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[Jan Stránský <question701438@xxxxxxxxxxxxxxxxxxxxx>]

Question #701438 on Yade changed:
https://answers.launchpad.net/yade/+question/701438

    Status: Needs information => Answered

Jan Stránský proposed the following answer:
Hello,

please read [3], section "Please, no external links!".
MWE can be put directly in the question (assuming satisfying M=minimal condition).

> even dt is small enough compared to the dt obtained from PWaveTimeStep()
> If I understood correctly, when dt is small enough, different dt should not affect the results. Do you have any ideas about it?

Straightforward answer could be that it is not small enough to neglect
the effect of its value

But, more importantly:
You are examining a few "random" particle's velocities in a simulation with "many" particles. 
Such DEM simulation is "chaotic", i.e. a small change in input may lead to big changes for such quantities like velocity or position of one individual particle.
You can try running exactly the same simulation (same O.dt, same initial configuration, everything the same) in parallel, let's say with "-j 4" option and you should get different result for each run [4].
So what you are experiencing with different velocities is the feature of DEM and its computer solution.

So you should be interested in some "overall" quantities, like average
velocity of some band or region of particles

Concerning premature exit, I have no idea.
The log files of those simulations does not contain the line "Running finished". But it has status: 0 (OK) result. So it must have been stopped somehow differently than by stopSimulation() function..

Cheers
Jan

[3] https://www.yade-dem.org/wiki/Howtoask
[4] https://yade-dem.org/doc/formulation.html#result-indeterminism

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