Journal ArticleDOI
Interfacial turbulence: Hydrodynamic instability and the marangoni effect
C.V. Sternling,L. E. Scriven +1 more
TLDR
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.read more
Citations
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Journal ArticleDOI
Surface instabilities
TL;DR: In this paper, a comprehensive review of the physical properties of convective instabilities at the interface of a free surface is presented. But the authors focused on the effect of the elasticity of a flowing liquid, which is inherent to polymer solutions and melts, on the character of interaction between the liquid and the solid wall.
Book ChapterDOI
Liquid Sloshing Dynamics: Linear forced sloshing
TL;DR: In this article, the free oscillations of liquid free surface in different container geometries were developed and the natural frequencies were determined from the free-surface boundary conditions, and the hydrodynamic forces were estimated by integrating the pressure distribution over the wetted area.
Journal ArticleDOI
Theoretical analysis of Marangoni instability of an evaporating droplet by energy method
Vai-Meng Ha,Chun-Liang Lai +1 more
TL;DR: In this article, the energy method was applied to investigate the stability of an evaporating droplet against disturbances of any amplitude, and the results predicted by the present study possess similar trends with those acquired by the linear stability analysis, indicating that both the increase of surface temperature reduction and the growth of the thermal boundary layer near the free surface are conducive to the onset of instability.
Journal ArticleDOI
Auto-Emulsification of Water at the Crude Oil/Water Interface: A Mechanism Driven by Osmotic Gradient
J. Duboué,Maurice Bourrel,E. Santanach Carreras,Alexandra Klimenko,Nicolas Agenet,Nicolas Passade-Boupat,François Lequeux +6 more
TL;DR: In this paper, the origin of spontaneous emulsification occurring at the oil/water interface was studied and it was observed for five crude oils tested as well as at the interface of...
Journal ArticleDOI
Adsorption kinetics and compositional surface elasticity of multicomponent surfactant solutions
TL;DR: In this paper, the Laplace transformation was used to generalize the Fourier elasticity concept to arbitrary periodic and nonperiodic surface deformations, and an operator surface elasticity E(s) was introduced, analogous to the complex transmittance of an electrical circuit.
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