LIGGGHTS® - Developer Forum

Hi,
I have got a question about the fix rigid.
When two clumps made of spherical particles (hybrid molecular granular) collide with each other, is the deformation on the particles that are participating at the collision calculated using the masses "m1 and m2" of each colliding sphere or the total masses "M1 and M2" of each clump?

I changed fix_move.cpp to have a two new commands: linearspin and spin. spin fixes omega without velocity, and has the same syntax as linear. Linearspin fixes both velocity and rotation, and has 6 parameters (vx vy vz wx wy wz).

NOTE: spin hasn't been tested (although it was a simple change and probably works).

I found these useful in real-life situations.

This is just a request for some of the new LIGGGHTS functions to use the "standard" LAMMPS logging prefixes (e.g. INFO, WARNING, ERROR) or else define a standard string. At the moment output like

Particle insertion: inserted 22276 particle templates (mass 0.068355) at step 1

is hard to trap for when reading in the thermo log file for plotting/processing (with the pizza.py log command, or otherwise).

Thanks!! Mark

Hi

Small recommendation for developers for next version:
File fix_gravity.cpp contains following code:

if (style == VECTOR) {
if (domain->dimension == 3) {
double length = sqrt(xdir*xdir + ydir*ydir + zdir*zdir);
xgrav = xdir/length;
ygrav = ydir/length;
zgrav = zdir/length;
} else {
double length = sqrt(xdir*xdir + ydir*ydir);
xgrav = xdir/length;
ygrav = ydir/length;
zgrav = 0.0;
}

If you give command such as:
fix gravi all gravity 9.81 vector 0.0 0.0 -1.0 # for 2d
or

Hi

I want to know what kind of syntax (macro) you use to write down names of header file in style_*.h. For example when I compile the LIGGGHTS,
#include "run.h"
is written in the file, style_command.h to execute run.command(). I wonder how it is made.

Thanks.

Masa

Hi to all,

the content of these questions is the file mesh_mover.cpp.
Is the time dt the scale of the timstep choosen by user at the inputscript?
Is the time dT the total time the simulation is using at any specific point in simulation (dt*number of simulation step)?

Many thanks in advance.

Cheers, Niels

Hi,

I want to build particles of complex shapes through using the multisphere approach with LIGGGHTS. I use:

atom_style hybrid granular molecular
(...)
neigh_modify delay 0 exclude molecule all
(...)
fix freezing all rigid molecule.

So far I did simulations where the beads composing a particle of complex shape have the same size. Everything works nice! Now the beads composing the complex particle can have different sizes and here I face a problem.

Hi all:

I wonder if in liggghts is implemented the formualtion of the family if Newmark beta integrators.

Regards

Rafael

Hello,

I'm looking around in pair_gran_hertz_history.cpp and I don't see a cohesion energy calculation like I see in pair_gran_hook_history.cpp. Where is cohesion calculated when using pair_style /gran/hertz/history???

Any help would be greatly appreciated.

Thanks!

Hi everybody,

I'm calculating per-atom-values in a fix within the LIGGGHTS-code. Now I'm wondering how is the easiest way for outputting them. Right now they are stored in an array like that:
peratom_prop = (double*)memory->create_1d_double_array(0, nlocal, "peratom_prop");

1.: Outputting the per-atom-vector by the fix, which then could be stored in a variable of the inputskript and which then also could be used within the dump custom command?

2.: directly access this per-atom-vector by the dump-custom-command.

Unfortunately I don't have a clue for both ways how to proceed...