[CFD-Post] Viewing max residuals

siw · July 26, 2012, 04:50

Hi,

Is it possible to view in CFD-Post where the maximum residual (as plotted by the CFD-solver during a simulation) is in a fluid domain? I've tried Isosurface, Contours, Function calculator but cannot find where to get the max residual locations.

If I can where it is occuring then I can improve the mesh in that area to improve the RMS residuals and convergence - even though I'm getting a constant residual and monitor point values the RMS residual valve needs to go down by another order of magnitude.

Thanks

Lance · July 26, 2012, 05:16

You can get the residuals in post if you have checked the "output equation residuals" in pre (under output control). Then they will show up in the variables list in post.

siw · July 26, 2012, 05:59

Thanks Lance.

I must have missed it in Output Control when I set up my monitor points.

However, I don't see any mention of residuals in the Variables list (even expanded all the lists in Variables). Have I done something wrong or am I looking in the wrong place (even though I think I've run out of place to look)?

Lance · July 26, 2012, 09:29

They should be in the variables list, named something like P.Mass Residual, etc.

After the "output eqn residuals" check box, did you change "Eqn. Residuals" to "All" from "None"?
If you run transient you'll need to check the "output eqn residuals" box under trn results as well to get the residuals in the trn files and not only in the .res file.

error404 · May 21, 2014, 07:32

You can visualize the max. or min. residuals with a "point".

Then you can refine your mesh at this location.

July 26, 2012, 04:50	[CFD-Post] Viewing max residuals	#1
siw Senior Member Stuart Join Date: Jul 2009 Location: Portsmouth, England Posts: 733 Rep Power: 25	Hi, Is it possible to view in CFD-Post where the maximum residual (as plotted by the CFD-solver during a simulation) is in a fluid domain? I've tried Isosurface, Contours, Function calculator but cannot find where to get the max residual locations. If I can where it is occuring then I can improve the mesh in that area to improve the RMS residuals and convergence - even though I'm getting a constant residual and monitor point values the RMS residual valve needs to go down by another order of magnitude. Thanks

July 26, 2012, 05:16		#2
Lance Senior Member Lance Join Date: Mar 2009 Posts: 669 Rep Power: 22	You can get the residuals in post if you have checked the "output equation residuals" in pre (under output control). Then they will show up in the variables list in post. Wei Liu likes this.

July 26, 2012, 05:59		#3
siw Senior Member Stuart Join Date: Jul 2009 Location: Portsmouth, England Posts: 733 Rep Power: 25	Thanks Lance. I must have missed it in Output Control when I set up my monitor points. However, I don't see any mention of residuals in the Variables list (even expanded all the lists in Variables). Have I done something wrong or am I looking in the wrong place (even though I think I've run out of place to look)? Last edited by siw; July 26, 2012 at 06:39. Reason: Update for finished simulation

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July 26, 2012, 09:29		#4
Lance Senior Member Lance Join Date: Mar 2009 Posts: 669 Rep Power: 22	They should be in the variables list, named something like P.Mass Residual, etc. After the "output eqn residuals" check box, did you change "Eqn. Residuals" to "All" from "None"? If you run transient you'll need to check the "output eqn residuals" box under trn results as well to get the residuals in the trn files and not only in the .res file.

May 21, 2014, 07:32		#5
error404 New Member Simon Join Date: Apr 2014 Location: Stuttgart, Germany Posts: 22 Rep Power: 12	You can visualize the max. or min. residuals with a "point". Then you can refine your mesh at this location.