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

Residual?

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

Reply
 
LinkBack Thread Tools Search this Thread Display Modes
Old   May 29, 2007, 08:38
Default Residual?
  #1
Beginner
Guest
 
Posts: n/a
Hi,

I would like to have an idea about formulas for calculating the residual over a domain with uniform grid to fix the convergence criteria.

Usually I use (Finite difference scheme):

res = sqrt((Un+1-Un)^2/N) where N is the number of nodes.

Is it correct???
  Reply With Quote

Old   June 1, 2007, 01:59
Default Re: Residual?
  #2
Shyam
Guest
 
Posts: n/a
Usually, when you have an equation as d(u)/dt + L(u) = S

where L(u) is the spatial operator and S is the source, you tend to represent (L(u)-S) as the residual.

For a steady state, this (averaged over all nodes) needs to be zero and hence the convergence criteria. There are many different methods.

For finite volume, it should be the average and not the integral quantity for a stringent condition. (For smaller cells near the physical boundary, this tends to be higher)

  Reply With Quote

Reply

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
transsonic nozzle with rhoSimpleFoam Unseen OpenFOAM Running, Solving & CFD 8 July 1, 2022 07:54
Extrusion with OpenFoam problem No. Iterations 0 Lord Kelvin OpenFOAM Running, Solving & CFD 8 March 28, 2016 12:08
How to write k and epsilon before the abnormal end xiuying OpenFOAM Running, Solving & CFD 8 August 27, 2013 16:33
Orifice Plate with a fully developed flow - Problems with convergence jonmec OpenFOAM Running, Solving & CFD 3 July 28, 2011 06:24
Differences between serial and parallel runs carsten OpenFOAM Bugs 11 September 12, 2008 12:16


All times are GMT -4. The time now is 09:38.