Buoyant horizontal jets in a stratified medium

Numerical simulations have been carried out using a time accurate fractional step Navier-Stokes solver defined on a non-staggered grid. Depending on the control parameters the jet remains horizontal, rises gradually or rises rapidly and attaches to the boundary above the jet inlet before, in all cases, transiting to an intrusion. Two main unsteady flow features have been identified for the attached jet which are believed to be associated with Tollmien-Schlichting- and Kelvin-Helmholtz-like instabilities. The Kelvin-Helmholtz and Tollmien-Schlichting waves are only observed for the attached flow. It is proposed that the Tollmien-Schlichting waves provide a base perturbation for the Kelvin-Helmboltz waves which are observed along the top half of the intrusion. There is strong mixing observed along the lower half of the intrusion for the attached flow and no waves are observed there.