roughness length vs roughness height
 

Hi All,

During my use of OpenFOAM, when ever I was to simulate a wall-bounded flow, I found it very hard to understand some of the terms used in wall-modeled boundary conditions, in particular, "roughness length" and "roughness height".

I understand that roughness height, often noted as z_0, which is the a fixed property of the system depending on the placement, shape, size of the roughness elements. And roughness height (K_s) on the other hand is a very loose concept. I read in a post on this furom, that it is around 20-30 times of z_0. Could anyone point me some more concrete material on how this term is defined?


Kind regards,
Sereff

Hi!I ran into the same problem,I suggest you read this artical： 《On the use of the k– model in commercial CFD software to model the neutral atmospheric boundary layer》