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Elvis1991 December 6, 2012 17:50

Modeling heat transfer fluid to solid
Hi all, I attempted to moleding a sort of heat exchanger between a hot fluid flow in an air duct ( something likes chimneypot) where the wall is made by steel. I want to set the external faces temperature (the wall faces not in contact with hot fluid, violet zone in image) and valuate the heat flow transfert in solid surface. I read something in the manual, in particular about wall thickness function, but as is written in the manual this model is not applicable to 2D or compressible fluids, so I want to know how I'v to set to modeling something like this whiout set the heat transfer coefficient or temperature in the wall in conctat with fluid.

As you relize this is a 2D problem, I set energy eq., k-eps model, and materials. Tell me if you want more info.

Thank in advance

diamondx December 6, 2012 18:40

this mesh does not look good to me, what did you use to mesh it ??

Elvis1991 December 6, 2012 18:41

Tanks for reply! I used the built in moldelr ad mesher of workbench. And how is the right way to mesh?

RodriguezFatz December 7, 2012 04:47

Fluent is able to solve heat conduction equation in solids. Thus, you could just mesh the solid too and set the boundary conditions just like in your picture.

For the meshing: Do you have ICEM?

Elvis1991 December 7, 2012 07:21

so i meshed something wrong.. but how is the right way to do it? I mashed in three domain as shown in the image: 2 for solid and 1 for fluid, but in boundary condition appear too many surfaces/edge (suface-...-shadow, I don't know what is this??). And then which condition I'v to set for the internal edge (in contact with fluid) and for the outer (exteral temperature 300 K)?
PS No I haven't.

RodriguezFatz December 7, 2012 07:50

Fluent creates these "shadow" surfaces between the fluid / solid. Don't worry about that. The interior surfaces should be set to the "coupled" thermal boundary condition, i.e. the temperature values are actually calculated there instead of hard-wiring it via a constant temperature.
The outer surfaces should set to your actual boundary conditions, if I get you right, this should be constant temperature (300K).

In your mesh it looks like you did not mesh the solid at all. Maybe you will get faster/more help in the meshing forum.

Elvis1991 December 7, 2012 10:08

thank for your reply! :) I done what you said: coupled for interior surfaces and 300K for outers, but energy equation doesn't converge, it stay around 1e4 (for residual), and in results win. it shows temperature constant everywhere!! Instead other parameters converge. So I think there is something wrong in my setting.. But I don't konw what! Fluent uses energy equaton also for solve the conductive domanis right?

Ps. the image doesn't show solid domanis! There are but they aren't show! ;) here there is the complete mesh:

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