Solution from heat transfer

noppawit · December 18, 2010, 23:28

I've 2 solid bodies, the first bodies is solved in steady-state mode to have a non-uniform initial temperature for the transient simulation. After that I attach the second body to the first one. The second body has another value of initial temperature.

Is it possible to do that? If yes, how can I do so?

Actually, I'm using ANSYS Mechanical but I can't find a forum of Mechanical. If CFX can do that, it's gonna be great.

Thank you.

bhatiadinesh · December 19, 2010, 23:47

When exactly does this second body get attached ??? Is it after the first body has reached steady state ?? Any body would be able to help you better if you could define what are you trying to simulate ?

noppawit · December 20, 2010, 06:56

Sorry...
All bodies are solid bodies. The first body is a wall, a big gray cube in the schematic, is supplied by a constant heat flux. Only first body is simulated at first to reach the steady-state. After the first body reaches steady-state, the second body is attached to the first one. The second body is a small yellow plate in the schematic.

I'm trying to simulate a heat flux measuring device. So I'll see the total heat flux in the small yellow plate.

My question: Is it possible to simulate the wall first to reach steady-state. Then attach the plate to the wall and simulate in transient.

I'm trying in CFX because I don't know how to continue after the first body reaches steady-state in ANSYS Mechancal: Thermal Analysis.

Thank you for your help.

This is my project schematic

bhatiadinesh · December 20, 2010, 07:19

That would be easy, it is exacty how you described it. first simulate only the grey body for a steady state simulation. I am guessing that you are going for conduction analysis only, so in that case after you get the steady state result of the grey body, use the results of the wall in contact with the plate as boundary condition for transient simulation of the plate.

Let me know If I have understood the problem correctly.

-Dinesh

noppawit · December 20, 2010, 07:33

Thank you for your reply. I think you've understood my project correctly.

I'll try it, if something goes wrong, I'll ask later.

Thank you again.
Noppawit

ghorrocks · December 20, 2010, 08:04

You can define on a per-domain basis where CFX gets the initial condition from. If you select automatic it will use the initial conditions file if one exists. If you use value it will use the value you specify.

So in your case if you use automatic in the domain to use the initial condition and value in the domain to use the defined condition it should work for you.

noppawit · December 20, 2010, 10:04

Thank you, I'll try that one.

noppawit · December 20, 2010, 11:39

I think it works from roughly look at the temperature.
But how can I see the (total) heat flux? Is it possible to see that?
How can I view the total heat flux like in Ansys Mechanical?
It shows me like this:

Thank you.
Noppawit

ghorrocks · December 20, 2010, 18:06

The Heat flux variable exists at the boundaries, not the internal parts.

December 18, 2010, 23:28	Solution from heat transfer	#1
noppawit New Member Noppawit Sippawit Join Date: Oct 2010 Posts: 14 Rep Power: 16	I've 2 solid bodies, the first bodies is solved in steady-state mode to have a non-uniform initial temperature for the transient simulation. After that I attach the second body to the first one. The second body has another value of initial temperature. Is it possible to do that? If yes, how can I do so? Actually, I'm using ANSYS Mechanical but I can't find a forum of Mechanical. If CFX can do that, it's gonna be great. Thank you.

December 20, 2010, 11:39		#8
noppawit New Member Noppawit Sippawit Join Date: Oct 2010 Posts: 14 Rep Power: 16	I think it works from roughly look at the temperature. But how can I see the (total) heat flux? Is it possible to see that? How can I view the total heat flux like in Ansys Mechanical? It shows me like this: Thank you. Noppawit Last edited by noppawit; December 20, 2010 at 11:59.

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December 19, 2010, 23:47		#2
bhatiadinesh Member D Join Date: Nov 2010 Posts: 50 Rep Power: 16	When exactly does this second body get attached ??? Is it after the first body has reached steady state ?? Any body would be able to help you better if you could define what are you trying to simulate ?

December 20, 2010, 06:56		#3
noppawit New Member Noppawit Sippawit Join Date: Oct 2010 Posts: 14 Rep Power: 16	Sorry... All bodies are solid bodies. The first body is a wall, a big gray cube in the schematic, is supplied by a constant heat flux. Only first body is simulated at first to reach the steady-state. After the first body reaches steady-state, the second body is attached to the first one. The second body is a small yellow plate in the schematic. I'm trying to simulate a heat flux measuring device. So I'll see the total heat flux in the small yellow plate. My question: Is it possible to simulate the wall first to reach steady-state. Then attach the plate to the wall and simulate in transient. I'm trying in CFX because I don't know how to continue after the first body reaches steady-state in ANSYS Mechancal: Thermal Analysis. Thank you for your help. This is my project schematic

December 20, 2010, 07:19		#4
bhatiadinesh Member D Join Date: Nov 2010 Posts: 50 Rep Power: 16	That would be easy, it is exacty how you described it. first simulate only the grey body for a steady state simulation. I am guessing that you are going for conduction analysis only, so in that case after you get the steady state result of the grey body, use the results of the wall in contact with the plate as boundary condition for transient simulation of the plate. Let me know If I have understood the problem correctly. -Dinesh

December 20, 2010, 07:33		#5
noppawit New Member Noppawit Sippawit Join Date: Oct 2010 Posts: 14 Rep Power: 16	Thank you for your reply. I think you've understood my project correctly. I'll try it, if something goes wrong, I'll ask later. Thank you again. Noppawit

December 20, 2010, 08:04		#6
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,872 Rep Power: 144	You can define on a per-domain basis where CFX gets the initial condition from. If you select automatic it will use the initial conditions file if one exists. If you use value it will use the value you specify. So in your case if you use automatic in the domain to use the initial condition and value in the domain to use the defined condition it should work for you.

December 20, 2010, 10:04		#7
noppawit New Member Noppawit Sippawit Join Date: Oct 2010 Posts: 14 Rep Power: 16	Thank you, I'll try that one.

December 20, 2010, 18:06		#9
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,872 Rep Power: 144	The Heat flux variable exists at the boundaries, not the internal parts.