the minimum aspect ratio (the circumsphere ratio) allowed for the resulting coarsened elements. The lower the minimum aspect ratio, the more elements in the mesh will be coarsened.

is the largest tetra size allowed by coarsening. Only elements below this size will be coarsened, and only up to this size. The larger this value, the more the mesh will be coarsened.

For surface elements (triangles), this option coarsens the elements based on the distance from the centroid of the element to the surface, in the direction normal to the surface. If this distance is less than the defined Max Surface Deviation, the elements will be coarsened.

is the number of smoothing iterations. Smoothing will be automatically performed after the coarsening process if this number is nonzero.

If this is enabled, then surface triangular elements will also be coarsened. If disabled, only tetra and prism volume elements are coarsened.

If this is enabled, it will attempt to coarsen up to the sizes prescribed on the geometry (points, curves and surfaces). Local coarsening can be achieved this way by only changing tetra sizes on specific entities. When tetra mesh is generated, the elements are divided to these sizes. So if no tetra sizes are changed after generating the tetra mesh, then enabling this option will prevent any coarsening from being performed.

specifies the parts which will not be coarsened. Nodes of these parts will remain fixed. If there is only one volume part, and this part is frozen, no coarsening will be performed.