Experiment and modeling of lift force acting on single high Reynolds number bubbles rising in linear shear flow

The lift force acting on single bubbles rising in a downward linear shear flow is measured experimentally. The flow is generated by a 90 degrees sharply bent rectangular water channel, with uniformly distributed vanes installed directly after the corner, and the linear velocity profile is validated by particle image velocimetry. In the flow, single contaminated bubbles with a volume equivalent diameter d ranging from 2 mm to 20 mm are tested, corresponding to a Reynolds number Re based on d and relative velocity of the bubble in the quasi-steady state from 440 to 7200. The experimental results of the lift coefficient C-L at d < 8 mm (Re < 2100) are consistent with both the data and correlation in the literature. In the case of d > 8 mm, the results of C-L exhibit similar tendencies and magnitudes to those of Li et al. (2016a). Based on the ideal modeling of the vortex detachment, the wake-induced contribution of C-L is estimated. Good agreement is achieved between the newly derived model and experimental results.