LIGGGHTS® - User Forum

Hi!
I'm a new user to LIGGGHTS and have a question about the units for cases. How does it work with units in LIGGGHTS; is the code always solving in the unit specified for solving equations or are there cases where it will automatically change to SI units instead?
Is it specified the dimensions of model parameters for example that youngsModulus should be in Force/L^2 i.e. pressure? How can i check what dimensions the model parameters should have?

Hi all,

I want to analyze the average force per contact by diameter.

Using the command "compute pair/gran/local force id pos", I can obtain the id of the two contacted particles. Then using the command "compute property/atom diameter", I can obtain the diameter of each id. Based on some coding in Matlab, I can obtain the average force per contact by diameter. This procedure may not be that direct and I want to know is there any better method to output what I need?

Dear friends,

Hi all,

In my simulation, I have particles with diameter d=0.1, 0.2, 0.5 and 1.0mm in the calculation region. I can obtain the total mass of all particle using the command "mass(all)". Now I want to know how to obtain the total mass of particle with d=0.1mm? Could anyone please give me any clues? Thanks ahead.

Best,
Rachel

Dear all,

I would like to check whether the value of the variable can be incremented or not? Here is a simplified example:

variable A equal 5
....
run 10000
Variable A equal "A*2"

Many thanks, Haithem

Dear all,

I am doing a compression test of soil particles and want to divide the sample into 3 parts with the same volume along the z direction. During the compression, the shape of the soil assembly will be compacted and thus the subdomain region also needs to be redivided. I don't know how to model such deformable regions so as to adapt the subdomain every step? Could anyone give me any clues? Thanks very much.

Cheers,
Rachel

Hello,

I'm having some difficulties in setting up a heat transfer model which involves heat transfer through a wall.

I've attached an image of my setup and what I'm trying to do.

I want to model heat transfer from a heat source (meshed wall A) through a powder (Powder B), through Wall B and onto Powder B.
As you can see from the attached image I cannot set up the model to allow heat to transfer through Wall B (which is an imported mesh).

Hey everyone,
has anyone tried using LIGGGHTS with python3? Right now I'm using python2, but i want to update it and use python3 . If I just try to use the install.py with python3 (and change the print structure to python3) I can't open files with a python3 script.

The python script only has the import and liggghts file call. With python2 it works fine but with python3 it says:

Hi all,

Form LIGGGHTS, I can output the contact forces acting on a selected particle in the soil assembly directly. Does anyone know whether LIGGGHTS can output the mean normal stress acting on a single particle and how to output this data? Some description of such mean normal stress (p'=sigma_ii'/3) can be seen in the attached picture.

Best,
Rachel

Hello,

I am having an issue with setting up one of my meshes as a heat source.

In my simulation I have two different meshes however I only want one mesh to be a heat source.
I assigned a constant temperature of 400 to cad2 as shown below but I get a nasty looking error message with this (copied to bottom of post)