Duct or open channel
 

Hi,
Im trying to determine values for my inlet and outlet boundary conditions,

I have came across the following formulas in the manual and on this forum:

For fully-developed flow in non-circular ducts the turbulent length scale can be estimated as 0.07dh where dh is the hydraulic diameter.

For fully developed pipe flow the turbulence intensity at the core can be estimated as:
I = 0.16*Redh^(-1/8) where Redh is Reynolds number determined from the hydraulic diameter,

I'm trying to model the flow in a flume of 4 m wide x 2 m deep, my question is can I use these equations?

I'm using fluent.

any advice would be greatly appreciated.
Thanks,