Experimental study of vertically vibrated granular matter: patterns and segregation

Abstract

This thesis explores the dynamical behavior of granular materials via experiments in a vertically vibrated granular bed. Experiments are designed with the primary objective to understand the pattern formation dynamics that manifests in a vertically-vibrated container filled with mono-disperse spherical particles as well as binary mixtures of equal sized spherical particles of different materials. While the aesthetically pleasing shapes and the novel phase-coexistence of these patterns have generated curiosity, the question of underlying mechanism for their genesis, in addition to their dynamics, must be addressed from a theoretical point of view in future. In this thesis, we report, for the first time, (i) a variety of “phase-coexisting” patterns having different spatial and temporal order, a novel “Ratcheting/Oscillatory” cluster, and the related phase diagrams in vibrated binary mixtures, (ii) a novel unsteady dynamics of the so-called “density-inverted” Leidenfrost state and (iii) the micro-structural signatures of the transition from the “bouncing-bed” to the Leidenfrost state. All these new experimental results are awaiting theoretical explanations.