yade-dev team mailing list archive

[Jerome Duriez <Jerome.Duriez@xxxxxxxxxxx>]

Yet another example of scattering: crack propagation in mode I+III (attached image). The crack pattern at the surface of the model (the yellow symbols) is not the same for different parallel runs of the same simulation.
The horizontal distance (along Y directions) of surface crack lines is significantly affected (but not the orientations). I faced probably a lot of skepticism in 3SR lab with that, but it is a fact for me.

Another example all of you may know: the post-peak behaviour (stress-strain curve) of a triaxial simulation, but here the differences between two parallel runs are clearly negligible, and the physical explanation is direct considering the peak stress as a bifurcation point.


Jerome

________________________________________
From: Yade-dev [yade-dev-bounces+jerome.duriez=ucalgary.ca@xxxxxxxxxxxxxxxxxxx] on behalf of Bruno Chareyre [bruno.chareyre@xxxxxxxxxxxxxxx]
Sent: March 5, 2015 8:00 AM
To: yade-dev@xxxxxxxxxxxxxxxxxxx
Subject: Re: [Yade-dev] results scatter with identical initial simulation

On 05/03/15 15:37, Václav Šmilauer wrote:
> (sorry for PM)
>> I assume you are running your simulation in parallel. If not identical
>> simulations should give identical results (at least in Yade).
> That's what everybody says, but did you try to run the same sim and see?
This, at least, yes. Even with quite complex solid-fluid coupling:

yadedaily oedometer.py (it is in example folder)
Yade [1]: O.run(100,1); print O.bodies[10].state.vel
Vector3(0.000765388955990568,-0.0021344971932796193,0.0008870185413005638)

and again:
...
Vector3(0.000765388955990568,-0.0021344971932796193,0.0008870185413005638)

I think the register vs. RAM thing is decided at compile time in many
cases, though not always.
I've read something about that recently (kind of webpage explaining why
(1.2+1)==(1+1.2) could return false eventually).

Bruno


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Attachment: crackProp.png
Description: crackProp.png