Laboratory and Numerical Experiments on Stem Waves due to Random Waves

Abstract

In this study, precisely-controlled laboratory experiments were conducted to investigate the characteristics of stem waves developed by the incidence of unidirectional random waves. The measured data were compared with numerical simulation results and analytical solutions. Numerical simulation using the non-hydrostatic wave model, SWASH, were performed. The followings were found: for the case of small amplitude waves no stem wave is developed, and the analytical solution agrees well with the measured data. However, for the finite amplitude waves the analytical solution gives no stem wave, while the measured data show clearly stem waves along the wall. On the other hand, the numerical results are found to agree well with the measured data. The width and normalized wave height of stem waves were found to be wider and smaller, respectively, as the nonlinear property of the incident waves increased. This tendency is the same as that generated by monochromatic waves. However, the normalized significant wave height distribution normal to the wall showed that, unlike in the case of monochromatic waves, no standing wave pattern is observed.