Roughness and Turbulent multiplier
 

Hi everyone

There is a problem about turbulent multiplier in USRWTM. In USRWTM user must set TMULT. I want to know how will I set this? In the solver manual(CFX 4.2) ROUGHNESS is set 1.0 (as a default) under the subcommand WALL BOUNDARIES. Could anyone tell me about this? Actually if it is the roughness factor, then its ok, but if it is the roughness height, I want to know the its unit.

Any suggestion about this will be appreciated.

Thanks

Sumon