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Looking for suggestions about how to set up a boundary condition

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Old   February 25, 2010, 18:08
Default Looking for suggestions about how to set up a boundary condition
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Pete Launie
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I would like to model a multi-component gas flowing over a membrane which allows one of the components to diffuse through it. Not sure how to set up the problem in star ccm.

can I define a boundary with a negative mass flow based on a field function which looks at the local mass fraction of that gas component?

Is this asking for trouble or does anyone have other ideas about how to set it up?

Thanks for your help.
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Old   February 28, 2010, 14:14
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Naimish Harpal (MS Aerospace Engr)
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Regrading your membrane BC, to diffuse multi-component gas, you can define that boundary as 'Pressure Outlet'. Then define pressure and the mass-fraction (between 0 and 1 w.r.t to total mass-fraction) of particular gas to be sucked out. You may calculate the pressure in terms of velocity and mass flow rate using simple Bernoulli' equation.

I hope that this may help you.
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Old   March 23, 2010, 16:12
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Pete Launie
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Quote:
Originally Posted by naimishharpal View Post
Regrading your membrane BC, to diffuse multi-component gas, you can define that boundary as 'Pressure Outlet'. Then define pressure and the mass-fraction (between 0 and 1 w.r.t to total mass-fraction) of particular gas to be sucked out. You may calculate the pressure in terms of velocity and mass flow rate using simple Bernoulli' equation.

I hope that this may help you.
On a pressure outlet boundary, doesn't the mass fraction (species specification) only apply when there is backflow?
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Old   April 6, 2010, 13:08
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CD-adapco said there is no way to specify a per species boundary condition and trying to come up with a work-around.
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