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-   -   Heat is not transfer across different regions (http://www.cfd-online.com/Forums/ansys/106758-heat-not-transfer-across-different-regions.html)

mike.franky September 7, 2012 06:20

Heat is not transfer across different regions
 
Hi,

I am using fluent (and have no prior experience with the software) to study the heat transfer properties of several fluids.

My geometry is very simple: It is a 3d box containing a heating element (also modelled as a box) inside it. In order for this heating element to heat the surrounding liquid, I set it's boundaries to have a certain heat flux passing through them. However, the heat doesn't seem to travel to the fluid; instead it only increases the temperature within the block of the heating element. I also tried different configurations with the parameters in the wall and shadow-wall of the heater but nothing seems to work.

There is obviously some problem with the interface between the heater and the surrounding liquid which I don't understand yet. Does anyone have any ideas as to what these problems might be?

Thanks in advance for any help

Orkun September 7, 2012 07:30

RE : Heat is not transfer across different regions
 
hi mike.franky!

i'm not sure but maybe your two domains (heating_box and fluid) are overlapping. if you used ansys's design modeler, you should make sure that you substract your bodie from the another one by boolean op.

hope that it may help, good luck
orkun

mike.franky September 7, 2012 07:39

Hi Orkun and thank you very much for your reply.

The mesh was created in ICEM. Now I have imported the .msh file in fluent.

Orkun September 7, 2012 07:53

RE : Heat is not transfer across different regions
 
So okay then, all i can say that you should check your mesh (by choosing the interior-part1 and interior-part2) whether an overlapping problem existing.

mike.franky September 7, 2012 09:11

do you know how to check for overlapping? Thanks again for your help!

Orkun September 7, 2012 11:04

Hi mike again,

There is no specific method or a demand_on_execute command in fluent as far as. It is something that you can notice.

Let's consider your case (a box in another box). Let first box(heat source) be the domain 1 and the other one be domain 2.

When you push the button display_mesh, a new screen showing the faces and interior parts of your physical domain pops up.

What you need to do is, select domain 2 (which is the enclosure in your case) see that wheter the there is mesh at where domain 1 is located.

If there is mesh, so there is an overlapping problem.

I hope that it helps, good luck !

mike.franky September 7, 2012 12:38

It looks like the two boxes do not overlap. Actually, looking at it slightly more carefully I think that the liquid right next to the boundary of the heater (the inner box) heats up. However after the first few cells nothing really happens. It is as if the effects of thermal conduction are not taken into account!


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