What are causes of difference between solution of similar cases?

mohsali · November 20, 2020, 07:07

Hi
im newbie in openFOAM and practicing tutorials of the user guide.in the "Breaking of a dam" tutorial, the results of my solution have differences from reported results in the user guide.
i did the tutorial step by step and exactly same as the user guide.
what are the causes of these small differences in the results?
thnx

simrego · November 20, 2020, 07:42

Hi!

If they case is "untouched", so you just download and run, it is possible that the results in the user guide made with slightly different setup, or simply something is changed in the code, and it can slightly affect the solution. Hopefully it became more robust and accurate.

For example sometimes the schemes are changing in the tutorials over time, and I think they don't update the figures in the user guide after every release.

So for really small differences I shouldn't spend too much time on it. If there are BIG differences, then there should be something wrong... Also this is modelling, so your results will be always "wrong", but hopefully they will be less and less wrong...

November 20, 2020, 07:07	What are causes of difference between solution of similar cases?	#1
mohsali New Member mohsali Join Date: Nov 2020 Posts: 1 Rep Power: 0	Hi im newbie in openFOAM and practicing tutorials of the user guide.in the "Breaking of a dam" tutorial, the results of my solution have differences from reported results in the user guide. i did the tutorial step by step and exactly same as the user guide. what are the causes of these small differences in the results? thnx

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November 20, 2020, 07:42		#2
simrego Senior Member anonymous Join Date: Jan 2016 Posts: 416 Rep Power: 14	Hi! If they case is "untouched", so you just download and run, it is possible that the results in the user guide made with slightly different setup, or simply something is changed in the code, and it can slightly affect the solution. Hopefully it became more robust and accurate. For example sometimes the schemes are changing in the tutorials over time, and I think they don't update the figures in the user guide after every release. So for really small differences I shouldn't spend too much time on it. If there are BIG differences, then there should be something wrong... Also this is modelling, so your results will be always "wrong", but hopefully they will be less and less wrong...