Modeled Three‐Dimensional Currents and Eddies on an Alongshore‐Variable Barred Beach

Circulation in the nearshore region, which is critical for material transport along coast and between surf zone inner shelf, includes strong vortical motions. The horizontal length scales vertical structure associated with motions are not well documented on alongshore-variable beaches. Here, a three-dimensional phase-resolving numerical model, Simulating WAves till SHore (SWASH), compared surfzone waves flows barred beach, used to investigate eddies. Model simulations measured bathymetry reproduce trends mean circulation patterns, including alongshore currents rip current cells observed offshore wave heights from 0.5 2.0 m incident directions 0 15° relative shore normal. of simulated eddies, quantified using wavenumber spectra vorticity, suggest that increasing directional spread intensifies small-scale eddies ((10) m). Simulations bathymetric variability ranging uniform highly variable indicate large-scale ((100) m) may be enhanced by variability, whereas less dependent variability. dependence magnitude scale (centroid) vorticity very low-frequency (f ≈ 0.005 Hz) weak outer zone, decreases toward shoreline. affected turbulence, shear, bottom boundary layer dynamics.