LIGGGHTS® - User Forum

LIGGGHTS® related topics can be discussed here: discussion about models, installation, feature requests and general discussion

Conservation of Energy after impact

Submitted by antoniosereno on Fri, 11/15/2019 - 17:55

Hi everyone.
I am working on a simulation that involves several impacts between particles; to gain a better understanding of the impact phenomenom I simulated a single impact between 2 particles and I noticed that although the friction coefficient was put to 0 and the coefficient restitution to 1, the conservation of energy and linear momentum was not respected.
Can I ask why? Is it related to the mechanism that the software uses to compute the contact forces or there may be some conceptual mistake I've made?
Thank you for your help

Adding PNG support to LIGGGHTS, image.cpp: undefined reference

Submitted by PurpleCrumpets on Mon, 11/11/2019 - 10:52

Dear all,

I am trying to add image support to LIGGGHTS. Based on the instructions found in the documentation, I believe I should be able to add the following lines to the Makefile.user file:

LMP_INC=-DLAMMPS_PNG
JPG_INC=-I/opt/pkg/filelib/libpng/1.6.34/gnu/7.2.0/64/opt/include/libpng16
JPG_PATH=-lpng
JPG_LIB=-L/opt/pkg/filelib/libpng/1.6.34/gnu/7.2.0/64/opt/lib

However, when trying to compile LIGGGHTS, I recieve the following error:

Error with pair/gran/local

Submitted by deepakpawar.2310 on Sat, 11/09/2019 - 16:18

Hi

I need to dump the local contact information between the particles for every step during the simulation.

But the whole script is in the loop for variable $a
Problem These particular compute (pair/gran/local) command is giving the error as follows
ERROR: Compute pair/gran/local (id cpg2): Need to define this compute before first run (../compute_pair_gran_local.cpp:127)
However the for variable equal to 1, script working fine, the problem starts with the next value of the variable

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