Experiments on plane negatively buoyant jets

Maria Voustrou, Panagiotis Yannopoulos, George Christodoulou

Wednesday 1 july 2015

11:30 - 11:45h at Antarctica (level 0)

Themes: (T) Special session, (ST) Marine outfall system

Parallel session: 9D. Special Session: Marine Outfall System

Dense effluents, such as desalination brines, are commonly discharged inclined upwards and form negatively buoyant jets (NBJ). In this paper, we report experiments on plane NBJ performed in a laboratory tank. The jets were discharged from a slot 20 cm long and 2 mm wide, placed at angles to the horizontal _ = 0º and 45º. The densimetric Froude number was in the range F= 15 - 38 and the Reynolds number Re = 1200 - 3200. The trajectory was measured by analysis of video recordings, whereas axial concentrations were determined by extracting small volumes of liquid, using a thin needle adapted on a flexible pipe of small diameter. The results are presented in dimensionless form and compared with existing data in the literature for _ = 0º, whereas for _ = 45º useful observations are made for the normalized terminal height of rise and the normalized distance to the return point compared to round NBJ. For both discharge angles, the results are found to agree reasonably well with model predictions.