Dear users and developers,
I am trying to familiarize with Liggghts starting from some simple example. I started filling a small cylinder with a mono-disperse cohesive powder. In the attached screenshot you should notice that the rest configuration of the particles after pouring is pretty odd. I see squared powder aggregates that resemble the processor grid, i.e. a 3x4x1 mesh. I thought this might come from the fact that the particle generation is independent for each core and, together with the strong adhesion force, the new particles are immediately attracted close to each other in the very first instants after the insertion. TO verify this hypothesis I run a calculation with no cohesion between particles and indeed the squared aggregates disappear. So far so good, now to simulate certain rheology experiments of mine I have to live with a strong adhesion, thus I thought to apply a small wiggle to the cylinder bottom to homogenize a little bit the powder during pouring (see attached input file) and here comes the problem: according to the on-line manual for the wall/gran fix it is not possible to apply a wiggle to a primitive wall, only a shear. I am a little used to LAMMPS so I tried to use the wiggle keyword in the LAMMPS way but I got a parsing error message:
ERROR: Fix wall/gran (id zwalls1): Unknown argument or wrong keyword order: 'wiggle' (../fix_wall_gran_base.h:118)
So how can I apply a wiggle to a primitive flat wall?
Thanks in advance for your help.