rib roughened duct flow

Joel

Hi,

I'm currently trying to set up a model which will allow me to measure the static lined with semi-circular roughness elements at regular spacings.

I confess to being no CFD expert and would very much appreciate some advice on how best to set this problem up. The Reynolds number of the fluid (air at 20 degrees - incompressible) is 100000. I'm using the standard Kechen turbulence model and the co-ordinate system is cartesian. At present the pressure drop between two stations, which is translated into a friction factor, is somewhat larger than expected.

A particular point that i'm unsure of is whether the use of a wall function is still possible for this roughened duct?

Many thanks in advance for any help.

Joel.