injectorPipe : initial blockMesh should not have 'empty' patches
Functionality to add/problem to solve
When using blockMesh to generate the initial block of cells for use in snappyHexMesh: in some cases the initial patches are not present in the snappyHexMesh. If so one can use the 'defaultFaces' fall-back for automatic patching of the outside faces. However the defaultFaces should not have a constraint type (e.g. 'empty') since this automatically implies some constraint (e.g. 1D/2D ness in case of empty). Instead use a generic 'patch' type. (the actual type does not matter since these patches are removed during the running of snappyHexMesh)