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Binary collisions of drops of immiscible liquids

Published online by Cambridge University Press:  01 December 2011

Ilia V. Roisman*
Affiliation:
Institute of Fluid Mechanics and Aerodynamics, Center of Smart Interfaces, Technische Universität Darmstadt, Petersenstrasse. 30, 64287 Darmstadt, Germany
Carole Planchette
Affiliation:
Laboratoire de Physique des Matériaux Divisés et des Interfaces, FRE 3300 CNRS, Université Paris-Est, 5 boulevard Descartes, 77454 Marne-la-Vallée CEDEX 2, France
Elise Lorenceau
Affiliation:
Laboratoire de Physique des Matériaux Divisés et des Interfaces, FRE 3300 CNRS, Université Paris-Est, 5 boulevard Descartes, 77454 Marne-la-Vallée CEDEX 2, France
Günter Brenn
Affiliation:
Institute of Fluid Mechanics and Heat Transfer, Technische Universität Graz, Inffeldgasse 25/F, 8010 Graz, Austria
*
Email address for correspondence: roisman@sla.tu-darmstadt.de

Abstract

This experimental and theoretical study is devoted to the investigation of head-on collisions of two drops of immiscible liquids. In the experiments, pairs of drops are made to collide at well-defined kinetic and geometric conditions. The sizes and relative velocity of the colliding drops close to the point of impact are measured by means of image processing. The deformed states after the impact, their evolution with time, and their stability are studied by visualization. The theory considers the dynamics of the rim formed at the edge of a radially spreading lamella due to capillary forces at the free surfaces of the lamella and at the liquid/liquid interface. The equations of the rim formation and motion are obtained from the volume, mass and momentum balance equations which account for the inertial, viscous and capillary effects. The theory predicts the evolution of the main geometrical parameters of the liquid mass formed by the drop collision: thickness of the lamella, diameter, and size of the rim cross-section. The theoretical predictions agree well with the experimental data, although no adjustable parameters are used in the model.

Type
Papers
Copyright
Copyright © Cambridge University Press 2011

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