Evaluation of mass transfer performance of a single bubble by use of 2D polarization measurement and LIF method under pressure-oscillating field

Abstract

The understanding of mass transfer of a tiny moving bubble is important in many industries. We have studied enhancement of gas absorption rate around a tiny bubble in viscoelastic fluid by pressure-oscillation. Applying the pressure-oscillation to the shear-thinning fluid is effective for enhancing bubble velocity. Due to expansion and contraction of the bubble at several hundreds of Hertz, complex flow structure may occur in the vicinity of the bubble. Such local flow structure around the bubble may enhance mass transfer. We use LIF method for visualizing pH distribution around the bubble. In addition, we use 2D high-speed polarization imaging for measuring the stress distribution around the bubble. Compared with these data, we discuss local flow structure around bubble under pressure-oscillating field.