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

Inviscid Flow Convergance issues

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

Reply
 
LinkBack Thread Tools Display Modes
Old   July 20, 2010, 23:49
Default Inviscid Flow Convergance issues
  #1
New Member
 
James Merkel
Join Date: Jul 2010
Posts: 1
Rep Power: 0
FormulaRacer is on a distinguished road
HI,

I am currently doing a inviscid flow simulation over a body and appear to be having a convergance issue. My Residuals were for momentum and continuity were settling around .1 and .01 and not dropping any lower. however when i monitor lift and lift coefficient, they appear to be converging perfectly within .5% Is this acceptable? i have tried dropping the relaxation values for the segregated flow model but still no change..

Thanks!
FormulaRacer is offline   Reply With Quote

Old   November 19, 2010, 15:18
Smile Re:
  #2
New Member
 
Tallness
Join Date: Nov 2010
Location: Upstate NY
Posts: 2
Rep Power: 0
yoyomatang is on a distinguished road
Depends what software you are using. With most CFD software (STAR-CCM+) you can set up monitors for different convergence factors and monitor those as well. For example, if you are interested in the concentration of a species in a sensitive area, you could set up a volumetric average monitor for that specific species and watch the actual number converge. Residuals are necessary, but can be misleading. You might have a converged solution in front of you and not know it by only looking at the residuals. Another example would be if you were modeling a small server room and were interested in the temperatures in that space. Instead of watching the residual for energy, you could set up a monitor to watch the volumetric average temperature throughout the room. You will notice this monitor converge towards a single number whereas your residual might not show what is considered convergence. Hope this helps..

-yoyo
yoyomatang 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
Flow meter Design CD adapco Group Marketing CD-adapco 3 June 21, 2011 09:33
Inviscid flow in a Laval nozzle Giorgio FLUENT 1 August 3, 2007 06:46
time step for inviscid supersonic wedge flow. yaseer Main CFD Forum 1 March 8, 2007 10:40
Inviscid flow Atit Koonsrisuk CFX 12 January 2, 2003 13:40
Velocity Gradients at Inviscid Flow Lada FLUENT 0 January 15, 2001 08:20


All times are GMT -4. The time now is 23:07.