Inclined layer Soret instabilities.
Linear stability of a binary mixture buoyant return flow in a differentially heated inclined infinite layer is investigated by asymptotic long-wave analysis and pseudospectral Chebyshev numerical solutions. The Soret coefficient is negative so that thermodiffusion separates the species with the heavier component migrating to the hot wall, thus, promoting unstable stratification except in the classical Rayleigh-Benard arrangement. It is shown that longitudinal instabilities with small wave numbers are triggered at any finite temperature difference at all angles of inclination except very close to the horizontal heated from the above or below arrangements. Numerical results are given for a specific water-ethanol mixture and are in excellent agreement with the asymptotic results. As is well known the heated from below horizontal layer is overstable while that heated from above is doubly-diffusive unstable. Transition from the longitudinal stationary instabilities in inclined layers to these instabilities in horizontal layers is also given for this mixture.
Zebib
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Mechanical and Aerospace Engineering, Rutgers University, Piscataway, New Jersey 08854, USA. zebib@rutgers.edu
Bou-Ali
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