6. A Long Wave around a Breakwater : Case of Perpendicular Incidence [3]

Abstract

In the present work, the calculations are carried out for the waves of large wave-length in the windward waters around the gap of the breakwater in order to examine the nature of the trapezoid of the crest lines, which was ascertained for the case of the long wave around an estuary in the previous work. The result of the computation reveals that the feature of the trapezoid appears in front of the gap of the breakwater in a form a little different from the trapezoid for the case of the long wave around the estuary and that the waves advancing to the entrance in the nearby waters of the terminus of the breakwater are retarded as the result of the collision of the waves with the breakwater wing. In the last part of this study, a brief note on the generation of the high waves along the windward part of the breakwater is made referring to other authors'works, which show the appearance of the high waves near the terminus of the breakwater.|筆者は河口における長波に関する前報告において,すでに河口前面において波の峰線が梯形をなして水路に進入することを確めた.この現象が防波堤の前面においてもおこることを予想して,防波堤前面における長波の峰線を計算したのが本報告である.その結果によると,波の峰線の梯形的性質は河口前面同様防波堤前面においても現われる.そのほか知られた著しい事実は防波堤端近くの波の峰線に一つのゆがみがおこることである.これは防波堤開口部に向って進む波が防波堤の端にぶつかり停滞をおこした結果生ずるものと考えられる.また本報告の後半においては,防波堤前面部に,最大波高が進人波の波高の2倍をこえる高波が現われることについて,他の著者の研究結果(その結果はいずれも前述の高波の発生を述べている)を参照しながら，簡単な註釈がおこなわれている