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[Jan Stránský <question685203@xxxxxxxxxxxxxxxxxxxxx>]

Question #685203 on Yade changed:
https://answers.launchpad.net/yade/+question/685203

    Status: Open => Answered

Jan Stránský proposed the following answer:
Hi,

> 'ring.txt' is in first comment. I really sorry for putting all of the
coordinates!

no need to sorry, thanks for following our instructions [1] :-)

> 1- When the polyhedrons are coming down, no force is applied on them!
why? Must be weight force on all the particles.

How do you know that "no force is applied on them"?
They are coming down (accelerating downwards) just because there is "weight force on all the particles"..

> 2- All the particles move down same as a block, non of them act
lonely, even those particles that are on the sides and are completely
free to fall down.

yes, it is a free fall. Do you want them to behave differently? Why?
How?

> 3- Particles move down very very very slow! Why?

because:
- their real velocity is low
- time step of the simulation is low
- polyhedrons contact evaluation takes long time (compared e.g. to spheres).
Overall, you have "slow" simulation.

> For saving time, when the particles are moving down, I increase the
gravity to 100000 (with simulation inspect window) for fast movement and
when they are near the ground, I set real gravity.

Not a good idea, by higher gravity, the particles get higher
acceleration and higher velocity than in the real case. Better idea is
to increase time step for the phase with no collisions.

> But when the lower particles reach the ground the whole particles stop
moving and nothing happens! they have to place in form of a pile.

Please be more specific what "nothing happens" mean and how you observe that "nothing happens".
I could not reproduce it, have tried your code and after reaching ground the simulation continues normally..

cheers
Jan

[1] https://www.yade-dem.org/wiki/Howtoask

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