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KAGAKU KOGAKU RONBUNSHU, Vol.23, No.6, 741-748, 1997
Vortex generation and properties of transition to turbulence in a Taylor-Couette flow system with small aspect ratio
The generation of vortices and transitional properties to turbulent flow in a Taylor-Couette flow system with an aspect ratio of 3 were investigated in terms of the effect of the acceleration of the inner cylinder rotation speed by using numerical, electrochemical and flow-visualization techniques. The three-dimen-sional simulation based on the SMAC method clarified the generation mechanism of vortices and temporal and spatial properties in a wavy vortex flow. The electrochemical and flow-visualization techniques revealed the temporal and spatial properties in wavy, quasi-periodic wavy and weakly turbulent wavy vortex flows. Lower acceleration rates produced the two-cell primary mode, while the four-cell secondary mode was generated in the case of higher acceleration rates. In a wavy vortex flow, the single fundamental frequencies, which correspond to the passing frequencies of the travelling azimuthal waves, velocity and velocity gradient power spectra depend on the flow modes. In quasi-periodic and weakly turbulent wavy vortex flows, the temporal-spatial properties also largely depend on the cell modes. These results suggest that the geometric structure of vortex cells influences flow characteristics.