LIGGGHTS® - User Forum

Hi All,

I want to use cohesion model washino/capillary/viscous for the simulation.

I have four different types of particles in the simulation. And, I want to apply cohesion to only two types of particles. For the remaining two types of particles, I want to apply only gran model hertz (without cohesion).

Can someone please help me, how to implement this?

Any help will be much appreciated.

Thanks,
Narendra

Hallo everyone,

since few days we try to install the current version of Liggghts on our Linux cluster (Ubuntu 14.04). The first steps were no problem, but we always get an error during the compiling process:

hey,
is it possible to do the immediate evaluation of variables for an atom-vector? For a scalar its simply
variable v equal vol
variable v0 equal $v
But for atom vectors it is not possible to use $
variable x atom x
variable x0 atom $x
this would fail.
Is there a way to safe the initial state of an atom vector and use it in further atom vector calculations?

kind regards
Joshua

Hi all!

I was looking into literature to find out more about coarse-graining in granular simulations. I have found the paper "Three-dimensional discrete element models for the granular statics and dynamics of powders in cavity filling - C. Bierwisch Ã, T. Kraft, H. Riedel, M. Moseler (2009)" where the dimensional analysis is explained.

My question is: do I have to adjust the material properties used by the gran model hertz (Youngs modulus, Poisson ratio, coeff of restitution, coeff of friction) if I scale the particles by a certain factor?

In the newly released LIGGGHTS,serial multisphere method is included.

Hi all,

Could you please tell me how can I use hybrid mpi/openmp parallelization in LIGGGHTS ?

thanks in advance,

Reza,

Greetings,

I've been having the same error for some time when meshing with GID and then executing a LIGGGHT's program.
After displaying information about elements that have 6 neighs, instead of the expected 5 neighs, it shows this:

ERROR on proc 0: Fix mesh: Bad mesh, cannot continue. Possibly corrupt elements with too many neighbors.
If you know what you're doing, you can try to change the definition of SurfaceMeshBase in tri_mesh.h and recompile (../surface_mesh_I.h:504)

Hey guys, I have done compression testing of particles in LIGGGHTS in 3D. Now, I want to do the same test in 2D. As per the documentation, I added command "dimensions 3" but I am getting an error while using "insert/rate/region" command and if I use "create_atoms" command by using the lattice for 2D, atoms are created, but the moment my wall touches the atoms, I get a message " Proc 0 Internal error", also in create atoms i am not able to add gravity. So, what is the correct procedure to model a simulation in 2D ?? and which visualization software is best to view it ??

Hi All,

I have a question related to the union of two region

In my simulation, I am currently defining a region as a sum of two adjacent cubes.
By looking at the .vtk of my simulation in paraview, I see that there is a small "empty space" (or gap) between the regions and I don't understand if

1) that comes from the division of the region (although it supposed to look like a single piece)
region regdown block 0.0 0.5 0.0 0.5 0.0 0.25 units box
region regup block 0.0 0.5 0.0 0.5 0.25 0.5 units box
region reg union 2 regdown regup units box

Hi All,

I have a problem/question about the servo wall

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

I want to first define two sub-regions, in which I want to insert two different particle distributions (pdd1 and pdd2 in the file).
After the distribution is complete, I want to insert a "servo - wall", from the top of the simulation box to compress both packings (pdd1 and pdd2)