Pavlov, Lucas and D'Angelo, M. Verónica and Cachile, Mario and Roig, Véronique and Ern, Patricia Kinematics of a bubble freely rising in a thingap cell with additional inplane confinement. (2021) Physical Review Fluids, 6 (9). 093605. ISSN 2469990X

(Document in English)
PDF (Author's version)  Requires a PDF viewer such as GSview, Xpdf or Adobe Acrobat Reader 2MB 
Official URL: https://doi.org/10.1103/PhysRevFluids.6.093605
Abstract
We analyze the behavior of air bubbles freely rising at high Reynolds numbers in a planar thingap cell filled with distilled water. The gap thickness of the cell is fixed to h≃2.8 mm (or h≃1 mm in additional experiments) and its inplane width W is varied from 2.4 to 21 cm. This allows us to investigate the evolution from unconfined thingap situations (i.e., large W and h≪W) controlled by the bubble characteristic lengths (diameter in the cell plane d>h and thickness close to the gap size h) to doubly confined situations controlled by the channel dimensions. As the bubble size d increases, and beyond a critical value that depends on W, we observe a mean rise velocity of the bubble, Vb, lower than that for larger W, along with a modification of the bubble shape. The departure occurs for oscillating bubbles of approximate elliptical shape, which becomes closer to circular as the lateral confinement increases. We further investigate how the bubble oscillatory motion is impacted by the transverse confinement. Assuming that the wall effect is related to the strength of the downward flow generated by the bubble, we introduce the relative velocity Urel=Vb/ξ, where ξ=1−d/W is the confinement ratio and found Urel≃Vb,∞ for all the cell widths considered, where Vb,∞ is the mean rise velocity in the absence of the transverse confinement (i.e., for W sufficiently large). This provides an estimation, at leading order, of the bubble velocity, that generalizes the expression proposed by Filella et al. J. Fluid Mech. 778, 60 (2015) and accounts for the additional drag experienced by the bubble due to the lateral walls. We then show that, for given d and ξ, the frequency and amplitudes of the oscillatory motion can be predicted using the characteristic length and velocity scales, d and Urel. As the bubble size is increased further, the bubble behavior becomes fully dominated by the channel dimensions. Cylindricalcapped shapes emerge, corresponding to a radius of curvature Rc at the front of the bubble, Rc≃0.31W, independent of the bubble size and of the gap thickness. At the same time, the mean rise velocity of the bubble saturates at a constant value, corresponding to a constant Froude number, Fr=Vb/√gW, that depends on the gap thickness h of the cell.
Item Type:  Article 

HAL Id:  hal03414109 
Audience (journal):  International peerreviewed journal 
Uncontrolled Keywords:  
Institution:  French research institutions > Centre National de la Recherche Scientifique  CNRS (FRANCE) Université de Toulouse > Institut National Polytechnique de Toulouse  Toulouse INP (FRANCE) Université de Toulouse > Université Toulouse III  Paul Sabatier  UT3 (FRANCE) Other partners > Consejo Nacional de Investigaciones Científicas y Técnicas  CONICET (ARGENTINA) Other partners > Universidad de Buenos Aires (ARGENTINA) 
Laboratory name:  
Statistics:  download 
Deposited On:  03 Nov 2021 15:45 
Repository Staff Only: item control page