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Interfacial dynamics of stationary gas bubbles in flows in inclined tubes

Published online by Cambridge University Press:  10 November 1999

DANIEL P. CAVANAGH  and
DAVID M. ECKMANN
DANIEL P. CAVANAGH
Affiliation:
Department of Biomedical Engineering, Robert R. McCormick School of Engineering and Applied Science, Northwestern University, Evanston, IL 60208, USA
DAVID M. ECKMANN
Affiliation:
Department of Anesthesia and The Institute for Medicine and Engineering, University of Pennsylvania, Philadelphia, PA 19104, USA
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Abstract

We have experimentally examined the effects of bubble size (0.4 [les ] λ [les ] 2.0), inclination angle (0° [les ] α [les ] 90°), and tube material on suspended gas bubbles in flows in tubes for a range of Weber (0 [les ] We [les ] 3.6), Reynolds (0 [les ] Re [les ] 1200), and Froude (0 [les ] Frα [les ] 1) numbers. Flow rates and associated pressure differences which allow the suspension of bubbles in glass and acrylic tubes are measured. Due to contact angle hysteresis, bubbles which dry the tube wall (i.e. form a gas–solid interface) may remain suspended over a range of flows while non-drying bubbles remain stationary for a single flow rate depending on experimental conditions. Stationary bubbles increase the axial pressure gradient with larger bubbles and steeper inclination angles leading to the greatest increase in the pressure gradient. Both the suspension flow range and pressure difference modifications are strongly dependent upon gas/liquid/solid material interactions. Stronger contact forces, i.e. smaller spreading coefficients, cause dried bubbles in acrylic tubes to remain stationary over a wider range of suspension flows than bubbles in glass tubes. Bubble deformation is governed by the interaction of interfacial, contact, and flow-derived forces. This investigation reveals the importance of bubble size, tube inclination, and tube material on gas bubble suspension.

Type
Research Article
Information
Journal of Fluid Mechanics , Volume 398 , 10 November 1999 , pp. 225 - 244
Copyright
© 1999 Cambridge University Press

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