LIGGGHTS® - User Forum

Hello everybody,
I need to import the particles created by LIGGGHTS to CAD software. I have defined a simulation box with all faces as walls and put some particles on it. When I dump the last frame outputs as a .stl file, nothing save in the file and CAD software show nothing. Should I mesh the particles? if yes, how?
I appreciate it if you help me.
Kind regards,
Mehran

Hi,
I am trying to implement a nested loop in the following manner.

label loop
variable a loop 10

#variable level equal 200

label loop
variable b loop 200

variable tar_loading equal ${sigma_3}*${sample_width}*${sample_width} + 0.5*$b*${sample_width}*${sample_width}

# APPLING LOADING
fix_modify twall_servo servo/target_val -${tar_loading}
run ${load_unload_step}

next b
jump SELF loop

label loop
variable c loop 180

Greetings,

I modeling a clogging process in a biological filter and I want a color map of concentration of particle per cell or a number of particle per cell. My simulation have bigger particles that filter the small particles and I want to evaluate where the small particles get stucked.

Thank you already,
Kesley

So i'm still quite new to liggghts and am having trouble with getting values for contact area and overlap. I found the compute command and realised i need to dump the data somewhere. so far im using the commands:

compute oLap_cArea all pair/gran/local delta contactArea

dump dmp2 all local/gran/vtk ${dumpstep} calculations/calc.pvtu oLap_cArea

the error im receiving is: ERROR: dump local/gran/vtk no longer allow parallel writing by setting the % character. Instead use a filename with suffix .pvtX (X = {u, p}). (../dump_local_gran_vtk.cpp:109)

Hi everyone

I am trying to install LIGGGHTS in Centos but I am unable to compile it.
------------------------ERROR--------------------
Makefile:815: *** 'Could not obtain VTK_MAJOR_VERSION. As AUTOINSTALL_VTK is not set to "ON" we cannot continue'. Stop.
make[1]: Leaving directory `/home/software/LIGGGHTS/LIGGGHTS-PUBLIC/src/Obj_auto'
make: *** [auto] Error 2
--------------------------------------------------------

I tried to install VTK manually by following steps but it did NOT work

Hello LIGGGHTS forum,
Really thank you for your help.

I have one more problem in my simulation.
I am trying to increase the radius of my particle from 0.01 to 0.2 or 0.3 but I encountered following error.

"""
ERROR: Unable to calculate region volume. Possible sources of error:

I would like to read in initial positions, velocities, etc. for multispheres rather than using insert/pack to get the multisphere particles into my simulation. It is easy enough to read data for single spheres or a rigid body following the tips in the LIGGGHTS documentation. However, there is no mention of how to do this for multispheres. It seems as though it should be possible since multisphere restarts are possible from binary files.

Hi,
I have been trying to apply a stress with the help of if-statement i.e., when the wall reaches a certain amount of force it should stop applying force.
I am not getting a proper way to implement this logic. Please let me know how can I extract dumped force and put it into if-statement.

Thanks in advance.

Hello i'm using a servo wall for a ring shear cell. Now i want to calculate the forces acting on the servo wall during a shear run. I have not been able to output the forces data. Can somebody help me? How can i output the data over time into a single .txt file. Thanks a lot!

Hello all,

We (my tutor and I) would like to study faults with DEM. We are interested in applying time- and temperature dependent contact laws. We understand we need to create our own pair_style. This one will be as the Hertz law. But friction coefficient (and maybe some other parameters) depends on time and temperature.

1. How is it possible to put the temperature of a particle into the new contact law ?