[nasir.iitd]

Dear everybody,
I'm using Ansys 15.0 Fluent for the simulation of V-cone flow meter to estimate discharge coefficient. For validation of Fluent code,I have experimental data. In V-cone flow meter, cone element is installed co-axially at the center of a circular pipe with surface roughness height 1 mm as the pipe is very old with rust. I have produced boundary layer mesh on the pipe-wall and cone element surface and the first layer height is 0.06 mm with growth factor 1.2. In Fluent wall boundary,I have set 1 mm roughness height and roughness constant 0.5. After well converged solution (SST k-omega and RNG k-epsilon), I calculated discharge coefficient. But these values are very high(Cd=0.84 i.e. similar to smooth pipe Cd value) as compared to experiments data(Cd=0.71).It seems that surface roughness height is not effective in simulation. Can anybody help me, how to get roughness effect in simulation?
Thanks in advance.
Nasiruddin