Dear users of the granular package
I have found a problem when I run the file I supply below (using the 15Mar11 version with the granular package enabled). I have added comments in to make it easier to inderstand, but I basically create a packing of overlapping spheres bounded by granular walls. I then apply viscous damping to remove any unwanted forces, and I am monitoring the grain z coordinate. Then I remove damping completely.
What happens is that I register different behaviour if I do run 10000 instead of run 5000, run 5000. This behaviour might be difficult to spot unless you run with zero damping, but is probably a bug.
So what I think is happening is that the run command deletes all the forces and recalculates them, and I think that something is not done properly in the way the shear force gets calculated for each interaction pair (ie in the way the last value of shear[] gets passed on to the pairs at the initial step after the command run Nsteps is found). I looked into the code a bit and indeed the function Verlet::setup seems to be running, which as I understand it deletes all forces and recalculates them, but also builds the neighbour list again and maybe (not sure) remaps the atoms to processors etc..
I am emailing because I have spent quite a lot of time trying to figure out how to do the force recalculation properly and I got lost- maybe recalculation needs to be disabled? I am not sure.. Help is gratefully appreciated.
Thanks,
George
# Created on 17/3/2011 for LAMMPS 15Mar version