Adriangibbons2007-10-29 14:06:37

Hello, I’ve just started using CFD with Fluent 6.0 with GAMBIT 2.0 and

I need to know how to model screens – how do I do this?

I’m working on a simulation of a wind tunnel. Its only 2D and I tried

to add a vertical edge and give it the boundary type “porous_jump” but

it doesn’t include this edge when I export it as a 2D mesh, why?

Any ideas?

Regards,

Adrian.

Jgk2007-10-29 14:06:40

Adrian,

I do not know Fluent, but some other packages do not show line boundaries,

if these boundaries are the same as a grid line.

Regards,

Jan Gerrit Kootstra

“Adrian Gibbons”

news:34a2acd5.0307220517.3a03ce06@posting.google.com…

Adriangibbons2007-10-30 02:10:27

OK, I’ve found in the manual something called a “Porous Jump Boundary

Condition”. This sounds like what I need – from the Fluent manual:

“Examples of uses for the porous jump condition include modelling

pressure drops through screens and filters”

I need to enter three parameters for this condition:

1) Face permeability (m^2)

2) Porous medium thickness (m)

3) Pressure-jump coefficient (1/m)

The first two are pretty obvious but I’m unsure what the third one is

and how to obtain it – any help would be greatfully appreciated.

Regards,

Adrian.

Pksc522007-10-30 02:10:28

Regarding GAMBIT not exporting the edge into FLUENT; GAMBIT will

export only those components which are a part of the geometry. In your

case, GAMBIT will not export the edge if it is just a hanging edge. it

has to be a part of one of the faces in the geometry. You may have to

split one fo the faces of the wind tunnel with the ‘porous jump’ edge

and then mesh the geometry. I am sure it should work after that.

About the parameters in porous jump BC, there is a section in the

user guide that tells you the various ways to find the variables in

the equation under “POROUS MEDIA CONDITIONS”. There are 2 ways to find

C2(porous jump coefficient). you can either obtain a value from

experiment or run a simulation purely for the screen and find the

coefficient. I am sure both these are described in detail in the

relevant sections. hope this helps.

Pavan

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