Surface discharge of negatively buoyant effluent in unstratified stagnant water

A series of laboratory experiments have been conducted for negatively buoyant effluents discharged through a protruding surface channel into unstratified stagnant water. The mixing behavior of the flow has been analyzed using digital video recordings of the dye colored discharge together with micro conductivity probe measurements. Plume trajectories and geometries have been determined by image processing and dilutions from the conductivity probe data. Comparison of non-dimensional results for plume characteristics showed similar features to those of submerged positively buoyant jets. However, notable differences are observed in the flow behavior prior to it plunging away from the free surface. As expected the overall dilution is lower when compared to submerged discharges. These differences are quantified and the new results provide information that can be used for the preliminary design of dense surface discharges.

► Negatively buoyant effluent discharged through a rectangular surface channel is examined. ► The mixing behavior of the flow has been analyzed. ► Plume trajectories and geometries have been determined. ► Differences were observed in the flow behavior prior to its plunging away from the free surface. ► Results provide information that can be used for the design of dense surface discharges.