Define delta in kOmegaSSTSAS turbulence model
 

Hi everyone,

I am implementing kOmegaSSTSAS turbulence model (using pimpleFoam solver) to simulate the flow around a cube for relatively high Re (between 10^4 and 10^7).

As far as I know, there are no tutorials using this specific turbulence model. I have noticed that kOmegaSSTSAS is derived from kOmegaSST. The only additional parameter required is "Delta" or "LES Delta".

I have read through the extended guide but I cannot understand the physical meaning of this parameter. Also, there are many different ways to specify Delta (https://www.openfoam.com/documentati...1LESdelta.html) and I don't know which one would be more appropriate for the kOmegaSSTSAS.

So far I have tried the "cubeRootVol" definition as suggested in https://develop.openfoam.com/Develop...kOmegaSSTSAS.H , but I am not sure if this is correct.

Could anyone help me with this?

Thanks in advance!

Cristina

I am also interested in kOmegaSSTSAS. Have you found the answer of your question?

Hi,
I was wondering if you have managed to run the kOmegaSSTSAS model or if you managed to find a tutorial for it?


I'd like to run it for a flow around an airfoil case , but i'm not sure where to get started

OpenFOAM SAS usage
 

the delta in kOmegaSSTSAS ist used equally to LES. SAS (Scale Adaptive Simulation) uses spatial averaging related to cell size, such as LES does. In OpenFOAM you can apply the SSTSAS-Model just like the usual SST-Model.

For delta you might define cubeRootVol, which only takes the cubic root of cell expansion in every spatial direction. But if the aspect ratios of your cells are not allways equal to 1 (especially at near wall regions), you might use the vanDriest damping function to calculate your spatial averaging width in combination with cubeRootVol.


I use it simply like this:
delta vanDriest;


vanDriestCoeffs
{
delta cubeRootVol;
cubeRootVolCoeffs
{
deltaCoeff 1;
}

smoothCoeffs
{
delta cubeRootVol;
cubeRootVolCoeffs
{
deltaCoeff 1;
}

maxDeltaRatio 1.1;
}

Aplus 26;
Cdelta 0.158;
}


I am not sure about all those parameters. But vanDriest allways needs to be combined with a geometric filtering function. Also have a look at this:

• vanDriest
• Menter-Egorov
• Menter-ANSYS