Numerical modeling of a buoyant round jet under regular waves

Chen, Yen Lung; Hsiao, Shih Chun

doi:10.1016/j.oceaneng.2018.04.093

Cited by 11 publications

(3 citation statements)

References 18 publications

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“…In literature, there are two main types of numerical models that can be used to study jet behaviors in the initial mixing zone. The first type is based on the solution of differential equations, which is costly in the computation, but has the ability to provide a detailed description of the jet mixing processes [12,13]. The second type is based on the solution of integral equations, which is efficient in the computation, but aims to describe the mean properties of the jet.…”

Section: Introductionmentioning

confidence: 99%

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

Fang

Chen

et al. 2019

Water

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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).

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Section: Introductionmentioning

confidence: 99%

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

Fang

Chen

et al. 2019

Water

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“…The dilution rate of buoyant jet can be significantly enhanced by the wave motion. The surface diffusion rate is also significantly higher than that in an environment with no waves [23][24][25][26]. A theoretical Lagrangian model that is potentially capable of describing this additional wave-induced mixing was developed [27].…”

Section: Introductionmentioning

confidence: 99%

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

Otoo

Chen

et al. 2019

Water

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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.

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“…Es una tubería sumergida a cierta profundidad en el océano que transporta aguas residuales tratadas desde una planta de tratamiento hacia el mar. Descargar chorros en áreas costeras es una práctica común en muchas aplicaciones industriales (Chen & Hsiao, 2018). La ubicación de descarga del emisor es primordial, ya que afecta la gradiente de dilución y el tiempo que necesita para llegar a la superficie marina (Inan, 2019).…”

Section: Emisor Submarinounclassified

Propuesta de mejoramiento de capacidad hidráulica del emisor submarino de la PTAR La Chira mediante el uso del coeficiente de contracción de las válvulas de retención tipo Duckbill en el tramo difusor

Sanchez¹,

Celis²

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Los emisores submarinos son preferibles para la descarga de aguas residuales domesticas tratadas, debido a la capacidad de asimilación del mar como una opción más económica. Si se eligen los sistemas de salida al mar, la ubicación es fundamental para evitar el retorno de las aguas residuales a la zona costera y la recuperación del ecosistema marino. Sobre la base de la regulación del control de descarga de efluentes que exige la Autoridad Nacional del Agua (ANA) de la República Democrática del Perú, la concentración de bacterias debe estar por debajo de un cierto valor en el área protegida. Esta tesis está basada en el método de investigación aplicativo, debido a que en el Perú no existe mucha información científica con respecto a los emisores submarinos. Por ello, esta investigación busca aumentar información científica de tal modo que para los siguientes proyectos que tengan que ver con emisores submarinos sean más eficientes a nivel hidráulico. Por otra parte, los efectos principales que influyen en la dilución son las corrientes costeras generadas por el viento y el transporte de aguas residuales en regiones costeras abiertas, como se encuentra en La Chira. Las predicciones del modelo de dispersión son precisas si cuentan con las características físicas del emisor submarino, del efluente y del océano, ya que nos brindan una perspectiva clara para la planificación del emisor submarino. En este estudio, se compara el caudal de diseño con el método de crecimiento geométrico, el cual es recomendado por la Organización Mundial de la Salud (OMS), con el caudal real del proyecto, donde se verifica que ambos caudales se aproximan. También, se verificó la capacidad hidráulica del emisor submarino para identificar las pérdidas de cargas totales que se producen a lo largo de todo el emisor. Además, el Visual Plumes, el cual es un software que genera modelos de dispersión de efluente en un cuerpo de agua, se utilizó para la dilución de campo cercano y la dilución de campo lejano del contaminante. Los resultados del modelo de dilución de campo cercano y de campo lejano muestran que el emisor submarino de La Chira cumple con las regulaciones legales ambientales.

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Numerical modeling of a buoyant round jet under regular waves

Cited by 11 publications

References 18 publications

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

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

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

Propuesta de mejoramiento de capacidad hidráulica del emisor submarino de la PTAR La Chira mediante el uso del coeficiente de contracción de las válvulas de retención tipo Duckbill en el tramo difusor

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