CFD Online Logo CFD Online URL
www.cfd-online.com
[Sponsors]
Home > Forums > Main CFD Forum

energy balance

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

Reply
 
LinkBack Thread Tools Display Modes
Old   November 18, 2009, 23:49
Default energy balance
  #1
New Member
 
Dezhi Zheng
Join Date: Sep 2009
Posts: 8
Rep Power: 7
zdz198728 is on a distinguished road
Hi, guys:
I am doing a combustion case with PDF model. I have opened the P1 radiation model. However, the energy balance are not good? I am not sure what the problem is. Is radiation is main reason of this problem? How could we get energy balance.

Thanks
zdz198728 is offline   Reply With Quote

Old   November 19, 2009, 01:07
Default
  #2
New Member
 
Charles Rundle
Join Date: Oct 2009
Posts: 9
Rep Power: 7
Charles Rundle is on a distinguished road
Hello,

I haven't worked with combustion to any extend to please take my advice from that perspective. It has also been awhile since I've used the P1 radiation model.

If I may ask, are you determining your energy balance based on a report provided at the end of the solver run or by comparing the energy flows in the post data? Also are you performing a transient or steady state analysis? If nothing else I would recommend checking to make sure the method you are using to determine the energy balance is correct. I would pay special attention to make sure that no energy sources have been left out.

If the method being used is correct I have a few suggestions. In the past I've found that sometimes a higher level of convergence is required to get good energy balance. Perhaps let it converge to a RMS value one magnitude lower to see it improves the energy balance. If I recall correctly, I'm away from my computer with the documentation on it, the P1 model works with rays, increasing the number of rays may improve you energy balance as well, although at the cost of computational effort.

I may also be linked directly to the fact this is a combustion problem in which case I'm afraid I'm out of my depth.

I hope I have been helpful. Have a good day.

CAR
Charles Rundle is offline   Reply With Quote

Reply

Thread Tools
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 On
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
Energy & Mass balance in RES file Lindel Phoenics 2 October 23, 2008 19:18
Energy Balance Harshad CFX 0 March 5, 2008 07:36
HELP needed: Energy balance in gaseous combustion James Willie FLUENT 11 August 10, 2005 04:58
Energy balance Eric FLUENT 1 February 17, 2004 20:33
energy balance fipost Ralf Kroeger FLUENT 0 May 19, 2000 10:25


All times are GMT -4. The time now is 09:37.