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amin.z November 25, 2013 13:29

1D Flow with Heat Addition
Hello dear engineers!

In first I must say that my English language is week! excuse me!

I'm modeling a thin air flow in a simple path like a simple channel.
Section of path is a rectangle.
The inlet condition: Mach=0.2, P=1 atm, T=273 K
and Heat is adding to the flow from top & bottom ( q=10^6 J/Kg)
I have modeled the top & bottom in CFX-Pre as wall with heat transfer and
I use mass rate for changing the "q: (J/Kg) " to "heat flux: (W/m^2)"
But when I run CFX-Solver it exit with return code 225!

1- Is selecting the top & bottom as wall correct?
2- Is the changing I did true?
3- What is cause of error in your opinion ?

thank you!

ghorrocks November 25, 2013 17:09

Can you explain what the heat flow is? What does q=10^6 J/kg mean? Per kilogram of what?

amin.z November 26, 2013 10:05


Originally Posted by ghorrocks (Post 463455)
Can you explain what the heat flow is? What does q=10^6 J/kg mean? Per kilogram of what?

consider a simple channel with triangle section. Heat is adding per mass of air that flow in channel .It's adding from up & down of channel. I have the inlet condition and want to find the Mach and pressure in outlet.

ghorrocks November 26, 2013 17:58

I do not know of a system where the heat transfer to the fluid is proportional to the mass flow rate. My question is that this sounds like a non-physical system and then it only makes sense that modelling it is difficult.

If there is a constant heat input at the wall then use a heat flux boundary. If constant temperature then use constant temperature. There are also convective boundaries it that is suitable.

myaccount January 17, 2014 11:57

Problem with 1D problem
Hi everyone!!!

I am trying to simulate a 1d heat transfer in a medium confined between two large walls (top and bottom wall). I created a 2d rectangle in icem cfd. For top and bottom lines I have given the boundary conditions as walls. But I am not clear what boundary condition I should use for left and right lines which are not supposed to be present. (I created them only for meshing)..

Pls reply.

ghorrocks January 18, 2014 05:04

Have a look at what the CFX tutorials do for the simulations where they need to put outer boundaries on which are not physically present.

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