Wave overtopping flow striking a human body on the crest of an impermeable sloped seawall. Part I: Physical modeling

Abstract

The present paper is the first of two companion papers on the investigations of wave overtopping flow striking a cylinder, which is the schematisation of a human body, on the crest of an impermeable sloped seawall with a deep foreshore. This paper presents the physical modeling part. The key measured physical quantities include the overtopping flow depth on the seawall crest and the inline force on the cylinder. It is found that the Iribarren number and the ratio of freeboard and incident wave height are the two key parameters that control wave breaking on the seawall slope and the overtopping flow on the seawall crest. Formulas are identified for quick estimation of the inline force due to overtopping flow. The maximum overtopping flow depth and the maximum inline force are found to decay exponentially with the distance from the seawall's edge, but the decay rates are rather low. By comparing the inline force experienced by a 3D-printed human model and a cylinder, the equivalent diameter of a human body is proposed to be 1.4 times the thigh width. Finally, a preliminary application was carried out to demonstrate the applicability of our research outcomes. It is found that the predicted maximum inline force on a human body exceeds the ground friction, when the smallest overtopping volume exceeds about 600 l/m (with a scatter range of 600–1 100 l/m), which is conservatively in consistent with the threshold proposed in the EurOtop manual.