# The difference between Heat Transfer Coefficient and the local one.

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 February 25, 2012, 07:20 The difference between Heat Transfer Coefficient and the local one. #1 Senior Member   Join Date: Dec 2011 Posts: 121 Rep Power: 6 I wonder if anyone can explain the differences between the HTC and the LocalHTC. I think the HTC in each mesh cell, is calculated by : dividing the heat transfer of that point by the temperature differences of that point and a reference temperature(which can be changed in the field function). Am i right? but what about the LocalHTC? because the local of a value is the integral of that value and in our case it should be integral value on our surface.but why it does not need any reference temperature? Can anyone explain about these concepts and the way StarCCM calculates them. Thanks in advance.

February 26, 2012, 16:49
#2
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Ryne Whitehill
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Quote:
 Originally Posted by omid88 I wonder if anyone can explain the differences between the HTC and the LocalHTC. I think the HTC in each mesh cell, is calculated by : dividing the heat transfer of that point by the temperature differences of that point and a reference temperature(which can be changed in the field function). Am i right? but what about the LocalHTC? because the local of a value is the integral of that value and in our case it should be integral value on our surface.but why it does not need any reference temperature? Can anyone explain about these concepts and the way StarCCM calculates them. Thanks in advance.
I don't have STAR-CCM+ infront of me, so I cannot be definitive but I believe the LocalHTC uses the temperature nearest to the wall to calculate the HTC, rather than a reference temperature.

February 27, 2012, 12:19
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Ryne Whitehill
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Quote:
 Originally Posted by omid88 I wonder if anyone can explain the differences between the HTC and the LocalHTC. I think the HTC in each mesh cell, is calculated by : dividing the heat transfer of that point by the temperature differences of that point and a reference temperature(which can be changed in the field function). Am i right? but what about the LocalHTC? because the local of a value is the integral of that value and in our case it should be integral value on our surface.but why it does not need any reference temperature? Can anyone explain about these concepts and the way StarCCM calculates them. Thanks in advance.
After looking in STAR:

Just plot the Local Heat Transfer Reference Temperature to see which temperature it is using for this calculation. The formula it is using is found in the help file (under "What Methods Are Available for Exchanging Heat Transfer Coefficients?")

March 12, 2012, 09:15
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Quote:
 Originally Posted by rwryne After looking in STAR: Just plot the Local Heat Transfer Reference Temperature to see which temperature it is using for this calculation. The formula it is using is found in the help file (under "What Methods Are Available for Exchanging Heat Transfer Coefficients?")

I set a same temperature for both the wall temperature around my body and also the reference temperature but the local heat transfer coefficient are 1000times more than the heat transfer coefficient.
Unfortunately the tuturial of the software has not explained the difference in a good way.

Last edited by fshak92; March 13, 2012 at 05:19.

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