CFD Online Discussion Forums - k-omega SST SAS High Wavenumber Damping Limiter

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k-omega SST SAS High Wavenumber Damping Limiter

Hello to everyone :),

i am trying to use the k-omega SST SAS model for my simulation.
By taking a look into the source code i recognized that the OpenFOAM-Version is very different from current versions proposed in the literature.

Besides the different formulation of the $P_{SAS}$ term in the $\omega$ -equation, the von-Karman length in newer papers is something like this:

$L_{vK}=max\left(\frac{\kappa\,S_2}{|\nabla^2\underline{u}|},HWDL\right)$

However, the OpenFOAM-2.3.x version reads

$HWDL=C_{s}\Delta$

whereas Egorov and Menter [1] propose the following:

$HWDL=C_s\,\Delta\sqrt{\frac{\kappa\zeta_2}{\frac{\beta}{C_{\mu}}-\alpha}}.$

Question 1: Did i understand it right, that OpenFOAM does not include the high wavenumber damping correctly? And what do you suggest for implementation?

The latter HWDL is based on the Smagorinsky SGS.
But taking a look into [2] the authors say, that a Smagorinsky SGS might not work well.
They propose, that it is better to construct a HWDL from a WALE SGS model.
Unfortunately, i don't have access to the reference [23] they give in [2].
Question 2: What do you think about that? Does this HWDL has that big impact on the results?

Maybe someone is familiar with the model as well as its different versions and brings a little bit light into the darkness ;).

Best regards,

Christoph

[1] Egorov, Y., and F. Menter. "Development and application of SST-SAS turbulence model in the DESIDER project." Advances in Hybrid RANS-LES Modelling. Springer Berlin Heidelberg, 2008. 261-270.

[2] Menter, F. R., and Y. Egorov. "The scale-adaptive simulation method for unsteady turbulent flow predictions. Part 1: Theory and model description." Flow, Turbulence and Combustion 85.1 (2010): 113-138.

Did you find any answers to your questions?

(Your missing reference can be found as printed book in several libraries in Germany, so you should be able to order it as "Fernleihe" from any university library: http://kvk.ubka.uni-karlsruhe.de/hyl...bit_redirect=1)

Hi Joachim,

i just used the plain OpenFOAM model for my first SAS simulations. The next step is to implement the standard model from CFX and Fluent into OpenFOAM, which is based on a Smagorinsky-like HWDL. I will check the deviations by simulating a wake flow behind a triangular cylinder [1].
Afterwards, i will try to couple the model with the WALE-SGS or the Vreman-SGS. If you know a good testcase for validation of flows, where the turbulent viscosity should vanish in certain regions, then feel free to reply :-).

Its just a side project. So it may take some time ;-).

Best regards.

Christoph

[1] Zhang, Xing, and Blair Perot. "Turbulent Vortex Shedding From Triangle Cylinder, Using the Turbulent Body Force Potential Model." Proceedings of ASME Fluids Engineering Division, FEDSM2000-11172, Boston, Massachusetts (2000).

So i don't found any answers regarding the different implementations...;-)

Hi guys,

Any updates on this one? :)

I recently made one implementation based on the 2010 papers, you can check it out here:

http://www.cfd-online.com/Forums/ope...nce-model.html

EDIT: Just noticed you are using LES, never mind :)