Large eddy simulations of turbulent oceanic flows

SOMAR-LES is a numerical tool combining adaptive mesh refinement and large eddy simulation developed to study high-resolution large-scale oceanic flows. In this study, we consider two different test cases: (1)stratified shear layer, (2)baroclinic front. In the first test case, a simple vertical shear layer is set up in a linearly stratified medium. Adaptive refinement is used to refine the mesh along the braids such that secondary instabilities are well captured. Results from this simulation are compared with DNS. Quantitative analysis of turbulent kinetic energy budget shows that the turbulent production, buoyancy flux, and the dissipation rate agree well with DNS results. In the second test case, the flow is initialized with a balanced geostrophic current and a lateral density gradient. The geostrophic current becomes unstable due to baroclinic instability and forms turbulent eddies which mix up the fluid in both vertical and lateral directions. Again, using the adaptive refinement, a fine resolution is achieved along the regions of high buoyancy gradients. It will be demonstrated that SOMAR-LES is both computationally efficient and accurate in computing turbulence and mixing parameters.