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-   -   The difference between Heat Transfer Coefficient and the local one. (http://www.cfd-online.com/Forums/star-ccm/97795-difference-between-heat-transfer-coefficient-local-one.html)

fshak92 February 25, 2012 07:20

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

rwryne February 26, 2012 16:49

Quote:

Originally Posted by omid88 (Post 346236)
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.

rwryne February 27, 2012 12:19

Quote:

Originally Posted by omid88 (Post 346236)
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?")

fshak92 March 12, 2012 09:15

Quote:

Originally Posted by rwryne (Post 346489)
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?")

Thank you for the answer.

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.


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