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Which turbulence model is applicable for Plain diffuser flow simulation in openFOAM?

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Old   January 29, 2015, 04:49
Default Which turbulence model is applicable for Plain diffuser flow simulation in openFOAM?
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Mominul MuKuT
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Dear Foamers!

Greetings. I want to simulate flow in a plain diffuser. I have modified pitzDaily tutorial for my simulation. The flow solver is simpleFOAM and turbulence model is k-spsilon. But I didn't get expected separation from simulation as it was in experiment. I assume inlet turbulence is isotropic and estimate the flactuation 5% of inlet velocity ( 4m/s). Turbulent length scale is considered as 10% of inlet height (200mm). Using these K=0.06 and epsilon is 0.1208

The velocity contour is as follows: I have used two blocks for the domain, one is in straight section just before the diffuser section and 2nd one is remaining straight section with diffuser.



But from simulation I didn't get expected separation which I have found in experiment. So, I seek suggestion from foamers regarding my simulation. Shall I use other turbulence model? If so, which one perfectly match with my purpose?

Last edited by mukut; January 30, 2015 at 02:55.
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Old   January 30, 2015, 01:04
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Mominul MuKuT
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I don't know how to post here to get attentions from others in this forum, if a preliminary user of openFOAM didn't get helps from experts of openFOAM, it is very difficult for us to go further smoothly. I am eagerly waiting for answer
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Old   January 30, 2015, 02:45
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Mominul MuKuT
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2nd part has been solved.

Hope I get some suggestion to choose an appropriate turbulence model.
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Old   January 30, 2015, 03:14
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Cedric DUPRAT
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Dear Mominul,

I think you could have a look at this link:
https://openfoamwiki.net/index.php/S...nical_diffuser
The idea is that you will not get any flow separation if you keep your configuration.
You have to add an extension to you configuration so that your outlet BC won't act in the core flow.
Following the link you'll also have some hints for the turbulence model and the settings.

I hope this will help you,

Cedric
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Old   January 30, 2015, 09:06
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Mominul MuKuT
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Quote:
Originally Posted by cedric_duprat View Post
Dear Mominul,

I think you could have a look at this link:
https://openfoamwiki.net/index.php/S...nical_diffuser
The idea is that you will not get any flow separation if you keep your configuration.
You have to add an extension to you configuration so that your outlet BC won't act in the core flow.
Following the link you'll also have some hints for the turbulence model and the settings.

I hope this will help you,

Cedric
Dear Cedric

Thanks for your reply. I have already completed experiment, now I try to simulate the flow. I am reading your given links.
Thanks again
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