STUDY OF BIFURCATION OF ROTATING FLOW IN A CLOSED SPACE AND ITS EFFECTS ON THE PARTICLE MOTION IN THE FLOW

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Rotating flow field is important for pure fluid mechanics but also for engineering problems and environmental problems. As a rotating flow paradigm, flow field in a closed vessel are investigated many years from various points of view but still many questions are remained to be clarified. In this research, two types of rotating flow are studied, one is Benjamin flow, that is Taylor vortex flow in finite length and the another is rotating disc flow. For Benjamin flow, we studied using numerical and experimental methods. Specifically, Nonlinear development of flow patterns in the case of decelerating cylinder is carefully calculated and details of bifurcation process is obtained. The comparison is made between an experiment, and the calculated results and excellent agreement is obtained. But in some cases bifurcation process is more complicated in the experiment. An important controversial point is to determine the flow pattern objectively from the computed results. We constructed a program which can clarify complicated formation process of Taylor vortex using artificial intelligence technique so we can classify various flow pattern without subjective knowledge. As the first step to analyze the motion of particles in rotating flow, an orbit of fluid particle is pursued using Runge Kutta scheme of which is written in JAVA and convenient GUI system is constructed. An experimental facility is made for flow visualization for the flow induced by a rotating disc in an enclosure. Aluminum powder method is used for visualization and flow field photographed by video camera recorder and analyzed by a graphic software. Regimes of flow field are classified according to increasing Reynolds number defined by the diameter of the rotating disc and peripheral velocity of it.