LIGGGHTS® - User Forum

Hi everyone,

As we know the command fix mesh/gran/stressanalysis command can analysis the stress on a wall. My question is how to use the pressure analysed by this command to control a loop in a script file. If I output the pressure on the wall first to a dump file, can I use any command to read the pressure in the dump file and then use it in the loop? Anybody can help me?

Many thanks.

J. Wang

hi all, i have jst installed liggghts and i dont knw how to start it using terminal. is there any user guide or documentation of liggghts so that i may learn this?

hallo ,
can anyone help me with good way for creating 3d box Obstacle in 3d flow using LAMMPS

?!
since fix indent supports just plane cylinder and spheres !!?

Hi my friends,

Are there anybody can explain a very basic question for me? In the document about the fix pour/dev/packing commad, it says:

vol values = fraction Nattempt
fraction = desired volume fraction for filling insertion volume
Nattempt = max # of insertion attempts per atom

What's the meaning of max # of insertion attempts per atom? Is it the maximum number of particles inserted in the box? What will happen if the maximum number of atoms have been reached but the desired solid fraction has not got yet?

Thanks.

Wang

Hi!
Is there some upper limit from the LIGGGHTS to the one and page values? If I increase the page value too much, I get memory error, when run is executed. If this is not an LIGGGHTS related, do you know is this Linux or hardware related issue? I'm using 64-bit Linux on distributed memory cluster with 8GB RAM on each node, and the LIGGGHTS is executed parallel in a distributed way.

Hi my friends,

I want to compress a packing by a specified force or pressure. Are there any command or code available now to control the force or pressure on a wall? Do I need write some extra code on LIGGGHTS to reach my purpose?

Thanks.

Jerry

Hi LIGGGHTS users,
Please anybody tell me if granular particles of LIGGGHTS are viscoelastic in nature? I mean we can transfer sound waves in the granular media.
Thanks,
A

Hi,

Does anybody know- is there any way to set the angular velocities of atoms to a specific value?
For velocities I can use fix_move and from a quick check I did I cannot find any similar option in LIGGGHTS as the rotate keyword does something slightly different.

Will I have to extend fix_move?

Thanks,

George

Hi,

I would like to model a viscous drag force (stokes drag) for a polydispersed simulation where the particle size distribution is specified using fix_particletemplate/sphere and fix_particledistribution/discrete. Since, all the particles have similar properties, I would also like to have one atom_type in the simulations.

In case anyone finds it useful here is some information about a method I use to couple Liggghts with a separate Lattice Boltzmann code written in Fortran.

The Fortran code is the driver, so it starts first calculates the fluid flow, writes the particle information to a file and then calls an external subroutine to run Liggghts automatically from the command line for one time step. See the following link.c file:

#include
#include
int dem_(int i)
{
printf ("Checking if processor is available...");
if (system(NULL)) puts ("Ok");
else exit (1);