Fluctuating Fluid Forces Acting on Circular Cylinders Commencing their Motion in Still Water.(Suppression of Nonrepeatability of Fluctuating Lift by Control of Boundary Layer Separation In Repeated Motion.)

摘要

When circular cylinders are moved in still water, it is known that fluctuating lift exhibits nonrepeatable characteristics even if the cylinders are repeatedly towed or swung under the same conditions. In this study, asymmetric wake is produced by control of boundary layer separation with placing tripping wire on the surface of circular cylinders in towed or swung motion to suppress the nonrepeatability of fluctuating lift. The effectiveness of the suppression was evaluated by standard deviation of ensembly collected lift data at each towed distances or swung angles and flow visualizations. The results obtained by this study will be applied to the development of manipulator arms operated in water where effects of mechanical vibrations are insignificant in comparison of that of fluctuating fluid forces associated with vortex formation.