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 Tomislav May 22, 2006 04:21

Interface problem

I am meshing a heat exchanger. I have an interface between air and a solid fin. In gambit I define this boundary as interface. In the first try Fluent automatically recognized it, and generated a shadow face. Now, with similar meshes, when I try to do it, Fluent does not recognize the interface, so I have to define it manually. However, when I solve it, the solution diverges or I obtain floating point errors. I supose the reson is the interface. What I am doing wrong? How can I make Fluent recognize automatically the interface and generate the shaddow face?

 mAx May 22, 2006 04:36

Re: Interface problem

Hi, In Gambit, Interface, means an interface between 2 differents mesh-topology.(for instance 2 volumes which are not connected but with a common "interface") Then in Fluent you have to define and activate your interfaces (pair) for a numerical extrapolation. Don't mix it with physics interface

 san May 22, 2006 05:48

Re: Interface problem

Hi,

i am working on heat exchanger in concentric tubes. i have considered only 1/4 th of Model due to symmetry.

know i want to know what is the BC given for shadow wall and the one we have declared.

i knew only the temperature of fluids on each side.

problem is for steady state analysis.

hot fluid is flowing inside tube and cold fluid is on outer tube.

thanks for showing interest in reading the problem.

with regards san

 galary May 22, 2006 21:06

Re: Interface problem

I think you can define it as a wall.If you define the adjacent zone as different property such as solid and fluid, and you can find the wall boundary to be as couple type.

 san May 23, 2006 00:49

Re: Interface problem

Hi,

but what will be BC on that wall ( shadow )

will it be ->

1. temperature of fluid 2. heat transfer coefficient

another option comes in the BC menu, that is wall thickness.

is it mandatory to mention it? if yes how to give it

i mean from hot fluid side assume 3mm thick.

but what about from cold fluid side ?

with regards san

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