Meshing and convegence the tangenbtial Cyclone
 

Hi all. I have two basic questions about the cyclones

1. one recommends the aspect ratio of 5-10 for cyclones. what mean the aspect ratio? is that the growth factor in boundary layer meshing? what happened if i don't consider any boundary layer for faces? I have some problem in internal integrity of boundary meshes in volume.

2. I get convegence with k-epsilon and RSM (first order) without injecting the particles (solid), but when turn on the DPM, the residual diverged, especially, when I increase the number of iteration in tracking parameters in DPM window. how can I be sure that the number of iteration in tracking pararmeter is enough?

Thanks dor your recommendation