Jets Issuing Into Fluid With A Density Gradient

Abraham, G.; Eysink, W. D.

doi:10.1080/00221686909500262

Cited by 25 publications

(18 citation statements)

References 8 publications

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“…In spite of the fact that Γ i → ∞ and σ i → 0, the theory can still be applied in this case since the terms Γ i σ 5/4 i and b i /Λ i remain finite: Fan (1967), Abraham & Eysink (1969) and Sneck & Brown (1974) and the relation (4.2).…”

Section: Plume-like Behaviourmentioning

confidence: 93%

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Naturally bounded plumes

2013

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International audienceThis paper investigates theoretically the vertical evolution of a turbulent plume into a linearly stratified ambient fluid, by regarding it as composed of two distinct regions. In the first region, called the positive buoyant region, the plume buoyancy and the plume momentum act in the same upward direction, whereas in the second region, called the negative buoyant region, they act in opposite directions. In a first step, analytical expressions for the plume variables at the transition height (i.e. between the two regions) are obtained from one-dimensional conservation equations, using the plume entrainment model and under the Boussinesq approximation. In a second step, these variables are used in order to determine analytically the buoyancy and volume fluxes as well as the density deficit of the plume at its top. In this investigation, the transition height (denoted z(t)) and the total plume height (denoted z(p)) are obtained in the form of two integrals. These integrals are evaluated asymptotically in three different cases associated with particular flow regimes. Finally, the limit of the Boussinesq assumption for such flows is discussed

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Section: Plume-like Behaviourmentioning

confidence: 93%

“…To compare (4.2) with experimental data, we use the laboratory experimental results of Fan (1967), Abraham & Eysink (1969) and Sneck & Brown (1974) reported by Carazzo, Kaminski & Tait (2008). The entrainment coefficients α n and α p have been set, respectively, to 0.07 and 0.12, as proposed by Carazzo et al (2008).…”

Section: Plume-like Behaviourmentioning

confidence: 99%

Naturally bounded plumes

2013

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“…5. The data of Fox [1], Fan [2], Abraham and Eysink [3]. Crawford and Leonard [4] and Ogino [5] fall close to a single line given by The maximum height x m of buoyant jets discharged into a linearly stratified ambient is proportional to (dTa/dxy m and (F r ) 1/3 .…”

Section: And 812 (Exit Froude Number F 2 = U 0 2 T M /[Gd(t 0 -T Ll()mentioning

confidence: 88%

“…Temperature or salinity stratification in the ambi ent fluid may cause the effluent to stop rising and spread laterally away from the buoyant jet axis before reaching the water surface. The experimental data and discussions for vertical round buoyant jets in static stratified environ ment were given by Fox [I], Fan [2], Abraham and Eysink [3], Crawford and Leonard [4] and Ogino et al [5]. The main purpose of this study is to present a kind of mathematical model and numerical method for prediction of this flow pattern in a temperature stratified environment.…”

Section: Introductionmentioning

confidence: 99%

Calculation of whole field for vertical round buoyant jets in static linearly stratified environment

Hum

1995

Journal of Hydraulic Research

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The k-Z turbulent model is used to obtain a mathematical model of a vertieal round buoyant jet in static, line arly stratified environment. The Hybrid Finite Analytic Method and a staggered grid are used to calculate the whole field of this flow pattern. The centerline velocity and temperature, the maximum height of rise, the height of neutral buoyancy, the demarcation between buoyant jet and mushroom-cloud regions, and the demar cation between mushroom-cloud and spreading layer regions are calculated. RÉSUMÉUn modèle k-Z turbulent esl utilise pour obtenir un modèle mathématique de jet vertical flottant circulaire dans un milieu ambiant slalique stratifié linéairement. La methode hybride analytique finie et les maillages décalés sont utilises pour calculer le champ entier de l'écoulement. Le modèle donne la vitesse et la temperature sur la ligne axiale, la hauteur maximale d'élévation, la cole du point ncutrc du jet flottant, la demarcation entre le jet flottant et la region du nuage en champignon, la demarcation entre les regions du nuage en champignon et de la zone d'étalement.

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“…Pantokratoras has, however, acknowledged large uncertainty in the estimation of the model coefficient (1.74). Taking this into account, one may take freedom to use the model coefficients derived from the experiments of Abraham and Eysink [42] on negatively buoyant jets issued into a stratified medium, namely 1.94 (Pantokratoras-Abraham prediction). The time evolution of the penetration depth modeled by the default and calibrated realizable and RNG k-e models corresponding to Re 5 3000 are given in Figure 10.…”

Section: Comparison Between the Calibrated Rng And Realizable K-e Modelsmentioning

confidence: 99%

Calibrated models for simulation of stratified hot water heat stores

Panthalookaran

El-Amin

Heidemann

et al. 2008

Int. J. Energy Res.

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SUMMARYHot water heat stores (HWHS) are generally used to overcome the diurnal or seasonal mismatch in the availability and demand of thermal energy. To enhance the system efficiency, good thermal stratification of the HWHS is required. In order to simulate different flow processes in stratified HWHS the effects of stratification on the turbulence are to be considered. Benchmark experiments have been conducted on turbulent flows into a continuously stratified HWHS. Based on these benchmark experiments, different two-equation turbulence transport models namely the RNG (ReNormalizable Group) and the realizable k-e turbulence models have been calibrated. The major improvement is provided to the e-equation by introducing the effects of the buoyancy field on the turbulence dissipation rate. It is achieved by calibrating the coefficient of the dissipation term (C e2 in the RNG and C 2 in the realizable k-e model) based on the benchmark experiments. A re-definition of the turbulent Prandtl number (Pr t ) incorporating the effects of stratification on turbulent thermal diffusivity improved the calibration further. The calibrated computational fluid dynamic models are found to predict the charging, discharging and storing processes of typical HWHS with good accuracy.

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Jets Issuing Into Fluid With A Density Gradient

Cited by 25 publications

References 8 publications

Naturally bounded plumes

Naturally bounded plumes

Calculation of whole field for vertical round buoyant jets in static linearly stratified environment

Calibrated models for simulation of stratified hot water heat stores

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