2006 Volume 49 Issue 4 Pages 1016-1021
A zigzag rising motion is a typical motion of bubbles in bubbly flows. Vortices shedding oscillatory behind a bubble and the wake of the bubble turning periodically similar to a sign of inequality are regarded as the most fundamental causes of the turbulence excited in bubbly flows, because these phenomena produce an alternating lift force on the basis of both conservation laws of circulation and momentum, respectively. In this paper, we discuss the lift production on a zigzag rising bubble trailing a hairpin vortex using a spinning sphere model, which is constructed by us to hold the aerodynamic universality independent of Reynolds number. We fluid-dynamically explicate the alternating lift production on a rising originally nonspin bubble and the zigzag turning of its path, and propose a chain of processes considered in this paper as a fluid-dynamic mechanism that produces the rising bubble zigzag motion.