[mchurchf]

I am wondering if anyone can help with a problem I am encountering. I need to apply boundary conditions on SGS stresses in addition to nuSgs. I would like to perform near-wall modeling in LES by setting the stess at the wall.

Therefore, I have reformulated the UEqn matrix in a PISO solver to look like:

fvm::ddt(U) + fvm:div(phi,U) + div(R) + laplacian(nu,U)

where R = turbulence->R(); Originally, the code is as follows:

fvm::ddt(U) + fvm:div(phi,U) + turbulence->divDevReff(U)

I am finding that if I set the value of the shear stress at the ground, the solution develops very oscillatory instabilities. If I set the boundary condition of R to zeroGradient, things are okay, but I need to be able to set specific stress tensor values at the ground.

Any ideas??

Thanks,

Matt