Effects of a temperature dependent viscosity on thermal convection in binary mixtures

Theoretische Physik I, Universita¨t Bayreuth, 95440 Bayreuth, GERMANY(Dated: October 3, 2013)We investigate the effect of a temperature dependent viscosity on the onset of thermal convectionin a horizontal layer of a binary fluid mixture that is heated from below. For an exponentialtemperature dependence of the viscosity, we find in binary mixtures as a function of a positiveseparation ratio ψand beyond a certain viscosity contrast a discontinuous transition between twostationary convection modes having a different wavelength. In the range of negative values of theseparation ratio ψ, a (continuous or discontinuous) transition from an oscillatory to a stationaryonset of convection occurs beyond a certain viscosity contrast, and for large values of the viscosityratio, the oscillatory onset of convection is suppressed.I. INTRODUCTION