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Air mixing, difficult question

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Old   July 17, 2008, 12:29
Default Air mixing, difficult question
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Hello world,

I want to modelize mixing between two flows with a 2d model.

The first one is a high pressure flow (30 to 100 psi, ie 2e5 to 7e5 Pa, positive x direction) The other one is low pressure flow (ambiant pressure, positive y or x direction, it depends mesh choice).

I tried to use different viscosity models ( the best one seems to be RNG k-epsilon). Segregated or Coupled solver, the coupled seems to be the best even if convergence is hard (oblige to turn off equations, decrease numbers,...).

But, I have a big problem, when i use : Display > path line i have not mixing between two flows. They are still segregated.

I tried to use define > model > multiphase > mixture with regular settings but i have still same results.

Have you an idea ?

Everything happens as one flow can't penetrate the other one. The high pressure jet can drag along the low pressure gas but nothing else.

Have you an idea ?

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Old   July 18, 2008, 00:40
Default Re: Air mixing, difficult question
ravi kumar
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try to use species transport model.. then u can see the mixing of the two gases in the contours of mass fraction.. hope this may be useful...

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Old   July 19, 2008, 17:34
Default Re: Air mixing, difficult question
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Thank you for your help

I fallowed your advice. But, because both of jets are air, the mass fraction is constant (=1) everywhere. Other Idea ? I will try to change one air stream for a benzene stream and check if the mixing happens. I don't need to take values on it but i want to be sure it occurs.

Best regards.
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Old   July 20, 2008, 10:30
Default Re: Air mixing, difficult question
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i hope there will not be any mixing. its natural that high pr fluid will tend to drag the low pr fluid.isn't it?

See Fluent tutorial no.1. I think it is same as ur problem.
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