Flux depending on wall shear stress in Fluent 5.2
 

I want to set the flux at the wall for a UDS. The flux depends on the magnitude of the wall shear stress at the wall, therefore i need to access the walue of the wall shear stress and the value of the UDS at the wall face in the UDF. I know that the UDS is available through F_UDSI(f,t,i). Is there a similar command for wall shear stress magnitude.

Greatful for all help