I am trying to simulate a heat sink in an air duct, but whenever I mesh with cfmesh most of the fins are combined into a single block.The heat sink is about 300x250x90mm with 5.25mm between fins. To simulate an air duct it's in a box 400x800x300 mm with a 330x250x100 mm refinement box around it. I've been trying to mesh with cfmesh (20mm base element size). I've tried both surface and internal volume refinement. The results have been essentially the same (as far as the problem goes). The picture below is a volume mesh with a relative element size of 0.175.
All of the fins are captured if I use gmsh or snappyhexmesh. Is there something special I need to do to mesh between the fins with cfmesh? Thanks!