HELP; Ansys 13.0 Combustion Problem!

burritolover · August 14, 2013, 16:15

Hello Everyone!

I desperately need assistance with the following problem. I have been trying to do combustion analysis for a couple of months now and have a repeating problem. During the solution portion of the simulation on FLUENT 13.0 I have the following read out on each time step...
"Minimum PDF table temperature in 9893 cells on zone 3"
The number of cells fluctuates greatly. I have a video of each step that I have done at the link below.

https://www.youtube.com/watch?v=-CDNB22fWFo

I have tried increasing the mesh, increasing the fuel and oxid temperatures without any results
DISREGARD THE FLOW RATES IN THE VIDEO! I have corrected them and they are not connected to the error.

THANK YOU IN ADVANCE!

diamondx · August 14, 2013, 17:07

the tips you found here in the forum, the advanced features has to be enabled via the TUI command, not the graphic interface...

burritolover · August 14, 2013, 17:16

Thank you so much for your speedy response!
I just realized where the TUI interface is on Fluent 13.0. Right smack in front of me!
I will try it and get back to you.
Again I greatly appreciate your help

burritolover · August 14, 2013, 17:54

Well I have tried to find the option for the Maximum Heat Loss Fraction and have not been able to find it. The following is as far as I got through the TUI command window. If anyone can help I would GREATLY appreciate it!
>
adapt/ file/ report/
close-fluent mesh/ solve/
define/ parallel/ surface/
display/ plot/ views/

> define

/define>
beta-feature-access materials/ profiles/
boundary-conditions/ mesh-interfaces/ solution-strategy/
custom-field-functions/ mixing-planes/ turbo/
dynamic-mesh/ models/ units
enable-mesh-morpher-optimizer? operating-conditions/ user-defined/
injections/ parameters/

/define> models

/define/models>
acoustics/ heat-exchanger/ steady?
addon-module multiphase/ unsteady-1st-order?
crevice-model? radiation/ unsteady-2nd-order-bounded?
dpm/ solidification-melting? unsteady-2nd-order?
energy? solver/ viscous/
eulerian-wallfilm/ species/

/define/models> species

/define/models/species>
diffusion-energy-source? off? thermal-diffusion?
inlet-diffusion? save-gradients? volumetric-reactions?
multicomponent-diffusion? species-transport?

/define/models/species>

diamondx · August 16, 2013, 13:56

try /define/model/species/non-premixed-expert

burritolover · August 16, 2013, 17:40

Hello,

Thanks for all the replies. I was finally able to find the location where I could lower the Maximum Heat Loss Fraction! You were correct it is under "non-premixed-combustion-expert". Originally it was set to 0.66, I set it to 0.4 and ran the simulation again. Unfortunately this did not help fix the error. I still have "minimum pdf table temp" error occuring on every iteration and to many cells.
I have also tried reducing the under relaxation factor for Energy to 0.6 and this did not help either.
I have increased the mesh as well as increased the inlet temperature to 600K for the fuel and the oxide to no avail.
I have noticed that my P1 residuals are acting strangely though. They are far below the other residuals.

Any thoughts?

diamondx · August 23, 2013, 17:30

change the minimum temperature in the limits !!!!

August 14, 2013, 16:15	HELP; Ansys 13.0 Combustion Problem!	#1
burritolover New Member Clan McKenzie Join Date: Aug 2013 Posts: 7 Rep Power: 13	Hello Everyone! I desperately need assistance with the following problem. I have been trying to do combustion analysis for a couple of months now and have a repeating problem. During the solution portion of the simulation on FLUENT 13.0 I have the following read out on each time step... "Minimum PDF table temperature in 9893 cells on zone 3" The number of cells fluctuates greatly. I have a video of each step that I have done at the link below. https://www.youtube.com/watch?v=-CDNB22fWFo I have tried increasing the mesh, increasing the fuel and oxid temperatures without any results DISREGARD THE FLOW RATES IN THE VIDEO! I have corrected them and they are not connected to the error. THANK YOU IN ADVANCE!

August 14, 2013, 17:07		#2
diamondx Super Moderator Ghazlani M. Ali Join Date: May 2011 Location: Tokyo, Japan Posts: 1,385 Blog Entries: 23 Rep Power: 29	the tips you found here in the forum, the advanced features has to be enabled via the TUI command, not the graphic interface... __________________ Regards, New to ICEM CFD, try this document --> https://goo.gl/KAOIwm Ali

August 16, 2013, 13:56		#5
diamondx Super Moderator Ghazlani M. Ali Join Date: May 2011 Location: Tokyo, Japan Posts: 1,385 Blog Entries: 23 Rep Power: 29	try /define/model/species/non-premixed-expert __________________ Regards, New to ICEM CFD, try this document --> https://goo.gl/KAOIwm Ali

August 23, 2013, 17:30		#7
diamondx Super Moderator Ghazlani M. Ali Join Date: May 2011 Location: Tokyo, Japan Posts: 1,385 Blog Entries: 23 Rep Power: 29	change the minimum temperature in the limits !!!! __________________ Regards, New to ICEM CFD, try this document --> https://goo.gl/KAOIwm Ali

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
[DesignModeler] ANSYS 13 - DesignModeler sketching problem	Novosiberian	ANSYS Meshing & Geometry	6	June 27, 2014 11:38
Oil combustion problem	brajh11	CFX	1	December 7, 2012 02:49
Problem of Ansys for machanical a element or a group of elements	lovelyeverything	ANSYS	0	April 18, 2012 23:54
[ANSYS Meshing] Import ".dbs" into Ansys 13.0	antallo	ANSYS Meshing & Geometry	2	February 17, 2011 14:33
ANSYS 13 problem	zona	ANSYS	0	December 16, 2010 07:48

August 14, 2013, 17:16		#3
burritolover New Member Clan McKenzie Join Date: Aug 2013 Posts: 7 Rep Power: 13	Thank you so much for your speedy response! I just realized where the TUI interface is on Fluent 13.0. Right smack in front of me! I will try it and get back to you. Again I greatly appreciate your help

August 14, 2013, 17:54		#4
burritolover New Member Clan McKenzie Join Date: Aug 2013 Posts: 7 Rep Power: 13	Well I have tried to find the option for the Maximum Heat Loss Fraction and have not been able to find it. The following is as far as I got through the TUI command window. If anyone can help I would GREATLY appreciate it! > adapt/ file/ report/ close-fluent mesh/ solve/ define/ parallel/ surface/ display/ plot/ views/ > define /define> beta-feature-access materials/ profiles/ boundary-conditions/ mesh-interfaces/ solution-strategy/ custom-field-functions/ mixing-planes/ turbo/ dynamic-mesh/ models/ units enable-mesh-morpher-optimizer? operating-conditions/ user-defined/ injections/ parameters/ /define> models /define/models> acoustics/ heat-exchanger/ steady? addon-module multiphase/ unsteady-1st-order? crevice-model? radiation/ unsteady-2nd-order-bounded? dpm/ solidification-melting? unsteady-2nd-order? energy? solver/ viscous/ eulerian-wallfilm/ species/ /define/models> species /define/models/species> diffusion-energy-source? off? thermal-diffusion? inlet-diffusion? save-gradients? volumetric-reactions? multicomponent-diffusion? species-transport? /define/models/species>

August 16, 2013, 17:40		#6
burritolover New Member Clan McKenzie Join Date: Aug 2013 Posts: 7 Rep Power: 13	Hello, Thanks for all the replies. I was finally able to find the location where I could lower the Maximum Heat Loss Fraction! You were correct it is under "non-premixed-combustion-expert". Originally it was set to 0.66, I set it to 0.4 and ran the simulation again. Unfortunately this did not help fix the error. I still have "minimum pdf table temp" error occuring on every iteration and to many cells. I have also tried reducing the under relaxation factor for Energy to 0.6 and this did not help either. I have increased the mesh as well as increased the inlet temperature to 600K for the fuel and the oxide to no avail. I have noticed that my P1 residuals are acting strangely though. They are far below the other residuals. Any thoughts?