Onset of convection in molecular dynamics simulations of grains

Cohesive, frictional powders: contact models for tension

“…In the bulk material, where many particles are in contact with each other, this dissipation mode is very inefficient for long-wavelength cooperative modes of motion [47,48]. Therefore, an additional damping with the background can be introduced, so that the total force on particle i is Plastic stiffness…”

Phase diagram of vertically shaken granular matter

“…Granular convection has been studied extensively at mild fluidization [23,44,45,46,47,48,49,50,51,52,53,54,55,56,57,58,59,60,61,62,63,64,65,66,67,68,69], for which the convection is principally boundary-driven. However, the buoyancy-driven convection observed here occurs at high fluidization and this has been reported much more rarely in the literature.…”

Subharmonic surface waves in vibrated granular media

“…Novel aspects of this phenomenon described recently include wave patterns having the form of stripes and hexagons [3,4], period doubling [4], and localized excitations [5]. Several simulations of vertically vibrated granular systems have been reported; the goal of the earlier work was, e.g., to examine the convective ows that develop [7], and the ability of vibration to segregate grains according to size [8]. Following the latest surface-wave experiments, two simulation studies have focused on the nature of the waves themselves [9,10]; both describe observations of standing-wave patterns at half the driving frequency in 2-D systems with rigid side walls.…”