Physical modelling of buoyant effluents discharged into a cross flow

摘要

This study focuses on physical modelling of turbulent vertical buoyant jets, discharged into a transversal current and interacting with localized background turbulence. The physical model was developed in the Coastal Engineering Laboratory of the Technical University of Bari. The physical model consists of a sophisticated system that allows to monitor and adjust all the characteristic parameters of both the channel flow (e.g. discharge, flow depth) and the buoyant jets (e.g. flow rate, temperature, salinity). Positively and negatively buoyant jets are realized by discharging water respectively at a temperature and salinity higher than that of the receiving environment. Due to the complexity of the jet-current hydrodynamic phenomena, a set of sophisticated instruments to measure the jet spreading within the cross flow is used. The average jet dilution is measured by (i) four different Resistance Temperature Detectors (RTD) for the positively buoyant jet, and (ii) a MicroScale Conductivity Temperature Instrument (MSCTI) of high resolution for the negatively buoyant jet. Whereas, a Nortek Acoustic Doppler Velocimeter (ADV) system is used to measure the field flow velocities, together with CollectV software for data acquisition and ExploreV software for data analysis. The measured scalar and vector fields will be illustrated in this paper, with the aim to emphasize that a well- set physical model is able to explain the behavior of buoyant jets in an open channel with ambient factors, such as cross flow and vegetation.