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Flow structures and dynamics in the wakes of sliding bubbles

Rudi O'Reilly Meehan ([javascript protected email address])

Rudi is currently pursuing his PhD under the supervision of Prof. Darina B. Murray. His PhD research focuses on experimental characterization of heat transfer and fluid dynamics in the wakes of air bubbles, sliding under inclinedheated surfaces in quiescent water, in collaboration with Bell Labs Ireland.

Principal investigator
Prof. Darina Murray ([javascript protected email address], Tel: +353 1 896 1129)

Description

It is known that vapour and gas bubbles can significantly increase convective heat transfer rates from an adjacent heated surface. One situation in which this is encountered is the impact, and subsequent sliding, of an air or vapour bubble along a heated inclined surface. This situation is encountered in two-phase flow in an inclined channel, a configuration common in many industrial processes, such as in shell and tube heat exchangers, water treatment and emulsification. In multiphase flow systems, bubbles play a large part in determining the process efficiency. Indeed, sliding bubbles play a central role in many phenomena, and span fields from electrolysis to food processing and medicine. However, the mechanisms responsible for the heat transfer enhancement offered by bubbles sliding along the underside of an inclined surface are not fully understood.

The heat transfer enhancement from sliding bubbles has two associated mechanisms: bluff body convection and vortex shedding in the bubble wake. The bubble wake has been identified as a key contributor to heat transfer, but few studies to date have focused on the mechanics of these wake structures. Thus, it is the objective of the current study to visualise, and thus quantify, the three-dimensional wake structures of a sliding bubble using the Particle Image Velocimetry technique. This will allow for later optimisation of heat transfer enhancement, and to develop two-phase flow applications of sliding bubbles.

Funding Body

Irish Research Council (Enterprise Partnership Scheme), in collaboration with Bell Labs Ireland