Gridgen Version 15.18 is now available for production use. It contains many improvements to the T-Rex (anisotropic tetrahedral extrusion) technique for hybrid meshing, in addition to many resolved issues.
Specific improvements in Gridgen V15.18 include
An increase in the number of prisms recovered from layers of T-Rex extruded tetrahedra
Upgrades in T-Rex's ability to extrude out of concave corners
Implementation of an optional Green-Gauss formulation for computing prism volume, which is less restrictive than a minimum component volume approach, resulting in more combined prism elements in some cases
More Information and Downloads
You can read about all the fixes in the Resolved Issues section of the Release Notes: www.pointwise.com/library/relnotes.pdf.