Storing particle overlap on first iteration to prevent explosions.

Hi,
This feature is somehow available through scripting (see #2 in
https://answers.launchpad.net/yade/+question/266828).
That would be good/simpler to have it also available conditionaly based on
bool Law2::zeroInitForce.
I guess it should be automatically turned off after iteration 1 though,
else people will forget to revert it and the simulation will loose
consistency.
Bruno

On 14 April 2017 at 13:23, Janek Kozicki <
<email address hidden>> wrote:

> New question #619109 on Yade:
> https://answers.launchpad.net/yade/+question/619109
>
> HI,
>
> I am reposting my question here, so that everyone can benefit from the
> answers.
>
> To calculate concrete the sample made of spheres (with cohesion) has some
> of these spheres overlapping. Since it is difficult to generate a sample
> where none of the spheres overlap. And with some overlapping the spheres
> want to "explode" until there is no overlap. Sometimes cohesion prevents
> this, but this means starting calculations with non-zero forces between
> spheres.
>
> To mitigate this problem, the initial overlap between spheres is stored
> [*] (on first iteration) and is treated as "zero" penetration depth during
> tension & compression.
>
> [*] "is stored" means that this change in code is implemented in my local
> copy of yade.
>
> My question is:
> 1. does yade already have such feature, so that I don't need to port it
> back to latest version of yade?
>
> So far Feng Chen has answered my question: http://www.mail-archive.com/
> <email address hidden>/msg12350.html
>
> > Regarding your question, as far as I know packmol (
> > http://www.ime.unicamp.br/~martinez/packmol/home.shtml) can handle
> initial
> > packing of spheres (or even complicated sphere clusters) by maintaining
> the
> > minimum distance between the sphere centers using a BOX-QUACAN
> > optimization, thus if you make the minimum distance greater than
> > max(r_i)*2, you should have zero overlap between the spheres.
>
> And PACKMOL is an interesting solution to the problem. Actually a better
> one.
>
> But the question still remains: shall I implement/port this feature to
> yade from my local yade copy?
>
> best
> Janek
>
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Thanks, this is great place for me to start. I will check this out, and I will let you know about my progress.

Hi
I could not find this command or attribute in yade documentation;
"zeroInitForce"

Any idea?

Thanks

Hi,

Bruno's idea is that I implement (port it from my local yade version) to official yade version using this name "bool Law2::zeroInitForce.". So it's not there yet. But it will be there in few weeks. Please just wait a little, and I will let you know in this thread when I do this, along with some example scripts :)

best regards
Janek

I change this back to "open", will mark as "solved" once implementation is finished.