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Turbulence model for lower Reynolds number in transient analysis

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Old   October 25, 2017, 06:14
Default Turbulence model for lower Reynolds number in transient analysis
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Dr Gurubasavaraju
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Hi all,

Could anyone please help me understand below questions.

1. How to choose turbulence models for laminar, transient analysis?

2. Which is best turbulence model for Reynolds number of around 200 (two hundred)?

3. Is SST compatible for Reynolds number of less than 500?

4. What are the consequences if we use turbulence model for lower Reynolds number.
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Old   October 25, 2017, 07:27
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Why would you use a turbulence model for a laminar flow type? Is your problem truely laminar as your Reynolds number might implicate?
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Old   October 25, 2017, 07:29
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Sorry,

It supposed to be Unsteady, transient flow.
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Old   October 25, 2017, 07:41
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Is it single or multiphase? Can you describe what you want to model/simulate? From your Reynolds number alone i would suggest to simulate without any turbulence model.
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Old   October 25, 2017, 08:14
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Not exactly a multiphase flow. But one portion region is non-newtonain and other is Newtonian (see attachment).
The simulation is on the flow of magnetorheological fluid in a damper. The flow of fluid is due to the motion of the piston head.
fluid flow inside the damper will be random.
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Old   October 25, 2017, 08:38
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SST k-omega is usually i good choice, but check the requirements.
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Old   October 25, 2017, 08:43
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yea,

I just wanted to understand,
whether the turbulence model can be used only based on the Reynolds number or some other factors are also need to be considered while choosing.
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Old   October 25, 2017, 10:18
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Quote:
Originally Posted by gbrajtm View Post
yea,

I just wanted to understand,
whether the turbulence model can be used only based on the Reynolds number or some other factors are also need to be considered while choosing.
You have to consider the physics of your problem and the Reynolds number can give only some information. Depending on the velocity and lenght scales used in defining the Re number, you can have turbulence at low Re number (Re_tau=180 was a well known test for turbulence in channel flow) while you can have laminar condition along a flat plate at higher Re_x numbers.
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Old   October 25, 2017, 11:34
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Thank you very much.
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