Three-Dimensional Non-Hydrostatic Modeling with LES Leray-α Turbulence Model: Applications to Complex Tidal Environments

Ocean turbulence modeling is still an open problem that is generally approached with the use of different modeling for the horizontal and vertical mixing due to the assumption of different turbulent length scales. In some cases, as Alderney Race, small three-dimensional (3D) turbulent structures with comparable horizontal and vertical length-scales are observed. To simulate these structures an integrated 3D modeling with the same turbulence model in the three dimensions is required. This will be achieved by integrating the Large Eddy Simulation turbulence model of Leray-α, which is based on the regularization principle of the Navier-Stokes equations first described by Leray in 1934, to the 3D non-hydrostatic solver of the CROCO oceanic model. The first step was to simulate the tide-induced hydrodynamics for an idealized configuration. A re-energization of the flow by the Leray-α turbulence model is observed, as found in former 2D studies. Then, the Leray-α model was used to simulate the turbulent hydrodynamics of Alderney Race, for which the results were compared to the ones obtained with classical turbulent models. The conclusions until now are the following: i) the Leray-α filtering procedure re-energizes the flow by changing the non-linear interactions, and ii) Leray-α is more computationally expensive than the LES Smagorinsky model and less expensive than the RANS k-ω model. The next step is to assess the accuracy of the Leray-α simulations with the use of in-situ data.