Imperial College London

Professor Omar K. Matar

Faculty of EngineeringDepartment of Chemical Engineering

Vice-Dean (Education), Faculty of Engineering
 
 
 
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Contact

 

+44 (0)20 7594 9618o.matar Website

 
 
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Assistant

 

Miss Nazma Mojid +44 (0)20 7594 3918

 
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Location

 

506ACE ExtensionSouth Kensington Campus

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Summary

 

Publications

Citation

BibTex format

@article{Balla:2019:10.1017/jfm.2018.774,
author = {Balla, M and Tripathi, MK and Sahu, KC and Karapetsas, G and Matar, OK},
doi = {10.1017/jfm.2018.774},
journal = {Journal of Fluid Mechanics},
pages = {689--713},
title = {Non-isothermal bubble rise dynamics in a self-rewetting fluid: three-dimensional effects},
url = {http://dx.doi.org/10.1017/jfm.2018.774},
volume = {858},
year = {2019}
}

RIS format (EndNote, RefMan)

TY  - JOUR
AB - The dynamics of a gas bubble in a square channel with a linearly increasing temperature at the walls in the vertical direction is investigated via three-dimensional numerical simulations. The channel contains a so-called ‘self-rewetting’ fluid whose surface tension exhibits a parabolic dependence on temperature with a well-defined minimum. The main objectives of the present study are to investigate the effect of Marangoni stresses on bubble rise in a self-rewetting fluid using a consistent model fully accounting for the tangential surface tension forces, and to highlight the effects of three-dimensionality on the bubble rise dynamics. In the case of isothermal and non-isothermal systems filled with a ‘linear’ fluid, the bubble moves in the upward direction in an almost vertical path. In contrast, strikingly different behaviours are observed when the channel is filled with a self-rewetting fluid. In this case, as the bubble crosses the location of minimum surface tension, the buoyancy-induced upward motion of the bubble is retarded by a thermocapillary-driven flow acting in the opposite direction, which in some situations, when thermocapillarity outweighs buoyancy, results in the migration of the bubble in the downward direction. In the later stages of this downward motion, as the bubble reaches the position of arrest, its vertical motion decelerates and the bubble encounters regions of horizontal temperature gradients, which ultimately lead to the bubble migration towards one of the channel walls. These phenomena are observed at sufficiently small Bond numbers (high surface tension). For stronger self-rewetting behaviour, the bubble undergoes spiralling motion. The mechanisms underlying these three-dimensional effects are elucidated by considering how the surface tension dependence on temperature affects the thermocapillary stresses in the flow. The effects of other dimensionless numbers, such as Reynolds and Froude numbers, are also investig
AU - Balla,M
AU - Tripathi,MK
AU - Sahu,KC
AU - Karapetsas,G
AU - Matar,OK
DO - 10.1017/jfm.2018.774
EP - 713
PY - 2019///
SN - 0022-1120
SP - 689
TI - Non-isothermal bubble rise dynamics in a self-rewetting fluid: three-dimensional effects
T2 - Journal of Fluid Mechanics
UR - http://dx.doi.org/10.1017/jfm.2018.774
UR - http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcApp=PARTNER_APP&SrcAuth=LinksAMR&KeyUT=WOS:000449631200003&DestLinkType=FullRecord&DestApp=ALL_WOS&UsrCustomerID=1ba7043ffcc86c417c072aa74d649202
UR - http://hdl.handle.net/10044/1/64782
VL - 858
ER -