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HELP! TURBULENCE k-e OR k-omega TURBULENCE MODEL?

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Old   July 25, 2003, 14:11
Default HELP! TURBULENCE k-e OR k-omega TURBULENCE MODEL?
  #1
Mirek Kabacinski
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Hello Fluent Users again? I have one short question (according to my previous e-mail 2 days ago): Is it possible to simulate CORRECT simulation of steady incompressible air flow around circular cylinder with the aid of mentioned k-eps or k-omega turbulence model in FLUENT (v.6.0.20). I can't get correct static pressure distribution on the back side of cylinder (2-D or 3-D). Diameter of cyl=10mm and Re=1E+3 to 1E+5 (in func. of cyl diameter). Can anybody help me? Thanks in advance.
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Old   July 26, 2003, 11:34
Default Re: HELP! TURBULENCE k-e OR k-omega TURBULENCE MOD
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Guess
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I feel the flow will become unsteady at these reynolds - 10^5! Please check it!
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Old   July 26, 2003, 13:59
Default Re: HELP! TURBULENCE k-e OR k-omega TURBULENCE MOD
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James Date
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I've got a feeling that unsteady vortex shedding (Von Karmen vortex street), occurs at a much lower than Rn = 10^5. Best to check in a good fluid dynamics text.

The first thing I think of with regard to problems like these is fine grids and lots of small time steps and a turbulence model which is not k-e, but possibly k-w.

James
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Old   July 27, 2003, 11:45
Default Re: HELP! TURBULENCE k-e OR k-omega TURBULENCE MOD
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Mirek Kabacinski
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Thanks for your help, but it dosn't solved my problem. Have you got any other ideas to solve my problem. Thanks in advance.
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Old   July 30, 2003, 22:06
Default Re: HELP! TURBULENCE k-e OR k-omega TURBULENCE MOD
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Mark
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Hi,

There is a limit for a k-eps or k-omega turbulent model used to predict flow with strong vortex like your case. However RNG-k-eps will be better than k-eps in this case. If it is possible, you can try RSM turbulent model or LES simulation, results will be more close to your experience. Hope it will giave you little help.

Mark

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Old   August 24, 2003, 22:31
Default Re: HELP! TURBULENCE k-e OR k-omega TURBULENCE MOD
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buffalo
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I have met the same problem before. In predicting pressure and heat transfer cofficient on surface cann't get satisfy result.
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