cell derminant in checkMesh too limiting

Functionality to add/problem to solve

For low-Re meshes, the high aspect ratio might trigger the cell determinant warning.

The cell determinant

• is a measure for how close the cell is to an ideal 'cube' shape.
• it does a principal axis determination based on amount of face-area (to internal faces)
• the determinant is then the product of the face-areas in all three principal directions

For high-aspect ratio cells or indeed 1D pipes the cell determinant is very small or zero. It probably should not look at the determinant but instead make sure there is at least one 'valid' direction (enough connectivity to neighbouring cells).

This is more a problem of what we want to output than problems with the mesh or checkMesh.

The problem is that in the default meshQualityDict in etc/caseDicts specifies a minimum cellDeterminant of 0.001. Maybe this needs reviewing.