二次元一様流中における平板型流れ藻滞留施設について

抄録

Aquaculture facilities hindering drifting algal fronds on which abalone and sea urchin feed began to be constructed in some fishing grounds in Japan. The basic functions of thefacilities may be divided into the hitching of a grating and the blockage of a normal plate. In an uniform flow tank, model experiments on the latter functions were carried out with the frond miniatures released from the upstream of the plate set normal to the tank floor. As a result, in a fast stream, few of the miniatures coming to the plate are settled at the front while some of them passlng over it remain close to the back. In this paper, a catch ratio of fronds was defined as the ratio of the number of fronds staying behind the plate to that of those passing it. The ratio lowers as the plate becomes higher or as the main stream becomes faster. The mean flow velocity over the plate, Uc was indicated to be the most explanatory factor ofthe ratio. The general parameter of the ratio was derived from the consideration of the law of similitude and it was tested by additional experiments with different model scales and materials of miniature fronds. In consequence, there is a possibility that the in situ catch ratio can be estimated by the relative magnitude between the drag exerted on a frond fluttering in the flow of velocity Uc and its submerged weight.