LIGGGHTS® - User Forum

Is there any way to modify the servo wall fix from:

fix servo all mesh/surface/stress/servo file plate.stl type 1 com 0. 0. 0. ctrlPV force axis 0. 0. 1. target_val 10 vel_max 1. kp 5.

to:

fix servo all mesh/surface/stress/servo file plate.stl type 1 com 0. 0. 0. ctrlPV torque axis 0. 0. 1. target_val 10 vel_max 1. ratio 0.01 mode auto

in between two runs?

Hello all,
I have a question about my code. I would like to simulate a shear test.
During the insertion of particles I got the following error
"ERROR on proc _: assertion failed (../region_neighbor_list_I.h:170)"

But if I increase the size of my domain following the z-axis the problem is solved.
You will find the file in the attachment.

The size of the box region :
region ri block 0.0 0.02 0.0 0.02 0.0 0.001 units box
(The problem is solved wiht region ri block 0.0 0.02 0.0 0.02 0.0 0.014 units box but I have too many particles)

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.