LIGGGHTS® - User Forum

Hello,

I'm facing a problem in pair_colloid.cpp
I designed a small testcase containing just 2 particles, radius 0.01µm and varying the initial distance between them. They are underlaying DLVO potential by hybrid overlay colloid and yukawa/colloid
For larger initial distances the simulation is working. At a distance of 2µm I get an unspecific error (seems like division by zero). For distances smaller than 2µm I get the error: "Overlapping large/large in pair colloid" (line 187 of pair_colloid.cpp).

Hi, after running :

examples/LIGGGHTS/Tutorials_public/superquadric/in.particle_particle

When I open the dump files in Paraview the variables quad1, qaud2, qaud3, quad4 are missing, while shape x,y,z and blockiness 1,2 are present. I would like to check the initial settings for quad. Does someone know why these values are missing?

(The Liggghts version is 3.8.0 and I used 'make auto' in the src folder then copied the lmp_auto executable to run the code.)

Many thanks, John

This might be a idiot question but I have been stuck for a while. I would like to ask how to assign number of multisphere particles into the insert region. I used the "multisphere_stone_restitution" in LIGGGHTS' example. There are 50 coordinations in the data file, and only 2 clumped particles were created. I wonder how to increase the number of clumped particles ? Should I increase the number of coordination? I read the LIGGGHTS' manual but it does not (or I missed it) mention about this problem.
Thank you for your time.

Hello everyone;
By some reasons, I need to use LIGGGHTS 3.2 to simulate my model. I need to clump the particles to make the irregular shape. I know the function fix particletemplate/multisphere can do that job, but it is only available in LIGGGHTS 3.3 onward. I tried to copy the fix_multisphere in src 3.3 to 3.2, but I could not compile. Can anyone suggest me a solution?
Thank you

Hello everyone,

I am working on liggghts, and I generated a particle packing in the geometry by command insert/stream, after particles become stationary in the bottom, i would like to make the packing position fixed and not be moved anymore. In other words, after packing formed, we treated it as a wall.

I tried the command fix freeze and fix setforce, but the particles not acted force tend to overlap with each other, and it is unexpected.

Do you know how to realize this ?

thanks.

I am simulating shaking grains in the vertical direction and I would like to speed up my simulation. I can use up to 24 cores. Since, the motion is predominantly in the z direction, should I maximize number of cores in this direction? Also, I noticed if I reduced the number of cores and let liggghts decide the optimum distribution, 20 cores make it faster instead of 24. I thought it was counter-intuitive but then again it could just be how liggghts distributes it. What should I do?

Hello everyone,

I want to simulate with a volume fraction of 0.4288 but this would lead to unreasonable high numbers for maxattempt to work.
So deactivated overlapcheck, but then the manual says the overlapping configuration has to be relaxed.
My problem: there is no word on how to do this.

Can anyone tell me how to relax properly? ;)

Thank you in advance.

Hello everyone,
I am a student doing a project work, as part of my task I need to calculate traction when my sample come in contact with soil. Here the problem is particles are inserted and now there is no contact of my sample with my particles as sample is just at the surface but due to clearance between sample and particles there is no contact. Can anyone help me with this to make contact between sample and particles.
Thanks & regards.
Rohith.

Hello Everyone,
I am a student working on a project, here I need some help regarding particles to be inserted. In my project I need to fill an bowl with flat surface full of particles but I don't know how many particles to be inserted to fill the bowl. I would be glad if anyone help me out of it.
Thanks in advance.

Hi all,

I am trying to fill a container with multisphere particles. Since filling the container will take a very long time (over 48 hours), I created a restart file. However, when I try to restart the simulation to continue filling the container, an error comes up.

First, it was
ERROR: Fix multisphere (id integr): requires an 'atom_modify map' command to allocate an atom map (../fix_multisphere.cpp:343)

So I added the line: atom _modify map array sort 0 0