Observations at the Columbia River plume show that wave breaking is an important source of turbulence at the offshore front, which may contribute to plume mixing. The lateral gradient of current associated with the plume front is sufficient to block (and break) shorter waves. The intense whitecapping that then occurs at the front is a significant source of turbulence, which diffuses downward from the surface according to a scaling determined by the wave height and the gradient of wave energy flux. This process is distinct from the shear-driven mixing that occurs at the interface of river water and ocean water. Observations with and without short waves are examined, especially in two cases in which the background conditions (i.e., tidal flows and river discharge) are otherwise identical.

Wave energy converters (WECs) often employ submerged heave plates to provide reaction forces at depths below the level of wave motion. Here, two sets of heave plate experiments are described, at varying scale. First, the Oscillator uses a linear actuator to force laboratory scale (30.5-cm diameter) heave plates in sinusoidal motion. Second, the miniWEC buoy uses vessel wakes to force field scale (1.5-m diameter) heave plates in open water with realistic energy conversion (damping). The motion and forces are analyzed using the Morison equation, in which the hydrodynamic coefficients of added mass C M and drag C D are determined for each set of Oscillator and miniWEC experiments. Results show strong intracycle variations in these coefficients, yet constant hydrodynamic coefficients provide a reasonable reconstruction of the time series data. The two test scales are examined relative to the Keulegan-Carpenter number (KC), Reynold's number (Re), and Beta number (β). The effects of asymmetric shape on hydrodynamic performance are found to be small.

Dynamic Wave Energy Converter (WEC) models utilize a wide variety of fundamental hydrodynamic theories. When incorporating novel hydrodynamic theories into numerical models, there are distinct impacts on WEC rigid body motions, cable dynamics, and final power production. This paper focuses on developing an understanding of the influence several refined hydrodynamic theories have on WEC dynamics, including weakly nonlinear Froude-Krylov and hydrostatic forces, body-to-body interactions, and dynamic cable modelling. All theories have evolved from simpler approaches and are of importance to a wide array of WEC archetypes. This study quantifies the impact these theories have on modelling accuracy through a WEC case study. Theoretical differences are first explored in a regular sea state. Subsequently, numerical validation efforts are performed against field data following wave reconstruction techniques. Comparisons of significance are WEC motion and cable tension. It is shown that weakly nonlinear Froude-Krylov and hydrostatic force calculations and dynamic cable modelling both significantly improve simulated WEC dynamics. However, body-to-body interactions are not found to impact simulated WEC dynamics.

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