LIGGGHTS® - User Forum

Hi. I want to use mesh/tet and insert/pack features.
I use in.insert_pack example file as basic for my simulation.
But I get an error when I use own insertion region geometry file instead of test.vtk:

LIGGGHTS 1.4.1 based on lammps-10Mar10
Created orthogonal box = (-1 -1 -1) to (1 6 2)
1 by 4 by 1 processor grid
Fix particledistribution/discrete (id pdd1): distribution based on mass%:
pts1: d=5.000000e-02 (max. bounding sphere) mass%=30.000000%
pts2: d=3.000000e-02 (max. bounding sphere) mass%=70.000000%

Hi all,

I had a look at the gran/hook/history/simple pair_style today. I thought that this pair_style should make you able to directly set the values for kn, kt, gamman and gammat depending on the contact-partners. So I was wondering why the values for the damping coefficients (gamman and gammat) are multiplied by meff. The same modification is done for wall-contacts.

I think that should be changed otherwise you have to take the multiplications into account when you set the values in the input-script.

Regards,

Yansan

Is it possible to use a gaussian distribution of radii for the particletemplate/sphere command? The documentation says it is possible but I am getting the following error:

ERROR: Random style gaussian not available for radius

My pertinent code is:
fix pts1 all particletemplate/sphere 1 atom_type 1 density constant 2500 radius gaussian 0.0003 0.00005
fix pdd1 all particledistribution/discrete 1. 1 pts1 1.0

Thanks,
Will

Hi all,

I have been playing with aggregated particles using a hybrid granular/molecular pair style, and am now introducing heat flow into the simulation. In the current implementation if I exclude the aggregates from neighbor calculations, there is no heat flow between member particles (this, of course, makes sense!). If I remove this exclusion, then heat does indeed flow, but at a rate determined by the thermal properties and the initial overlap when the aggregates are created (i.e. determining the contact area).

I would prefer either to be able to either:

I have an idea about vizing the superquadrics using paraview.
first, creat a superquadric source;
then, read your vtk files including particles postions;
the last, use glyph with custom sources. The following image shows what I have done.

Chen

Hi!
Is it possible to insert group of particles, so that their initial velocity would be against gravity field? I've tried it with

fix pour/dev

command, but it gives me an error message:
ERROR: fix pour: z-velocity must not not be <0.

Thanks,

Timo

This probably relates to this problem, but I've posted a new topic to attach some images...

I have just tried to verify the coordination number for some simple packings (in this case simple cubic). I have computed and dumped the coordination number using computer coord/gran. I was expecting a coordination number of 6 everywhere apart from at the edges...

Hi,
What is the best technique of making dense granular packings in liggghts?
Thanks in advance
Amrita K

I am about to start working both with cohesive materials, and also with heat flow - in both of these cases the contact area between particles is an important parameter. It would be great if this value could be exposed to compute pair/gran/local so that it could also be output via dump local...

I can probably figure out the changes if nobody else finds it useful, but I haven't yet started to dig into the code base ;-)

Thanks! Mark

Hi everyone,

I've been running a simulation that uses a hybrid granular/molecular style, and performing the integration with a "fix rigid molecule". Once these aggregates have settled, I then heat the lower boundary and want to study the heat flow through this material.