Near-field dilution of a turbulent jet discharged into coastal waters: Effect of regular waves

et al. 2019

Water

The integral model developed by Chin (1988) for modelling a non-buoyant turbulent jet in wave environment is improved by introducing two new parameters, i.e., the jet spreading rate c1 and the shortening rate pe. The parameter c1 is used to simplify the model by explicitly describing the radial velocity and scalar profiles under the assumption of “instantaneous” Gaussian distribution. By doing so, the governing equations can be easily solved by simultaneously integrating the conservation laws of momentum and scalars across the jet cross-section. The parameter pe is used to shorten the initial length of zone of flow establishment (ZFE), so as to more accurately account for the wave effect on the jet initial dilution near the jet nozzle. The parameters are calibrated by the particle image velocimetry (PIV)-measured data from three groups of jet experiments, i.e., the group of vertical jet towards the wave direction (vertical jet), the group of horizontal jet along the wave direction (co-wave jet) and the group of horizontal jet opposing to the wave direction (op-wave jet). The results show that both parameters are well related to the ratio of jet and wave characteristic velocities in the same group, but it is not able to be generalized among different groups. Under the same wave condition, the value of c1 in the vertical jet is larger than that of the horizontal jets; while the value of pe in the vertical jet is smaller than that of the horizontal jets, which indicates that the jet has a faster decay rate of centerline velocity and a wider width of jet cross-section profile in the near field when it is vertically discharged into the wave environment. With the well-calibrated parameters, the improved model can achieve a higher accuracy than the original model developed by Chin (1988).

Section: Model Calibrationmentioning

confidence: 99%

An Improved Integral Model for a Non-Buoyant Turbulent Jet in Wave Environment

Fang

et al. 2019

Water

“…(Chen et al, 2008(Chen et al, , 2012Fang et al, 2019;Otoo et al, 2019Otoo et al, , 2022Y. Wang et al, 2015;Xu et al, 2016Xu et al, , 2017Xu et al, , 2018Xu et al, , 2019Xu et al, , 2020, which will inevitably have a significant impact on the movement of sediment particles in the sediment-laden jet. Therefore, to fully capture the true movement of the sediment-laden jet under the marine dynamic environment, the interaction between sediment-laden jet flow with wave and current needs to be tackled.…”

Section: Research Questions and Possible Ways Forwardmentioning

confidence: 99%

“…For primary treatment, solids with the size >200 μm are removed while smaller solids are discharged through outfalls. These sediments deposit close to the outfall and negatively impact the benthic ecology (Maldonado et al, 2000; Miller et al, 2018; Pritchard, 1997; Roberts et al, 2010; Santschi et al, 2001; Xu et al, 2017).…”

Section: Pathways Forward To Improve the Study Of Sediment‐laden Wast...mentioning

confidence: 99%

“…Dumping (Figure 1d) of sediment or waste materials into the ocean as sediment‐laden flow also affects aquatic resources. Additionally, the balance and stability of human health and the ecosystem can be gravely threatened by pollutants from submarine wastewater discharges (Figure 1f) as such pollutants are a potential threat to the local marine environmental and ecological systems (Roberts et al, 2010; Xu et al, 2017).…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Transport dynamics of sediment‐laden jet: A review

Otoo

et al. 2022

River

Self Cite

Wastewater disposal through the dumping of spoil and sludge into the river, lake, or ocean is typically in the form of a sediment‐laden jet. The inorganic and organic solids from the effluent settling close to the source often result in the formation of sludge banks which can have a damaging effect on the marine ecosystem. Therefore, predicting the transport and deposition of sediment‐laden wastewater jet flows has been a focus of intense research for decades. In this paper, we discussed the fundamental understanding of sediment‐laden jets and the progress made in their predictions. We also highlighted some of the pertinent research challenges revealed by the previous studies and identified some key research issues that need to be addressed to achieve sustainable marine wastewater disposal in the face of increasing river, lake, and marine pollution.

“…In conclusion, it is evident that the buoyant jet has been studied by many researchers over the years. Since 2016, the authors [35][36][37] have focused on the behaviors of a single non-buoyant jet in the wavy cross-flow environment and quantized the effect of surface waves on jet discharge. Nevertheless, the knowledge of buoyant jets in the wavy cross-flow environment is still limited, especially for the multiple buoyant jets.…”

Section: Introductionmentioning

confidence: 99%

2D PIV Measurement of Twin Buoyant Jets in Wavy Cross-Flow Environment

Otoo

et al. 2019

Water

Self Cite

The multiport diffuser effluent discharge facilities constructed beneath the coastal waters were simplified in the laboratory as twin buoyant jets in a wavy cross-flow environment. The near-field flow structure of twin jets was studied by series of experiments conducted in a physical wave–current flume. The particle image velocimetry (PIV) system was used to measure the velocity field of the jets in various cross-flow-only and wavy cross-flow environments. By means of flow visualization, the distinctive “effluent cloud” (EC) phenomenon was clearly observed and the jet penetration height was found to be notably increased compared with that of cross-flow-only environment at the downstream position. It was found that the wave-to-current velocity ratio Rwc is a very important parameter for effluent discharge. A new characteristic velocity uch and the corresponding characteristic length scale lmb for twin buoyant jets in the wavy cross-flow environment were defined. Using curve-fitting, a new equation to estimate the effects of the jet-to-current velocity ratio (Rjc), wave-to-current velocity ratio (Rwc) and Strouhal number (St) on the jet trajectory were derived to enhance understanding the physical processes underpinning the rise and the dilution of buoyant jets, which is critical to the design of discharge facilities.