Negatively Buoyant Slot Jets

The behavior of negatively buoyant slot jets discharged from near the bottom of stagnant and flowing receiving-water environments of uniform density was studied in laboratory experiments. In particular, the locations of the maximum height of rise and maximum horizontal displacement were determined as well as the centerline dilutions at those points. Experiments in stagnant environments were conducted for discharges at angles of 30°, 45°, 60°, and 90° from the horizontal and with discharge densimetric Froude numbers of 10, 20, 30, 40 and 50. For flowing environments, discharges at angles of 45° and 90° for the same range of densimetric Froude numbers were directed into uniform currents with discharge to ambient velocity ratios of 15 and 25. The reattachment eddy formed between the jet and bottom boundary was found to have significant effects on the slot jet trajectories and dilutions. Dilutions at the maximum height of rise and maximum horizontal displacement were less than those predicted for slot jets far removed from the influence of the bottom boundary. The strictly two-dimensional discharges studied provide lower bounds on the dilutions to be expected for the cases of slots of finite length or merged multiport diffuser discharges in which the reattachment eddy is not as well developed.