Impact of undular surges on a vertical wall

In the current study, the impact of undular surges on a vertical wall was experimentally investigated under complex base flow conditions where the velocity and flow depth were instantaneously varied. Undular surges of different wave types and with a wide spectrum of wave amplitudes were generated in a long horizontal wave tank by the filling operation of a downstream tank. Two characterized maximum wave pressures were observed during wave-wall interactions: pulsating wave pressure at an elevation close to the base flow surface and impact wave pressure occurring at a much higher elevation. It was found that the pulsating wave pressure could be solely estimated from the maximum wave run-up height, independently of the surge type. Moreover, the maximum wave load exerted by nonbreaking undular surges also depended on the maximum wave run-up height. Furthermore, the present results indicated that the influence of base flow conditions on undular surge-wall interactions were negligible. In addition, the breaking criterion of solitary waves in shallow water region could be used as an estimate of the transition in surge type, independently of the base flow conditions.