単一気泡から気泡流の大規模構造まで

- その階層構造を通して -

抄録

Research topics I have been working for the last 27 years related to rising bubbles are reviewed with the emphasis of surfactant effect on the multiscale structure of bubbly flows. Small amounts of surfactant can drastically change single bubble behaviors. For example, a bubble in aqueous surfactant solution rises much slower than one in purified water. This phenomenon is explained by the so-called Marangoni effect caused by a non-uniform concentration distribution of surfactant along the bubble surface. More interestingly, this Marangoni effect influences not only the rising velocity, but also the lateral migration in the presence of mean shear. Furthermore, these phenomena influence the multiscale nature of bubbly flows and cause a drastic change in the bubbly flow structure. In this article, these interesting phenomena are reviewed for the celebration of 30th anniversary of the Japan Society of Multiphase Flow