LIGGGHTS® - User Forum

I want to servo the wall with a target confining pressure in LIGGGHTS. But, there are only "target force" that can be choosn in LIGGGHTS. So, we need to obtain the area of the wall and update the area timely. It confuses me a lot.

In addition, can we define functions, use "if" statement and "for" statement like python and other high level programming languages?

I look forward to your answers very much, if you have the relevant code, I would not be very grateful.

Thank you!

Wang Xiukai

Hi all,

i am running simulations on a redhat cluster and found that the number of particles that are added during a run is depending on the number of CPU's i use for that.
So for example if i use 8 Cores i get the number 44K particles that are added but if use 16 cores with the exact sam in-file i only get 32K particles also i get an error about the timestep being suddenly too large which i haven't encountered running on my local machine with 8 cores.

Is this a known problem? How can this be fixed?
Thanks for your suggestions!

Im trying to insert particles in a stream from a ternary number based distribution and the resultant distribution does not resemble the desired one.

Hello LIGGGHTS forum,
I was trying to simulate a spherical particle motion in a flat rotating platform with an initial push given to the ball such that there is no slipping between ball and the rotating platform. Now according the several studies the balls angular velocity should be 2/7 of the rotating platform angular velocity with maintaining a stable circular orbit.
The simulation results were successfully maintaining a stable circular orbit but the ball angular velocity is quite higher than the reported value.

Hello LIGGGHTS forum, I am trying to run a simulation in an inclined surface. Till now my script is working nicely.
I want to add viscous and damp command in my script.

When ever I added it as ` fix 1 viscous 0.1 ` or `fix 1 damp viscous 0.5 scale 3 2.5` I got following message.
```
ERROR: Could not find fix group ID

```

I also tried to add as `fix m6 viscous...` got the same error.

How do I add them correctly?

Any help would be appreciated.

Thanks a lot.

My script

```

# Initialize

Hello everyone!

Hi all,

i want to install Liggghts on a redhat server and there are issues with the VTK part. The AUTOINSTALL_VTK flag is not working. I get the error: "Could not determine suitable appendix of VTK library with VTK = ... etc." when doing "make auto".

So i tried to manually install VTK. Configuration and Generation went without errors, altough i switched OFF everything besides mpi usage of VTK. After that i built VTK without error. But i do not find a folder usr/local/include. So i can not set the path in the Liggghts make file.

Hi all,

i want to model particle agglomerates that are hold together by Van der Waals force. For 1 agglomerate i read in the particle positions that form 1 agglomerate. What can i do to insert multiple particles of the same sort and size? Defining every particle position by hand is very tedious. I have 200K agglomerates in total. Multipsheres work nicely but they break ALL at once and i don't want this beaviour if i model the cohesion by Van der Waals force.

THANKS for any hints!

Hi all,

First thanks for the great resource, I have been working on this for hours before I decided to post here.

I have followed the steps of this post: https://www.cfdem.com/forums/installation-error

and think I have VTK installed and have gotten past several issues. Now when I select make auto it runs for a while which is encouraging, but gets stuck on the same errors from this post:

Hi, my name is Joaquin Gonzalez, currently im doing a job in LIGGGHTS.
Its about a test of wear in a mining dump truck, when im in the multisphere case, i recieve the follow error: Energy calculated for multisphere particles is currently not correct.
i will be so thankful if someone can helpme whit this.
I attach the input script and a picture of the screen with the error
Thank you