# Local heat transfer coefficient around a cylinder

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 January 14, 2012, 12:29 Local heat transfer coefficient around a cylinder #1 New Member   Benjamin Join Date: Jan 2012 Posts: 1 Rep Power: 0 Hello, I'm trying to get the local Nusselt number around one cylinder in an external air flow. (http://siam51.free.fr/air_flow.bmp) The mesh is fine enough to have y+~1 near the wall. I got the total temperature near the wall, the heat flux near the wall (W/mē) and the total heat flux exchanged (W) To calculate the local heat transfer coefficient, I tried two methods : h1 = [ heat flux near the wall (W/mē) ] / (383-263) h2 = [ total heat flux exchanged (W) ] / (383-total temperature near the wall) Values are completely different! h1~50-450 h2~250-600 I wonder what would be the best formula to use? Thanks in advance! elham-u likes this.

January 20, 2012, 14:23
#2
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Join Date: Jun 2011
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You have to use static temperature in your calculation not the total temperature.

Quote:
 Originally Posted by dal_fry Hello, I'm trying to get the local Nusselt number around one cylinder in an external air flow. (http://siam51.free.fr/air_flow.bmp) The mesh is fine enough to have y+~1 near the wall. I got the total temperature near the wall, the heat flux near the wall (W/mē) and the total heat flux exchanged (W) To calculate the local heat transfer coefficient, I tried two methods : h1 = [ heat flux near the wall (W/mē) ] / (383-263) h2 = [ total heat flux exchanged (W) ] / (383-total temperature near the wall) Values are completely different! h1~50-450 h2~250-600 I wonder what would be the best formula to use? Thanks in advance!

March 29, 2013, 14:35
#3
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elham usefi
Join Date: Mar 2013
Location: iran
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Quote:
 Originally Posted by dal_fry Hello, I'm trying to get the local Nusselt number around one cylinder in an external air flow. (http://siam51.free.fr/air_flow.bmp) The mesh is fine enough to have y+~1 near the wall. I got the total temperature near the wall, the heat flux near the wall (W/mē) and the total heat flux exchanged (W) To calculate the local heat transfer coefficient, I tried two methods : h1 = [ heat flux near the wall (W/mē) ] / (383-263) h2 = [ total heat flux exchanged (W) ] / (383-total temperature near the wall) Values are completely different! h1~50-450 h2~250-600 I wonder what would be the best formula to use? Thanks in advance!
hi
i have the same problem!
but i have a problem in calculating the local heat transfer around the cylinder!
should i choose some points by surface-point-coordinate?i think cartesian coordinate isn't accurate! plz help me!