Advances in Turbulent Buoyant Jets

A special issue of Fluids (ISSN 2311-5521).

Deadline for manuscript submissions: closed (15 November 2020) | Viewed by 6466

Special Issue Editor


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Guest Editor
School of Civil Engineering, National Technical University of Athens, 9 Iroon Polytechniou St., 15780 Athens, Greece
Interests: hydraulics; experimental methods; fluid mechanics; civil engineering; turbulent buoyant jets

Special Issue Information

Dear Colleagues,

Round and plane vertical buoyant jets (forced plumes) and fountains (reverse buoyancy jets) have been studied extensively over the past 65 years, from the time of the pioneering publications of Rouse, Yih and Humphreys (1952), Priestley and Ball (1955), and Morton, Taylor and Turner (1956). Since then, significant advances have been made in the knowledge of such flows, as a result of the continuously improved measurement and numerical techniques and methodologies, along with theoretical analyses. However there are issues that have not yet been resolved because the subject is very broad with numerous extensions.

We are inviting authors who have been working on round and plane buoyant jets and fountains to submit papers that will further our knowledge on the subject. The ambient fluid where they discharge may be infinite or confined, calm or moving, homogeneous or density-stratified.

Rouse, H.; Yih, C.S.; Humphreys, H.W. Gravitational convection from a boundary source. Taylor & Francis. 1952, 4, 201–204.

Priestley, C.H.B.; Ball, F.K. Continuous convection from an isolated source of heat. Quart. J. Roy. Met. Soc. 1955, 81, 144–157.

Morton, B.R.; Taylor, G.I.; Turner, J.S. Turbulent gravitational convection from maintained instantaneous sources. Proc. Roy. Soc. London. 1956, 234, 1–23.

Prof. Panos Papanicolaou
Guest Editor

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Keywords

  • buoyant jet
  • fountain
  • turbulent diffusion
  • injection angle
  • stratified ambient
  • cross-flow
  • dilution
  • entrainment
  • round jet
  • plane jet
  • Richardson number
  • Froude number

Published Papers (3 papers)

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Research

20 pages, 2689 KiB  
Article
Vertical Round Buoyant Jets and Fountains in a Linearly, Density-Stratified Fluid
by Panos N. Papanicolaou and George C. Stamoulis
Fluids 2020, 5(4), 232; https://doi.org/10.3390/fluids5040232 - 4 Dec 2020
Cited by 2 | Viewed by 1814
Abstract
Turbulent round buoyant jets and fountains issuing vertically into a linearly density-stratified calm ambient have been investigated in a series of laboratory experiments. The terminal (steady-state) height of rise and the mean elevation of subsequent horizontal spreading have been measured in positively buoyant [...] Read more.
Turbulent round buoyant jets and fountains issuing vertically into a linearly density-stratified calm ambient have been investigated in a series of laboratory experiments. The terminal (steady-state) height of rise and the mean elevation of subsequent horizontal spreading have been measured in positively buoyant jets (at source level), including pure momentum jets and plumes, as well in momentum-driven negatively buoyant jets (fountains). The results from experiments confirmed the asymptotic analysis that was based on dimensional arguments. The normalized terminal height and spreading elevation with respect to the elevation of injection of momentum-driven (positively) buoyant jets and fountains attained the same asymptotic values. The numerical results from the solution of entrainment equations, using an improved entrainment coefficient function, confirmed the results related to buoyancy dominant flows (plumes), while their predictions in momentum-driven flows were quite low if compared to measurements. Full article
(This article belongs to the Special Issue Advances in Turbulent Buoyant Jets)
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13 pages, 2687 KiB  
Article
Simplified Modelling of Inclined Turbulent Dense Jets
by Ilias G. Papakonstantis and George C. Christodoulou
Fluids 2020, 5(4), 204; https://doi.org/10.3390/fluids5040204 - 10 Nov 2020
Cited by 5 | Viewed by 1783
Abstract
An analytical approximation to the entire centerline trajectory of inclined round dense jets in dimensionless form is proposed, in terms of a fourth degree polynomial. The coefficients of the polynomial for a certain inclination angle can be easily obtained if the position of [...] Read more.
An analytical approximation to the entire centerline trajectory of inclined round dense jets in dimensionless form is proposed, in terms of a fourth degree polynomial. The coefficients of the polynomial for a certain inclination angle can be easily obtained if the position of the maximum height and the return point are known. Experimental data of the authors are used to determine these coefficients for six inclination angles between 35° and 75°. The resulting trajectories are then compared to data of other investigators and found to be in good agreement. The variation of the polynomial coefficients with inclination angle is also studied. The proposed analytical expression allows for a straightforward computation of the trajectory length for any inclination angle in the range studied. It is found that the longest trajectory occurs for the 60° angle. The relation between the computed length and the measured minimum (centerline) dilutions at the location of maximum height and at the return point is examined. Finally, the laws governing the variation of the minimum dilution with the axial distance from the source are explored and similarities with the laws of simple jets and plumes are discussed. Full article
(This article belongs to the Special Issue Advances in Turbulent Buoyant Jets)
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21 pages, 5932 KiB  
Article
Revisiting Mean Flow and Mixing Properties of Negatively Round Buoyant Jets Using the Escaping Mass Approach (EMA)
by Aristeidis A. Bloutsos and Panayotis C. Yannopoulos
Fluids 2020, 5(3), 131; https://doi.org/10.3390/fluids5030131 - 8 Aug 2020
Cited by 6 | Viewed by 2351
Abstract
The flow formed by the discharge of inclined turbulent negatively round buoyant jets is common in environmental flow phenomena, especially in the case of brine disposal. The prediction of the mean flow and mixing properties of such flows is based on integral models, [...] Read more.
The flow formed by the discharge of inclined turbulent negatively round buoyant jets is common in environmental flow phenomena, especially in the case of brine disposal. The prediction of the mean flow and mixing properties of such flows is based on integral models, experimental results and, recently, on numerical modeling. This paper presents the results of mean flow and mixing characteristics using the escaping mass approach (EMA), a Gaussian model that simulates the escaping masses from the main buoyant jet flow. The EMA model was applied for dense discharge at a quiescent ambient of uniform density for initial discharge inclinations from 15° to 75°, with respect to the horizontal plane. The variations of the dimensionless terminal centerline and the external edge’s height, the horizontal location of the centerline terminal height, the horizontal location of centerline and the external edge’s return point as a function of initial inclination angle are estimated via the EMA model, and compared to available experimental data and other integral or numerical models. Additionally, the same procedure was followed for axial dilutions at the centerline terminal height and return point. The performance of EMA is acceptable for research purposes, and the simplicity and speed of calculations makes it competitive for design and environmental assessment studies. Full article
(This article belongs to the Special Issue Advances in Turbulent Buoyant Jets)
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