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Simulating inlet consisting of many small holes

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Old   October 14, 2008, 10:53
Default I wonder if someone could help
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Christian Lindbäck
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I wonder if someone could help me with the following. Air is pumped into a room through a plate with a lot of small holes. If I don't account for this, the velocity will be wrong given a specific volume flow which I know.

On the other hand, accounting for these tiny holes through meshing is out of the question. So what can I do? The area of the inlet will be too big if I disregard the fact that the inlet really is a perforated plate.

But what if I increase the fluid density on the inlet. Then the momentum (rho*U) will be correct as well as the volume flow (U*A). I mean, inside the domain, density is evaluated from other properties (I'm using bouyantSimpleFoam and buoyantFoam), not solved as a transport equation. This should work, right or wrong? But there will be a momentum over the entire inlet, in reality this momentum only occurs through the holes of the perforated plate. Consequences?

Hope to hear your comments.

Best regards,
Christian Lindbäck
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Old   October 15, 2008, 01:35
Default Hi Christian, why don't you
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Uwe Janoske
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Hi Christian,

why don't you model the perforated plate as a porous zone? If you have different volume flows the pressure drop over the plate will change automatically.

Uwe
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Old   October 15, 2008, 02:11
Default Hi Uwe, What I want is to s
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Christian Lindbäck
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Hi Uwe,

What I want is to set a volume flow V on an inlet with area A. However, due to the fact that the inlet is a perforated plate, I would want the velocity not to be U = V/A but V/(f*A) where f is an area factor between 0 and 1. Another option would be to increase the density at the inlet boundary so that the momentum is correct.

How can I do this with a porous zone?
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Old   October 15, 2008, 02:56
Default Hi Christian, why don't you
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Hi Christian,

why don't you extend the computational domain and set the inlet at a certain distance of the porous plate?

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