Development of Hybrid RANS/LES Model for Oceanic Turbulent Flows

The ocean plays a crucial role in Earth's climate as it acts as a reservoir of heat, energy, and carbon dioxide. As such, it is imperative to develop numerical methods and parameterizations to predict global ocean circulation flows efficiently. Although direct-numerical and large-eddy simulation techniques are optimal for achieving high-fidelity ocean computations, the cost of resolving all or most turbulent scales makes these methods excessively expensive for practical applications. In contrast, Reynolds-Averaged Navier-Stokes (RANS) parameterizations can significantly reduce the cost of ocean simulations. However, the limitations of such parameterizations representing ocean physics often lead to low-fidelity computations. We extended the hybrid RANS/LES Partially-Averaged Navier-Stokes equations (PANS) to oceanic flows by developing a scale-aware closure for such a class of problems. The PANS model aims only to resolve scales that are not amenable to parameterizing. This strategy leads to the concept of accuracy-on-demand and can significantly increase the efficiency of ocean computations. This work presents the governing equations of the new PANS closure and discusses the results of the predictions of the flow problems constituting the initial validation space of the model.