CFX temperature initialization

jp_ · August 26, 2014, 09:42

I encountered a weird CFX behaviour today (in transient runs)...

1-I set up a non-temperature dependant analysis (ex Isothermal) and get some preliminary results
2-Make a new config in which I introduce non-isothermal aspects (ex wall temp, etc), use (1) as "Continue from file" and an initialization condition for temperature (automatic with value), run it.

However when you open up results, you notice that it
a-takes fluid velocities & pressures from (1), as expected
b-initializes not at the initialization temperature set in (2) (as you would expect), but at each of the fluid's reference temperature set in (2)...

I did find the expert parameter below, but it seems very vague in what it does. Any clue?
transient initialisation override
Type
Logical
Default Value
f
Description
When set to 't', enables solver default values to be used for initialization in a transient simulation.

Is (b) known behaviour? Why should ref temp take precedence over explicitly specified initialization? Is there a way around?

ghorrocks · August 27, 2014, 00:19

This sounds strange. It might be a bug. Have you reported it to ANSYS?

jp_ · August 28, 2014, 10:02

Hi Ghorrocks,

Turns out you can change meshes and do all sorts of stuff, but adding heat transfer to an existing run produces less than ideal results... I'll just have to include heat transfer in the stabilization phase (1)

Cheers!

ghorrocks · August 28, 2014, 10:06

That sounds like a useful work-around. But what you describe sounds like a bug so it would be worth while to report it to ANSYS and get it fixed.

August 26, 2014, 09:42	CFX temperature initialization	#1
jp_ New Member Join Date: Aug 2014 Posts: 11 Rep Power: 12	I encountered a weird CFX behaviour today (in transient runs)... 1-I set up a non-temperature dependant analysis (ex Isothermal) and get some preliminary results 2-Make a new config in which I introduce non-isothermal aspects (ex wall temp, etc), use (1) as "Continue from file" and an initialization condition for temperature (automatic with value), run it. However when you open up results, you notice that it a-takes fluid velocities & pressures from (1), as expected b-initializes not at the initialization temperature set in (2) (as you would expect), but at each of the fluid's reference temperature set in (2)... I did find the expert parameter below, but it seems very vague in what it does. Any clue? transient initialisation override Type Logical Default Value f Description When set to 't', enables solver default values to be used for initialization in a transient simulation. Is (b) known behaviour? Why should ref temp take precedence over explicitly specified initialization? Is there a way around?

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August 27, 2014, 00:19		#2
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,870 Rep Power: 144	This sounds strange. It might be a bug. Have you reported it to ANSYS?

August 28, 2014, 10:02		#3
jp_ New Member Join Date: Aug 2014 Posts: 11 Rep Power: 12	Hi Ghorrocks, Turns out you can change meshes and do all sorts of stuff, but adding heat transfer to an existing run produces less than ideal results... I'll just have to include heat transfer in the stabilization phase (1) Cheers!

August 28, 2014, 10:06		#4
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,870 Rep Power: 144	That sounds like a useful work-around. But what you describe sounds like a bug so it would be worth while to report it to ANSYS and get it fixed.