Radiation / Convektion / CFD in ANSYS-CFX / Workbench

ehrenwirth · March 31, 2009, 15:56

Hi there!

I´m quite new in ANSYS-CFX and trying to simulate a pretty simple Channel with a rib in the middle. This "Channel" has been created by modelling first the Channel itself and then taking out the fluid-volume. Below you can see a picture.

My aim is to simulate a heat-source on the channel-housing and how the flow (for example water) is affecting the temperature. I expect that the temperature is decreased by the flow.

In Ansys Workbench i started a thermal-transient Analysis to get the temperature along the Channel after a certain time, in my case after half an hour. I made two screenshots, see below:

Maybe you will ask why i made this in Workbench and not in CFX. The Reason is, that simulating this situation in CFX costs quite a lot time! Okay, not really THIS situation, but i have another very huge modell which i really dont want to simulate transient in CFX.
My problem now is how to get the thermal results from the Workbecnh simulation into CFX.

Or generell, do you think i am on the right path with this strategy? Do you think it would be better to simulate all this in CFX?

Please keep in mind that i dont want to make a transient analysis in CFX actually.

And last but not least: At the moment, the channel is warmend because at one side I loaded a constant temperature (100°C), see the pictures. In future i would like to get this heat-input by radiation from an area distanced a certain length away. Is this possible? And how do i need to rebuild my modell? Or is it just neccesary to create a certain amount away and tell this plane that it should have a temperature?

I really hope that u understand my problem(s) and my english is not too bad.

Thanks in advance,
greetings

ghorrocks · March 31, 2009, 17:39

Hi,

If you are just doing thermal modelling (ie no fluid flow - I assume this is what you did in WB) then CFX can do this and it is very fast. Just as fast as WB and probably faster. Then you don't need to import it into CFX.

You can do this by setting the domain to be a solid, then the temperature equation is the only one it solves.

Glenn Horrocks

ehrenwirth · April 1, 2009, 00:29

Hi ghorrocks!

Thanks for your reply! If i simulate the heat exchange in CFX, can i define there the radiation?
And, even more important: After i simulated the heat exchange between solid and fluid domain, how can i save theese results in such a way as to enable them to be a (steady-state)-constraint in a following simulation? I mean how can i say to one area of the channel that it should not have one temperature but a temperature gradient?

Again, thanks for your reply!

shyam sunder · July 28, 2011, 06:34

i want radiation analysis method for compressor.......in cfx

ghorrocks · July 28, 2011, 08:13

CFX has a full-featured radiation solver. Depending on what options are chosen it can add significantly to simulation time and complexity.

shyam sunder · July 30, 2011, 03:47

how to compare the cfx results to analytical results in radiation.......if any one knows the formule send me

ghorrocks · July 30, 2011, 08:08

You can find analytical solutions to radiation in any decent heat transfer textbook.

sepidecent · October 22, 2013, 00:06

Hi all,

I am modelling free falling particles in gas in a rectangular box with the slot opening at the top of the box, using Eulerian-Eulerian approach of CFD. I know CFX doesn't support multi-phase systems regarding radiation. I was wondering how can I include it? Do I have access to the source code or I have to write a new code in Fortran and recall in CFX?

Thank's
Sep

ghorrocks · October 22, 2013, 05:12

Why do you say CFX does not support radiation in multiphase? It most certainly does!

Ha ha ha - you want the source code. How can ANSYS make money if they give out the source code? You obviously have not used commercial software much. (apologies for the sarcasm).

Most probably you have no need for user fortran either, you can model most interactions with the normal interface. But if you need more access CFX does have user fortran.

March 31, 2009, 15:56	Radiation / Convektion / CFD in ANSYS-CFX / Workbench	#1
ehrenwirth New Member Join Date: Mar 2009 Posts: 21 Rep Power: 17	Hi there! I´m quite new in ANSYS-CFX and trying to simulate a pretty simple Channel with a rib in the middle. This "Channel" has been created by modelling first the Channel itself and then taking out the fluid-volume. Below you can see a picture. My aim is to simulate a heat-source on the channel-housing and how the flow (for example water) is affecting the temperature. I expect that the temperature is decreased by the flow. In Ansys Workbench i started a thermal-transient Analysis to get the temperature along the Channel after a certain time, in my case after half an hour. I made two screenshots, see below: Maybe you will ask why i made this in Workbench and not in CFX. The Reason is, that simulating this situation in CFX costs quite a lot time! Okay, not really THIS situation, but i have another very huge modell which i really dont want to simulate transient in CFX. My problem now is how to get the thermal results from the Workbecnh simulation into CFX. Or generell, do you think i am on the right path with this strategy? Do you think it would be better to simulate all this in CFX? Please keep in mind that i dont want to make a transient analysis in CFX actually. And last but not least: At the moment, the channel is warmend because at one side I loaded a constant temperature (100°C), see the pictures. In future i would like to get this heat-input by radiation from an area distanced a certain length away. Is this possible? And how do i need to rebuild my modell? Or is it just neccesary to create a certain amount away and tell this plane that it should have a temperature? I really hope that u understand my problem(s) and my english is not too bad. Thanks in advance, greetings

July 28, 2011, 06:34	On cfx	#4
shyam sunder New Member shyam Join Date: Jul 2011 Posts: 2 Rep Power: 0	i want radiation analysis method for compressor.......in cfx

July 30, 2011, 03:47	radiation problem	#6
shyam sunder New Member shyam Join Date: Jul 2011 Posts: 2 Rep Power: 0	how to compare the cfx results to analytical results in radiation.......if any one knows the formule send me

October 22, 2013, 00:06	Radiation in CFX	#8
sepidecent New Member sepideh Join Date: Jul 2011 Posts: 21 Rep Power: 14	Hi all, I am modelling free falling particles in gas in a rectangular box with the slot opening at the top of the box, using Eulerian-Eulerian approach of CFD. I know CFX doesn't support multi-phase systems regarding radiation. I was wondering how can I include it? Do I have access to the source code or I have to write a new code in Fortran and recall in CFX? Thank's Sep

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March 31, 2009, 17:39		#2
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,703 Rep Power: 143	Hi, If you are just doing thermal modelling (ie no fluid flow - I assume this is what you did in WB) then CFX can do this and it is very fast. Just as fast as WB and probably faster. Then you don't need to import it into CFX. You can do this by setting the domain to be a solid, then the temperature equation is the only one it solves. Glenn Horrocks

April 1, 2009, 00:29		#3
ehrenwirth New Member Join Date: Mar 2009 Posts: 21 Rep Power: 17	Hi ghorrocks! Thanks for your reply! If i simulate the heat exchange in CFX, can i define there the radiation? And, even more important: After i simulated the heat exchange between solid and fluid domain, how can i save theese results in such a way as to enable them to be a (steady-state)-constraint in a following simulation? I mean how can i say to one area of the channel that it should not have one temperature but a temperature gradient? Again, thanks for your reply!

July 28, 2011, 08:13		#5
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,703 Rep Power: 143	CFX has a full-featured radiation solver. Depending on what options are chosen it can add significantly to simulation time and complexity.

July 30, 2011, 08:08		#7
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,703 Rep Power: 143	You can find analytical solutions to radiation in any decent heat transfer textbook.

October 22, 2013, 05:12		#9
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,703 Rep Power: 143	Why do you say CFX does not support radiation in multiphase? It most certainly does! Ha ha ha - you want the source code. How can ANSYS make money if they give out the source code? You obviously have not used commercial software much. (apologies for the sarcasm). Most probably you have no need for user fortran either, you can model most interactions with the normal interface. But if you need more access CFX does have user fortran.