Onset of convection in a two-phase binary mixture with the Soret effect in weightlessness

Тип публикации: статья из журнала

Год издания: 2015

Идентификатор DOI: 10.1063/1.4926891

Ключевые слова: Binary mixtures, Temperature, Weightlessness, Concentration gradients, Conservation of mass, Critical temperature difference, Interfacial concentrations, Latent heat release, Mechanical equilibrium, Onset of convection, Temperature differences, Mixtures

Аннотация: The linear stability of mechanical equilibrium in a two-layer system formed by different phases of the same binary mixture is investigated. The temperature difference is applied to the layers by heating and cooling the opposite rigid boundaries. In the state of mechanical equilibrium, the applied temperature gradient induces concentration gradients due to the Soret effect. The conservation of mass for the mixture components leads to the dependence of layer thicknesses on the applied temperature difference. In weightlessness, the main mechanisms of instability in the considered system are related to phase change and Marangoni effect. The calculations are performed for cyclohexane-methanol binary mixture, which has a liquid-liquid miscibility gap. The analytical solution of amplitude equations for monotonic perturbations is found and expression for the critical temperature difference is derived. It is shown that the phase change instability is long-wave and favoured when the difference between interfacial concentrations in the basic state decreases. When the Marangoni effect is taken into account, additional monotonic and oscillatory modes appear. They result from the interplay between thermocapillarity and phase change with latent heat release/absorption. The most unstable monotonic and oscillatory modes are identified depending on the heating regime and relative thickness of the layers. (C) 2015 AIP Publishing LLC.

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Издание

Журнал: PHYSICS OF FLUIDS

Выпуск журнала: Vol. 27, Is. 7

ISSN журнала: 10706631

Место издания: MELVILLE

Издатель: AMER INST PHYSICS

Авторы

  • Ryzhkov Ilya I. (Inst Computat Modelling SB RAS, Krasnoyarsk 660036, Russia; Siberian Fed Univ, Inst Space & Informat Technol, Krasnoyarsk 660041, Russia)
  • Tsarev Sergey P. (Siberian Fed Univ, Inst Space & Informat Technol, Krasnoyarsk 660041, Russia)

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