Plume Dilution for Diffusers With Multiport Risers

Isaacson, Morton S.; Koh, Robert C. Y.; Brooks, Norman H.

doi:10.1061/(asce)0733-9429(1983)109:2(199)

Cited by 34 publications

(4 citation statements)

References 2 publications

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“…They all support the equivalent slot concept for multiport diffusers. Isaacson et al [37] report a study for diffusers with risers with up to 8 rosette-type ports as well as for unidirectional diffusers with up to 4 ports per riser (spread over an angle of 90 • ). They find that the downstream plume behavior after merging is essentially independent of the port arrangement and is determined solely by the line buoyancy flux.…”

Section: Complex Merging Processesmentioning

confidence: 99%

Integral Model for Turbulent Buoyant Jets in Unbounded Stratified Flows Part 2: Plane Jet Dynamics Resulting from Multiport Diffuser Jets

2006

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An integral model for the plane buoyant jet dynamics resulting from the interaction of multiple buoyant jet effluxes spaced along a diffuser line is considered as an extension of the round jet formulation that was proposed in Part I. The receiving fluid is given by an unbounded ambient environment with uniform density or stable density stratification and under stagnant or steady sheared current conditions. Applications for this situation are primarily for submerged multiport diffusers for discharges of liquid effluents into ambient water bodies, but also for multiple cooling tower plumes and building air-conditioning. The CorJet model formulation describes the conservation of mass, momentum, buoyancy and scalar quantities in the turbulent jet flow in the plane jet geometry. It employs an entrainment closure approach that distinguishes between the separate contributions of transverse shear and of internal instability mechanisms, and contains a quadratic law turbulent pressure force mechanism. But the model formulation also includes several significant three-dimensional effects that distinguish actual diffuser installations in the water environment. These relate to local merging processes from the individual multiple jets, to overall finite length effects affecting the plume geometry, and to bottom proximity effects given by a "leakage factor" that measures the combined affect of port height and spacing in allowing the ambient flow to pass through the diffuser line in order to provide sufficient entrainment flow for the mixing downstream from the diffuser. The model is validated in several stages: First, comparison with experimental data for the asymptotic, self-similar stages of plane buoyant jet flows, i.e. the plane pure jet, the pure plume, the pure wake, the advected line puff, and the advected line thermal, support the choice of the turbulent closure coefficients contained in the entrainment formulation. Second, comparison with data for many types of non-equilibrium flows with a plane geometry support the proposed functional form of the entrainment relationship, and also the role of the pressure force in the jet deflection dynamics. Third, the observed behavior of the merging process from different types of multiport diffuser discharges in both stagnant and flowing ambient conditions and with stratification appears well predicted with the CorJet formulation. Fourth, a number of spatial limits of applicability, relating to terminal layer formation in stratification or transition to passive diffusion in a turbulent ambient shear flow, have been proposed. In sum, the CorJet integral model appears to provide a mechanistically E-mail: jirka@uka.de 44 GERHARD H. JIRKA sound, accurate and reliable representation of complex buoyant jet mixing processes, provided the condition of an unbounded receiving fluid is satisfied.

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Section: Complex Merging Processesmentioning

confidence: 99%

Integral Model for Turbulent Buoyant Jets in Unbounded Stratified Flows Part 2: Plane Jet Dynamics Resulting from Multiport Diffuser Jets

2006

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“…In addition, emissions in a calm atmosphere originating from groups of two or more cooling towers or chimneys arranged on apexes of a regular polygon yield similar buoyant flows. Usually, model predictions provide valuable Isaacson et al (1983), Wong and Wright (1988), are useful in validating models.…”

Section: Introductionmentioning

confidence: 99%

Round turbulent buoyant jets discharged vertically upwards forming a regular polygon

Bloutsos

Yannopoulos

2009

Journal of Hydraulic Research

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Round turbulent buoyant jets discharged vertically upwards forming a regular polygon Jets ronds flottants turbulents émis verticalement vers le haut en formant un polygone régulier ARISTEIDIS A. BLOUTSOS, Postgraduate student, ABSTRACT The simplified partial differential equations of momentum and tracer for the mean motion are integrated on the reduced cross-sectional area within the field of one buoyant jet from a group issued vertically upwards from a rosette-type riser. The solutions yield the dimensionless centerline axial velocities and concentrations. Mathematically, the one-jet field is separated from the entire group by employing the Entrainment Restriction Approach (ERA) applicable in interacting buoyant jets with symmetry planes. ERA was herein improved by incorporating the Second Order Approach (SOA). Interaction effects are highlighted by normalizing the mean-flow properties. The role of buoyancy on merging is introduced by a dynamic parameter, which combines proximity effects with buoyancy, thus termed dynamic proximity number. In addition, the distributions for mean dilution, kinetic energy flux and local Richardson number are also predicted, discussed, and compared with data reported in the literature. Findings may be useful for design purposes and environmental impact assessment. RÉSUMÉLes équations aux dérivées partielles simplifiées de la quantité de mouvement et du traceur pour l'écoulement moyen sont intégrées sur la section transversale réduite d'un seul jet flottant regroupant les émissions verticales vers le haut d'une colonne montante de type rosette. Les solutions fournissent les vitesses et des concentrations axiales sans dimensions le long de la ligne centrale. Mathématiquement, le champ du jet unique est séparé du groupe entier en utilisant l'Approche de Restriction d'Entraînement (ERA) applicable aux jets flottants interactifs avec plans de symétrie. La méthode ERA a été ici améliorée en y incorporant l'Approche du Second Ordre (SOA). Les effets d'interaction sont mis en relief par la normalisation des propriétés de l'écoulement moyen. Le rôle de la flottabilité sur le fusionnement est introduit par un paramètre dynamique, qui combine les effets de proximité et de flottabilité, nommé nombre dynamique de proximité. En outre, les distributions de la dilution moyenne, du flux d'énergie cinétique et du nombre de Richardson local sont également calculées, discutées, et comparées aux données rapportées dans la littérature. Les résultats peuvent être utiles pour des objectifs de conception et l'évaluation de l'impact environnemental. assistance in the design and environmental impact assessment of such a system. The operation of these systems and the possible measures taken to minimize probable environmental impacts may also be evaluated by employing computer models in conjunction with field observations. Due to buoyant-jet merging, the flow and mixing field is generally complicated and difficult to resolve. Regarding ocean outfalls using diffusers with rosettetype risers including those with...

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“…In order for the flow to be fully turbulent, as it is from a real diffuser, the discharge must have a Reynolds number greater than 4000 [19]. The Froude number, which determines how soon the discharge evolves from a jet to a plume, is defined as the ratio of inertial to buoyancy forces in the flow…”

Section: Discharge Propertiesmentioning

confidence: 99%

LIF Measurement of the Diluting Effect of Surface Waves on Turbulent Buoyant Plumes

Sharp¹,

Shawcross²,

Greated³

2014

JFCMV

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Plume Dilution for Diffusers With Multiport Risers

Cited by 34 publications

References 2 publications

Integral Model for Turbulent Buoyant Jets in Unbounded Stratified Flows Part 2: Plane Jet Dynamics Resulting from Multiport Diffuser Jets

Integral Model for Turbulent Buoyant Jets in Unbounded Stratified Flows Part 2: Plane Jet Dynamics Resulting from Multiport Diffuser Jets

Round turbulent buoyant jets discharged vertically upwards forming a regular polygon

LIF Measurement of the Diluting Effect of Surface Waves on Turbulent Buoyant Plumes

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