Frictionless conveying of frictional materials

Following a brief review of the technology and previous analyses of vibratory conveying of granular materials, a general solution is derived for a well-known rigid-slab model of slide-conveying in open and closed conduits, with Coulomb friction at the walls. The solution is applied to periodic rectangular-wave and sinusoidal forcing, and it is shown that the rectangular-wave forcing admits ideal cycles in which the kinematically optimal transport is also thermodynamically optimal, in the sense that no energy is dissipated by sliding friction.