[bernarde]

Hi all

Does anybody have any experience using the roughness function in Star-CCM+?

I have a simulation where I have flow through a tube with a very small diameter. I suspect that the relative surface roughness plays an important role. I have tried changing the "Wall surface specification" of the tube to "rough", and setting a roughness height, but I haven't seen any change in my results.

I'm making use of the k-omega turbulence model, and a low yplus grid to resolve the boundary layer completely. Does the roughness function only affect the wall function the turbulence model uses, and therefor have no effect if you are resolving the boundary layer?

I would ideally not like to explicitly add the roughness (ie draw it into the 3d model). Any suggestions are appreciated.

Thanks