LIGGGHTS® - Developer Forum

Hi all,

I am trying to simulate one the hand partilces with bonds ( see https://github.com/richti83/LIGGGHTS-WITH-BONDS) and multispheres into one simulation.

After implementing the files from richti83 and adjusting the given bond-example, this issue works very well. Also the simulation of only multispheres works fine.

Hi,

currently I'm investigating if it is possible to create custom contact model for wall. I'm interested in having simple lubrication cohesion model when particle is in close proximity to the wall.

I've created new lubrication cohesion model which seems to be working for pair_gran style. Now I wish to have the similar model adopted for atom wall interactions.

Hello all,

Heat transfer between two particles is calculated by fix heat/gran with the equation given on

http://www.cfdem.com/media/DEM/docu/fix_heat_gran_conduction.html

Hi,

I am trying to use history in liggghts law (like in tangential_history or normal_model_hooke_hysteresis). I have observed a positive history value becoming negative.

I have reproduced this comportment in a slightly modified tangential_history law. I only add a second value memorized, initialised at 1 (if -0.1 < value < 0.1, then value = 1). If this value become negative, liggghts stops. The input file is packing official example without modification and modified tangential law is linked. Liggghts stops between the 7000 and 8000 time step.

Hi,

I already tried the new version 3.4.0.
But now I get an error during simulation. After insertion phase I got this particular error.

run 1
Setting up run ...
ERROR on proc 0: surface mesh feature remove not available in this version (../surface_mesh_feature_remove.h:1)

Please help me to fix this error.

Hi All,

Some of you may have seen my old post that describes how to add quaternions to spheres, found here:
http://www.cfdem.com/forums/fix-nvesphereorientation
I'm trying to use it with fix insert/pack but it seems quaternions are not inherent particle properties, even though I set 'atom style hybrid sphere ellipsoid." I have a suspicion that fix insert/pack automatically creates spheres without quaternions, but I'm not sure.

I'm not sure if this is intended behavior, but it seems that the coefficient of restitution ("e") specified in the input file is *not* the same as the actual measured ratio of the velocity of a particle after/before a collision.

The restitution coefficient for a collision can be defined as:

e = vel_{after} / vel_{before}

Hi everyone,

Maybe this is a naive question, but is there a way to speed-up the compilation of LIGGGHTS when you only make changes to one fix (e.g., fix_cfd_couple_forces)?

For example, when compiling OpenFOAM, executing 'wmake' will only recompile libraries whose source code changed since the last build.

Hello everyone,

I am wondering how can I debug LIGGHTS. Does anyone here have the experience of debugging LIGGHTS with gdb or any other debugging tool?

Thanks.

All,

I got some question when I was trying to figure out what kind of algorithm is used in LIGGGHTS to detect sphere and triangle surface interaction. So guys, please help to clear my mind on this problem. In the TriMesh::resolveTriSphereContactBary, I saw this two lines:

vectorSubtract3D(cSphere,n[0],node0ToSphereCenter); //double **n = node_(nTri);
MathExtraLiggghts::calcBaryTriCoords(node0ToSphereCenter,edgeVec(nTri),edgeLen(nTri),bary);