Mesh under region close to wall
 

Hello, I am trying to simulate a flow over a mountain. The forest cap is defined as a porous region 3 meters above the ground (wall boundary) with a thickness of 10 meters. What is the best way to mesh the space between the ground and the forest region? I have tried many ways to do this, but there are always pierced or close proximity faces on the bottom side of the forest,the one facing the ground. Any suggestions please?

Re: Mesh under region close to wall
 

I forgot to notice, I am using Star-ccm