pouring particles of complex shape?

Submitted by ericparteli on Mon, 08/13/2012 - 18:50

Hi,
is there a fix for pouring or inserting particles of complex shapes (like rods or rice grains), defined using the multisphere method or via fix rigid and pair_style hybrid granular molecular?
If not, is there such an utility for LIGGGHTS in preparation which will be made available for public usage in a forthcoming version?
Best
Eric

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msbentley's picture

msbentley | Mon, 08/13/2012 - 20:52

I haven't "poured" particles in this way, but I've generated packings of aggregate particles (using a hybrid sphere/molecular style) using an external tool, and then read that packing into LIGGGHTS with read_data to run the simulation proper. In my case I used functions from YADE (https://yade-dem.org) to generate ballistic aggregates, and then pack them into a volume.

Cheers, Mark

ericparteli | Mon, 08/13/2012 - 22:07

Hi, Mark,
thanks for this great hint!
Indeed I generate complex particles with an external code and then use read_data of LIGGGHTS. However I did not know how to make ballistic deposition of such aggregates. YADE sounds a great hint. Which function exactly do you use for making ballistic deposition of complex particles there?
Cheers
Eric

msbentley's picture

msbentley | Tue, 08/14/2012 - 10:28

What I do is first run a separate small scale simulation in YADE to build aggregates of, say, 100 monomers via particle-cluster aggregation. Groups of spheres can be aggregated in YADE into "clumps" in their terminology. These clumps can then be packed into a volume using the makeClumpCloud function in yade.pack. I find this kind of "non standard" stuff easier in YADE, but LIGGGHTS is much more powerful/scalable for the real simulation. So I then simply dump the partition positions to a data file, read them into LIGGGHTS with read_data and let them fall under gravity to achieve my final packing. Then I run the real simulations from there...

ericparteli | Tue, 08/14/2012 - 13:41

Thanks, Mark,
Using YADE for producing the clumps sounds really useful, I will have a look - just installed YADE and have to get through its documentation before I can run something :)
Nevertheless I guess adapting e.g. the fix insert/stream to allow users to pour particles of a complex geometry (e.g. pre-defined in a read_data file containing a sample particle) could be very useful adding to LIGGGHTS, what do you think?
Maybe you have a different idea and we could come up with a useful and feasible suggestion about this to the developers (if they are interested and if it is really of general interest as I suspect :))?
Best
Eric