Anexperimentalinvestigationofdropdeformation-Core.PDFVIP

J . Fluid Mech. (1986), vol. 167,p p . 241-283 24 1 Printed in eat Britain An experimental investigation of drop deformation and breakup in steady, two-dimensional linear flows By B. J. BENTLEYt AND L. G. LEAL Chemical Engineering Department, California Institute of Technology, Pasadena, CA 91 125, USA (Received 11 April 1985 and in revised form 21 December 1985) We consider the deformation and burst of small fluid droplets in steady linear, two-dimensional motions of a second immiscible fluid. Experiments using a computer- controlled, four-roll mill to investigate the effect of flow type are described, and the results compared with predictions of several available asymptotic deformation and burst theories, as well as numerical calculations. The comparison clarifies the range of validity of the theories, and demonstrates that they provide quite adequate predictions over a wide range of viscosity ratio, capillary number, and flow type. 1. Introduction I n this paper, we discuss the behaviour ofa fluid drop, freely suspended in a second, immiscible, viscous fluid which is undergoing a general linear two-dimensional flow. The flow-induced stress on the drop surface tends to deform the drop, and the interfacial tension between the phases resists this deformation. Under some conditions, the interfacial forces are insufficient to balance the viscous stresses, and the drop bursts. The problem is of both practical and academic interest, and has thus received considerable attention in the fluid-mechanics literature over the past fifty years. Our particular contribution lies in a systematic investigation of the effect of vorticity in the imposed flow for so-called ‘strong’flows, w