LIGGGHTS® - User Forum

Hi all,

Having faced the issure of re-assignment of atom IDs for the LIGGGHTS post-processing. As I want to record the position or velocity of some certain particles using
the following commands:
---------------------------------------------------
...
variable x1 equal x[512]
variable y1 equal y[512]
variable z1 equal z[512]
fix pos all print 1000 "${time} ${x1} ${y1} ${z1}" file post/pos_512.txt
....
_____________________________

here 512 is the atom ID (in Paraview as PointID) at time = 0.

Good Day,

I have two different particles, m1 (oranges) and m2 (Apples) in transportation with a conveyor belt (m3). I want to be able to identify m1 and m2 by their type (group) in the simulation. Also, m1 and m2 have different mesh/surface/planar fixes as they are getting into the domain at different positions and times as shown in the attached screenshot. Some sections of the script have:

create_box 3 reg (for m1, m2 and m3)

Hello all,

I am calculating the pair wise contact forces using the compute pair/gran/local command.

If my output of the simulation is : id1 id2 fx fy fz

then, what is the direction of the force between particles of id1 and id2? Is it towards id1's (particles one) centre or id2's (particle two) centre?

I understand fx, fy and fz are the x, y and z components of the force between the particles.

Can someone please help me with this?

Best,

Naren

Hi everyone,

I tried to run my simulations in liggghts and open it in Paraview. I tried to modify the dump file using custom/vtk and I tried to install the liggghts plugin in paraview as well but all my visualization seems to appear in squarish appearance as shown in the image i provided in this forum post.

I heard some used pizza.py and lpp for the visualization but I am unsure on how to use them. I installed pizza.py by using the steps:

Hi all

I am using ParaView to view LIGGGHTS dump files after converting to vtk format. However, the rendering is not so good, as I see only the centres particles. How can I change this, so that I can view complete particles? (I have attached an image showing what I mean)

Thanks,
Joel

Hi all

I was wondering if LIGGGHTS had the feature of a conducting wall, where I could set the wall conductivity. I could only find the option to set wall temperature, but not a conducting wall.

I don't want to measure wall properties. Instead, I just want to change boundary conditions on the particles near the wall, so that, instead of having to interact with a wall at fixed temperature, the particles are now interacting with a wall whose heat flux is given by q=-k(dT/dx)

Hi everyone,

I was trying to compute a moving laser on a heat bed. I successfully define the heating at one region which is defining the coordinate of the region of the heat bed but I am trying to make that region to move ( just like a laser moving on the heat bed) where my x coordinate moves from 0,1,2,3,4,5....or should I say its something like the function x=x+1. Do you know what command that I can use to resolve this issue?

Can someone help me with this?

Thanks.

Hi every one....!
i am trying to simulate a mixer that contain glass beads with impeller in the middle.I am a new user of LIGGGHTS, i don't know how to make geometries for this setup.I means which components to be made in CAD?? which CAD software is to be used ???currently i made a vessel and impeller in PRO E and saved in STL format.when i use this then vessel geometry does'nt import nd i get problem with this.

I am studying the granular flow on inclined plane with different angels. In my simulation, x is flow direction and z is perpendicular to the plane. On achieving the steady state, profile for velocity, volume fraction, shear rate, shear stress and pressure seems fine. But when profile for shear stress in direction perpendicular to the plane (in my case it is zz) and shear stress in xz direction are not in accordance with the profile obtained from the momentum balance equation.

As I am still trying to figure out why is this happening? Can anyone suggest to make it right?

I am a beginner and trying to figure my way around liggghts. I am using 3x materials (1x big particle, 1xsmall particle, 1xbin). As the particles are of difference sizes which command do I use to define the different particle sizes and how would this affect the neighbour lists.

thanks in advance for your help.