浅水域を横移動する船体に働く横力と水槽側壁影響

概要

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Estimation of the lateral force acting on VLCC moving slowly and laterally in shallow water is an important work for the berth manoeuver by using tug boats. However, since numerical values of the lateral force coefficient C_<wy> shown by some research institutions are remarkably different, it is difficult to estimate appropriately the force mentioned above. In this paper, on the supposition that the difference of C_<wy> values is caused by the blockage effect due to side walls of water tank, C_<wy> is investigated experimentally. From the present studies, following results were obtained: (1) The blockage effect of side walls have clearly influence on C_<wy> especially in shallow water, like the ratio of water depth to ship draft h/d=1.1. (2) In order to avoid the blockage effect, the water tank breadth b is needed to be over 6 times of the model ship length L, namely b/L>6. (3) When being the unrestricted shallow water h/d=1.1, C_<wy> of an oil tanker ship model is about 2.1. This numerical value is approximately equal to the drag coefficient of the flat plate in the two dimensional flow.
1991-09-25