Dynamics of Rotating 2D Ellipse in Stratified Flow

Submersible vehicles that move through seawater are subjected to a variety of effects. Seawater has a non-uniform density because of uneven heating and the tendency of dense saltwater to sink. This non-uniform density distribution induced by gravity is known as stratification and introduces vertical confinement and internal gravity waves to flows around bodies. Along with translational motion, these vehicles also perform rotational motion. To identify the effects of density gradient, body shape, and rotation on the flow, 2D direct numerical simulations (DNS) are run and analyzed. The simulations are conducted using the open-source CFD solver Nek5000, utilizing its overset-grid-based methodology. The results show previously unreported patterns of drag and lift acting on rotating bodies, and show the regime when rotating motion of the ellipse results in formation of internal gravity waves.