Topical Issue on Dygram 2006
Instabilities in vertically vibrated fluid-grain systems
School of Physics and Astronomy, University of Nottingham, Nottingham, NG7 2RD, UK
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Published online: 17 January 2007
When a bed of fluid-immersed fine grains is exposed to vertical vibration a wealth of phenomena may be observed. At low frequencies a horizontal bed geometry is generally unstable and the bed breaks spatial symmetry, acquiring a tilt. At the same time it undergoes asymmetric granular convection. Fine binary mixtures may separate completely into layers or patterns of stripes. The separated regions may exhibit instabilities in which they undergo wave-like motion or exhibit quasi-periodic oscillations. We briefly review these and a number of related behaviours, identifying the physical mechanisms behind each. Finally, we discuss the magneto-vibratory separation of binary mixtures which results from exposing each component to a different effective gravity and describe the influence of a background fluid on this process.
PACS: 45.70.-n Granular systems –
© EDP Sciences/Società Italiana di Fisica/Springer-Verlag, 2007