An experimental investigation was performed to study the fluid resistance acting on an oscillating disk over a wide range of Reynolds numbers. Data were reduced by the method of Fourier analysis to obtain average values of the added-mass and drag coefficients over one cycle of oscillation, i.e., k
av andC
Dav respectively.
The relationships between these coefficients and the modified Reynolds number, d
2ω/v, were found to change between two regions of d
2ω/v, where the flow pattern induced by the disk also changed. In the Reynolds number region where inner circulations are induced exclusively, k
av and C
Dav decreased with an increasing d
2ω/v and k
av was independent of the amplitude of oscillation. In the Reynolds number region where inner and outer circulations coexist, k
av was dependent only on the amplitude ratio,
a/d; C
Dav was almost independent of d
2ω>/v and correlated well with
a/d, provided d
2ω/v200. The maximum force on the disk during a cycle of oscillation was also examined. Empirical equations for the added-mass, drag and maximum resistance coefficients were presented for each region.
The average power number, N
Pav, was defined and correlations for N
Pav were theoretically derived from those obtained for C
Dav.
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