Local wave effects near a front advancing into calm water

Abstract

A theory is developed which describes the local wave effects near a wave front advancing into calm water and is uniformly valid near the front. The waves generated by an oscillating vertical boundary (a wavemaker) and propagating out into infinitely long channel are investigated both theoretically and experimentally. Comparison of the theoretical and experimental results indicates that the theory does predict the wave phenomena about the front to a good degree of accuracy. Conclusions are drawn regarding the transient wave response to a wavemaker and compared to those of John W. Miles regarding the transient gravity wave response to an oscillating pressure. The transient features of the wave front considered are the width of the transient zone at a given time since the disturbance to the free surface of the fluid and the length of the transient period at a given distance from the disturbance. It is shown that the conclusions regarding transient gravity wave phenomena apply without qualification to the waves generated by both oscillating pressure sources and moving surfaces.