Many mesh generators create meshes with cell volumes that grow very rapidly with distance from boundaries. While this avoids a dense grid as a matter of course, it might also create problems if the mesh is not fine enough to resolve the flow. But if it is known a priori that a finer mesh is required in a certain region of the solution domain, the mesh can be refined using region adaption.
The region adaption function marks or refines cells inside or outside a region defined by text or mouse input. Presently, the grid can be refined or marked inside or outside a hexahedron (quadrilateral in 2D), a sphere (circle in 2D), or a cylinder. The region-based marking/adaption feature is particularly useful for refining regions that intuitively require good resolution: e.g., the wake region of a blunt-body flow field. In addition, you can use the region marking to create mask adaption registers that can be used to limit the extent of the refinement and coarsening.