Development of Active Wave-induced Overtopping Control System [AWOC] using a Self-adaptive Floating Structure

Abstract

In this study, an active overtopping control system [AWOC] that could effectively supress the flooding caused by storm surge was presented, and numerical simulations to verify the overtopping control effect of AWOC were also carried out using OlaFlow, an OpenFoam-based toolbox. In the AWOC, the floating structure that works as the overtopping controller is submerged in a mild sea, and when exposed to a storm, it rises when the sea level are getting increased due to a storm surge, and as a result, would effectively supress the wave-induced overtopping. Due to these characteristics, the AWOC has the advantage of controlling overtopping at the minimum opportunity cost to preserve the beautiful beach landscape. In the numerical simulation, the motion of a floating structure that rises or descends coupled with the sea level during a storm surge or harsh waves was described by solving the structure motion equation using the water pressure acting on it as an external force. In doing so, Dynamic Mesh was used for the sake of more accurate numerical simulation, in which the computational mesh is updated whenever floating structure moves. Numerical result shows that even though overtopping flow becomes more energetic compared to that in the rubble-mound breaker due to the emhanced reflection after the deployment of AWOC, AWOC could effectively control the enhanced overtopping. It is also shown that an obliquely descending flow from the first quadrant to the third quadrant is formed in the front of AWOC due to the offshore-directed flow commencing from the floating structure of AWOC.