Multigrid acceleration and turbulence models for computations of 3D turbulent jets in crossflow

Demuren, A. O.

doi:10.1016/0017-9310(92)90299-8

Cited by 16 publications

(7 citation statements)

References 21 publications

(31 reference statements)

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“…Reynolds stress models, i.e. solving transport equations for the Reynolds stresses, reproduce peak vorticity and CRVP strength very well, and predict Reynolds stresses better than k − ε models (Demuren 1992). Crabb, Duarão & Whitelaw (1981) and Andreopoulos (1982) found regions of high streamline curvature, where the flow is locally anisotropic.…”

Section: Canonical Round Jet In Crossflowmentioning

confidence: 99%

Scalar mixing in a confined rectangular jet in crossflow

Plesniak¹,

Cusano²

2005

J. Fluid Mech.

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An experimental investigation of a confined rectangular jet in crossflow was performed. The rectangular jet is highly confined in that it spans almost 80% of the crossflow duct, rather than issuing into a semi-infinite crossflow. Furthermore, the jet is confined in the cross-stream direction because it issues into a relatively narrow duct. In addition, the flow rate of the secondary jet is large (up to 50% of the crossflow flow rate) which also influences the jet–crossflow interaction. Configurations of this type are found in a variety of different industrial manufacturing processes used to mix product streams.A systematic variation of three pertinent parameters, i.e. momentum ratio, injection angle and development length, was performed. A full factorial experiment was run using three velocity ratios ($Vr\,{=}\,0.5, 1.0, 1.5$), three downstream distances ($x/D_{h}\,{=}\,6, 10, 19$) and six injection angles ($\alpha\,{=}\,18^\circ, 24^\circ$, 30^\circ, 48^\circ, 60^\circ, 90^\circ$). A planar Mie scattering mixing diagnostic system was used to evaluate the relative mixing effectiveness at various conditions within the parameter space studied. Three regimes for the jet–crossflow interaction and the resulting scalar concentration field were revealed: ‘wall jet’, ‘fully lifted jet’ and ‘reattached jet’. To understand the flow physics in these regimes, a more detailed exploration of the secondary flow and coherent structures was required. This was accomplished by acquiring velocity field data at measurement locations and conditions that demarcate the different regimes ($\alpha\,{=}\,30^{\circ}$ and $48^{\circ}, Vr\,{=}\,1.0$ and 1.5, $x/D_{h}\,{=}\, 3, 6, 10$, 15 and 19) using a laser-Doppler velocimetry (LDV) system. The combined scalar concentration and velocity field data provided an understanding of the large-scale mixing and the role of coherent structures and their evolution. The investigation revealed that the flow does not necessarily develop symmetrically and also highlighted some of the effects of confinement.

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Section: Canonical Round Jet In Crossflowmentioning

confidence: 99%

Scalar mixing in a confined rectangular jet in crossflow

Plesniak¹,

Cusano²

2005

J. Fluid Mech.

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Section: Influence Of Siphon Flow On the Plumementioning

confidence: 99%

“…This suggested that excurrent jets for small clams were more erect and the bulk mean crossflow had more of a tendency to deflect around the jet (Andreopoulos & Rodi 1984), the wake vortices were more dominant than the shear layer vortices (Fric & Roshko 1994, Meyer et al 2007, and the counter-rotating vortex pair was more dominant than the horseshoe vortices (Jabbal & Zhong 2008, Sau & Mahesh 2008. In contrast, excurrent jets for the larger clams were more severely bent over and the bulk mean crossflow tended to deflect over the jet (Andreopoulos & Rodi 1984, Demuren 1992, the shear layer vortices were more dominant with respect to the wake vortices (Fric & Roshko 1994, Meyer et al 2007, and the hairpin vortices were more dominant with respect to the counter rotating vortex pair (Jabbal & Zhong 2008, Sau & Mahesh 2008.We also found that at the smallest bulk mean crossflow velocity, the jet-to-crossflow velocity ratio was larger than the other bulk mean crossflow velocities used here. In this small bulk mean crossflow velocity case, the jet-to-crossflow velocity ratio indicated dominance of the counter rotating vortex pair (Sau & Mahesh 2008), dominance of the wake vortices (Fric & Roshko 1994, Meyer et al 2007, and a more erect jet with bulk mean crossflow deflecting around the jet (Andreopoulos & Rodi 1984).…”

mentioning

confidence: 99%

Unsteadiness of bivalve clam jet flow according to environmental conditions

Delavan¹,

Webster²

2011

Aquat. Biol.

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To determine whether hard clams Mercenaria mercenaria alter excurrent jet velocity as a function of environmental factors, this laboratory study quantified the excurrent jet velocity as a function of bulk mean crossflow velocity, density of clam patch, and clam size. The excurrent velocity was measured via the non-intrusive particle image velocimetry technique. The flow and unsteady patterns in the time records of vertical velocity near the tip of the excurrent siphon were analyzed by calculating the mean, variance, power spectral density, fractal dimension, lacunarity, and mean jet-to-crossflow ratio. The results revealed that clams vary their excurrent flow characteristics according to bulk mean crossflow velocity; in particular, the texture of the time record of velocity varied. Further, the jet-to-crossflow velocity ratio was larger for smaller clams, and the response of clams to the density of the clam patch was dependent on the size of the animal. These observed behaviors may impact the predation success of blue crabs Callinectes sapidus and knobbed whelks Busycon carica under various environmental conditions. In this context, the results indicated that blue crabs dominate the predator-prey system because of the dependence on clam size and bulk mean crossflow velocity. Alternatively, the varying clam excurrent siphon velocity behavior may provide hydrodynamic signaling of the clam patch recruitment status to settling larvae.KEY WORDS: Predator-prey · Olfactory predation · Jets-in-crossflow · Bivalve · Non-consumptive predator effects · Lacunarity Resale or republication not permitted without written consent of the publisherAquat Biol 13: [175][176][177][178][179][180][181][182][183][184][185][186][187][188][189][190][191] 2011 acteristics of the excurrent flow as a function of bulk mean crossflow velocity and clam size are of interest because the predators of this system, blue crabs and knobbed whelks, both consume clams and use olfactory navigation as a means of locating prey, but the turbulence regimes in which they are successful are highly disparate. Blue crabs are less successful predators during highly turbulent hydrodynamic conditions (Jackson et al. 2007). In contrast, knobbed whelks are successful in highly turbulent regimes (Ferner & Weissburg 2005). Also, blue crabs prefer clams of a small size range despite the fact that they can consume prey over a wide size range (Micheli 1995). Therefore, as clams increase in size, they become less susceptible to predation by blue crabs while maintaining their susceptibility to whelk predation. Thus, there may be alternate strategies for predator avoidance depending on the size of the clams and the turbulence regime of the environment in which they live.The influence of the density of the clam patch was also of interest because there may be predator avoidance strategies depending on the proximity of conspecifics. High-density patches may appear as one large, hard to eat prey to blue crabs, and small clams may have higher survival rates in these ...

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“…Generally, the subject of round and square jets in crossflow has been studied both experimentally and numerically over the years. Most of these studies focused on the global flow behavior of the jet, e.g., [1][2][3][4][5][6][7][8][9][10][11][12]. The vortex systems observed in the structure of round jet in crossflow have also been the subject of other experimental and numerical studies [13][14][15][16][17][18].…”

Section: Introductionmentioning

confidence: 99%

On the Dynamics of Environmental Pollution: Simulation of the near Field of a Jet in Crossflow

Eleshaky

2008

Energy & Environment

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This paper investigates numerically the complex flow in the near field of a rectangular jet discharging vertically downward into a uniform crossflow. This flow situation exists when pollutants generated from many industrial processes are released into the environment. Examples include those released from petrochemical plants, power plants, and desalination units. A thorough understating of turbulent dispersion of such pollutants is a first step towards the development of appropriate control methods. Using general purpose Computational Fluid Dynamics (CFD) software, the turbulent Navier-Stokes equations for unsteady, three-dimensional, incompressible flows are numerically solved in this study. The accuracy of this computational software is assessed by comparing the computed results with Laser Doppler Anemometry (LDA) measurements for two flow cases. Both cases (jet-tocrossflow velocity ratios 3 and 5) yield favorable agreement for the turbulence characteristics of the flow. The present computational methodology not only allows us to capture the coherent structures of the flowfield which include tornado-like vortices, counter-rotating vortices, and a horseshoe-type vortex, but also helps in understanding the mixing processes of pollutants with the ambient. This, in turn, may help in the utilization, enhancement, or suppression of selected vortices in many environmental pollution problems. NOMENCLATURE ᐉ nozzle length d nozzle exit width h water depth of channel g i gravitational acceleration in the i-direction k turbulent kinetic energy 1 2 u u i j ' '

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Multigrid acceleration and turbulence models for computations of 3D turbulent jets in crossflow

Cited by 16 publications

References 21 publications

Scalar mixing in a confined rectangular jet in crossflow

Scalar mixing in a confined rectangular jet in crossflow

Unsteadiness of bivalve clam jet flow according to environmental conditions

On the Dynamics of Environmental Pollution: Simulation of the near Field of a Jet in Crossflow

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