The user FORTRAN routines are used for - Complex features not available through the command language > Non-uniform velocity profiles, variable material properties, moving grid, etc…
The geometry is a set of hexahedral solids which have a logical representation. Each block in the geometry is called a ‘solid’. Each solid in the geometry can represent a fluid, porous or solid region
Simplify the problem - Simplify geometry > Ignore features that do not affect the flow > Use as many blocks as possible to set the geometry > Make blocks meet at complete faces
