LIGGGHTS® - User Forum

I need to know an example about id group and how can i include a armonic movement in sph example?

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