LIGGGHTS® - Developer Forum

Hello everyone,

imagine a belt conveyor, where only one side along the longitudinal axis would have to be modelled.

Is there a way to model a symmetric boundary condition with LIGGGHTS?

Best regards,
MiRa

Hi, everybody

Hope everything is going well.
I noticed that the group option is allowed in fix property/atom
However, it is ignored in fix property/global automatically.
Wonder if it's possible to modify the source codes, so that I could use fix property/global with atoms in different groups?
Many thanks.

Best Regards,
Renge

Hello,

I am trying to modify the hertz contact model to include an adhesive force. So far I have hard-coded the modifications into the normal_model_hertz.h, which works fine. Now I want to do some parameter analysis and it would therefore be more convenient to define the relevant parameters in the LIGGGHTS script.

Let's say I want to define a matrix property, surfaceEnergyDensity, to be used. Below I included the modifications I did to normal_hertz_model.h and global_properties.cpp. I attached the log file.

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I'm now stuck trying to calculate the time-rate-of-change of pebble overlap, d(deltan)/dt, in order to create a kind of 'viscous damping' term in a contact model.

I've looked through lammps developer guide and there are walkthroughs on how to grow an array to grant access per/atom properties from previous timesteps (i.e. position, velocity, etc.). But contact information is a little more difficult because I have to use something similar to the tangential_model_history where there's a flag for contact, so I can't just create some generic array that maintains all overlap values.

Hello everybody,

I have made some adjustments in the contact models to suit my purpose but that included hard coding a length into the tangential history model.
I have decided now to switch the unit system from si to nano and I was wondering if there is a way to set a value depending on the unit system.
Here a code example showing the idea:

if (units=="si"){
adjustLen = a;
} else if (units =="nano"){
adjustLen = b;
}

I just don't know how to access the units. Can anybody tell me?

Regards
VBaric

Someone please provide procedure / steps for this.

Are we to simply place the files we edited / wish to add in the 'src' directory of the downloaded source files and compile??

Thanks,

Nasser

Hello all,

disclaimer: i've only just begun learning c++ so please correct me when I use the wrong syntax...

I'm trying to build a new normal model that has temperature dependence on the normal force. I created a new normal_model_etc based on the standard hertz file. I've done the first few modifications and tested that up to this point i can actually compile LIGGGHTS without error. But now I'm trying to access temperature and am not sure how to proceed.

Hi everyone,

Hi all,

I am trying to simulate one the hand partilces with bonds ( see https://github.com/richti83/LIGGGHTS-WITH-BONDS) and multispheres into one simulation.

After implementing the files from richti83 and adjusting the given bond-example, this issue works very well. Also the simulation of only multispheres works fine.

Hi,

currently I'm investigating if it is possible to create custom contact model for wall. I'm interested in having simple lubrication cohesion model when particle is in close proximity to the wall.

I've created new lubrication cohesion model which seems to be working for pair_gran style. Now I wish to have the similar model adopted for atom wall interactions.