(201d) Strange Phenomena and Resonance in Vibrationally Fluidised Beds

It is well known that vibrated granular materials can show a menagerie of peculiar phenomena. This paper presents a study of vibrationally fluidised beds of cohesion-less granular materials and adds one more odd characteristic to the stable. The focus of the work was to investigate the resonant behaviour of fluidised granular emulsions compared to predictions based on the work of Roy et al 1990. To this end, the harmonic response of several granular materials was measured under a variety of different excitation levels and pore pressures. Some correlation between the resonant behaviour at high levels of excitation and a ?granular gas? prediction was demonstrated. During this work several curious phenomena were observed. The strangest of these was at low pore pressures where the top surface of the emulsion moved in two, entirely out-of-phase, and discontinuous sections. This Strange behaviour is presented without explanation.

Roy, R., Davidson, J., and Tuponogov V. (1990), ?The velocity of sound in fluidized beds? Chem. Eng. Sci., v45 pp.3233-3245.