Numerical simulations of oil droplets rising in a sharply stratified fluid*

Rising droplets and bubbles in stratified fluids are a physical feature of many atmospheric and oceanic systems. For example, the Deepwater Horizon oil spill in 2010 resulted in large plumes being trapped as they rose through stratified layers in the Gulf of Mexico. To begin understanding how and why these plumes became trapped, we produced high fidelity numerical simulations of a single oil droplet rising in a stratified ambient flow. The numerical methods we use include a modified pressure correction projection method on adaptive non-graded octree grids and a coupled level set-reference map method to capture the moving interface. These simulations are compared against recent experimental results, which characterized the velocity and dynamics of the retention of a droplet rising in stratification. Through simulations, we provide a detailed analysis of the forces acting on the droplet.