Experimental study of the plunging wave process

Abstract

By means of flow visualization techniques, the key features of a two-dimensional plunging wave process had been identified. Previous literature was synthesized and new observations utilized to develop a qualitative picture of the breaking process. In the overturning stage, visual evidence suggested that the undulations on the underside of the plunging jet contributes to the roughness and instability of the air tube, affecting the length scales of its breakdown in the form of the sprayback. It was also realized that the shape of the sprayback can be attributed to the kinematics of individual particles forming the streamline. Scaling the sprayback suggested that they are at an order of five to ten centimeters apart. It was also found that the «wail» phenomenon previously noted in Kway (2000) is actually part of the front face of the elliptical air tube submerged into the water. The length scale of the bubble penetration visually suggested that the direct effects of breaking were felt to a depth of the order of the wave height, which was approximately fifteen centimeters in this experiment. © 2007 World Scientific Publishing Co. Pte. Ltd.