Which thermal boundary condition?

norger · May 14, 2012, 04:37

Hey,

my task is to simulate a body, e.g. a cylinder, which rotates with an angular velocity.
Also I have to regard the temperature of the cylinder and the fluid (air) around it.

My problem is the setting of the temperature. The cylinder should have a constant temperature of 400K and the air 293K and I want to know how the air influences the temperature of the rotating cylinder.

My solution:
I would use thermal conditions -> temperature but I don´t know whether this is right.
I don´t know furthermore what to write in the fields: wall thickness and heat generation rate.
I read that wall thickness should be zero but what about the heat generation rate and is my approach good or is it better to use heat flux?

Thank you for your efforts.

unver · May 15, 2012, 16:54

Dear Norger;
If understood correctly, you have a cylindrical shell rotating in the air and needs to be at 400K.

First of all your physical problem must be represented in numerics as well in every detail needed. And Physically, you can only achieve this scenario by controlling the heat generation at every point separately. And this is impossible to realize. But if you wanna try it any way, I would solve the problem as a constant wall temperature first and obtain a wall heat flux. And then reverse the problem, and apply a heat generation profile on the surface. That should give the same or very close constant temperature distribution.

May 14, 2012, 04:37	Which thermal boundary condition?	#1
norger New Member Norger Join Date: Oct 2011 Posts: 25 Rep Power: 15	Hey, my task is to simulate a body, e.g. a cylinder, which rotates with an angular velocity. Also I have to regard the temperature of the cylinder and the fluid (air) around it. My problem is the setting of the temperature. The cylinder should have a constant temperature of 400K and the air 293K and I want to know how the air influences the temperature of the rotating cylinder. My solution: I would use thermal conditions -> temperature but I don´t know whether this is right. I don´t know furthermore what to write in the fields: wall thickness and heat generation rate. I read that wall thickness should be zero but what about the heat generation rate and is my approach good or is it better to use heat flux? Thank you for your efforts.

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May 15, 2012, 16:54		#2
unver New Member unver Join Date: Sep 2009 Posts: 10 Rep Power: 17	Dear Norger; If understood correctly, you have a cylindrical shell rotating in the air and needs to be at 400K. First of all your physical problem must be represented in numerics as well in every detail needed. And Physically, you can only achieve this scenario by controlling the heat generation at every point separately. And this is impossible to realize. But if you wanna try it any way, I would solve the problem as a constant wall temperature first and obtain a wall heat flux. And then reverse the problem, and apply a heat generation profile on the surface. That should give the same or very close constant temperature distribution.