LIGGGHTS® - User Forum

Since command 'group' is invalid for multisphere clump, how can I select a single component sphere of a clump and exert force on it? Is there anyone else encountered this problem?

Dear all,

I am trying to simulate the breakage of a granulate, which is formed by small particles, by pressing it using a servo-wall.
I observated the forces on the wall, it worked very well. I wrote also the restart files every xxx time steps.
However, if I load the restart file (and the current stl of geometry, because the wall moved) and want to simulate it further, the forces on the wall are totally gone, after many steps they can not reach the value I had earlier.

Is it because the accuracy of the written restart and stl files?

I am using LIGGGHTS to generate a cylindrical packing of spheres.
When I change the diameter of the spheres to 2 mm in the attached script, it doesn't converge to a solution. It works with 3, 4 and 5 mm values for the diameter, but not with 2 mm.
Do you know why?
Thanks in advance.

Hello,all
I'm a new user of liggghts and I'm studying the problem of heat transfer.
I took as a template the input file from the examples "heatTransfer_1" and it works fine with my parameters and configuration.
After that in some stage on calculation I need to heat up the particles in the special region more (to add for example 100 degrees to the existing temperature of each particle).

I guess I need to define the new variable

variable newtemp atom "temp+100"
or
variable newtemp atom "f_Temp[0]+100."

Hi every one ....i am trying to simulate a mixer that contain glass beads with impeller in the middle through LIGGGHTS. when i run the code and see the result in paraview its shows particles with spaces in between them.i want to see the particles in packed form means with no spaces as we see in real situation,is there any problem with code in LIGGGHTS or its the problem with paraview setting or it always shows like this?Kindly guide me,i am new user of LIGGGHTS.

Hi
I am trying to consolidate a periodic cell. the cell is a cubic one which right and left sides are defined as periodic boundaries.
During the consolidation phase that is done by moving the upper platen, the lateral pressure exceeds the normal stress which means that the specimen has ko=sigma(zz)/sigma(xx)>1. however, replacing the periodic boundary by rigid walls results in ko=0.5 that is reasonable.
I was wondering if the problem is related to the periodic boundaries or this phenomenon has a physical explanation. I do need to model a specimen with ko=0.5.

Hi, everyone

Wonder if there's any approach to output atom position and then link to specific variables?
I tired:
compute atom/property xs ys zs
variable z equal zs-0.05
however, I got errors with either ${zs} or v_zs
Thinking maybe I need to achieve this with other command?
I'm using LIGGGHTS 3.0.2
Appreciate it very much if anybody could help.

Mos

Hi All,

I want to extract information about contact duration and maybe I have found a really simple way to do it.

In cohesion_model_easo_capillary_viscous.h there is a history_value "contflag" that is used to understand if two particles have been in contact, such that the capillary force is created only after the contact occurs.

The contflag is set to 1 in case of contact, then set to 0 when the liquid bridge is broken. One can increment the contflag rather than setting to 1 and the condition still works.

contflag[0] = contflag[0] + 0.0;

Hi !, I'm starting to use liggghts , I was wondering if anyone has simulated a rock fracture due to the free fall of a steel ball . Someone has done it before? or if there are any similar example to this topic that help me as a guide support.

I appreciate the comments , greetings !

PS : My English is not the best , excuse the wording .

Hello.

I was doing a simulation with 1.710.000 particles in 1.500.000 steps of time inside a mill. When the simulation reaches the step of time 600.000, the kinetic energy that shows on screen is zero and remains in this value for the rest of the simulation. However, there seems to be no other problem with the discharge of particles of the mill because the mass flow does not change.

I want to know if this problem of the kinetic energy is important to be consider in future simulations and why this ocurred?

Best regards,

Nicolás.