LIGGGHTS® - User Forum

I am gonna to use multisphere commands in LIGGGHTS-PUBLIC, since public version only support serial single processor. So whether it will caculate faster if I build LIGGGHTS-PUBLIC with dummy MPI library in STUBS, and does the compiler(g++,mpic++,icc) I choose have effect on caculating speed?

Greetings to all of you,

I was running a simulation in liggghts, and this message appears:

Mesh output: element id 100384 (line 702690) has 6 neighs, but only 5 expected

It appears several times but with other elements, and in the end, this error message appears:

ERROR: Mesh output: elements 164318 and 163297 (lines 1150228 and 1143081) are duplicate
ERROR on proc 5: Fix mesh: Bad mesh, cannot continue. You can try re-running with 'heal auto_remove_duplicates' (../surface_mesh_I.h:468)

what is the meaning of the 6 neighs, but only 5 expected?

Hi guys,

I have a question.

I am running simulations that needs to be constrained in the z axis and periodic in x and y.
Since I am working with high volume fractions (higher than 0.7), I use the particletemplate/sphere command with an initially low volume fraction, then I compress the box to higher it.
This compression has to preferrably be isotropic (https://www.comsol.nl/model/isotropic-compression-with-cam-clay-material... - for more info).

Hi all,

I am getting following error while using wall/reflect function.

ERROR: Invalid fix style: "wall/reflect" (modify.cpp:820)

The command written is

fix walls all wall/reflect xlo EDGE ylo EDGE zlo EDGE xhi EDGE yhi EDGE zhi EDGE units box

I am using liggghts 3.3.0 version.

NOTE: The idea behind using wall/reflect is to avoid particles crossing wall. The wall is already defined as granular wall using fix/gran.

Appreciate your help in resolving this.

Thanks
Tuks.

Greetings,

I'm writing because i can't understand how to use the point_at_outlet keyword. Specifically, i don't know how it works. What i understand is that you define a point in the "outside" part of the mesh, but what simbolize that point?. For example, my cylinder-shaped mesh is in the coordinates 4.48,0,0. I would have to set the point in 4.9,0,0 in order to the keyword works?

Another thing, the inside_out keyword, how it works too?

I hope that someone can answer my doubts.

Nicolás.

Hi

## version 3.3.0

I am running this code, which inserts two layers made of two sets of random generated packings.
Since I need to compress the volume in order to reach a relatively high volume fraction (higher than 0.8), I apply an isotropic compression to the box, reducing its final dimension.

The problem I have is that the potential energy of the system during compression and relax, is always zero, while the kinetic energy has quite reasonable values.

I am simulating particles rotated by an impeller in a cylindrical container (see sample image attached here). The impeller has two blades (180 degree apart) and is rotating at defined speed.

The LIGGGHTS 3.3.0 release announcement states: "Also made an important improvement to region mesh/tet. The all_in yes feature was implemented, and some algorithms necessary for particle insertions have been improved considerably. You should see a speed-up when using tet meshes for insertion."

Is this feature fully implemented ? All_in seems to be only an option for "fix insert".

Inspecting the code reveals that a mesh/tet region always enforces the caluclation of the corresponding surface of the region

Hello,

I would like to compute the total force acting on only some portion of a stl mesh.
I know that dump mesh/vtk output the stress components.

What I am looking for is to obtain an output like
fix ... ave/time ... f_cad[1] f_cad[2] f_cad[3] file.dat
but not on the whole cad, only in some parts of it.

Maybe should I split the cad file in different parts and import different stl files?

Thanks,
rob1

Hi,

For nano-particle simulations (particle-wall and particle-particle collision), can I use granular model? or do I need to go with something else?
(wall/gran and pair/gran)

Any suggestions?

Thank you.