temperature rises to 5000 degree C

umair64 · September 2, 2015, 16:57

hi im facing a problem that in cfx temperature of vapours increases to 5000 degree centigrade while my heating source is at 920 degree C.
i m using water morphology as droplets(phase change) and small droplets as phase change model.
please help me how to overcome this problem,,,, @ghorrocks

ghorrocks · September 2, 2015, 20:07

Your simulation is numerically unstable. While this FAQ is on floating point errors, the effect is the same - you need to improve the numerical stability.

http://www.cfd-online.com/Wiki/Ansys...do_about_it.3F

umair64 · September 2, 2015, 20:51

actually system converges well,, everything else results are very close to reality and acceptable... only vapour temperature shoot unexpectedly and i totally failed to understand it,,,,,i think there is another problem,,,, some problem in cfx,,,,,,

umair64 · September 20, 2015, 09:01

@ghorrock,,,, @glenn

ghorrocks · September 20, 2015, 19:02

An expected problem happens in your simulation so you blame the software? Sounds unlikely to me.

Something is causing your temperatures to go strange and it is almost certainly something to do with the way you set the simulation up. If you want us to help you with this problem please post some image of what you are modelling including your mesh and the results you are getting, and the CCL of your setup.

September 2, 2015, 16:57	temperature rises to 5000 degree C	#1
umair64 New Member Muhammad Umair Join Date: Aug 2015 Posts: 24 Rep Power: 11	hi im facing a problem that in cfx temperature of vapours increases to 5000 degree centigrade while my heating source is at 920 degree C. i m using water morphology as droplets(phase change) and small droplets as phase change model. please help me how to overcome this problem,,,, @ghorrocks

September 20, 2015, 09:01	please help	#4
umair64 New Member Muhammad Umair Join Date: Aug 2015 Posts: 24 Rep Power: 11	@ghorrock,,,, @glenn

September 20, 2015, 19:02		#5
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,870 Rep Power: 144	An expected problem happens in your simulation so you blame the software? Sounds unlikely to me. Something is causing your temperatures to go strange and it is almost certainly something to do with the way you set the simulation up. If you want us to help you with this problem please post some image of what you are modelling including your mesh and the results you are getting, and the CCL of your setup. umair64 likes this.

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September 2, 2015, 20:07		#2
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,870 Rep Power: 144	Your simulation is numerically unstable. While this FAQ is on floating point errors, the effect is the same - you need to improve the numerical stability. http://www.cfd-online.com/Wiki/Ansys...do_about_it.3F

September 2, 2015, 20:51		#3
umair64 New Member Muhammad Umair Join Date: Aug 2015 Posts: 24 Rep Power: 11	actually system converges well,, everything else results are very close to reality and acceptable... only vapour temperature shoot unexpectedly and i totally failed to understand it,,,,,i think there is another problem,,,, some problem in cfx,,,,,,