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Journal ArticleDOI

Interfacial turbulence: Hydrodynamic instability and the marangoni effect

01 Dec 1959-Aiche Journal (John Wiley & Sons, Ltd)-Vol. 5, Iss: 4, pp 514-523
TL;DR: In this article, a simplified mathematical model has been analyzed in order to detail the mechanism of the "interfacial engine" which supplies the mechanical energy of interfacial turbulence, which is a manifestation of hydrodynamic instability, touched off by ever present, small, random fluctuations about the interface.
Abstract: The origin of interfacial turbulence, spontaneous agitation of the interface between two unequilibrated liquids, has been explained in terms of classical flow, diffusion, and surface processes. The essence of the explanation is the long-known though much neglected Marangoni effect, wherein movement in an interface is caused by longitudinal variations of interfacial tension. It is proposed that interfacial turbulence is a manifestation of hydrodynamic instability, which is touched off by ever present, small, random fluctuations about the interface. A simplified mathematical model has been analyzed in order to detail the mechanism of the “interfacial engine” which supplies the mechanical energy of interfacial turbulence. In its present form the analysis incorporates several drastic simplifications, though ways of removing some of these have been suggested. The groundwork has been laid for the more elaborate analyses that are needed for a decisive test of the theory. The analysis shows how some systems may be stable with solute transfer in one direction yet unstable with transfer in the opposite direction, a striking result. It also suggests that interfacial turbulence is usually promoted by (1) solute transfer out of the phase of higher viscosity, (2) solute transfer out of the phase in which its diffusivity is lower, (3) large differences in kinematic viscosity and solute diffusivity between the two phases, (4) steep concentration gradients near the interface, (5) interfacial tension highly sensitive to solute concentration, (6) low viscosities and diffusivities in both phases, (7) absence of surface-active agents, and (8) interfaces of large extent. That some of these effects have been observed in the laboratory lends credence to the theory.
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Journal ArticleDOI
TL;DR: In this paper, an attempt was made to elucidate the mechanisms of formation in terms of interfacial turbulence between two unequilibrated liquid phases involving flow, diffusion and surface tension decrease (Marangoni effect).

2,017 citations

Journal ArticleDOI
TL;DR: The existence of a slip velocity at solid/fluid interfaces opens a class of flow problems not generally recognized by the fluid-dynamics community as mentioned in this paper, and the existence of slip velocities at solid and fluid interfaces has been studied in the literature.
Abstract: In a historical context the interface between two phases has played only a minor role in the physics of fluid dynamics. It is of course true that boundary conditions at interfaces, usually imposed as continuity of ve­ locity and stress, determine the velocity field of a given flow; however, this is a more or less passive use of the interface that allows one to ignore the structure of the transition between two phases. When an interface has been assigned a more active role in flow processes, it generally has been assumed that one parameter, the interfacial (surface) tension, accounts for all mech­ anical phenomena (Young et al. 1 959, Levich & Krylov 1969). In these studies, kinematic effects of the interface were not considered, and the "no-slip" condition on the velocity at interfaces was retained. The basic message of this article is that the interface is a region of small but finite thickness, and that dynamical processes occurring within this region lead not only to interfacial stresses but also to an apparent "slip velocity" that, on a macroscopic length scale, appears to be a violation of the no-slip condition. The existence of a slip velocity at solid/fluid interfaces opens a class of flow problems not generally recognized by the fluid-dynamics community. Three previous articles in this series deal with flow caused by interactions between interfaces and external fields such as electrical potential, tem­ perature, and solute concentration. Melcher & Taylor ( 1969) and Levich & Krylov (1969) consider fluid/fluid interfaces where stresses produced at the interface by the external field dictate the flow. Saville ( 1977), on the other hand, discusses the action of an electric field on a charged solid/fluid interface and reviews the currently accepted model for electrophoretic

1,343 citations

Journal ArticleDOI
01 Jul 1960-Nature

1,130 citations

Book
19 May 2005
TL;DR: In this article, the authors present a detailed review of liquid sloshing dynamics in rigid containers, including linear forced and non-linear interaction under external and parametric excitations.
Abstract: Preface Introduction 1. Fluid field equations and modal analysis in rigid containers 2. Linear forced sloshing 3. Viscous damping and sloshing suppression devices 4. Weakly nonlinear lateral sloshing 5. Equivalent mechanical models 6. Parametric sloshing (Faraday's waves) 7. Dynamics of liquid sloshing impact 8. Linear interaction of liquid sloshing with elastic containers 9. Nonlinear interaction under external and parametric excitations 10. Interactions with support structures and tuned sloshing absorbers 11. Dynamics of rotating fluids 12. Microgravity sloshing dynamics Bibliography Index.

920 citations

Journal ArticleDOI
TL;DR: In this article, a new mechanism for the formation of macrovoids in phase-inversion membranes is proposed based on the observed difference in type of demixing of a thin film of a polymer solution when immersed in a nonsolvent bath.

801 citations