LIGGGHTS® - User Forum

Hello!
I am using LIGGGHTS 3.0.7.
I am trying to add a force to the group of particles of a particular type.

Here, what i do:
//create region in which the force should be applied
region field_region block -0.1 0.1 -0.1 +0.1 0 0.1 units box
//define group gg which consists only of particles of type 1
group gg type 1
//trying to apply the force which will try to decrease the speed of the particles
fix mag_field gg addforce 0.0 0.0 +0.3 region field_region

I am trying to extract the total torque on a mesh that rotates about the x axis and I'm having trouble getting the syntax right (LIGGGHTS-3.3). As an example, defining the wall as:
fix mixer all wall/gran model hooke tangential history mesh n_meshes 2 meshes cad1 cad2 store_force yes

can I access the stored forces as shown below?
variable torque atom force_mixer*sqrt(y*y+z*z)

If I try to reduce the x component of the total torque using:
compute c2 all reduce sum v_torque[1]

Greetings,

I have a doubt about the use of a data file. Recently, i was simulating a mill, and instead of use the particletemplate/sphere keyword, i was using a data file to load all the particles. The total amount of particles that i used was 1344278. However, in a second simulation, i increased the number to 1728272, and when compile LIGGGHTS, the program generated a error and then it close unexpectedly.

My question is if there is a limit of particles in a data file, or is a problem with the computer that i use for simulations. My computer has 8 processors.

Hello Everyone,

I have a question about the fix wall/gran command - I am using the ver. 3.3.1. of LIGGGHTS.

I am using boundary p p f and I want three walls, two bounding the simulation and one in the middle (to create two layers)

fix zwallsdown all wall/gran model hertz tangential history primitive type 1 zplane ${bottom_plane}
fix zwallsmid all wall/gran model hertz tangential history primitive type 1 zplane ${mid_plane}
fix zwallsup all wall/gran model hertz tangential history primitive type 1 zplane ${upper_plane}

Hello everybody,
I am a new user of LIGGGHTS and I am running simulations by inserting a particle packing in a fixed volume:

insert/pack ... particles_in_region 100000

Of course, as I expect, I have a "less inserted than required" since less than 100000 particles are needed to fill the volume.

Dear users and developers,

Hi,
(SEE EDIT)

*****UPDATE****
- I have this simulation with a capillary model for cohesion.
- The simulation run without any problem on 32 cores.
- If I add a compute pair/gran/local, a Segmentation Fault happens for 32 cores depending on the mapping of the processors!
- No ERROR for 8, 16 cores or single core.
- If I change the maxSeparationDistanceRatio to 2.0 I have the error for single core!

Do you think there is a bug?
********

*****ORIGINAL POST****

In the manual:

radius values = random_style param1 (param2)
random_style = 'constant' or 'uniform number' or 'uniform mass' or 'gaussian number'

If I understand it right one can specify a low and high radius value and the pts interpolates uniform by mass. This would excactly what I need for my sieving analysis. But the codes stops with:
"ERROR: mass distribution not implemented for uniform (c:\liggghts3-bonds\liggghts-with-bonds\src\probability_distribution.h:170)"

Hi all!

I try to set the velocity and the angular momentum to zero at a certain point in my simulation and I want to use the velocity command.
For the velocity it works fine, but for the angular momentum I couldn't get it working.

Hi all,

I would like to know which is the algorithm behind the cluster/atom compute. Is anyone aware of that? Any reference?

Thank you!

Giuseppe