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 yann February 1, 2006 11:39

buoyancy

When I modelise the heat tranfert from a hot air through a thin wall to the water, I can't take into account the buoyancy. When I don't take the buoyancy into account, the model is fine, but of course, the water doesn't move. When I define a buoyancy in the water, with a density variation based on a isobaric model, then, my heat transfer doesn't occur, and even the wall remains at the same temperature. Did someone had about the same problem, or does someone see what can be wrong? Yann

 yann February 1, 2006 17:23

buoyancy becomes crasy

The simple fact to activate the buoyancy for the water seems to stop the heat transfer through the wall. (no of the cell of the wall increase in temperature), wherease when I just take off the buoyancy, the heat transfert takes place: it is crasy! Thanks to all, if you have any ideas! Yann

 Lucy February 2, 2006 09:17

Re: buoyancy becomes crasy

I have had about the same problem. I changed the turbulence model for the air, and the heat transfert appeared to work again through my plate which was in aluminium. I have no idea why such a problem had occur. When I disabled the turbulence agin to put a laminar flow, the heat transfert through the plate stopped. (I still had the buoyancy option activated for the water). The simple fact to disable the buoyancy for the water allowed the heat transfert to take place, iven without turbulence in the air. That's all what I can say, I didn't really manage to solve the problem, and I am still working on it. Regards, Lucy

 yann February 2, 2006 14:21

Re: buoyancy becomes crasy

Thanks Lucy, for your help, let me know if ever you find a solution. To be more precise the problem is that one: WATER(l)|wall, stainless stell (1mm thickness)|Air, 400°C, v=2m/s . Why would the simple fact to put the buoyancy on would refrain the heat transfert through the wall? Thanks to all, even if you don't see the problem! Yann

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