LIGGGHTS® - User Forum

Hello everyone,
I have been using Liggghts for a couple weeks and I have already done a simple shear test but now I want to do a triaxial test. I read about the servo control walls but since the test is a cylindrical moving boundary I dont think that is a proper boundary because of two reasons:
1. The walls are rigid boundary and in reality they are flexible.
2. I can not think of moving the cilindrical walls with out changing the shape or leaving a gap.

Hi everyone,
I tried to give the wall an angle velocity with "fix move/mesh" command. It gives as "fix c1 all move/mesh mesh cad1 rotate/variable origin 0 0 0 axis 1 1 1 omega 0.5". However, the result shows "ERROR: Variable name 1 for fix move/mesh rotate dynamic does not exist (mesh_mover.cpp:329)". Does anyone know how to modify it? My LIGGGHTS version is 2.2. Thanks.

Hello everyone,

Could anyone be kind to tell me how to define a group based on particle diameter? Say, "group sub diameter <= A".

In the newest version of LAMMPS, this could be done by using 'variable' keyword with group command, as described in http://lammps.sandia.gov/doc/group.html

However, in the current version of LIGGGHTS (2.3.6), the 'variable' keyword cannot be used with group command.

Thank you in advance!

Lei

Hi all, I am trying to create a wall in Liggghts in gran style to track the particle-wall interaction force. Well I want my wall be tilted for 45 degrees, so not perfectly xplane or yplane or zplane.... and also can move horizontally forward with constant velocity. basically it looks like this. \ ------> A tiled wall moving in horizontal direction. I don't see how to set it through fix wall/gran command. Is it possible in Liggghts? I am not expecting it to be very difficult....

Thanks for any reply.

xiuhan

HI Hello friends, I am new to this and would like to know how to install LIGGGTHS in ubuntu 12.04 ?

Thanks!! :D

Hi,

Edit: Deleted. Just needed some sleep... ;-)

Regards,
Paul

Is there a simple way to change the speed of a conveyor (surface velocity).

The only thing I can think of is to start with one fix mesh/surface with a certain surface velocity. stop the simulation and write a restart file.
Restart the sim with a new surface velocity...

I'm sure there is a better way though.

Thank you for your help,

Kirk

Hi,

I have been running my simulations with 2 cpu's and I use

write_restart restart-%-*.rstrt

to create a restart at the end of the simulation.

I was wondering if I can restart with a different number of cpus. I would like to use 6 now. my read_restart looks like

read_restart restart-%-*.rstrt

Whould I have more luck if I used

write_restart restart-*.rstrt

and

read_restart restart-*.rstrt

instead?

Thank you,

Kirk

Hi,

Hi Chris,

My question is pretty much same as the title. To explain in more detail (please also take a look at this post: http://cfdem.dcs-computing.com/?q=node/1745 ), the following command is used to insert particle steam:

fix ins nve_group insert/stream seed 5330 distributiontemplate pdd1 &
nparticles 20000 particlerate 8000 overlapcheck yes vel constant 0.0 5.0 0.0 &
insertion_face inface extrude_length 0.02