Natural convection in a closed domain help!

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 March 21, 2011, 22:23 Natural convection in a closed domain help! #1 New Member   Gregory Join Date: Mar 2011 Posts: 11 Rep Power: 8 Hi guys, I am currently trying to simulate natural convection in a closed car cabin being subjected to irradiation. However, due to the lack of time I have no time to explore the use of the radiation models. What thermal wall boundary conditions would be best suited for the task? I am assuming that the heat comes in only from the front and rear windscreens and the rest of the walls are adiabatic. Please help if you are able to, thanks!

 March 23, 2011, 04:37 help? #2 New Member   Gregory Join Date: Mar 2011 Posts: 11 Rep Power: 8 Hi if it helps more, I am trying to get a temperature distribution that makes physical sense in a car cabin model. Model is meshed using tri and quad cell types. Data shows that the front and rear windscreens reach a temperature close to 330-340K on a very hot day, irradiation = 550 W/m^2. I am currently relying solely on the flow and energy equations to get my results out. The big problem is that I am unsure where to plug my values into the boundary conditions for the front and rear windscreens, which i have defined as walls. If i put 550W/m^2 into the heat flux under the Thermal tab, temperature of the cabin space reaches well over 5000K. And with the other tabs such as temperature and convection i get strange images (like a green space with red spots) Please advise!

 March 23, 2011, 05:32 #3 Senior Member   JSM Join Date: Mar 2009 Location: India Posts: 168 Rep Power: 13 Hi, If you know heat flux value in the windscreen then you can directly apply in wall boundary. But solve in the transient solver. If temperature rise is around 340k, I think you need not to enable the radiation. But I am not sure how much radiation heat will go in to the cabin. __________________ With regards, JSM

March 23, 2011, 06:27
#4
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Gregory
Join Date: Mar 2011
Posts: 11
Rep Power: 8
Quote:
 Originally Posted by jsm Hi, If you know heat flux value in the windscreen then you can directly apply in wall boundary. But solve in the transient solver.
By wall boundary do you mean the Heat generation rate + wall thickness parts?
Also, what do you mean by transient solver? Density solver or unsteady state solver? Is the a certain procedure for that? Thanks for replying by the way!

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