Study on Scale Effect of the Resistance due to Stem Wave Breaking

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(1) Clarification of the water flow structure just behind a transom stemThe detailed observation of water flow just behind a transom stem has clarified that reverse flow exists on water surface there and that the reversed flow is blocked out by the stem end and then flows along the stem end towards both sides and finally goes out into side flow. It has been also exprimentally confirmed that the reverse flow is generated as a result of forward-oriented wave breaking.(2) Development of methods to treat forward-oriented wave breakingWater flow just behind a transom stem has been approximated with trochoidal wave. Criteria for forward-oriented wave breaking occurrence have been proposed. Based on these, a method to estimate what thickness of flow layer under water surface breaks and an equation to estimate resistance due to forward-oriented wave breaking have been developed.(3) Clarification of forward-oriented wave breaking characteristicsStudies of the phenomenon by the methods developed in 2 have clarified that the phenomenon is much affected by the vertical flow speed distribution at stem end as assumed at the start of this study, it has, therefore, scale effect and non-dimensional coefficient of resistance due to the phenomenon decreases with increase of model ship size. On the other hand, it has been clarified that height of remained following waves, which is generated at stem end, not broken and propagated afterwards, increases with increase of model ship size to the contrary.(4) Study plan from nowRemained fallowing waves is to be studied at first. Next, scale effect of stem waves which consist of two components different in characteristics forward-oriented wave breaking and remained following waves is to be studied by the methods developed.