Interaction of two non-coalescing bubbles rising in a non-isothermal self-rewetting fluid
File(s)
Accepted version
Author(s)
Balla, Mounika
Tripathi, Manoj Kumar
Matar, Omar K
Sahu, Kirti Chandra
Type
Journal Article
Abstract
The attractive and repulsive behaviours of a pair of initially spherical gas bubbles rising side-by-side in a channel with non-uniformly heated walls containing a self-rewetting liquid are investigated numerically. The surface tension of a self-rewetting fluid exhibits a parabolic temperature dependence with a well-defined minimum, as opposed to linear (common) fluids whose surface tension decreases almost linearly with the increasing temperature. It is found that, for low Reynolds numbers, while in an isothermal medium, two gas bubbles display a repulsive behaviour, they attract in non-isothermal systems. The bubbles in the self-rewetting fluid undergo a plastic collision and show a ‘squeezing and relaxing’ behaviour, whereas they attract and then bounce in the linear fluid. A regime map demarcating the repulsive and attractive behaviours for a self-rewetting fluid is plotted in the Weber number (We) and the dimensionless linear component of the surface tension gradient (M1) space. It isfoundthatthebubblesintheself-rewettingfluidremainsphericalevenforhighWebernumberswhilethey deform considerably in the case of the linear fluid indicating that the attractive behaviour of the bubbles in the self-rewetting fluid is due to the lift force generated by the thermocapillary stresses and not due to the deformation. The mechanism underlying the observed phenomenon is elucidated by studying the drag and lift forces acting on the bubbles, their orientations, and the flow field around them.
Date Issued
2021-05-01
Date Acceptance
2021-01-25
Citation
European Journal of Mechanics - B/Fluids, 2021, 87, pp.103-112
ISSN
0997-7546
Publisher
Elsevier BV
Start Page
103
End Page
112
Journal / Book Title
European Journal of Mechanics - B/Fluids
Volume
87
Copyright Statement
© 2021 Elsevier Masson SAS. All rights reserved. This manuscript is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International Licence http://creativecommons.org/licenses/by-nc-nd/4.0/
Sponsor
Engineering & Physical Science Research Council (EPSRC)
Engineering & Physical Science Research Council (EPSRC)
Petronas Research Sdn. Bhd.
Identifier
https://www.sciencedirect.com/science/article/pii/S0997754621000091?via%3Dihub
Grant Number
EP/K003976/1
EP/T000414/1
N/A
Subjects
01 Mathematical Sciences
02 Physical Sciences
09 Engineering
Fluids & Plasmas
Publication Status
Published
Date Publish Online
2021-02-01