海底構造物によって誘起される人工湧昇流の可視化実験

概要

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The upwelling current brings up nutrient-rich water from subsurface towards sea surface. If a plenty of nutrient are supplied intothe euphotic zone, the primary productivity will be increased there by enhancement of photosynthesis. As a result of a food chain,the upwelling region becomes an area of higher fishery production. In order to generate the upwelling artificially, various shapes ofmarine structures installed on the seabed are studied so far. The present paper describes the results of flow visualization carried outfor models of marine structures which generate upwelling effectively. The shapes of marine structure used in the experiments are atriangle cylinder like mountain range, a vertical wall, V-shaped structure and various combination of two V-shaped structures, such asX-shaped, W-shaped and so on. Flow visualization tests were carried out in a small towing tank whose dimensions are 4m long, 0.5mwide and 0.4m deep. The carriage runs on the bottom of the tank with constant speed by use of towing wire. The malachite green ofbasic dyes was used as a tracer. The height of models used is 3cm and the speed of carriage is 0.05m/s, and then Reynolds numberwas about 1350. It is found that if the subsurface current flows in one way direction, V-shaped structure induces the most effectiveupwelling. On the other hand, X-shaped structure generates upwelling effectively in all directions of current.
2011-12-25