simpleFoam kOmegaSST k, w and nut initial and boundary values

Ezel Bayraktar · December 6, 2021, 01:23

Hello Everyone,

I am trying to simulate flow over an airfoil using simpleFoam and turbulence model kOmegaSST. I have taken k, w and nut values from http://ichrome.com/blogs/archives/342 and http://www.wolfdynamics.com/tools.html?id=110. But after several iterations, soltion diverges. After changing these values many times, I have obtained a stable solution. My question is; how could we select values of these turbulence parameters.

with all respect...
Ezel Bayraktar

sqek · December 6, 2021, 07:46

For inlets, I'd use things like turbulentIntensityKineticEnergyInlet and turbulentMixingLengthFrequencyInlet - you give them an intensity/length scale, and they look at the velocity and calculate k/omega for you, in a similar way to the sites you linked.

For initial values, as long as its roughly the right order of magnitude, it should converge eventually, but the further from reality the slower - stuff like the sites you linked are probably the best option. Something that can help is to use the less accurate and more stable fvSchemes/fvSolution settings first, then change them once you have a converged-but-inaccurate flow

December 6, 2021, 01:23	simpleFoam kOmegaSST k, w and nut initial and boundary values	#1
Ezel Bayraktar New Member Ezel Bayraktar Join Date: Jul 2020 Posts: 4 Rep Power: 5	Hello Everyone, I am trying to simulate flow over an airfoil using simpleFoam and turbulence model kOmegaSST. I have taken k, w and nut values from http://ichrome.com/blogs/archives/342 and http://www.wolfdynamics.com/tools.html?id=110. But after several iterations, soltion diverges. After changing these values many times, I have obtained a stable solution. My question is; how could we select values of these turbulence parameters. with all respect... Ezel Bayraktar

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December 6, 2021, 07:46		#2
sqek Member Join Date: May 2017 Posts: 31 Rep Power: 8	For inlets, I'd use things like turbulentIntensityKineticEnergyInlet and turbulentMixingLengthFrequencyInlet - you give them an intensity/length scale, and they look at the velocity and calculate k/omega for you, in a similar way to the sites you linked. For initial values, as long as its roughly the right order of magnitude, it should converge eventually, but the further from reality the slower - stuff like the sites you linked are probably the best option. Something that can help is to use the less accurate and more stable fvSchemes/fvSolution settings first, then change them once you have a converged-but-inaccurate flow