ORDER-PARAMETER EQUATION AND MODEL EQUATION FOR HIGH PRANDTL NUMBER - RAYLEIGH-BENARD CONVECTION IN A ROTATING LARGE ASPECT RATIO SYSTEM

We derive the order parameter equation which describes the evolution of spatio-temporal patterns close to the Benard instability in a rotating large aspect ratio system for high Prandtl number fluids. Since this order parameter equation contains rather complicated nonlinear terms we present a model equation which can be obtained from the order parameter equation by suitable simplification of the nonlinearity. For this model equation we calculate the family of roll solutions and investigate their stability with respect to long scale instabilities and examine the onset of the Kuppers-Lortz instability. Then we present spatiotemporal patterns which are obtained from a numerical evaluation of the model equation.