LIGGGHTS® - User Forum

Hello Friends, I have found from the documentation that the following property definitions should be used in order to use hooke/stiffness model.

fix m1 all property/global kn peratomtypepair 1 1e03
fix m2 all property/global kt peratomtypepair 1 0.0
fix m3 all property/global gamman peratomtypepair 1 0.0
fix m4 all property/global gammat peratomtypepair 1 0.0
fix m5 all property/global coefficientFriction peratomtypepair 1 0.0
fix m6 all property/global coefficientRestitution peratomtypepair 1 1.0

So I'm trying to simulate a vibratory feeder using the "wiggle command" to move particles up a 3 degree incline. I used a cylindrical path to drop the particles into and its supposed to shake and move the particles upward the 3 degree incline. For some reason I was not able to model an inclined ramp so I modeled it flat and modified the gravity vector to simulate an incline. The particles climb up the ramp at a 5 to 6 degree incline but not at a 3 degree incline. Can someone look at my code and see if possible my gravity vector is incorrect or some other settings needs to be adjusted?

Hi!

Hello Friends, Greetings. We all know that particle simulations are high dissipation systems. Lets say we have a cuboid container defined by 6 primitive planes oriented along X-Y-Z axes, filled with spherical particles to a certain height, gravity acting along Z. When this system is fluidized (that is, particles are set into motion),

1. How can we calculate energy that is being lost due to (a) collisions, (b) friction?

I'm tracking instantaneous net energy of the system using compute totRotKE all erotate/sphere and compute totLnrKE all ke.

Hello Friends, Greetings.

Lets say we have a cuboid container defined by 6 primitive planes oriented along X-Y-Z axes, filled with spherical particles to a certain height, gravity acting along Z. When this system is at rest,

1. How can we calculate net downward force acting on bottom wall (as a single value)? This must be equal to weight of all particles combined.
2. Is it possible to get force field on this bottom wall? This must be uniform, vectors pointing downwards (assuming flat or constant hFill) and sum of all field must be equal to weight of all particles.

hi i need to charge particles the set command charges atom or molecules i need granules charged to insert them in an electric field to change the particles directions if anyone could help me it would be great i could not find a solution i wanna perform the same thing as in the electrostatic example in the site https://www.cfdem.com/electrostatics thanks in advance hope someone helps me i am stuck for weeks on this thank you in advance

I'm trying to run a simulation like that in Podlozhnyuk et al. (2017) Fig. 7, where superquadric particles are piled up in a container. However, in a small test with 138 I find that the particles fall towards the bottom surface then start to 'dance around' and they never come to rest (see attached animation). I've tried altering the simulation parameters, including adding coefficient of rolling friction, but the problem still occurs. Could anyone suggest what might be incorrect or missing in the script (below).

Many thanks !

Liggghts version 3.8.0

Hi,all

I need to define two “pair_style” using “pair_style hybrid”,however,I faced an error.

ERROR:Incorrect args for pair coefficients

Here is the part of my input script.

pair_style hybrid gran model Hooke tangential history gran cohesion easy/capillary/viscous
pair_coeff * *

Thank you.

Hi,

i have the common task to track the mixing status in my apparatus. For this i need to find the number of particles Type 1 and Type 2 in specific regions. Lets say i want to have cylinders and count the number of particles in them every 10000th time step and print the result to a file, How can i do that? Is there a way to do that in the input file?

Thanks and kind regards

hello everyone hope ur all well i am stuck on a problm i am trying to make a script to push or attract particles using an electrostatic field but i have a problme the same error keeps popping and i could not resolve the problm i know it is not a big problm for some of you but it is for me and i would apreciate any tips on how to improuve my script to reach my goal it is far from finnished thank you all

ERROR: Numeric index is out of bounds (../force.cpp:786)

#falling particles in electric field