Flow regimes and flow transitions in liquid fluidized beds

Using two-dimensional liquid fluidized beds of glass particles in water, we have been able to identify at least four discrete fiow regimes. The points of transition between these regimes are sharp and non-hysteretic. The regimes include (in the order of increasing gm/gm_mf), wavy fiow, wavy fiow with transverse structure, fine-scale turbulent flow, and bubbling states. Characterization of each of these regimes is given in terms of the rime and length scales of the motion, as measured by light transmission, optical scanning, and digital time-series analysis. Features of the mechanics of these states are discussed. Observation of the bubbling state for particles of moderate density (ρ_s = 3990 kg/m³) in liquid beds is new, and is shown to be related fo anomalous expansion data reported by earlier investigators.