarsening (LEVEL).