LIGGGHTS® - User Forum

Hi,

Hello,

I'm creating a simulation with CFDEMcoupling, but I think this is more of a LIGGGHTS question. My goal is to have a tube (cross-section in XY, length in Z) with a vertical fluid flow in the Z direction. I'm inserting particles in the tube, which may drift to the top. I would like to delete the particles when they get "stuck" to the top wall. I've put in two delete_atom commands, but neither seems to be working the way I expect them to (or at all). Here's the code:

in.liggghts_init

Hi everyone,
I'm trying to analyse the packing fraction after pouring steel pellets into a container. Is there an inbuilt tool in liggghts which computes packing fraction as a function of distance from the origin (or any other reference)?

Thanks for the help.

Joel

Hi all.
I'm pouring steel pellets into a container. When I set the young's modulus to 2.1 e11 , the pellets seem to go right through the wall, which I have created using fix wall/gran ( i.e. fix xwalls1 all wall/gran model hertz tangential history primitive type 1 xplane -0.1 limitForce 'on' ).
The pellets don't go through the wall if I lower the young's modulus to around 2.1 e9
Can someone explain why this is happening?

Thanks

Joel Martis

Hi all,
I'm trying to simulate pouring of particles into various containers. By default, there are only two geometries available (cuboid and cylinder) in the fix wall/gran command. How do I create more complex geometries? Is there an open source software to create stl files which I can import using fix mesh/surface? This would then enable me to create complex geometries.

Thanks for the help.

Joel Martis

I am going through installation tutorial as mentioned in "http://www.cfdem.com/installation-tutorial" but in second step where i have to install openmpi by giving command "sudo apt-get install openmpi openmpi-devel" it does not get installed. It says:

Reading package lists... Done
Building dependency tree
Reading state information... Done
E: Unable to locate package openmpi
E: Unable to locate package openmpi-devel

What should I do?

I am working on Ubuntu 14.04LTS 64bit operating system

Hello, everyone,

I am trying to add the Van der Waals forces in LIGGGHTS 3.2.1. The easiest way should be using the L-J potential. However, the L-j model is not available in the new Version of LIGGGHTS 3.2.1 any more. Could somebody tell me, how can I implement such contact loss forces in LIGGGHTS 3.2.1 without the potential, or is it possible to compile the solver with L-J potential model?

Many thanks!

Zhen

Hi all !

I have trouble with the potential energy computation. I always get a zero value for potential energy, whatever the conditions (sollicitation type, contact law, number of particles) and the compute used (pe, atom/pe).

I linked a small test case with an input script (two particles in periodic box, compressed at constant strain rate) and the thermo result I get in the log file. The particles indent in one another, but the potential energy remains zero. It seems that there is no pe computation in LIGGGHTS-PUBLIC/examples/LIGGGHTS/Tutorials_public.

I need to make a Triaxial Test but am pretty lost on how to fix all the errors I'm getting using LIGGGHTS. I'm running LIGGGHTS through cygwin, and was wondering if someone had already made a triaxial test that I could use. I found one online that I'm getting invalid pair errors for. Thank you very much for help.

Hi everyone
I was running my input script, but I got the following error:
'' Neighbor list overflow, boost neigh_modify one ''
and after that the simulation aborted at the first step.
Can you help me please within this problem?

I am inserting 10000 small particle in a spherical region and dragging them toward the center point to make a large agglomerate using the following script:

# initialization
units cgs
newton off
boundary f f f
atom_style granular
communicate single vel yes