Flow structure and mixing dynamics of the advected line thermal

Ocean outfalls are modelled as buoyant jets. The final behaviour in a deep ocean is the advected line thermal, which is dominated by the jet buoyancy and the ambient velocity. The dilution of the effluent along its path is of interest, in some cases the traditional time averaged information is needed and in others the instantaneous or peak concentrations are needed. Laser induced fluorescence (LIF) is used to study the instantaneous flow structure and the mixing dynamics of the advected line thermal. Large scale structures in the flow are identified as subthermals and their development influences the flow behaviour. Statistical measures of the magnitude of the concentration fluctuations and the intermittency of the flow are obtained from LIF images.