Characteristics of two-dimensional counter-flowing wall jets

Wastewater plant effluents discharged into streams are expected to undergo dilution in a short reach. Jets provide rapid mixing and enhance dilution of the effluent discharged into the stream. The counter-flowing wall jet expansion angle, the geometry of the dividing streamline and the jet penetration length were found using the measured mean axial jet velocity data. These jet characteristics were expressed in terms of the jet velocity ratio (jet exit velocity against main stream velocity). A salt solution of known concentration was injected into the jet flow. The distribution of the salt concentration was determined at several cross-sections of the jet wake using a concentration meter. The standard deviation of the salt concentration provided a measure of jet mixing. When standard deviation reached zero at a cross-section, mixing was considered to be complete.