生物が付着したホタテ養殖籠の流水抵抗について

概要

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Net cages become inevitably encrusted with marine organisms in scallop culture. The darg of the net cage composed of 10 compartments (0.5m in diameter and 2m high, covered with 0.8mm polyethylene mono-filament net of mesh size 4.0cm) encrusted with marine organisms is still not sufficiently clear. In this study, we measured the drag of three net cages (named cage A, cage B and unused cage) with different encrusted conditions of marine organisms in an experimental tank. The cage A was suspended by a main rope in an actual scallop culture facility for 3.5 months in winter season and marine organisms weighed 0.62kg in water without scallops. The cage B was used by a scallop culturist over a period of 14 months in the same facility, and its overall weight in the water consisted of 1.6kg of cage, 5.5kg of 100 scallops grown up to average size of 120mm, and 2.4kg of marine organisms. The unused cage was an empty new cage. The experimental results were drawn in CD-Re diagrams (CD: drag coefficient, Re: Reynolds number) For each of the three cages the change of CD to Re was small within the experimental range of 5.0×104<Re<3.0×105. The mean value of CD was 1.2 for cage A, 1.9 for cage B and 0.39 for the unused cage when set in normal to the water flow and 1.6, 1.8 and 1.4 when set in parallel, respectively.
日本水産學會の論文