Sand Grain Roughness
 

Hello, everybody

Does anybody know the definition of Equivalent Sand Grain Roughness? How does it relate to the real roughness of a material?

For example, if i know the real roughness of a material, how should i set the sand grain roughness for simulating a friction wall in CFX?

Thanks

that depends on how your "real roughness" was determined and what data you have available (Ra, Rz, some older type ...).

there won't be a single, precise answer, i can tell you that :)