Experimental and Numerical Modelling of Stratified Exchange Flows and Blocking over a Submerged Sill

Results are presented showing direct comparisons between physical laboratory experiments and lab-scale numerical simulations using the Bergen Ocean Model (BOM), a three-dimensional general ocean circulation model (https://org.uib.no/bom), of stratified exchange flow and saline intrusion blockage across an idealized, submerged sill. The experiments were conducted in a large rectangular channel with a trapezoidal sill incorporated to control exchange flow between adjacent saline and fresh water basins (Cuthbertson et al., 2018). The sill submergence depth, density difference between fresh and saline waters, and relative magnitude of inflow volume fluxes into each basin were varied systematically in the simulations. High resolution particle image velocimetry and micro-conductivity probes were used to measure velocity fields and density profiles generated across the sill under different parametric conditions. Experimental and numerical results indicate that saline water intrusion across the sill, as part of a well-defined, two-layer, stratified exchange flow, can be blocked under specific parametric conditions that depend on the relative magnitude of the fresh and saline water inflows and the sill submergence depth. BOM simulations are now being extended to consider the influence of rotation (i.e. Coriolis effects) on the exchange flow dynamics and saline blockage mechanisms.