Linear Damping Characteristics of Oscillating Rectangular Flat Plates and Their Effect on a Cylindrical Float in Waves

摘要

The linear viscous-drag coefficients of rectangular flat plates oscillating in the direction normal to their plane surfaces were obtained from experiments over a range of frequency and aspect ratio, with holes of various numbers and sizes cut in the plates. The effect of the number of holes on the drag coefficient is not as significant as the solidity and the aspect ratio. A solidity of 0.8, together with aspect ratios 1 or 2, seems to give the highest value of drag coefficient. A cursory study of the wave exciting force on a plate-float combination indicates that the added-mass force on the plate tends to cancel the bouyant force on the float. The canceling effect of the plate can be controlled by its size and depth of submersion, so that it seems feasible to find a plate-float combination together with a float support configuration which will tend to minimize the motions of a vehicle floating in a specified seaway. (Author)