How to get the total pressure in the UDF?

zgzhai · September 12, 2012, 06:50

Hello all:
My case is incompressible single phase flow, and I want to get the total pressure and static pressure of some nodes. But the C_P could only get the static pressure, but how to get the total pressure in the UDF? Thank you very much.

BTW: i search a very old thread that said the fluent interior data structure. The total pressure is the 'derived' term, not the 'variable'. So it can not be got , should be calculated by 'total pressure = static pressure + operation pressure + 0.5*rho*v*v '. but I find the true case is not like this. I use the PLOT to print out the total pressure, dynamic pressure and static pressure. The total pressure from the PLOT is bigger than the calculated total pressure with the above formula. I guess maybe there is a coefficient before the '0.5*rho*v*v' .

ghost82 · September 12, 2012, 07:02

Hi,
have you read this thread?
http://www.cfd-online.com/Forums/flu...-pressure.html

zgzhai · September 12, 2012, 07:15

thanks to ghost82. I have read this thread. But I think the conclusion is not clear. if total pressure = static pressure + operation pressure + dynamic pressure, my question still exists . Thank you again.

deenriqu · September 24, 2018, 17:12

Im not sure if this is the solution to your question, but technically,

total pressure = static + operating + dynamic + hydrostatic

The hydrostatic term may be influencing your solution if you gravity on

September 12, 2012, 06:50	How to get the total pressure in the UDF?	#1
zgzhai New Member Zhi-Gang Zhai Join Date: Sep 2012 Location: karlsruhe, Germany Posts: 7 Rep Power: 14	Hello all: My case is incompressible single phase flow, and I want to get the total pressure and static pressure of some nodes. But the C_P could only get the static pressure, but how to get the total pressure in the UDF? Thank you very much. BTW: i search a very old thread that said the fluent interior data structure. The total pressure is the 'derived' term, not the 'variable'. So it can not be got , should be calculated by 'total pressure = static pressure + operation pressure + 0.5rhovv '. but I find the true case is not like this. I use the PLOT to print out the total pressure, dynamic pressure and static pressure. The total pressure from the PLOT is bigger than the calculated total pressure with the above formula. I guess maybe there is a coefficient before the '0.5rhovv' .

September 24, 2018, 17:12	Hydrostatic pressure	#4
deenriqu New Member dan Join Date: Jan 2017 Posts: 24 Rep Power: 9	Im not sure if this is the solution to your question, but technically, total pressure = static + operating + dynamic + hydrostatic The hydrostatic term may be influencing your solution if you gravity on

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September 12, 2012, 07:02		#2
ghost82 Senior Member Rick Join Date: Oct 2010 Posts: 1,016 Rep Power: 27	Hi, have you read this thread? http://www.cfd-online.com/Forums/flu...-pressure.html

September 12, 2012, 07:15		#3
zgzhai New Member Zhi-Gang Zhai Join Date: Sep 2012 Location: karlsruhe, Germany Posts: 7 Rep Power: 14	thanks to ghost82. I have read this thread. But I think the conclusion is not clear. if total pressure = static pressure + operation pressure + dynamic pressure, my question still exists . Thank you again.