BEACH RESPONSE IN FRONT OF WAVE-REFLECTING STRUCTURES

Roy C. Seaman, Tom O'Donoghue

Abstract


The results of an experimental study of beach response in front of wavereflecting structures are presented. The particular beach response problem is the so-called "N-type" response where sand is eroded in the area between the node and antinode and is transported towards the node. The characteristics of the equilibrium beach profile are presented and an equation describing the profile is proposed. The beach response is fundamentally dependent on the interaction between the flow and the ripples superimposed on the larger bedforms. Particle image velocimetry (PIV) has been used to look closely at the ripples and the flow. It is found that the sand transport towards the node results from larger vortex growth on the antinodal side of ripples than on the nodal side caused by the asymmetry in the main flow velocity time history which itself is a result of the superposition of the non-linear incident and reflected waves.

Keywords


reflection; beach response

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