A Simple Nonlinear Eddy Viscosity Model for Geophysical Turbulent Flows

Eddy viscosity models in turbulence modeling can be mainly classified as linear and nonlinear models. Linear formulations are simple and require less computational resources but have the disadvantage that, those can’t predict actual flow pattern in complex geophysical flows where streamline curvature and swirling motion are predominant. A constitutive equation of Reynolds stress anisotropy is adopted for the formulation of eddy viscosity including all the possible higher order terms quadratic in the mean velocity gradients and a simplified model is developed for actual oceanic flows where only the vertical velocity gradients are important. The simplified formulation is used for the study of natural convection flow in a vertical water column and the results are compared with the observational data and predictions of other existing turbulence models. The developed formulation can be incorporated in other computational fluid dynamics codes for the flow analysis in various engineering applications. The model predictions of marine turbulence and other related data (e.g. sea surface temperature, surface heat flux and vertical temperature profile) can be utilized in determining the effective siting for the Ocean Thermal Energy Conversion (OTEC) plants and in particular for the development of tidal energy projects.