Dynamics of Buoyancy-Driven Exchange Flow over an Obstacle

Buoyancy-driven exchange flows arise in the natural and built environment wherever bodies of fluids at different densities are connected by a narrow constriction, and two layers of fluids have enough momentum to develop a strong shear-layer at the interface. This often leads to complex flow and mixing patterns. A prime example of this flow observed between the North and South sides of the Great Salt Lake (GSL), Utah. Recent seminal experimental research on this class of flows by Lefauve and Linden [1,2] and complementary numerical study [3] has quantified the turbulent structures of the flow at mixing interface. The current study, inspired by the obstacle hindered flows between the North and South sides of the flow observed at the GSL [4], quantifies the effect of a rectangular obstacle on the dynamics of the flow. The results will focus on the steady-state long-term dynamics at the mixing interface, investigating the effect of the obstacle and the impact of Reynolds number and densimetric Froude number on the mixing dynamics. The study will use direct numerical simulations (DNS) of the governing equations under the Boussinesq approximation, solved using high-order spectral element method.