LIGGGHTS® - User Forum

Dear particle friends

Based on a LIGGGHTS-Tutorial I have set up a planar sandglass. As first step I will fill in some particles and let them settle. A simple case I guess. But the gravity is totally inactive. I checked the input script several times tried some changes, checked the help, the forum an so on. It's no use.

Is there anybody who can quick check my script and check if it runs properly?

Thanks a lot for help.
Cilo

Does LIGGGHTS have a compute style to calculate the total unbalanced force in the system? Or better yet, a ratio of the total unbalanced force to the sum of all the contact forces? I use such a ratio in other programs to determine whether my simulation has reached a stable state, and I'd like to move onto using LIGGGHTS now.

Hi there,

I'm a master's student beginning to work with multispheres in LIGGGHTS.

I want to know what is the best way to do the Step 2 of this example: http://www.cfdem.com/multi-sphere-method-resolved-non-spherical-particles

Hi everyone,

hello,

i compiled the bondpackage model by Potyondy and Cundall and i could make the fracture simulation of a bonded particle model and also a simulation of a no bond breakage by specifying a very high bond-break radius.
But i haven't been able to simulate both behaviors at the same time for two bodies separately because i cant use a hybrid bond style with gran.

Can someone helpme with this?. i have little knowledge about c++ so its hard for me to hack de source code.

Any suggestion or question will be greatly appreciated.

Have a nice day,

Hallo everyone,

I am interested in charged particles and their interaction with an external field. (comparable with the video "Electrostatic" on this website). Can I use the efield command in Liggghts? And how can I define a charged particle (attribute q)?

Thanks for your help. Best wishes

Johannes

I understand that using command
fix xwalls1 all wall/gran model hertz tangential history primitive type 2 xplane 0.0
can create a infinite X-plane wall at x=0.

Could anyone tell me how to create a finite plane wall? For example, a wall from (0, 0) to (0, 2) in 2D or in 3D formed by 4 points.
Or it can only be done by importing mesh file?

Thanks!

Jason

hello,

I'm trying to insert particles in any region that you want, something like a custom region.

I was wondering if there is a software that can make a geometric figure and then export the file in VTK format for later use it as a mesh / tet in the region command.
Something similar when you make a figure using SolidWorks and then export the file in a stl format for use it as a mesh/surface.

Any suggestion or question will be greatly appreciated and I'm sure it will be considered.

Have a nice day,

zealakis.

Hi,

I try to count all collision events as a function of time in a granular system using contact/atom. This works fine. I get all contact events for each single particle and timestep, but in most cases the collision time is longer than one timestep. As a consequence of this multiple counts for one collision event are recorded. If I use larger timesteps I might miss some collision events.

Is there already any solution for this problem or has anyboy an idea how to fix it? I'm not a c++ expert, therefore it is difficult for me to change the source code.

Hello,

I would like to change how the CPUs are distributed along my simulation box. In particular I am interested in finding a way to change the type of seeding by which each CPU is allocated to a region of the simulation domain.

E.g. By using the command

processors 4 4 1

I will get 4 CPUs along x, 4 CPUs along y and 1 CPU along z. Each CPU will be allocated to a region of space given by:
domain length along x / CPUs along x
domain length along y / CPUs along y
domain length along z / CPUs along z