The particle imaging velocimetry, or PIV is applied to investigate unsteady flows inside and outside a hollow circular cylinder with impulsively starting to rotate in a uniform flow in order to obtain some fundamental data about the historical force effect and flow features. These flows are visualized by the solid particle tracer technique and analyzed using the PIV based on the two-dimensional binary image cross-correlation method in which three consecutive frames are used to detect positions of particles and to obtain particle velocity vectors. A one-dimensional unsteady model is used to analyze the flow inside the rotating hollow cylinder. For the outside flow, the velocity and pressure in the Navier-Stokes equation are solved based on control volume method in space and an implicit scheme in time. Velocity vectors, streamline patterns, lift and drag are obtained for Re=40 and rotating speed #alpha#=1.
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