Journal of Fluid Science and Technology
Online ISSN : 1880-5558
ISSN-L : 1880-5558
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Bubble Generation by a Cylinder Moving Beneath a Free Surface
Ichiro KUMAGAIYuichi MURAIYuji TASAKANaoya NAKAMURA
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2011 Volume 6 Issue 6 Pages 851-859

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Abstract

Wave breaking and air bubble generation by a 2-D cylinder moving beneath a free surface were experimentally investigated. Measurements of the free surface profile and visualization of the air bubbles yield the threshold and the regime diagrams of the bubble generation, which depend on the cross-sectional shape of the cylinder, Reynolds number, effective Froude number, normalized depth of the cylinder and angle of attack. As the Reynolds and Froude numbers increase, the surface deformation becomes substantial in the downstream of the cylinder. A breaking wave with air entrainment occurs when the ratio of the wave height to the wave length is greater than ∼0.1. Our results provide useful information for design of facilities such as marine constructions and a hydrofoil air pump for drag reduction of ships.

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© 2011 by The Japan Society of Mechanical Engineers
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