Nearshore Wave-Induced Current in the Laboratory
Paul Bayle (TU Delft - Environmental Fluid Mechanics)
Jessamy Mol (TU Delft - Environmental Fluid Mechanics)
Kai Kang (Student TU Delft)
Colin Whittaker (The University of Auckland)
Wout Bakker (TU Delft - Coastal Engineering)
Ton van den Bremer (TU Delft - Environmental Fluid Mechanics)
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Abstract
The study of nearshore wave-induced currents, which play a critical role in marine transport, has motivated numerous laboratory experiments, and yet, the understanding of cross-shore wave-induced currents under controlled laboratory conditions remains incomplete. For the first time, 3D Particle Tracking Velocimetry is applied in a laboratory flume to measure Lagrangian wave-induced currents in front of a slope under five different regular wave conditions. The wave-induced velocity profiles evolve over time, reaching a quasi-equilibrium after approximately one hour. In most cases, the observed profiles do not align with the theoretical Stokes or conduction solutions. The surface drift is consistently smaller than theoretically predicted, and in some cases even negative, indicating the presence of a strong Eulerian-mean return current in the upper portion of the water column. The observed patterns cannot be explained solely by the relative water depth kh and wave steepness ka, leading to the hypothesis that convection processes contribute to these discrepancies. Further investigation of visually observed coherent convective structures, such as vortex trains, will be undertaken.
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