Showing papers on "Marangoni effect published in 1979"
TL;DR: In this article, the state of oscillatory Marangoni convection in crystal growth from melt is described and the dependence of the number of oscillations on the zone length is investigated.
239 citations
TL;DR: In this article, the transition from the steady to the oscillatory Marangoni convection in a floating zone under reduced influence of the gravity is visualized by means of the already proved method of light-cut-technique.
232 citations
15 Mar 1979
TL;DR: In this paper, the motions of air bubbles in a viscous silicone oil in response to buoyancy and Marangoni forces have been studied, and the temperature dependence of the surface tension, γ′, was found to be −0.055 mJ/m 2 s.
Abstract: The motions of air bubbles in a viscous silicone oil in response to buoyancy and Marangoni forces have been studied. The Marangoni forces are produced by establishing a temperature gradient in the oil which generates a surface tension gradient over the bubbles. From the thermal gradients required to balance the buoyancy and Marangoni forces, the temperature dependence of the surface tension, γ′, is found to be −0.055 mJ/m 2 s. This is in agreement with an independent measurement of γ′ using the pendant drop technique.
202 citations
01 Oct 1979
TL;DR: In this article, the propagation of a continuous local surface pressure perturbation Δπ is studied using an original method, which allows the interpretation of the results by considering the dynamics of the liquid substrate and of the film.
Abstract: The linear propagation of a continuous local surface pressure perturbation Δπ is studied using an original method. The theoretical approach allows the interpretation of the results by considering the dynamics of the liquid substrate and of the film—the Marangoni effect. It is shown that the spreading of Δπ under continuous compression can be described by a diffusion of particle velocity mechanism with a constant Du = (E/αμ), where E is the dilatational modulus of the elastic film, α the Bressler-Talmud coefficient depending on the substrate hydrodynamics, and μ the substrate viscosity. The values of Du are in the range 350–3400 cm2 sec−1. Those of α → 6.8 ± 8 cm−1. The relation of this type of continuous compression experiment with periodical longitudinal waves is discussed. It is stressed that the system studied and the interpretation may be useful for the study of stagnant aqueous films, on solids, bearing a monolayer on their free surface.
60 citations
15 Mar 1979
TL;DR: In this article, a general formalism is developed to study interfacial instability of two immiscible incompressible fluids, and necessary and sufficient instability conditions for oscillating and non oscillating regimes are given for long wavelengths.
Abstract: A general formalism is developed to study interfacial instability of two immiscible incompressible fluids. Mass diffusion fluxes across the interface are the determining step. The surface mass balance equation depends upon the surface diffusion and convection and on the net flux. Discussion is restricted to longitudinal perturbations. Using the concept of surface elasticity, necessary and sufficient instability conditions for oscillating and non oscillating regimes are given for long wavelengths. The obtained criteria are extensions of the Sternling and Scriven ones.
59 citations
01 Sep 1979
TL;DR: In this paper, the plane Poiseuille flow of two immiscible fluids in a non-isothermal "capillary" channel under the combined action of pressure gradients, gravitational fields and surface tension gradients is studied.
Abstract: Abstract Plane Poiseuille flow of two immiscible fluids in a non-isothermal “capillary” channel under the combined action of pressure gradients, gravitational fields and surface tension gradients is studied. Conditions for attaining a Poiseuille-type regime are derived. Closed form solutions are obtained and discussed.
47 citations
TL;DR: Dimitrov et al. as discussed by the authors used the theory developed in Part I and a Maxwell model for a viscoelastic two-dimensional fluid to deduce specific relaxation time for lipid-rich mixed films for their experimental conditions.
37 citations
21 citations
01 Jan 1979
20 citations
01 Jan 1979
TL;DR: In this article, it was shown experimentally that the Marangoni phenomenon is the primary mechanism for the movement of a gas bubble in a nonisothermal liquid in a low gravity environment.
Abstract: It was shown experimentally that the Marangoni phenomenon is a primary mechanism for the movement of a gas bubble in a nonisothermal liquid in a low gravity environment A mathematical model consisting of the Navier-Stokes and thermal energy equations, together with the appropriate boundary conditions for both media, is presented Parameter perturbation theory is used to solve this boundary value problem; the expansion parameter is the Marangoni number The zeroth, first, and second order approximations for the velocity, temperature and pressure distributions in the liquid and in the bubble, and the deformation and terminal velocity of the bubble are determined Experimental zero gravity data for a nitrogen bubble in ethylene glycol, ethanol, and silicone oil subjected to a linear temperature gradient were obtained using the NASA Lewis zero gravity drop tower Comparison of the zeroth order analytical results for the bubble terminal velocity showed good agreement with the experimental measurements The first and second order solutions for the bubble deformation and bubble terminal velocity are valid for liquids having Prandtl numbers on the order of one, but there is a lack of appropriate data to test the theory fully
01 Jan 1979
TL;DR: Theoretical results have been obtained with a cylindrical melting zone as discussed by the authors, and compared with experimental results in a very small liquid zone, thus minimizing the effect of gravity.
Abstract: A temperature gradient along a liquid surface produces a surface tension gradient (generally in the opposite direction) and thus initiates, by the action of viscosity, a convection flow in the interior of the liquid zone. Theoretical results have been obtained with a cylindrical melting zone. They are compared with experimental results in a very small liquid zone, thus minimizing the effect of gravity. The Marangoni convection becomes unstable beyond a critical Marangoni number, and an oscillatory flow is set into motion which induces temperature oscillations. The Marangoni convection can be influenced by superposition of rotational flow or electromagnetic fields.
TL;DR: Fawzy et al. as discussed by the authors presented an analysis of the Orthogonality of Generally Normalized Eigenvectors and Eigenrows for linear non-conservative systems.
Abstract: 'Meirovitch, L., Analytical Methods in Vibrations, Macmillian Co., New York, N.Y., 1967. Beliveau, J. G., \"Eigenrelations in Structural Dynamics,\" AIAA Journal, Vol. 15, July 1977, pp. 1039-1041. Fawzy, L, \"Orthogonality of Generally Normalized Eigenvectors and Eigenrows,\" AIAA Journal, Vol. 15, Feb. 1977, pp. 276-278. Fawzy, I., and Bishop, R. E. D., \"On the Dynamics of Linear Non-Conservative Systems,\" Proceedings of the Royal Society of London, A., Vol. 352, 1976, pp. 25-40. Lund, J., \"Linear Transient Response of a Flexible Rotor Supported in Gas Lubricated Bearings,\" ASME Paper 75-Lub-40.
TL;DR: In this article, the authors considered the convergence of thermocapillarity in a fluid filling a rectangular enclosure at low Marangoni numbers and solved the problem in analytic form by means of biorthogonal functions.
01 Jun 1979
01 Jan 1979
TL;DR: The critical Marangoni number Ma(T)c for the onset of oscillatory MARM convection is of the order of 104 as discussed by the authors, and the frequency dependence of the oscillations on zone length and diameter is reported.
Abstract: Marangoni convection in a radiant heated 6 mm × 6 mm NaNO3 floating zone has been observed to dominate over natural convection and to provide effective flow mixing. Stationary Marangoni convection induced by a concentration gradient of a surface active impurity has been observed to be strong. Experiments on floating half zones showed oscillatory Marangoni convection. The frequency dependence of the oscillations on zone length and diameter is reported. The critical Marangoni number Ma(T)c for the onset of oscillatory Marangoni convection is of the order of 104. The state of oscillatory Marangoni convection is described.