LIGGGHTS® - User Forum

Hello everybody,

each simulation run it appears the following warning after the "Setting up run...".

WARNING: Energy calculated for multisphere particles is currently not correct (../fix_multisphere.cpp:1014)

Does everyone knows how to solve the problem ?
A typical multisphere command in my code looks like this :

fix ms1 all particletemplate/multisphere 1 atom_type 1 density constant 1566 nspheres 552 ntry 1000000 spheres file data/mstemplate scale 0.001 type 1

Thank you!

Command ”compute pair/gran/local" calculates a local array, of witch the row number equals the number of pairs. So how to get the exact rows on a specified step?
thankyou

Hi all,
After insertion of particles, I want compact the particles with a controlled stress, so I use the mesh/surface/stress/servo command. I followed the instruction of manual and tutorial, but when I using the following commands:

fix sslab all mesh/surface/stress/servo file meshes/slab3_mesh.stl type 3 stress on com 1.75 0. 0.006 &
ctrlPV force axis 0. 0. 1. target_val -10. vel_max 1. ratio 0.01 mode auto
fix tempslab all wall/gran model hertz tangential history mesh n_meshes 1 meshes sslab

I am wondering whether it is possible (or someone has already implemented) to model electrical current running through packed arrangement of particles?

Effective conductivity should depend on the contact area between particles.
So that effectively particles centers are connected with pieces of wire of various diameter (various resistance depending on contact area).

In my understanding it should be analogous to heat transfer, so technically possible using LIGGGHTS.

Am I right or is it more complex than I think?

Hello everybody,

assume we have a liggghts simulation with only 1000-2000 particles (single spheres) and a timestep size in the order of X^(-6) seconds. We have to simulate a fixed time period of 8 seconds.

I read in this forum that parallelization will speed up simulations when there are approx. 10,000 particles per CPU. However, I do not think it will speed up the above simulation, where the timestep size is the limiting factor, will it?

Hello,
The following webpage is not found.
http://www.cfdem.com/media/DEM/docu/fix_property_global.hmtl

Page not found
The requested page "/media/DEM/docu/fix_property_global.hmtl" could not be found.

Could you please update it. I would like to know the properties defined.

can the multisphere clump generated at a specified location?

Hi,

Since command 'group' is invalid for multisphere clump, how can I select a single component sphere of a clump and exert force on it? Is there anyone else encountered this problem?

Dear all,

I am trying to simulate the breakage of a granulate, which is formed by small particles, by pressing it using a servo-wall.
I observated the forces on the wall, it worked very well. I wrote also the restart files every xxx time steps.
However, if I load the restart file (and the current stl of geometry, because the wall moved) and want to simulate it further, the forces on the wall are totally gone, after many steps they can not reach the value I had earlier.

Is it because the accuracy of the written restart and stl files?