Abstract
The lift force acting on circular cylinders submerged in sinusoidally oscillating flows was studied in a water tunnel. The measurement of the lift force reveals that the frequency of the force fluctuation is locked in that of the oscillatory flow for broad band of the KC number. The lift coefficient is correlated with the KC number and the β number. The flow visualization made with fine polystyrene particles showed that the fluctuation of the lift force is correlated with the vortex shedding and decaying, and the variation of the lift force with time was reasonably reproduced from the vorticity field. The intermittency of the lift force, i. e. beat, was successfully explained in terms of the instability of the vortex shedding.
