LIGGGHTS® - User Forum

Hello all,

I cannot get the servo wall to move in the -Z direction, even if I use a negative target_val. This is how I issue the command:

variable lid_force equal -1400
fix lid0 all mesh/surface/stress/servo file LIGGGHTS_files/STL_files/in/p_lid.stl type 2 move 0 0 ${lid_height} com 0. 0. ${lid_height} ctrlPV force dim z target_val ${lid_force} vel_max 0.01

When I print the z coordinates of the wall, f_lid0[9], they are strictly increasing over time no matter what values I input for target_val.

Hello all,

I am a beginner in LIGGGHTS, I am trying to implement something similar to or the same as in the http://www.youtube.com/watch?v=muZuukjb_6k video. Did anyone work on similar use case using LIGGGHTS? I am now actually not sure if this can be implemented with LIGGGHTS. Any ideas/suggestions?

Thanks,
Pradeep

Hi everybody,

In the new version of liggghts I can not create a cylindrical wall with fix wall/gran/hertz/history. I am using this code to specify the cylwall:

fix cylwalls all wall/gran/hertz/history primitive type 1 zcylinder 0.1 0. 0.7

Is there any error in this line?

Regards,

David

Hi, all!
Today, I just saved a point data of my project from "Paraview". And i found that in my "output.csv" had something strange.
Normally, In my understanding one ID(of particle) can be assigned to only one particle so that means when you save point data from Paraview inside your output.csv file for each line shouldn't have the same ID i mean no any ID is duplicated in output.csv file (if it's duplicated that mean that the particle can be located on multiple places at one time and that's impossible)
What are you thinking about this?

I am attempting to run drum mixing simulation of packed granular bed. The trial outputs in two cases of simple cubic and HCP packing are attached with the link below:

Consider a situation in which particles have been packed between two plates and say one of the plate is being moved. The boundary conditions are periodic in the direction of movement of the plate (the plate, an imported stl, is being moved in x direction using a linear style in fix move/mesh and the boundary conditions are periodic in this dimension, but it takes the plate out of the simulation box). Is there any command in liggghts which can help. If not is there any other way to implement it in liggghts ? Please suggest, I am a new user.

I called command insert/pack to insert particles with a constant horizontal velocity(Vx). when particles hit a wall,　the wall started to move and region created by create_box become larger and larger. particles moved out of original region area. I could not understand why reason it cause region box became larger and larger.
Does it means that results of calculation is wrong and some parameters like horizontal velocity, radius of particle etc. should be changed.

Thanks in advance.

Simon

Hi richti83,

I want to calculate the total number of atoms used in simulation. How can I find the function of this purpose ? thanks a lot.
yyu

Does anybody know if I can add hydrogen ion or hydroxide ion in solution to simulate the pH effect on the surface charge of the mineral surface? Thanks

I am trying to analyze the effect of packing style on the granular motion. A particular region needs to be filled by packed bed of specific style (bcc, fcc, hcp).

Is there any way or inbuilt command in LIGGGHTS to handle this task? On the other way, I think it is possible to replace the particle coordinates in dump file with the coordinates (that suits the specific style of packing)
generated by third-party package. But still, if there is a simple way to do the same?