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using convective cooling

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I am solving heat transfer in solid for a 2D rectangular problem which has symmetry in one boundary and convective cooling in 3 other boundaries. I have chosen to solve it transient and would like to find temperature profile after 300s. The initial temperature is 2.8C and surronding temperature is 30C.
The problem is that when I decrease the heat trasnfer coefficient, temperature at each point increases and when "h" increases temperature of that specific point decreases.
I know it should be the other way aorund but I am not sure what the problem is. I appreciate your help
Mahshad


1 Reply Last Post 17.02.2012, 04:46 GMT-5
Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)

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Posted: 1 decade ago 17.02.2012, 04:46 GMT-5
Hi

first of all you are in 2D-Axi which means not a rectangle but a cylinder

if h increases the convecting cooling is increasing so the texchange should increase and T drop (if Tin > Tout) or the opposite for Tin < Tout (you have defined hotter souside so far)

Check the sign in the equations (COMSOL equation view turn on via preferences) between convective cooling and heat boundary I/F

--
Good luck
Ivar
Hi first of all you are in 2D-Axi which means not a rectangle but a cylinder if h increases the convecting cooling is increasing so the texchange should increase and T drop (if Tin > Tout) or the opposite for Tin < Tout (you have defined hotter souside so far) Check the sign in the equations (COMSOL equation view turn on via preferences) between convective cooling and heat boundary I/F -- Good luck Ivar

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