Quantifying the influence of source variability on unsteady buoyant jets

The discharge of domestic and industrial effluents into estuarine or coastal waters (as marine wastewater
discharges) or the atmosphere (as industrial emissions), along with naturally-occurring atmospheric discharges (such as volcanic eruptions), are examples of turbulent buoyant jets, where the nature and structure of these discharges intrinsically determine the quality of the surrounding environment (water or air). Understanding and modelling the fundamental behavior of buoyant jets is therefore crucial to minimizing potential environmental and socio-economic impacts associated with these discharges. Well-established, one-dimensional integral model theories have been developed, based on the time-averaged behavior of buoyant jets under the assumption of steady-state source conditions, which are utilized widely for the rapid prediction of ash clouds from volcanic eruptions (Folch et al., 2016) and/or the near-field dilution of effluents discharged into the marine environment (Jirka, 2004). The current study assesses, through scaled laboratory experiments, the limitations associated with these steady-state buoyant jet models by investigating the influence that source variability has on the structure of the unsteady buoyant jets generated and, in particular, their deviation from
well-established integral (time-averaged) properties.