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constant gradient rate bounday

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Old   October 23, 2007, 12:05
Default constant gradient rate bounday
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kostas
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Hi. I am new to cfx and I am trying to apply a constant gradient rate boundary in an inlet, but i can't find a B.C. like this. Is there any way to apply such a B.C. in cfx?

thank you
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Old   October 23, 2007, 13:04
Default Re: constant gradient rate bounday
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opaque
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Dear Kostas,

I imagine you mean a constant flux, that is grad(phi).normal vector . Then, you can use the Flux in condition, and divide by the "diffusion coefficient" of that equation.

Would you mind explaining what guarantees a gradient at an inlet boundary? Is it for an additional variable with no advection?

Good luck,

Opaque

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Old   October 23, 2007, 20:57
Default Re: constant gradient rate bounday
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HekLeR
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For which equation?
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Old   October 24, 2007, 04:31
Default Re: constant gradient rate bounday
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kostas
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thnks for the reply

My problem is o buoaunt flow between vertical parallel plates with openings on the top (outlet) and the botton (inlet).

I want to apply a classic Neumann outlet b.c. for the velocity and pressure (without prescribing values for velocity or pressure).

Thank you
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