[MaherEid]

Hello!

I am trying to simulate a fully developed channel flow using streamwise and spanwise periodicity in Fluent (with LES).
My goal is to get a specific Re_tau (based on friction velocity) = 550

I known from experimental data what the flow rate should be and I confirmed it with a RANS steady state.

When I set the periodic condition to this mass flow rate, the shear is way below the expected one and the flow looks laminar (all turbulent structures decays and turb viscosity drops) even though I added fluctuations at time 0.

However when I use pressure gradient to get my target shear, the flow rate increases too much (almost double of what it should be) and turbulence is present.

My problem is if I use the pressure gradient all the velocity field is wrong and U+ is way higher than it should be. I already tried delayed/DES and URANS and same behavior.

Any suggestions?

Thanks in advance.