LIGGGHTS® - Developer Forum

Dear liggghts-developers,

the newly released 2.3.7 version of LIGGGHTS has the following changelog-entry:

> + Fixed a sign bug in fix mesh/surface/stress/servo.

as I understand, the fix is in src/fix_mesh_surface_stress_servo.cpp :

For doing a project I face some unknowns.

The one is that I want to simulate crack propagation in shale (a type of
sand) and investigate crack pattern in shale if I decrease the temperature by LIGGGHTS. I need to know how I can decrease it (temperature of the simulation box)?

Second is that do you know the material properties of shale?

Thanks a lot for your attention in advance.

Sincerely,
Rasoul

Hi,
I had a question about the exchange function in Comm class Comm::exchange(). The comment in the code says that atoms are exchanged with 6 stencil neighbors. However in 3d would not there be 26 neighbors of any given (internal) grid cell? It is certainly possible that particles could move to the "diagonal" processors. Can someone please explain why the exchange occurs with only 6 neighbors.

Thanks,
Rahul

Hi everyone,
According to the dump code, it could output the stl style of wall with the normal direction. However, I want to call it in the source code. Does anyone know how to modify the code? I found the "dump_mesh_stl.cpp" source code has the definition of the "surfaceNorm". Is it to call this code to obtain it?
Thanks.

Dear Christoph, dear Andreas,
Could you please provide some reference(s) that use(s) or derive(s) the equations of the cohesion models used in LIGGGHTS (skrj and skrj2 equations; see below)?
Thanks so much!
Best
Eric
---------------------
A simple linear cohesion model can be activated by setting cohesion = 'sjkr' or 'sjkr2' (simplified Johnson-Kendall-Roberts model). If two particle are in contact, it adds an additional normal force tending to maintain the contact, which writes

F = k A,

Hi all,

I modified the pair_gran_hook/hertz history style to take into account the Van der Waals adhesion force following JKR model. The model is described in this paper http://www.sciencedirect.com/science/article/pii/S002199910800572X where
Fn = F_adhesionJKR + F_damp

The simulation is able to run, but I got unreasonable results. I find it was caused by the formulation of "ccel" in LIGGGHTS that I used. Currently, I use the expression:

ccel = - F_adhesionJKR - F_damp

Dear Users and Developers,

I am trying to get LIGGGHTS and CFDEM running for two days now and read almost all threads related to compiling and installing in this forum.

So far, I was able to compile LIGGGHTS 2.3.6 on my ubuntu 12.04 (precise) machine and obtained the executable similar to the steps described in the forum by PaulWinkler.

I can start LIGGGHTS and I tested some tutorials, like the cohesion-noCohesion example, and it worked fine.

Hi All,

I am trying to add the water evaporation function of particles during the heating process. I am now working out CFDEM coupling. And I would like to add water evaporation into LIGGGHTS. I have already done the literature review on theory of water evaporation, but I am not sure how to add in program of LIGGGHTS. Anyone could provide a general outline of code writting and compiling? I am highly appreciating any comments!

Thanks!

Kun

Hi all,

I am trying to add a modified bond model to the LIGGGHTS source code.

I have added 3 files which are similar to bond create, bond break and bond_quartic. I also added some more parameters to the atom class and modified the file atom_vec_sphere.cpp to include the new parameters in the atom class.

I keep getting this error when I run in parallel.

I noticed that a large (hours-long) simulation ran much slower when I put a primitive wall/gran/hertz/history on the left side of the box (at xlo), than in an identical simulation but where the primitive wall is on the right side (at xhi). After a little bit of head scratching, I found this at line 124 of primitive_wall_definitions.h:

static bool resolveNeighlist(double *pos, double r, double treshold, double *param)
{
double dMax = r + treshold;
double dist = pos[d::x] - *param;