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I can't seem to make the molecular particles immediately settle when they fall through a solidified cylinder to the bottom and remain still. Instead, they jitter, shake, bounce off each other, then slowly... rise... almost like dough. (See the video)

I'm trying to get some realistic dirt or ground till to interact with. Any help would be greatly appreciated.Thanks!

Link to a simple Blender test file I made to showcase the issue: download .blend file

Thanks in advance.

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  • $\begingroup$ i am a newbie but i have an idea cause me too i am interested into particles and molecular atoms, may be you should setup the bottom as a steady plane means no velocity on it, like boundary conditions . $\endgroup$ – Hamza.w Jun 11 '15 at 12:54
  • $\begingroup$ dampening should help, try adding dampening in particle physics section $\endgroup$ – BluePrintRandom Aug 4 '15 at 20:19
  • $\begingroup$ It looks like that the spheres you have entered collide with the cylinder am i correct? $\endgroup$ – xlxs Sep 10 '15 at 11:07
  • $\begingroup$ Hamza, appreciate the suggestion, however had little effect. BluePrintRandom, seemed to affect the particles very little, but turning up the dampening in molecular add-on and the colliding cylinder. xlxs, yes, they're colliding with the cylinder as well as each other. I tried solidifying the cylinder, applying the modifier, then re-baking, but to no avail. $\endgroup$ – Jesse Sep 18 '15 at 19:28
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According to the addon description, the 2 features it provides are self-collision of particles and spring-based interaction. (Disclaimer: i haven't used the addon yet nor looked at the code)

Collision may be suitable for some types of granular material, but i think that for true sand-like behavior you would need a tremendous amount of particles and a number of friction effects would simple not be captured by this approach. Already with the moderate amount of particles in your example the solver becomes somewhat unstable (this is simply a limitation of the method as far as i can tell, not a bug).

Spring-based interaction otoh leads to soft-body type motion and probably cannot produce sand material effects either. Connecting particles this way creates elastic forces that don't allow particles to flow past each other.

I would suggest to try and model the sand surface with keyframe animation instead, possibly with displacement and shape keys you could get enough control.

Non-Blender remarks:

In current research and other simulation packages material point methods (MPMs) have been developed in recent years, which allow a much wider range of material simulations, which don't fit well into the soft-body or pure fluid simulation categories. Unfortunately to my knowledge none of these have found their way into Blender at this point, but it might be possible to use external software in the meantime.

For reference: http://www.cs.ubc.ca/~rbridson/docs/zhu-siggraph05-sandfluid.pdf

The sample principle methods have been applied to snow and foam like materials:

https://www.youtube.com/watch?v=O0kyDKu8K-k

https://www.youtube.com/watch?v=3_DdAXV3IDw

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  • $\begingroup$ Appreciate the info' and suggestions. May just be one of the weak points of Blender at this moment in time. Creating interactive particles like sand may be improved in the future. Only time will tell. :) $\endgroup$ – Jesse Oct 27 '15 at 18:37

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