LIGGGHTS® - User Forum

Hello Everyone, I want to simulate a bubble column which bubbles spray out from a gas distributor into water.

Bubbles were considered as the discrete phase and their flow behaviour was simulated using DEM. The water phase was continua phase which was simulated using Euler method. The diameter of bubbles was supposed to be a constant(5mm).

I want to use Herz-Mindlin Granular contact model to complete the simulation. I just consider the bubbles the same as any other solid particles simply.

Can I use liggghts to simulate the bubbles contact?

Hello cfdem community,

I am currently trying to setup a granular simulation which drags a cylindrical intruder through a bed of granular material. ideally the granular material would be setup to act like glass. i can get the simulation to run on a large scale (5cm beads) but when i set the granular material size to 5mm and scale the bed size down appropriately the granular material will never settle in the bed it will simply bounce around forever.

my input script is as follows:

# Moving cylinder mesh example

atom_style granular
atom_modify sort binsize 0.0025

Hi,

I find that the actual mass inserted is about three times greater than the requested mass when using insert/pack with a lognormal distribution. It is about 10% greater than the requested mass when using a gaussian distribution and slightly greater when using a uniform random distribution. Using volumefraction_region instead of mass_in_region gives about the same results. I can live with a few percent error, but it looks like something is very wrong with the mass calculation for the lognormal distribution. Here is a short script that demonstrates each case.

David

Hi,
I have a problem with memory. My memory is about 16 GB but not enough for my simulation. It can not finish because It stuck an error seems like memory is full. How to figure out this problem?
P.S. When i implement code with cohesion it will use so much memory. If don't use cohesion it quite OK can run till finished

##Technical Info:##
error messages:

ERROR on proc 0: Failed to allocate 783451440 bytes for array neigh:binhead (memory.cpp:45)
--------------------------------------------------------------------------

2 questions:

1. Is there any way to change the moment of inertia for particles separate from changing the mass? I'd like to run granular simulations where the particles can't rotate as easily, but I don't want to give them an arbitrarily high mass (density). Does LIGGGHTS support this?

Dear all:

I use 'fix roch all move/mesh mesh ch rotate/variable origin 0 0 0.6 axis 0 0 1 period 6.28' in in.simulation file in order to rotate 'ch' around the z axis under certain angular velocity.

But I get a error

ERROR: Variable name 1 for fix move/mesh rotate dynamic does not exist (mesh_mover.cpp:328)

How to solve the problem?

My LIGGGHTS is 2.1.X.

Hello everyone.

I've been working on a pebble bed for which I'm trying to do some numeric experiments with stiff, brittle, ceramic pebbles. As a first-order test of the bed, I'm using the fix/evaporate command to remove pebbles from the bed and watch how the new ensemble evolves under load. I'm also monitoring pebble contact forces with the compute of pair/gran/local. I've run into a bit of a snag.

Hi Guys!

I´m trying to configure a simple test case. I took movingMeshGran as a start point for my angle of repose test, but I find that the inserted particles pass through the solid "bucket.stl". Post-proccesing the result I find that the bucket "became" a solid at 150 paraview timestep.

http://imageshack.us/a/img10/5841/screenshot3zl.png

Hello,
I had installed liggghtsdev 2.0.5 version which was updated automatically to the new 2.2. version. Opening the manual(http) from the doc folder I encounter the problem that the liggghts commands resemble the 1.5.3 commands. E.g., the new arguments of the mesh/gran/stressanalysis I saw for 2.0.5 before, are replaced by the arguments as for the 1.5.3 version (the same for pair_style gran/hertz/history). Is there any other possibility to access the manual or commands?
Thanks!

Hi guys,

I am setting up a test case with a sand particle colliding into a sand bed. When I do small particles, I got the error saying that volume expectancy was too small. I want to have a mix of 100 micrometer and 10 micrometer particles. It seems there is a limit set in the particle template code.
What is the minimum diameter for particles that LIGGGHTS can handle? If I want to do smaller particles, can I scale gravity and other coefficients to overcome the limit?
There was a similar topic before:

node/493