Inline force on human body due to non-impulsive wave overtopping at a vertical seawall

Abstract

Wave overtopping endangers pedestrians on a seawall’s crest area, but quantitative assessment of the risk is still a challenge. In this study, a circular cylinder is taken as a schematisation of human body. Physical model tests and numerical simulations were conducted to investigate the inline force on the cylinder due to overtopping flow at a vertical seawall. It is found that the overtopping flow is well reproduced by the numerical model. When the overtopping flow encounters the cylinder, a high pressure zone is developed on the front surface of the cylinder due to the local flow stagnation, while a shallow wake flow occurs behind the cylinder due to the blockage effect. The asymmetric pressure distribution produces the inline force on the cylinder. When the cylinder is further moved inland, the depth of the local overtopping flow it faces is smaller. However, the inline force does not decay accordingly, which is due to the variation of the flow velocity along the seawall’s crest. Finally, a predictor is developed for desktop computation of the maximum inline force. A prototype-scale numerical case study is carried out to demonstrate the capability of this predictor.