LIGGGHTS® - User Forum

In Liggghts, can we set an initial quaternion and update it for a multisphere particle, or hybrid sphere molecule clump?
Same as asphere, can we also output the cumulative quaternion (compare to quaternion at time = 0) of each clump/multisphere?
Such that we can not only track the positions (center of mass) but also the degree of rotation of all clumps.

Greetings,
David

Hi Friends,

Good morning,

I am using a hybrid granular bond/gran model and reading the structure with read_data.
How to solve the error "Incorrect atom format in data file"? The file structure I have is below.

Thank you,
rob1

---
LAMMPS data file via write_data, version Version LIGGGHTS-PUBLIC 3.7.0, compiled 2017-08-14-17:13:57 by XXX, git commit unknown, timestep = 750001

30000 atoms
2 atom types
1549 bonds
1 bond types

Hi everyone,

I want to use the Set command with multi-sphere simulation but it gives following error.
set region factory property/atom VMoistureMass 7.065e-6

ERROR: Set command may not be used together with fix multisphere (../set.cpp:112)

please help me how to add moisture in case of multisphere instead of using set command.

thanks in advance

This is a notice for people trying to get LIGGGHTS working on current mac os systems.

The Xcode8 command line tools GCC compiler will not successfully compile the LIGGGHTS source code with the couple most current versions of MPI. It's possible that using older revisions of MPI will work, I haven't attempted that. What will work is installing a more recent version of GCC. I stepped through this guide to making GCC on mac OS:

https://solarianprogrammer.com/2017/05/21/compiling-gcc-macos/

Hi All,

I want to have time variation of particle through its history. Let's say there are 1000 particle and I have to concentrate on single particle that means variation of its properties vs time. I tried to search in LIGGGHTS commands but do not find. I am using paraview for post processing.

With regards,
Govind Sharma

Hey,

I was wondering how i can use the last dump file of a simulation as an initial state for another simulation. Which commands do i need for the import and the rerun of them?

Thanks

Hi!

I need to calculate the numbers of contacts between particles and walls, something similar to compute contact/atom, so i tried to determine the overlap on the mesh. My question is what´s the difference between compute wall/gran delta (overlap of the contact) and fix wall/gran contact_area overlap?.

For compute wall/gran delta, i got just one column of data, but for fix wall/gran contact_area overlap, i have 8 columns of diferents information depending on how many f_Id[x] i define.

Where can i check which information f_id[x] is showing?

Hi All,

In my work I have to do stress analysis for particles in domain(there is no stl file). With stress/atom and compute reduce I have some doubts, however I have gone through previous discussions on stress analysis. stress/atom generates a vector and we can access its elements like c_stress[1] to c_stress[6]. Now as explained in user document :

I want to insert particle in lattice. But I have found that I can create atoms in lattice via create_atoms command but I have not found any tutorial how to insert particle in lattice. Is atoms and particles behave same in liggghts? Any help is highly appreciated. Thanks