LIGGGHTS® - User Forum

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)

Does anyone know if the electrostatic EWALD method is implemented in LIGGGHTS? This page suggests it is https://www.cfdem.com/electrostatics however I've been unable to find anything in the documentation to support it.

Thanks,
Thomas

Where can I get detailed information about the " Easo" method?

Thanks

Hello,
As a part of my project, I need to insert particles of different range in different concentration (particle size distribution). How should I enter my code.
Thank you.

Hello everyone.

I am trying to implement the standard JKR cohesion model into LIGGGHTS. I modified the equations as required in normal_force_hertz.h. For speed and efficiency reasons I created an external file (a lookup table), which provides the value of the contact radius based on the overlap distance (deltan). So with the available "deltan" value, I need to access this lookup table and interpolate the corresponding value of the contact radius. As mentioned before, I need this interpolated value of the contact radius in order to ease the calculations in normal_force_hertz.h.