how I can define the roughness Yr?
 

Hi, CFX friends, who knows how to specify the roughness height Yr in CFX 5.5 in order to simulate the roughness of wall in ducts when I failed to use inflation near the wall? And who has experience ralated to the relationship between the geormy size and the thickness of the inflation. The problem always come out when I use the inflation. Thanks a lot.

Hannah Liang