Using Cp polynomial

Idanst · July 23, 2024, 01:39

Hello,

I am looking to simulate a real gas using a Cp(T) polynomial instead of the constant value of 1004.703 J/kg*K for air.

I noticed a line for CP_POLYCOEFFS in the template SU2 file, but I couldn't find any information on how to enable it. Can this be used with the STANDARD_AIR fluid model, or do I need to select a different model?

Thanks,

bigfootedrockmidget · July 23, 2024, 13:54

It can be used when you set the fluid to incompressible polytropic gas.

From config_template.cfg:

Code:

% ---- IDEAL GAS, POLYTROPIC, VAN DER WAALS AND PENG ROBINSON CONSTANTS -------%
%
FLUID_MODEL= INC_IDEAL_GAS_POLY
SPECIFIC_HEAT_CP= 1004.703
MOLECULAR_WEIGHT= 28.96
CP_POLYCOEFFS= ( 1004.703, 0.1, 0.0, 0.0, 0.0)

An example can be found in Testcases/incomp_navierstokes/cylinder/

Idanst · July 24, 2024, 01:27

Thank you!

I am looking to simulate compressible flow at high Mach numbers, around Mach 5. Could you recommend a more suitable fluid model for this scenario? I plan to account for variations in the heat capacity ratio caused by the high pressures and temperatures.

bigfootedrockmidget · August 1, 2024, 16:49

Hi, sorry for the long wait, so you could maybe also use the NEMO solver, which targets hypersonic flows. There are some examples in the testcases repository.

Idanst · August 8, 2024, 07:08

I'll check it, thank you

July 23, 2024, 01:39	Using Cp polynomial	#1
Idanst New Member Join Date: Nov 2017 Posts: 7 Rep Power: 8	Hello, I am looking to simulate a real gas using a Cp(T) polynomial instead of the constant value of 1004.703 J/kg*K for air. I noticed a line for CP_POLYCOEFFS in the template SU2 file, but I couldn't find any information on how to enable it. Can this be used with the STANDARD_AIR fluid model, or do I need to select a different model? Thanks,

July 23, 2024, 13:54		#2
bigfootedrockmidget Senior Member bigfoot Join Date: Dec 2011 Location: Netherlands Posts: 596 Rep Power: 17	It can be used when you set the fluid to incompressible polytropic gas. From config_template.cfg: Code: % ---- IDEAL GAS, POLYTROPIC, VAN DER WAALS AND PENG ROBINSON CONSTANTS -------% % FLUID_MODEL= INC_IDEAL_GAS_POLY SPECIFIC_HEAT_CP= 1004.703 MOLECULAR_WEIGHT= 28.96 CP_POLYCOEFFS= ( 1004.703, 0.1, 0.0, 0.0, 0.0) An example can be found in Testcases/incomp_navierstokes/cylinder/

July 24, 2024, 01:27		#3
Idanst New Member Join Date: Nov 2017 Posts: 7 Rep Power: 8	Thank you! I am looking to simulate compressible flow at high Mach numbers, around Mach 5. Could you recommend a more suitable fluid model for this scenario? I plan to account for variations in the heat capacity ratio caused by the high pressures and temperatures. ShengZhang likes this.

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August 1, 2024, 16:49		#4
bigfootedrockmidget Senior Member bigfoot Join Date: Dec 2011 Location: Netherlands Posts: 596 Rep Power: 17	Hi, sorry for the long wait, so you could maybe also use the NEMO solver, which targets hypersonic flows. There are some examples in the testcases repository.

August 8, 2024, 07:08		#5
Idanst New Member Join Date: Nov 2017 Posts: 7 Rep Power: 8	I'll check it, thank you