Vastly reduces the scattering and churning behaviour of packed beds.
Development provided by Will Bainbridge <github.com/will-bainbridge>
See also http://www.openfoam.org/mantisbt/view.php?id=1994
For multi-region cases the default location of blockMeshDict is now system/<region name>
If the blockMeshDict is not found in system then the constant directory
is also checked providing backward-compatibility