連続球型浮魚礁の抵抗特性に関する基礎的研究

概要

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Spherical FADs (Fish Aggregating Devices) are one of several kinds of buoyant fishing attractants, designed to enhance coastal and offshore fishing grounds. To obtain fundamental data for the rational design of a series of spherical FADs, we investigated the drag force on spherical floats, changing the diameter and number of spheres linked in series in a circulating water channel. We used three kinds of spheres, 4.8cm, 9.2cm and 11.0 cm in diameter and moored them horizontally in the channel, to a maximum number of twenty. We measured the drag force increasing the flow velocity. Furthermore, we measured the drag force on the two linked spheres changing the distance between them. The drag force on two or three linked spheres was slightly less than that on one sphere. However, when the number of linked spheres was increased (>3), the drag force gradually increased although the rate of increase of drag force was much smaller than that of the increase in number of spheres. When the distance of two linked spheres became two to three times that of the diameter, it was considered that the linked spheres were independent.
2012-07-15