Convection in binary fluid mixtures: A model of four coupled amplitudes

We consider the bifurcation scenario that is found in Rayleigh-Benard convection of binary fluid mixtures like ethanol-water at positive separation ratios and small Lewis numbers leading to a bifurcation sequence of square, oscillatory crossroll, stationary crossroll, and roll patterns. We propose a system of four coupled amplitudes that is capable to model all important properties.