A Study of Spherical Bubbles in a Vertical Turbulent Boundary Layer

Abstract

Liquid forces acting on individual bubbles in this turbulent boundary layer were also explored. This task was accomplished by employing a cinematic Particle Image Velocimetry system. Quadruple-pulsed images were obtained in a temporal sequence, such that the instantaneous liquid velocity and bubble trajectories could be accurately determined. Bubble velocity, acceleration, and buoyancy force were obtained from the trajectory data. Analysis of the force results indicate that drag coefficient decreases with increasing Reynolds number, but decreases with increased turbulence intensity. The lift coefficient is much higher than creeping flow or inviscid theory and tends to decrease with increasing bubble Reynolds number.