Multiphase Science and Technology A Quarterly

ISSN for PRINT: 0276-1459

For Online Access

Best Paper Award Selection - Editorial Board Site

2005, Volume17

Issue 4

84 pages

DOI: 10.1615/MultScienTechn.v17.i4

Issue price - $140.00

H. Takahira
Dept. of Energy Systems Engineering, Osaka Prefecture University, 1-1 Gakuen-cho, Sakai, Osaka 599-8531, Japan

T. Nagata
Graduate Student, Graduate School of Engineering, Osaka Prefecture University, 1-1 Gakuen-cho, Sakai, Osaka 599-8531, Japan

T. Hozumi
Graduate Student, Graduate School of Engineering, Osaka Prefecture University, 1-1 Gakuen-cho, Sakai, Osaka 599-8531, Japan

The growth or shrinkage of a laser-trapped microbubble and the merger of microbubbles are observed with a high-speed camera. We investigate the influence of gas diffusion on the stability of trapped or merged microbubbles. Two kinds of equilibrium radii are observed for shrinking microbubbles. The first one is related to the equilibrium surface concentration of surfactant. The other is related to the decrease of the surface tension due to the compression of the surface area at the maximum surfactant concentration. The experimental results are compared with numerical solutions by taking the influence of the variation of surface tension on the gas diffusion into account. The simulations agree with the experimental results. The laser trapping technique is also applied to the motion of a microbubble in a shear flow. We observe the motion of a microbubble initially trapped in a narrow channel under shear flows. It is shown that as the radius of a microbubble becomes small, the bubble escapes from the laser trap being more repelled by the optical force. The oscillatory translation, which is induced by the rotation of the laser cone, is observed when the bubble is inside the laser cone. The theoretical predictions in which the buoyancy force, the fluid dynamics forces and the optical force are taken into account agree with the experiments.

DOI: 10.1615/MultScienTechn.v17.i4.20 Download article, 321-342 pages

Article price - $45.00

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