Simulations of oscillatory convection in 3 He – 4 He mixtures in moderate aspect ratio containers

sReceived 9 May 2004; accepted 28 March 2005; published online 26 May 2005d Simulations of He– He mixtures with negative separation ratios in two-dimensional containers with realistic boundary conditions and moderately large aspect ratio G are described. The system exhibits a large variety of states with complex time dependence including intermittent wave localization and chaotic “repeated transients.” Steady but localized states are also found. Particular attention is paid to the transitions that occur for sR−Rcd /Rc<G, where R is the Rayleigh number and Rc its critical value for the primary instability, in order to clarify the gradual transition from a small number of active degrees of freedom fsR−Rcd /Rc!Gg to many active degrees of freedom fsR−Rcd /Rc@Gg. © 2005 American Institute of Physics. fDOI: 10.1063/1.1920349g