BUOYANCY-DRIVEN MOTION OF DROPS AND BUBBLES IN A PERIODICALLY CONSTRICTED CAPILLARY
作者:
M. HEMMAT,
A. BORHAN,
期刊:
Chemical Engineering Communications
(Taylor Available online 1996)
卷期:
Volume 148-150,
issue 1
页码: 363-384
ISSN:0098-6445
年代: 1996
DOI:10.1080/00986449608936525
出版商: Taylor & Francis Group
关键词: Buoyancy;Drops;Bubbles;Constricted capillary
数据来源: Taylor
摘要:
Buoyancy-driven motion of viscous drops and air bubbles through a vertical capillary with periodic constrictions is studied. Experimental measurements of the average rise velocity of buoyant drops are reported for a range of drop sizes in a variety of two-phase systems. The instantaneous drop shapes at various axial positions within the capillary are also quantitatively characterized using digital image analysis. Periodic corrugations of the capillary wall are found to have a substantial retarding effect on the mobility of drops in comparison with previous experimental results in a straight cylindrical capillary. For systems characterized by small Bond numbers, drop deformations are found to be periodic. In large Bond number systems, however, drop breakup eventually occurs as the drop size is increased beyond a critical limit. The observed mode of breakup is a tail-pinching process similar to that observed by Oibricht and Leal (1983) for pressure-driven motion of low viscosity ratio drops through a sinusoidally constricted capillary. In contrast to their results, however, the same mode of breakup was also observed for systems withO(1) viscosity ratios,
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