definition of u* for y+<10
 

Does anyone know how Fluent specifies the value of u* in equation 10.5-32 (Fluent 6 user manual) which defines the wall value of the omega boundary condition (k-omega turbulence model)? The only definition I can find in the manual is u*= C_mu**0.25 k**0.5, which is valid in the log layer, but not the viscous sublayer. If that is used then u*->0 as the grid is refined. Perhaps it is defined as sqrt(tau_wall/rho)?