Internal Energy of the Fluid (Heat Transfer)

Cosme · July 17, 2013, 14:16

Hello everyone

I'm doing a combustion simulation in CFX and would like to know:

The variable "Heat Flux" considers the values of internal energy of the fluid?

I have calculated the resulting heat of combustion reactions, and would like to see if I can make a balance with the heat at the output (all walls are adiabatic).

Greetings.

ghorrocks · July 17, 2013, 18:41

The heat flux/Wall heat flux variable only exists at the walls. It has nothing to do with the internal energy of the fluid, it is just the heat flux through the wall.

See the documentation for more details: Reference guide/Variables in ANSYS CFX/List of Field Variables

Cosme · July 18, 2013, 09:13

Ok Glenn.

That means that the variable can not be used to measure the heat output of a fluid?

Greetings!

ghorrocks · July 18, 2013, 18:58

What do you mean by heat output of a fluid? Are you sure you are not getting confused with the fluid enthalpy, temperature and internal energy?

As I said, the heat flux/wall heat flux variable is the heat flux through the wall. This is pretty obvious given the variable name.

Cosme · July 19, 2013, 09:04

Sorry, I thought the name of the variable "Heat Flux" also applied to off the wall.

Thanks Glenn!

July 17, 2013, 14:16	Internal Energy of the Fluid (Heat Transfer)	#1
Cosme New Member Join Date: Nov 2011 Posts: 10 Rep Power: 14	Hello everyone I'm doing a combustion simulation in CFX and would like to know: The variable "Heat Flux" considers the values of internal energy of the fluid? I have calculated the resulting heat of combustion reactions, and would like to see if I can make a balance with the heat at the output (all walls are adiabatic). Greetings.

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July 17, 2013, 18:41		#2
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,703 Rep Power: 143	The heat flux/Wall heat flux variable only exists at the walls. It has nothing to do with the internal energy of the fluid, it is just the heat flux through the wall. See the documentation for more details: Reference guide/Variables in ANSYS CFX/List of Field Variables

July 18, 2013, 09:13		#3
Cosme New Member Join Date: Nov 2011 Posts: 10 Rep Power: 14	Ok Glenn. That means that the variable can not be used to measure the heat output of a fluid? Greetings!

July 18, 2013, 18:58		#4
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,703 Rep Power: 143	What do you mean by heat output of a fluid? Are you sure you are not getting confused with the fluid enthalpy, temperature and internal energy? As I said, the heat flux/wall heat flux variable is the heat flux through the wall. This is pretty obvious given the variable name.

July 19, 2013, 09:04		#5
Cosme New Member Join Date: Nov 2011 Posts: 10 Rep Power: 14	Sorry, I thought the name of the variable "Heat Flux" also applied to off the wall. Thanks Glenn!