[Many]

Hi foamers,

I am trying to do an internal flow computation using k-omega SST model in OpenFOAM. The solver used is simpleFoam.

After reading several posts and theoretical, I am a bit lost yet...I cannot reach a convergent solution of my model.

The mesh is created with cfMesh. About 5 layers of prism cells are placed close to the wall of the bifurcated pipe. The first layer height is about 5e-05.

I have tried several BCs for k, omega and nut. I attach the main 3 options I have used.

Simulation residuals never fall below 1e-03 (for pressure it uses to be 1e-02).

So, here are my questions:

1. The yPLus value I have obtained using yPlusRAS utility (some people say that it is ystar, I have not read the code yet) is about 2-3. I want to resolve boundary layer ,so, could this be the problem? Should I go to a yplus value of 1 or below? Is this really the theretical yPlus? Can I apply wall functions in this case (I think wall function approach is better for a not well resolved mesh at the boundary, let's say yPlus between 30 and 300 or so)?

2. CheckMesh present some warnings, but I guess these come from the cells close to the wall, which are expected to be high aspect ratio cells. What about non orthogonal correctors?

3. As I am not finding a convergent solution, I started to think in solvers in fvOptions and discretization schemes in fvSchemes. I attach it too. I would like to go to second order schemes.

4. I know that my initial values could be better computed, but at the beginning the simulation residuals fall fast. The poblem is that at some point, they stay constant in a quite high value, although both flow rate and averaged outlet velocity remain constant. Do you think initial values could have influence in the convergence behaviour after several iterations?

I am using OF 2.2.2, but I will update to 2.3 soon.

Thanks in advance. I cannot solve this!

NOTE that in attached files sometimes one of the inlets is treated as a wall. This is not a mistake, I have decided to close it for some reasons, but the residuals behaviour is almost the same...