Motion of a Bubble in a Branch Flow Channel under a Pressure-Oscillating Field

Abstract

The motion of a bubble in a flow of shear-thinning fluid under pressure-oscillating field was investigated experimentally. The enhancement of rising velocity of air bubble in shear-thinning fluid was presented by Iwata et al. by applying pressure-oscillation to a quartz cell. The key point is the superposition of a strain field on fluid surrounding the bubble, which results in decreasing shear viscosity. This technique was applied to an in-line process. Pressure-oscillation was achieved by throttled valves upstream and downstream of the branch flow and applying vibration through a diaphragm at the bottom of the test section. Bubbles were introduced by electrolysis from coupled electrodes placed in the flow field. With the help of strobe scope lighting, we successfully monitored the path of the moving bubbles clearly with a high resolution video camera. It was shown that the present method successfully enhanced the bubble rising velocity under a pressure-oscillating field. Additionally, introducing a bubble as a trap inside the flow channel changed the path of a bubble to be removed, and finally enhanced the defoaming performance.