THE CHAOTIC EVOLUTION OF PATTERNS IN BENARD-MARANGONI CONVECTION WITHSQUARE SYMMETRY

We present the results of a Benard-Marangoni convection experiment in a square container with small aspect ratio. When the control parameter s are slightly changed, a sequence of bifurcations is observed. Moreov er, in some measurable region of parameter space, a chaotic behaviour is evidenced. We show that this dynamics can be explained by assuming that the system is close to a codimension two (Takens-Bogdanov) bifurc ation after taking into account the symmetries of the system. The dyna mical model deduced from these simple observations reflects many of th e features present in the experiment. The characteristics of the chaot ic regime are also compared with those of the model.