Behavior of a small single bubble rising in a rotating flow field |
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Authors: | T Yamaguchi M Iguchi T Uemura |
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Institution: | (1) Graduate School of Engineering, Hokkaido University, North 13, West 8, Kita-ku, 060-8628 Sapporo, Japan;(2) Division of Materials Science and Engineering, Graduate School of Engineering, Hokkaido University, North 13, West 8, Kita-ku, 060-8628 Sapporo, Japan;(3) Department of System Management Engineering, Kansai University, 3-3-35 Yamate, 564-0073 Suita, Osaka, Japan |
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Abstract: | A small single bubble was generated with a single-hole nozzle facing upward in a water bath contained in a rotating cylindrical
vessel. The bubble size falls in the surface tension force dominant regime. The vertical, radial, and tangential migration
velocities of the bubble were measured with two CCD cameras and a high-speed video camera. The tangential velocity component
of water flow was measured with particle image velocimetry. A helical motion of the bubble was observed under every experimental
condition. The direction of the helical motion was the same as that of the tangential velocity component. This helical motion
is associated with the large initial shape deformation of the bubble near the nozzle exit and the subsequent regular shedding
of vortices behind it. The period and amplitude of the helical motion were obtained by analyzing the trajectory of the bubble.
These quantities were non-dimensionalized by the volume equivalent bubble diameter and the terminal bubble velocity in the
vertical direction and correlated as functions of the Eotvos number. Empirical equations were proposed for the period and
amplitude.
Originally published in the Journal of JSEM, Vol. 4, No. 2, pp. 38–45 (2004). |
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Keywords: | Bubble helical motion zigzag motion rising velocity rotating flow Eotvos number continuous casting mold argon gas |
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