Thermodiffusion phenomena.

The aim of this article is to present briefly a summary of the state of art in theoretical, experimental and numerical approaches in thermodiffusion. The concepts and equations giving the mass flux of constituents in binary, ternary and multicomponent mixtures are presented

Two-dimensional numerical analysis of the Poiseuille–Bénard flow in a rectangular channel heated from below

The Poiseuille–Bénard flow (PBF) is studied by a two-dimensional numerical simulation for a Prandtl number equal to 6.4 (that of water at 23 °C) and for a wide range of Rayleigh (Ra) and Reynolds (Re) numbers: Ra⩽6000 and Re⩽3. The two observed flow configurations are (1) thermally stratified Poiseuille flow and (2) thermoconvective transversal rolls superimposed to the basic Poiseuille flow. The time evolution of the velocity components, the spatial development of the transversal rolls, their frequency, wavelength and velocity, the Nusselt number, together with the stability map in the Ra–Re plane, are studied in detail. Whenever possible, quantitative comparisons are made with published results: most of the experimental data, based on laser-Doppler anemometry (LDA), are recovered with amazing accuracy; a good agreement with results of convective stability deduced from a weakly nonlinear Ginzburg–Landau theory is also obtained

Étude expérimentale de la convection mixte entre deux plans horizontaux à températures différentes—II

Une investigation expérimentale par anémométrie laser est réalisée pour déterminer les conditions d'apparition de la convection mixte sous forme de rouleaux transversaux ou longitudinaux dans un canal rectangulaire. Les expériences sont effectuées pour des nombres de Reynolds Re et des nombres de Rayleigh Ra dans le domaine 0,03 ⩽ Re ⩽ 3,3 et Ra ⩽ 4700, utilisant l'eau comme fluide d'étude

Onset of Free Convection in Solutions with Variable Soret Coefficients

It is not unusual for a Soret coefficient to change sign with temperature. We develop the theory for the onset of convection in such systems, heated from below or from above, provided that the mean temperature is precisely that at which the change of sign occurs. We also consider the realistic case of rigid, conducting, impervious boundaries for later comparison with laboratory experiments

Le problème de Bénard dans les mélanges : cas de surfaces libres

Platten Jean Karl. Le problème de Bénard dans les mélanges : cas de surfaces libres. In: Bulletin de la Classe des sciences, tome 57, 1971. pp. 669-683

Critical slowing down of the Soret-driven convective instability in a two-component liquid layer heated from below

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Etude numérique non linéaire de la convection libre à deux dimensions

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The two-component Bénard problem with flow. II. further numerical results

A numerical solution for the two-component Benard problem with flow is presented, taking into account the contribution of thermal diffusion to the total density gradi-ent. The results are compared with the approximate solution obtained by the variational technique of the local potential introduced some years ago by Glansdorff and Prigogine. With a transverse rolls pattern, the destabilizing effect of a flow in a fluid mixture stabilized by the thermal diffusion effect is confirmed. A further checking of these results is presented. Using again the local potential technique, calculations are conducted with a Chebyshev polynomial expansion as trial functions. The two methods produce critical Rayleigh numbers which are in agreement with each other. Thus it is conjectured that a decrease of the critical Rayleigh number with the Reynolds number, is a real phenomenon. © 1978, Walter de Gruyter. All rights reserved.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Nonlinear temperature and velocity distributions in the two-dimensional Bénard problem

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Dynamics of the Rayleigh Benard and Soret driven instabilities

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