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Uniform pressue increase over fan

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Old   August 30, 2011, 01:32
Default Uniform pressue increase over fan
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Alexander
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Hi!

I'm modeling a closed-circiut windtunnel in ANSYS CFX v13 and am using an interface in CFX-Pre to simulate the fan in the tunnel. I.e I have ha fluid fluid interface with general connection between the two adjacent faces that is supposed to be the fan. Under "Additional Interface Models" I've selected Conservative Interface Flux and a pressure change of 450 Pa. In this simulation I'll neglect the vortices caused by the fan so I want a uniform flow out of the fan.

My problem is that when I do it this way I get a pressure gradient in the cross section of the fan since the flow before the fan isn't uniform and the interface just increases the pressure at each point by 450 Pa (I guess?). Does anyone have any idea about how I can make the flow out of the fan uniform?

Thanks!
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Old   August 30, 2011, 06:23
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Glenn Horrocks
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Why not just use a velocity inlet and a pressure outlet? Then everything is much easier.
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Old   August 30, 2011, 06:39
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Quote:
Originally Posted by ghorrocks View Post
Why not just use a velocity inlet and a pressure outlet? Then everything is much easier.
I tried that first but I don't want a hole in my tunnel which I seemed to need to do as you say.
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Old   August 30, 2011, 06:49
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The only reason you would link it up is because the inflow to the fan affects the outflow somehow - but as you say you want an even pressure that does not seem the case. So do not link it but define it separately and things will be much easier.
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Old   August 30, 2011, 19:15
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Quote:
Originally Posted by ghorrocks View Post
The only reason you would link it up is because the inflow to the fan affects the outflow somehow - but as you say you want an even pressure that does not seem the case. So do not link it but define it separately and things will be much easier.
You're probably right. I'll try do it that way again. Thanks!
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