LIGGGHTS® - User Forum

Hi there,

Hi all,

I am trying to get the coordination number of every atom during a simulation and I set out coord/atom command as

#Output settings, include total thermal energy
fix ts all check/timestep/gran 1000 0.15 0.15
compute rke all erotate/sphere
compute nconts all coord/atom 0.015 mix yes
thermo_style custom step atoms ke c_rke c_nconts f_ts[1] f_ts[2] vol
thermo 1000
thermo_modify lost ignore norm no
compute_modify thermo_temp dynamic yes

I am doing a simulation of sandpile formation. I am wodering how can I get the instant number of particles in the sandpile since I use "lost ignore" to delete the paticles that gose to far from the pile.

Actually, I want to use this number in a judgement condition of a loop to control the max number I should pour on the sandpile.

Hi everyone,

I am trying to learn more about the LIGGGHTS. In this scenarios, I tried to set a moving region with constant temperature, so I wrote

variable dy equal "0.08*(step-20000)/30000"
region pos_source block -0.05 0.05 -0.05 -0.03 0.0 0.05 move NULL v_dy NULL
fix test all print 1000 "${dy}"
set region pos_source property/atom Temp 500

But the result shows the set command only affect once and give the same result as

Hi all,

I'm new to LIGGGHTS. I want make a particle spin in the simulation.
At first, the atom_style in my simulation is granular. Under these circumstances, I set the angular velocity via "velocity......setAngular......" , and the terminal give a feedback:

"set Angular requires the atom property 'angmom' as defined by atom_style ellipsoid. (../velocity.cpp:426)"

Then I use atom_style "ellipsoid", but the terminal give a feedback this time:

"Fix wall/gran (id boxwalls_x1): requires atom attributes radius, omega, torque (../fix_wall_gran.cpp:107)"

I was surprised to find that radius expansion can also work on multisphere clumps, but I noticed that the kinematic parameters (mass, mass center, moments of inertia) of a multisphere clump were determined and output on the moment when the clump was inserted. So I wonder whether the kinematic parameters of a clump will change dynamatically during the radius expansion process or just remain unchanged. Any hint is appreciated.

Hi all, I am currently trying to run a LIGGGHTS script of granular particles sliding down a chute. I have tested the code with a monodisperse size distribution and now want to match the size distribution given for a specific sand that I'm using in my experiments. My understanding is that I should be able to use the following code to produce a distribution with 3 different particle sizes:

I am newer to LIGGGHTS so I am still learning my way around assigning properties to particles. In my simulations the particles are spheres, and they are in a packed bed. Over time the particle's properties need to change based upon their position, in particular radius, Youngs Modulus and Poissons ratio. I am using the granular hertzian pair style without history.

All the particles are inserted in the first step, but I want to make these particles flow from the inlets step by step. I don't know what the problem is , here is my input commands, pls help me , thx~

Inputs:
"
....
neighbor 0.004 bin
neigh_modify delay 0 one 20000 page 500000
....ere the input

Hi,

I am wondering if there is a way to extract each individual contact force acting on a sphere clump (a multisphere)? I know there is a method called pair/gran/local that is able to get per-sphere contact forces. However this command does not offer an option indicating the id_multisphere that each specific sphere belongs to and computing stress through contact force and branch vector can be very difficult since we need identify the center of mass coordinates of two multisphere bodies that are in contact. Any suggestion is greatly appreciated!

Best,
Liuchi