Role of Slip Velocity in the Behavior of Stratified Multiphase Plumes
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This paper presents direct measurements of multiphase plumes in stratification and correlates characteristic plume properties with the nondimensional slip velocity UN. UN is defined as the ratio of the bubble slip velocity us, to a characteristic plume fluid rise velocity (BN)1/4; B is the total kinematic buoyancy flux, and N is the buoyancy frequency. UN is derived by dimensional analysis and is compared to other nondimensional parameters for multiphase plumes in the literature. To investigate correlations of the nondimensional numbers with plume properties, laboratory experiments were conducted in linear stratification using dispersed phases of air, oil, and glass beads (creating an inverted plume). A new type of plume behavior is identified, called Type 1* in which the horizontal motion in the first detrainment event disperses the relatively weak bubbles, creating a diffuse bubble plume that forms out of the intrusion. Measurements from these and previous experiments for type behavior, trap height, and intrusion layer flux are presented. Measurements are also presented for the new parameters peel height, mass fraction of passive tracer peeled, and bubble spreading ratio. The results show that correlations with the single parameter UN, which replaces other two-parameter models, are successful. ASCE.