Total Enthalpy does not equal Cp*Total Temperature

sasanghomi · December 16, 2019, 00:39

Hey,

Does anybody have an idea about the difference between Total Enthalpy and (Specific Heat Capacity at Constant Pressure * Total Temperature) ?

In fact, these parameters are supposed to have the same values but I have seen many cases that CFD Post shows different values for these parameters at a specific plane, for example!!

What is the source of this discrepancy?

BR
Sasan Ghomi

Opaque · December 16, 2019, 08:44

Have you done such comparison on a locator which does not require CFD-Post manipulation of the data?

Say Minimum and Maximum value of both variables?

Say a boundary plot of both quantities, if you switch the plotted variable from Total Enthalpy to Total Temperature the plot should be identical except a variable range change.

sasanghomi · December 18, 2019, 07:06

I am talking about the difference at a specific plane. In fact, I used massFlowAve() function in order to calculate the values.
It is strange to me that what could be the source of the difference!!

Opaque · December 18, 2019, 08:06

Did you do the check as suggested above?

What is the outcome of the check suggested above?

December 16, 2019, 00:39	*Total Enthalpy does not equal CpTotal Temperature**	#1
sasanghomi Senior Member Sasan Ghomi Join Date: Sep 2012 Location: Denmark Posts: 292 Rep Power: 14	Hey, Does anybody have an idea about the difference between Total Enthalpy and (Specific Heat Capacity at Constant Pressure * Total Temperature) ? In fact, these parameters are supposed to have the same values but I have seen many cases that CFD Post shows different values for these parameters at a specific plane, for example!! What is the source of this discrepancy? BR Sasan Ghomi

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December 16, 2019, 08:44		#2
Opaque Senior Member Join Date: Jun 2009 Posts: 1,804 Rep Power: 32	Have you done such comparison on a locator which does not require CFD-Post manipulation of the data? Say Minimum and Maximum value of both variables? Say a boundary plot of both quantities, if you switch the plotted variable from Total Enthalpy to Total Temperature the plot should be identical except a variable range change.

December 18, 2019, 07:06		#3
sasanghomi Senior Member Sasan Ghomi Join Date: Sep 2012 Location: Denmark Posts: 292 Rep Power: 14	I am talking about the difference at a specific plane. In fact, I used massFlowAve() function in order to calculate the values. It is strange to me that what could be the source of the difference!!

December 18, 2019, 08:06		#4
Opaque Senior Member Join Date: Jun 2009 Posts: 1,804 Rep Power: 32	Did you do the check as suggested above? What is the outcome of the check suggested above?