LIGGGHTS® - User Forum

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.

Dear All:

I am trying to run a parallel packing as a simulation starting point just using the examples provided by LIGGGHTS 3.3.1 which lies in:

LIGGGHTS-PUBLIC/examples/LIGGGHTS/Tutorials_public/packing

As I am running on a cluster, I want to utilize all the 16 cores on a node (each node has 16 cores), thus LIGGGHTS 3.3.1 is compiled using Intel Compiler 14.0.2 using OpenMPI 1.6.3 (other versions of MPIs, e.g. mvapich2 are tested as well, with similar results), the only change I made to the in.packing is that I added one line at line 10:

processors 2 2 4

Hi There

It appears that all the links to to the LPP files are broken on git hub - or is this just me ?

Have installed an older version with python 35 and are getting this problem

File "C:/cygwin64/home/Admin/liggghts/liggghts/LPP/src/lpp.py", line 45
raise ValueError, "Invalid or no argument given for chunksize"

Tried manually setting chunksize with no result

Any ideas ??

Best Regards

John

Hi All

New installation on 8 core HP workstation works fine in serial mode with Windows / Cygwin install

In parallel the analysis completes but the program hangs with all 8 processors working.

Only way I can exit is to close down Cygwin and end the processes

The output post files appear fine

Help please !

John

Hello all,

I'm trying to simulate heat transfer in a packed bed. When I reduce the simulation box dimension and particle size, I get the following error:

ERROR on proc 0: Too many neighbor bins

Does anyone know why?

Thanks!
Joel

Hi all,

Having faced the issure of re-assignment of atom IDs for the LIGGGHTS post-processing. As I want to record the position or velocity of some certain particles using
the following commands:
---------------------------------------------------
...
variable x1 equal x[512]
variable y1 equal y[512]
variable z1 equal z[512]
fix pos all print 1000 "${time} ${x1} ${y1} ${z1}" file post/pos_512.txt
....
_____________________________

here 512 is the atom ID (in Paraview as PointID) at time = 0.

Good Day,

I have two different particles, m1 (oranges) and m2 (Apples) in transportation with a conveyor belt (m3). I want to be able to identify m1 and m2 by their type (group) in the simulation. Also, m1 and m2 have different mesh/surface/planar fixes as they are getting into the domain at different positions and times as shown in the attached screenshot. Some sections of the script have:

create_box 3 reg (for m1, m2 and m3)

Hello all,

I am calculating the pair wise contact forces using the compute pair/gran/local command.

If my output of the simulation is : id1 id2 fx fy fz

then, what is the direction of the force between particles of id1 and id2? Is it towards id1's (particles one) centre or id2's (particle two) centre?

I understand fx, fy and fz are the x, y and z components of the force between the particles.

Can someone please help me with this?

Best,

Naren