Laboratory and numerical experiments on stem waves due to monochromatic waves along a vertical wall

Abstract

Abstract. In this study, both laboratory and numerical experiments are conducted to investigate stem waves propagating along a vertical wall developed by the incidence of monochromatic waves. The results show the following features: For small amplitude waves, the wave heights along the wall show a slowly varying undulation. Normalized wave heights perpendicular to the wall show a standing wave pattern. Thus, overall wave pattern in the case of small amplitude waves show a typical diffraction pattern around a semi-infinite thin breakwater. As the amplitude of incident waves increases, both 15 the undulation intensity and the asymptotic normalized wave height decrease along the wall. For larger amplitude waves with smaller angle of incidence, the measured data show clearly stem waves. Numerical simulation results are in good agreement with the results of laboratory experiments. It is found from a simple geometric relationship of wave pattern that the lengthening of wave length due to the nonlinearity of waves is responsible for the development of stem waves along the wall. The existence and the properties of stem waves for sinusoidal waves found theoretically based on numerical 20 simulations are fully supported by the physical experiments conducted in this study.