THE DEVELOPMENT OF ASYMMETRY AND PERIOD-DOUBLING FOR OSCILLATORY FLOWIN BAFFLED CHANNELS

We report experimental and numerical observations on the way initially symmetric and time-periodic fluid oscillations in baffled channels de velop in complexity. Experiments are carried out in a spatially period ic baffled channel with a sinusoidal oscillatory flow. At modest Reyno lds number the observed vortex structure is symmetric and time periodi c. At higher values the flow progressively becomes three-dimensional, asymmetric and aperiodic. A two-dimensional simulation of incompressib le Newtonian flow is able to follow the flow pattern at modest oscilla tory Reynolds number. At higher values we report the development of bo th asymmetry and a period-doubling cascade leading to a chaotic flow r egime. A bifurcation diagram is constructed that can describe the prog ressive increase in complexity of the flow.