Inlet B.C. of generating a homogenous flow?

David

Hi,

Some references suggest the following inlet boundary conditions could generate homogenous flow in the simulation of atmosphere boundary layer in the absence of obstructions, and the simulated boundary layer will be self-sustaining. This means the inlet and outlet profiles of velocity and turbulence kinetic energy will keep the same. B.C.: U(z)=u*ln(z/z0)/k, K=u*^2/SQRT(Cu),Epsilon(z)=u*^3/k/z, k is the von Karman¡¯s constant.Cu=0.09.

I just use this B.C., but the outlet profile of TKE varies much comparing with the inlet one.The result is not self-sustaining. My case is 3D incompressible, rectangular flow field, structured mesh, Standard K-Epsilon model, scalable wall function, roughness wall, second order, rsm residuals 10-5. Could anyone explain why? Thanks.