LIGGGHTS® - User Forum

I've been looking for some documentation on the "characteristic" velocity used in the Hooke contact model. I have a simulation that is essentially a hopper filling/draining problem, but I also have the particles fall on and impact different surfaces once they leave the hopper. Thus, I have 2 different characteristic velocities in my simulation:

1. The very low velocities present in the hopper
2. The relatively higher velocities the particles have when they strike the surfaces outside the hopper.

Hi All,

I am doing some hopper flow discharge simulation of granular material. The hopper is fitted with a "stopper" at the discharging outlet. I want to periodically open the stopper (translation motion) from closed position to fully open within say 10 seconds of simulation time.

Which command do I use to allow the "stopper" fix to open periodically.

I look forward to your help.

Regards,

Theo_Score

Hallo,

in order to use the fix bond/create and fix bond/break command for my bond model i need the MC package, which is not available in LIGGGHTS-PUBLIC version 3.5 . Therefore, i have copied the MC file from LAMMPS (17 Nov 2015) stable version in my LIGGGHTS-PUBLIC src directory and tried to compile it using the command make g++. When i tried to compile it it gave the following error:

Hello,

I have coded an algorithm to generate multi-spheres to describe the shapes I need.

The problem I have now is that, since the spheres generating the multi-spheres are in the order of microns (10-60 microns) and use units SI, when I try to run the LIGGGHTS script I get the following error:

ERROR: Fix particletemplate/multisphere (id pts1): Volume expectancy too small. Change 'volume_limit' if you are sure you know what you're doing (../fix_template_sphere.cpp:447)

Hi,

Why Fix wall/gran and pair/gran allow only one compute of type wall/gran/local and pair/gran/local ???
I want to have normal contact force, tangential velocity and contact length (history) of a contact, simultaneously.

Hossein

Hallo LIGGGHTS expert,

i am using LIGGGHTS-PUBLIC version 3.5. I was wondering if i can install any packages which provides the tool to use the atom_style bond/gran style. If yes then can anyone tell me the procedure for that.

This will be great help for me.

Thanking You
Braj

Hi, I am installimg the public software for the first time in my computer and at first un error with mpi appeared but I was able to solve to then face an error with something about VTK, or so I think. the error message is the following:

I am having trouble extracting data using "compute multisphere". I added the line "compute multi all multisphere property xcm" to the in.multisphere example file just below the already-existing compute command. I then run in.multisphere through the python interface by typing:

from lammps import lammps
lmp=lammps()
lmp.file('in.multisphere')

The file ran fine on 1 processor and all output seemed normal. Then I attempted to extract the value from the compute by typing: xcm = lmp.extract_compute('multi',1,0).

So in a script I read in the restart file, then I defined a compute wall/gran/local. But there is error said compute wall/gran/local should be defined before the first run, which means it should be defined before the read_restart. Okay, I moved compute wall/gran/local to before the read_restart. But there is error again, said fix wall/gran is not defined yet. Okay, so I move fix wall/gran part to before the compute wall/gran/local, which is also before the read_restart. But there is error again, said the wall cannot be defined before the domain box is defined.

I would like to study the particle dynamics of confined flow at a depth where the stress field is fully developed, i.e. the pressure is constant and independent of the vertical position. In order to limit the total number of particles in the simulation, I was wondering if it is possible in LIGGGHTS to define a region in which a higher gravity value can be assigned?
Also, if you can think of another way to achieve this I would be happy to hear your thought.