LIGGGHTS® - User Forum

LIGGGHTS® related topics can be discussed here: discussion about models, installation, feature requests and general discussion

Error with no log and dump recorded data

Submitted by nci.root.infor@... on Tue, 04/25/2023 - 10:06

Hello,

I am a new LIGGGHTS user and during my simulation, I got a strange thing related to no log and dump recorded data at some steps.

The data is suddenly stopped recorded at numerous steps and then it works.

I have checked at several times and got the same phenomenon but in different simulation steps.

Please see attached figures for the details.

I am wondering that does anyone see a similar problem

I appreciate your helps to solve this problem

Thank you in advance.

LTT

Shear Cell Test

Submitted by sohaibmalik on Sun, 04/23/2023 - 22:00

Hi I want to perform numerical experiment of a Shear cell test by applying the periodic boundary conditions (as shown in Figure, on a box of 0.0015*0.0015*0.0015m). The aim is to find the friction properties of the particles. The particles are inserted using a factory for 4 seconds (0-4 sec) and then a force of (0.225N) is applied through a top plate for one second (4-5sec). For the next 20 seconds (5-25sec), the force on the top plate is changed to (0.9N) an the shearing action is planned to be induced due to motion of the top plate with a velocity of (1mm/s) in the negative x-direction.

Illegal group command

Submitted by chuchu697 on Tue, 04/18/2023 - 06:50

Hi, all,
I am trying to put atoms that meet a certain boolean condition to a group called "inwardatom". This is the code:

variable eatom2 atom "(v_DH>50e-6)&&(v_inOut<0)"
group inwardatom variable eatom2

The error message says:

ERROR: Illegal group command (group.cpp:341)

Can anyone tell me what causes it?

Thanks a lot!

belt with variable speed

Submitted by willDEM on Fri, 03/17/2023 - 00:14

Hello, I am a new user of LIGGGTHS public.

I am working on a project which involves a variable speed belt. However, I couldn't find an example or detailed explanation on this.

How can I simulate this with LIGGGTHS public?

Could anyone shade a light on this? I think this is a common problem in a real project?

Thanks.

pair/gran/local contactArea

Submitted by Xeniya on Tue, 02/28/2023 - 06:27

I used compute pair/gran/local in order to find the contact area between two superquadrics. The output gives me 260 mm^2 while the diameter of the particles is 11 mm. The contact is edge-face, so basically this small overlap between face and edge, according to the output, produced the contact area more than twice the face-to-face total contact between the particles.

The question is what does "contactArea" exactly represent? What are the possible reasons why the contactArea found is so large?

Thanks everybody for Your replies in advance!

Need help to insert bigger particles in my simulation

Submitted by gibel on Sat, 02/25/2023 - 11:39

Hello guys,
Recently I am having a problem in particle insertion in drum.

I don't have problem with small size of particles with small drum. However, I am trying to use a bigger drum with width 2m and diameter 6m (si unit).
For bigger geometry I am trying to insert two types of particles with 1 m and 0.8 m. Whenever I increased the particles size, it doesn't increase the required number of particles in insertion. Instead it just insert 10, or 12 particles. I gues it is trying to control some of the calculation like fill mass rate or insertion.

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