LIGGGHTS® - Developer Forum

Hi,
I want to add a new contact model but I don't understand the file structure for liggghts. What I want to do is to add a full JKR model.
I was thinking then to make a copy of "normal_model_hertz.h", rename it to normal_model_jkr and work in this one.
What do I need to change to be able to use this model with a input file as "pair_style gran model jkr"?

I guess I should change the start of the file:
#ifdef NORMAL_MODEL
NORMAL_MODEL(HERTZ,hertz,3)
#else
#ifndef NORMAL_MODEL_HERTZ_H_
#define NORMAL_MODEL_HERTZ_H_

A new efficient numerical model of particle scale radiation is developed.
The paper is "Wu, H., Gui, N., Yang, X., Tu, J., & Jiang, S. (2018). Particle-scale investigation of thermal radiation in nuclear packed pebble beds. Journal of Heat Transfer, 140(9), 092002."

And the link is http://heattransfer.asmedigitalcollection.asme.org/article.aspx?articlei...

modifying LIGGGHTS with bonds to work with 3.8.0 by changing the seed argument to type char

in fix_bond_create_gran.h:

69: delete "seed" from int declarations
add "const char *seed"
add "bool proc_shift = 1;"

in fix_bond_create_gran.cpp:

90:delete line
112: get rid of atoi so seed is still the string
129:change to "random = new RanMars(lmp,seed,proc_shift,1);"

It should now compile just fine and has the same functionality as the original for random bond creation.

Hello,

I'm wondering if there's any existing LIGGGHTS simulation that alters the number of particles throughout the simulation.
For my case, I want the particle number in a powder bed to reduce linearly with time.

Has anything like this been achieved to date. Or has anybody any thoughts about how it could be done?

Any feedback greatly appreciated.

Thanks.

Hello,

Hi developers,

I am implementing a new normal contact model which needs the impact velocity (the velocity just before the collision) as an input parameter. A basic idea is to get the previous and current particle distance , and then extract the velocity just before there is an overlap. Is there any simple method to access the previous particle distance or any easier method to get the impact velocity?

Thank you.
Linhan

Hello, I'm writing to ask why the Comm::forward_comm() method is needed. Comm::exchange() and Comm::borders() and pretty clear, but I couldn't understand why should be necessary to send particles coordinates to neighbour process every timestep.

Why?

Thank you very much.

Hallo,

a want to simulate an agglomeration process in a multi-particle system with two types of particles (A&B). When two particles get in contact with each other they should stick together with certain probabilities (etaAA, etaBB and etaAB) or get reflected. How can this be realized in LIGGGHTS?

Best
kalei

Richti,

Have you been able to restart your bonds package with a different number of processors than were initially in the simulation? I've been trying to make this work for a little while now, as both the bond forming process, as well as the mesh/tet region style seem to have trouble with spanning processors, but I need to run simulations with ~100k-1M particles, so running on a single processor is not feasible.

Thanks,
Thomas Leps

Hi everyone,

I am working on a project to introduce new heat transfer model into LIGGGHTS of which the main task is to implement another heat transfer equation. I find the following source codes should be responsible for the current model in LIGGGHTS.
fix_heat_gran.cpp
fix_heat_gran.h
fix_heat_gran_conduction.cpp
fix_heat_gran_conduction.h
fix_scalar_transport_equation.cpp
fix_scalar_transport_equation.h