Flow patterns and mixing characteristics of horizontal buoyant jets at low and moderate Reynolds numbers

Shao, Dongdong; Huang, Dingyong; Jiang, Baoxin; Law, Adrian Wing‐Keung

doi:10.1016/j.ijheatmasstransfer.2016.10.022

Cited by 24 publications

(8 citation statements)

References 27 publications

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“…In some cases, as a result of these instabilities, the plume stem becomes so distorted that the local Rayleigh number is supercritical. This leads the original plume to collapse with new plumes originating from the original plume stem (see, e.g., Cortese and Balachandar 100 ; Vincent and Yuen 116 ; and Shao et al, 117 ). Moreover, as proven by Hier Majumder et al, 90 , the vortices in the lobes of the IVND plume can form Kelvin-Helmholtz waves, the susceptibility to form such waves being measured by the (local) gradient Richardson number:…”

Section: Plume Unsteady Dynamics and "Pillar" Formationmentioning

confidence: 99%

On the highly unsteady dynamics of multiple thermal buoyant jets in cross flows

Lappa

2019

Physics of Fluids

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Thermal plumes of small scale generated by spatially separated heat sources can form, like atoms in a chemical compound, complex structures of different kind and with distinct behaviors. The situation becomes even more complex if plumes can interact with imposed vertical shear (a horizontal wind). In this analysis a 'minimal framework' based on the application of a filtering process to the governing balance equations for mass, momentum and energy (falling under the general heading of 'Large Eddy Simulation' approach), is used together with Direct Numerical Simulation to inquiry about the relative importance of buoyancy and vertical shear effects in determining the patterning scenario when highly unsteady dynamics are established (turbulent flow). Emerging patterns range from the flow dominated by a static rising jet produced by the aggregation of plumes, which are pushed by horizontal leftwards and rightwards winds towards the center of the physical domain, to convective systems with disconnected thermal pillars of smaller scale, which travel in the same direction of the prevailing wind. The classical sheltering effect, which for flows that are steady 'in mean' simply consists of an increased deflection of the leading buoyant jet with respect to the trailing ones, is taken over by a variety of new phenomena, including (but not limited to) fast plume removal-rebirth mechanisms (with local increase in the velocity frequency and shrinkage in the related amplitude), 'bubble' formation-rupture and local departure of the frequency spectrum from the Kolmogorov similarity law.

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Section: Plume Unsteady Dynamics and "Pillar" Formationmentioning

confidence: 99%

On the highly unsteady dynamics of multiple thermal buoyant jets in cross flows

Lappa

2019

Physics of Fluids

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“…where Z is the vertical displacement of a cross section, and D is the port diameter. The cross-sectional concentrations of a free buoyant jet or a laterally confined vertical buoyant jet at different representative cross sections can be fitted to a Gaussian profile as [19,32]:…”

Section: Analysis Of a Laterally Confined Vertical Buoyant Jetmentioning

confidence: 99%

Multigene Genetic-Programming-Based Models for Initial Dilution of Laterally Confined Vertical Buoyant Jets

Yan

Mohammadian

2019

JMSE

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A new approach based on the multigene genetic-programming (MGGP) technique is proposed to predict initial dilution of vertical buoyant jets subjected to lateral confinement. The models are trained and tested using experimental data, and the good matches demonstrate the generalization and predictive capabilities of the evolved MGGP-based models. The best Pareto-optimal MGGP-based model is also compared with the model evolved using a single-gene genetic-programming (SGGP) algorithm and an existing regression-based empirical equation. The comparisons reveal the superiority of the MGGP-based model. This study confirms that the MGGP technique is promising in evolving an explicit, accurate, and compact model, and the developed models can be employed to estimate effectively and efficiently the dilution properties of a laterally confined vertical buoyant jet.

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“…Finally, there have been a number of experimental studies of buoyant jets injected horizontally into a quiescent ambient fluid, the source of the buoyancy being either a temperature difference 24,25 or a compositional one [26][27][28][29] . These experiments are similar to the configuration of Torricelli's curtain in that gravity acts normal to the jet axis, but different in that the jet and the ambient fluid have comparable viscosities and no surface tension.…”

Section: Introductionmentioning

confidence: 99%

Torricelli's Curtain: Morphology of Horizontal Laminar Jets Under Gravity

Tramis,

Merlin-Anglade,

Paternoster

et al. 2021

Preprint

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Viscous fluid exiting a long horizontal circular pipe develops a complex structure comprising a primary jet above and a smaller secondary jet below with a thin fluid curtain connecting them. We present here a combined experimental, theoretical and numerical study of this 'Torricelli's curtain' phenomenon, focusing on the factors that control its morphology. The dimensional parameters that define the problem are the pipe radius a, the mean exit velocity U of the fluid, the gravitational acceleration g, and the fluid's density ρ, kinematic viscosity ν and coefficient of surface tension γ.Rescaling of experimentally measured trajectories of the primary and secondary jets using a for the vertical coordinate and L D = U (a/g) 1/2 for the horizontal coordinatex collapses the data onto universal curves for x < 10L D . We propose a theoretical model for the curtain in which particle trajectories result from the composition of two motions: a horizontal component corresponding to the evolving axial velocity profile of an axisymmetric viscous jet, and a vertical component due to free fall under gravity.The model predicts well the trajectory of the primary jet, but somewhat less well that of the secondary jet. We suggest that the remaining discrepancy may be explained by surface tension-driven (Taylor-Culick) retraction of the secondary jet. Finally, direct numerical simulation reveals recirculating 'Dean' vortices in vertical sections of the primary jet, placing Torricelli's curtain firmly within the context of flow in curved pipes.

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Flow patterns and mixing characteristics of horizontal buoyant jets at low and moderate Reynolds numbers

Cited by 24 publications

References 27 publications

On the highly unsteady dynamics of multiple thermal buoyant jets in cross flows

On the highly unsteady dynamics of multiple thermal buoyant jets in cross flows

Multigene Genetic-Programming-Based Models for Initial Dilution of Laterally Confined Vertical Buoyant Jets

Torricelli's Curtain: Morphology of Horizontal Laminar Jets Under Gravity

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