Rough wall model

bono

Hi,

I am doing LES with surface roughness at the wall. I use the universal log law which includes effect of roughness as the wall model:

u/u_tau=log-law - D, where D is function of ln(ks), with ks is roughness size.

But I am not so satisfied with the result. Anybody knows a better way (and references please) to model the surface roughness than this old model by Nikuradse (Schlichting Ch.20) and Cebeci&Chang (1978)?

Thanks