CFD Online Logo CFD Online URL
www.cfd-online.com
[Sponsors]
Home > Forums > Software User Forums > ANSYS > FLUENT

Convergence issue for high speed combustion with radiation.

Register Blogs Members List Search Today's Posts Mark Forums Read

Reply
 
LinkBack Thread Tools Search this Thread Display Modes
Old   July 24, 2014, 06:32
Unhappy Convergence issue for high speed combustion with radiation.
  #1
New Member
 
Goutham S
Join Date: Jul 2014
Posts: 2
Rep Power: 0
Goutham cet is on a distinguished road
Sir,
I am currently modelling a supersonic (m=3)combustion of hydrogen injected transversely into the flow field.Using a density based solver ,k E turbulence model .p1 and do for radiation .i am using all under relaxation factor 0.1, combustion includes reaction using mechanism.To get good convergence i initiated reaction mechanism after sufficient iteration.

i am getting the value of residual for continuity is of the order of 9.0204 * 10^-3 after 20000 iteration and remains constant .On the other-hand the residual for energy still remains of the order of 1 to 10^-1 .all the values remains same for any number of iteration.

Is this correct ,or what should i do to bring the convergence of both continuity and energy further down.

Note-good grid quality has been chosen.

Thanks in advance for helpers ...please do help...
Goutham cet is offline   Reply With Quote

Old   July 25, 2014, 13:43
Default
  #2
New Member
 
Join Date: Jun 2011
Posts: 22
Rep Power: 15
sescobar is on a distinguished road
Hello Goutham,
Did you try to take a look at the local residual values for the energy equation?
This may allow you to elucidate if mesh quality needs to be improved locally.
A quick way to check if this is the cause is to refine your mesh in Fluent based on the local value of energy residual. Then solve for a given number of iterations. If the overall residual drops, then you may have found the cause.
sescobar is offline   Reply With Quote

Old   July 30, 2014, 07:22
Default
  #3
New Member
 
Goutham S
Join Date: Jul 2014
Posts: 2
Rep Power: 0
Goutham cet is on a distinguished road
Thanks a lot....i tried refining my mesh ...and the problem somewhat cleared , now both are in 1 e^-3 range ,while the mass flow rate shunting between 1333.29-1333.28 units.and its not allowing to converge further.. thinking may be there will be instability's associated flow with combustion.
Goutham cet is offline   Reply With Quote

Reply

Tags
continuity, energy converngence

Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
Convergence issue with continuity equation Jake FLUENT 8 June 6, 2018 03:41
Speed of Convergence faster with smaller time step Torque_Converter CFX 1 May 15, 2012 19:22
Modeling both radiation and convection on surfaces - Ansys Transient Thermal R13 s.mishra ANSYS 0 March 31, 2012 04:12
Convergence issue in SST for Porous model Raj CFX 0 May 2, 2008 02:43
CFX-Solver, issue with convergence behavior Andy CFX 7 September 5, 2006 03:24


All times are GMT -4. The time now is 03:15.