Cole, D.E., and Liow, J.V. (2004) Bubble entrapment during water drop impacts. In: Proceedings of the 15th Australasian Fluid Mechanics Conference. From: 15th Australasian Fluid Mechanics Conference, 13 - 17 December 2004, Sydney, NSW, Australia.

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Abstract

In the splash of a liquid drop on a deep pool of water, bubble entrapment occurs over a limited range of Froude number. Using high speed video photography at framing rates between 10000-100000 fps, the bubble entrapment regime was studied for water drops impacting on a deep pool of water. It is known that a high speed jet accompanies the entrapment of a bubble. In this study it was found that preceding the appearance of the high speed jet, a series of high speed droplets, having diameters up to a magnitude smaller than droplet previously observed, appears. The speed of these droplets were 50%higher than those formed from the high speed jets. We believe that these smaller high speed droplets were the result of a focusing of the ejecta sheet into a thin high speed jet. This thin high speed jet breaks up rapidly on formation and cannot be observed above the bath free surface. In conjunction with the upward high speed jet, an entrapped bubble was found to be expelled downwards from the cavity with a high speed downward jet of liquid penetrating into the bubble. If the high speed downward jet penetrated far enough into the bubble, such that its length exceeded Rayleighs wavelength for instability, it broke up to form a single drop within the bubble. The entrapped drop would then bounce around inside the bubble before the drop coalesced with the bulk liquid through a coalescence cascade with a geometric similarity given by We = 8.

Item ID:	14763
Item Type:	Conference Item (Research - E1)
ISBN:	978-1-86487-695-6
Keywords:	bubble; high speed video; microjet; splashing drops
Related URLs:	http://www.aeromech.usyd.edu.au/15afmc/p...
Date Deposited:	19 Nov 2010 03:26
FoR Codes:	09 ENGINEERING > 0915 Interdisciplinary Engineering > 091504 Fluidisation and Fluid Mechanics @ 100%
SEO Codes:	97 EXPANDING KNOWLEDGE > 970102 Expanding Knowledge in the Physical Sciences @ 100%
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