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Old   January 31, 2007, 11:30
Default Turbulence in pipe flow.
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Hello all,

A simple 90 (smooth bend for better fluid flow) bend pipe of 10 cm diameter and about half meter long before and after the bend. Inlet vel 0.8 m/s.

I used already three CFD codes. In all of them what I see is, the velocity in the bend is higher near the inner surface and not outer surface. When it has to be other way around. Any suggestions what I missed in my physics setup. This is a first try, so my liquid is water. No heat transfer. Turbulence included, K epsilon model. inlet conditions, besides velocity, turbulence intensity set as 0.05. Dissipation rate, hydraulic diameter 0.1 m. In the outlet the same with respect to turbulence settings. coming to wall conditions, roughness height 0.001 m.

Thanks in advance.
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Old   January 31, 2007, 23:06
Default Re: Turbulence in pipe flow.
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why do u think that it will be other way round..? I think it shud be the way it is...
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Old   February 1, 2007, 12:19
Default Re: Turbulence in pipe flow.
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I agree with Ragh. Your results obtained with three different codes should have prompted you (among other things) to do some research on pipe flow and re-examine your expectations. (Typically, I would suggest to do that before even starting to run CFD.)
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Old   February 2, 2007, 09:18
Default Re: Turbulence in pipe flow.
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I think we also need the radius of the 90 sweep. This will effect the eddy formation, which can act like a bottle neck and force the fluid to travel faster at certain places.
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