TURBULENT BUOYANT CONVECTION FROM A SOURCE IN A CONFINED TWO-LAYERED REGION.

The paper considers the time evolution of a layer of fresh water placed on top of a layer of salt water in a laboratory tank when denser salt water is supplied to a nozzle at the free surface. The inflow is carried out slowly so as to form a pure plume, which at first does not penetrate through the interface. The two basic processes that govern the time evolution of the initially fresh-water layer are the filling-box process and the entrainment through the end of the plume which impinges upon the density interface. A theoretical model that takes these two processes into account is presented, with the numerical solution of the asymptotic state, valid at large times. The asymptotic solution and experiment are in good agreement. The entrainment rate obtained from changes in thickness of the upper layer with time can be expressed as a function of the Froude number. The buoyancy flux across the interface, which is nondimensionalized by the rate of buoyancy input, also changes as a function of Fr. Refs.