What are causes of difference between solution of similar cases?

mohsali · November 20, 2020, 08:07

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, 08:42

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, 08:07	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

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
Convergence	Centurion2011	FLUENT	48	June 15, 2022 00:29
Initial solution from potentialFoam (or similar)	Gerry Kan	OpenFOAM Running, Solving & CFD	4	February 20, 2020 11:58
How to compare temperature difference at same position between two cases?	Dorasemon	FLUENT	3	December 19, 2018 06:54
Naca 0012 (compressible and inviscid) flow convergence problem	bipulsaha	FLUENT	1	July 6, 2011 08:51
About the difference between steady and unsteady problems	Lisa	Main CFD Forum	11	July 5, 2000 15:37

November 20, 2020, 08:42		#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...