LIGGGHTS® - User Forum

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

Dear friends,

The installation of Liggghts and CFDEM following the instruction on this website (git and cfdemCompLIG) was successful on my PC (Ubuntu 14/04).
However, when I tried to install it on our university's server (CENTOS 6.3), it always showed an error:
-lstdc++ -o ../lmp_fedora_fpic
ld: cannot find -lbat
make[1]: *** [../lmp_fedora_fpic] Error 1
Log file is also attached.

Could anyone please tell me how to solve it? Do I need to install the libbat.so or make a symbolic link or other ways?
Thanks!

I want to simulate the one-way coupling condition ( solid particle movement in fixed flow field (water) ),
so I tried to add 'drag'& 'buoyancy' force (using fix drag & fix buoyancy).

But I have a problem with the 'fix drag' command.
the drag force depends on the velocity of solid particle, so it should be changed with the particle velocity, but in 'LIGGGHTS manual',

fix ID group-ID drag x y z fmag delta
(example)
fix center small-molecule drag 0.0 10.0 0.0 5.0 2.0

I have installed 3.4.0 version of Liggghts, and it did not read my restart file, a segmentation fault error accured.
Then I installed older version 2.3.6. this version had no problem in reading restart file.
however I have other problem with this version: particle crosses the stl walls after some steps.
I also have tried the latest version 3.5.0. but it doesnt read restart file too.
it will be so appreciated if somebody can help me by this matter.

Talat,