Three-Dimensional Numerical Study of Multiple Vertical Buoyant Jets in Stationary Ambient Water

Gildeh

Nistor

2020

Water

Self Cite

Effluent discharge mixing and dispersion have been studied for many decades. Studies began with experimental investigations of geometrical and concentration characteristics of the jets in the near-field zone. More robust experiments were performed using Laser-Induced Fluorescence (LIF) and Particle Image Velocimetry (PIV) systems starting in the 20th century, which led to more accurate measurement and analysis of jet behavior. The advancement of computing systems over the past two decades has led to the development of various numerical methods, which have been implemented in Computational Fluid Dynamics (CFD) codes to predict fluid motion and characteristics. Numerical modeling of mixing and dispersion is increasingly preferred over laboratory experiments of effluent discharges in both academia and industry. More computational resources and efficient numerical schemes have helped increase the popularity of using CFD models in jet and plume modeling. Numerous models have been developed over time, each with different capabilities to facilitate the investigation of all aspects of effluent discharges. Among these, Reynolds-averaged Navier-Stokes (RANS) and Large Eddy Simulations (LES) are at present the most popular CFD models employing effluent discharge modeling. This paper reviews state-of-the-art numerical modeling studies for different types and configurations of discharges, including positively and negatively buoyant discharges, which have mostly been completed over the past two decades. The numerical results of these studies are summarized and critically discussed in this review. Various aspects related to the impact of turbulence models, such as k-ε and Launder-Reece-Rodi (LRR) models, are reviewed herein. RANS and LES models are reviewed, and implications for the simulation of jet and plume mixing are discussed to develop a reference for future researchers performing numerical investigations on jet mixing and dispersion.

mentioning

confidence: 99%

CFD Modeling of Effluent Discharges: A Review of Past Numerical Studies

Gildeh

Nistor

2020

Water

Self Cite

“…The volume fraction of the fluids, α, in mixing problems can be calculated using a transport equation [5], which can be expressed as…”

Section: The 3d Cfd Modelmentioning

confidence: 99%

“…Regarding turbulence modeling, the previous study reported by Yan et al [6] demonstrated that the RNG (renormalization group) k-ε turbulence model outperformed the standard k-ε model without significantly increasing the computational costs, and thus the RNG k-ε turbulence model was used in this study. Compared with the other three different turbulence closures, including the standard k-ε, standard k-omega, and k-omega shear stress transport (SST) models, the RNG k-ε model has been found by Yan et al [5] to be the most accurate for multiple buoyant jets. Therefore, in this research, the RNG k-ε model was adopted.…”

Section: The 3d Cfd Modelmentioning

confidence: 99%

“…Estimating the flow and mixing processes of effluent discharges is crucial for reliable environmental impact assessments, sound design of treatment and outfall systems, and proper disposal of wastewater discharges [1][2][3]. Effluents are known as buoyant jets if they have a lower density than the receiving water, and they are often used for municipal and desalination purposes [4][5][6]. A key factor influencing the mixing processes of effluents is the diffuser type.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Simulations of the Concentration Fields of Rosette-Type Multiport Buoyant Discharges Using Combined CFD and Multigene Genetic Programming Techniques

Yan

Wang

et al. 2021

JMSE

Self Cite

Rosette-type diffusers are becoming popular nowadays for discharging wastewater effluents. Effluents are known as buoyant jets if they have a lower density than the receiving water, and they are often used for municipal and desalination purposes. These buoyant effluents discharged from rosette-type diffusers are known as rosette-type multiport buoyant discharges. Investigating the mixing properties of these effluents is important for environmental impact assessment and optimal design of the diffusers. Due to the complex mixing and interacting processes, most of the traditional simple methods for studying free single jets become invalid for rosette-type multiport buoyant discharges. Three-dimensional computational fluid dynamics (3D CFD) techniques can satisfactorily model the concentration fields of rosette-type multiport buoyant discharges, but these techniques are typically computationally expensive. In this study, a new technique of simulating rosette-type multiport buoyant discharges using combined 3D CFD and multigene genetic programming (MGGP) techniques is developed. Modeling the concentration fields of rosette-type multiport buoyant discharges using the proposed approach has rarely been reported previously. A validated numerical model is used to carry out extensive simulations, and the generated dataset is used to train and test MGGP-based models. The study demonstrates that the proposed method can provide reasonable predictions and can significantly improve the prediction efficiency.

“…Numerous CFD studies have been carried out to analyze buoyant jet discharges into stagnant receiving environments by using the RANS modeling approach [3,[61][62][63][64][65][66][67][68][69][70][71][72][73]. In addition, Zhang et al [60,74] and Jiang et al [75] applied the LES modeling approach to simulate dense jet discharges.…”

Section: Numerical Modeling: Jet Integral Models and Computational Fl...mentioning

confidence: 99%

Buoyant Jets in Cross-Flows: Review, Developments, and Applications

Taherian

2021

JMSE

Self Cite

Significant environmental effects from the use of marine outfall discharges have led to increased efforts by both regulatory bodies and research groups to minimize the negative impacts of discharges on the receiving water bodies. Understanding the characteristics of discharges under conditions representative of marine environments can enhance the management of discharges and mitigate the adverse impacts to marine biota. Thus, special attention should be given to ambient cross-flow effects on the mixing behaviors of jet discharges. A buoyant jet in cross-flow has different practical applications such as film cooling and dilution, and provide a higher mixing capability in comparison with free jets or discharges into stationary environments. The main reason for this is believed to be the existence of various complicated vortical structures including a counter-rotating vortex pair as the jet expands downstream. Although tremendous research efforts have been devoted to buoyant jets issuing into cross-flows over the past five decades, the mixing process of an effluent at the discharge point is not yet well understood because of the highly complex fluid interactions and dispersion patterns involved. Therefore, there is a need for a deeper understanding of buoyant jets in cross-flows in order to obtain better predictive methods and more accurate design guidelines. The main aims of this study were (i) to establish the background behind the subject of buoyant jets in cross-flows including the flow structures resulting from the interaction of jets and cross-flows and the impacts of current on mixing and transport behavior; (ii) to present a summary of relevant experimental and numerical research efforts; and finally, (iii) to identify and discuss research gaps and future research directions.