LIGGGHTS® - User Forum

Hello
Can anybody help me in calibrating cohesionEnergyDensity. I dont know how to calibrate cohesionEnergyDensity for a material.
Is there any standard procedure for adjusting cohesionEnergyDensity value.

Hi,
I am trying to install LIGGGHTS in a gnu server. When I trying to create makefile.user using command 'make auto' its not creating. As it is required to set the vtk path. Can anyone please tell me what am I missing?

Hello Guys,

I'm new to Liggghts. I created code from Particle size distribution, but I'm not understanding how to make it in group and insert particles randomly in cylinder disc.

Please help me.. thank you

Hello, the code sends me the following error:
ERROR: Fix massflow/mesh (id mass): need to change 'vec_side', it is currently in or to close to the mesh plane (../fix_massflow_mesh.cpp:245)
In the documentation of liggghts it states:
vx, vy, vz = vector components defining the “outside” of the mesh.

Why does the program indicate that error? I have tried with several vectors that are not "close" to the counter mesh
thank.

i have some questions in my mind,
1. JKR model only describes the contact radius and normal force.
a^3=R^*/E^* [√(6 λπR^* f_n+(3λπR^* )^2 )+f_n ]
The expression for the force of cohesion, which is accounted in the eqn of motion of the particles, is missing? i mean in JKR equation there is Fn (normal force )term but no Fcoh ( cohesion force term) .
2. The value of the coefficient of restitution that we use in input scripts, corresponds to gamma_n or gamma_t?

i have few questions in my mind..
1. How cohesive energy density (CED) is calculated? In my system i used 4% moisture content , how i can calculate CED for my system. is there any simple procedure for calculating the same?
2. which parameter in JKR model accounts for this ??? is it the same as Lamda??

Kindly help me if some one can answer
thanks

Hi,
I need to insert 8 µm spheres, and have considered an empty margin for the insertion face:
(real) inlet face:

• x= 0
• y_min= -1e-4, y_max=1e-4
• z_min= 0, z_max= 1e-4

particle insertion face:

• x=1.8e-5
• y_min= -8.2e-5, y_max=8.2e-5
• z_min= 1.8e-5, z_max= 8.2e-5

I get ERROR: Fix insert/stream (id ins): insertion volume could not be distributed properly in parallel. Bad decomposition or insertion face extrusion is too small or outside domain (../fix_insert_stream.cpp:551).

Hello, I am working on quantifying the fragmentation of material by breaking bonds. I use liggghts-with-bonds, I would like to quantify how many bonds were broken to obtain the particle size of the rock after being fragmented by compression.
Could you tell me commands to give me information about the status of the bonuses, please?

Hi,
I just noticed, that the limitations for the youngs modulus in src/global_properties.cpp were changed in version 3.8 quite drastically (by two orders of magnitute), but only for the CGS-system. Does anyone know why that happend and if it is of any relevance for the equivalence of simulations done with 3.7 and 3.8?
Thanks in advance

Hi, I installed LIGGGHTS-WITH-BOND then to add the MOLECULA package:
make yes-m or l e c u l e
make g ++
Anyway I get an error:
WARNING: Granular Bond: This is a beta version - be careful! (../bond_gran.cpp:83)
ERROR: Illegal region command (../region.cpp:426)