Hydrodynamic and turbulence under breaking waves at the CIEM flume, Hydralab +

The experiments here planned seeks a unique experimental campaign in the CIEM large‐scale wave flume over a fixed barred beach profile, with the key aim of measuring detailed hydrodynamics and turbulence in the surf zone, thus extending the initial exciting insights gained within the SINBAD and previous Hydralab projects and further advance model development. In particular, our collaborative research efforts will focus on:

Wave Boundary Layer Dynamics: to enhance knowledge of boundary layer dynamics across the breaker bar, especially the effect of wave breaking generated turbulence on the wave boundary layer velocities, turbulent shear stresses and the bed shear stress.

Time‐Averaged Velocities: these mean velocities within the water column (undertow) and wave boundary layer (streaming) are of particular importance to sediment transport but also to the dispersion of pollutants in the surf and shoaling zones. Undertow (offshore directed) and streaming (onshore or offshore) interact, and the vertical structure of the resulting time‐averaged flow is affected by processes such as turbulence, beach profile, flow uniformity, bed roughness and wave shape. To date, reliable simultaneous measurements of undertow and streaming for rough turbulent boundary layers are lacking (Scandura and Foti, 2011).

Specific project objectives:

• to obtain a high quality, high‐resolution, data set of hydrodynamics and turbulence in the outer flow and wave boundary layer around a breaker bar, under different wave conditions;
• to apply the findings from the dataset to test and improve state‐of‐the‐art numerical modelling approaches and to develop new parameterisations for use in practical models