Localized Waves without the Existence of Extended Waves: Oscillatory Convection of Binary Mixtures with Strong Soret Effect

Abstract

Spatially confined solutions of traveling convection rolls are determined numerically for binary mixtures like ethanol-water. The appropriate field equations are solved in a vertical crossection of the rolls perpendicular to their axes subject to realistic horizontal boundary conditions. The localized convective states are stably and robustly sustained by strongly nonlinear mixing and complex flow-induced concentration redistribution. We elucidate how this enables their existence for strongly negative separation ratios at small subcritical heating rates below the saddle-node of extended traveling convection rolls where the quiescent fluid is strongly stable.Comment: 4 pages text. The high quality figures can be downloaded at http://www.uni-saarland.de/fak7/luecke/publications.htm