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The problem of the interaction between two oppositely swirled jets of viscous incompressible fluid issuing from parallel tubes into the submerged space is considered. The scenario of the confluence of the two jets into a single je...
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The problem of the interaction between two oppositely swirled jets of viscous incompressible fluid issuing from parallel tubes into the submerged space is considered. The scenario of the confluence of the two jets into a single jet is determined on the basis of a numerical solution. It is shown that far from the sources the flow is described by the self-similar axisymmetric Landau solution for a single swirled jet. The longitudinal vorticity field far from the source is also self-similar, with a complex decay rate. The asymptotic structure of the far field of the jet is discussed.
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Jets have been the subject of experimental and numerical research for over five decades. Plane jets and multiple jets are used in verity of applications especially in heating and ventilation. In these applications parameters like ...
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Jets have been the subject of experimental and numerical research for over five decades. Plane jets and multiple jets are used in verity of applications especially in heating and ventilation. In these applications parameters like the jet spread rate and potential core decay play a strong role in deciding the mixing properties. Shear layer is the region in which most of the interactions and mixing between the ambient and jet fluid takes place. In multiple jet interaction the shear layer of the individual jets will interact with themselves and with the ambient fluid, apart from this the potential core of the individual jets will interact with each other making the mixing and merging process more complex. In the present study the interaction of different isothermal two dimensional twin jet models are studied by varying the diameter of the jets and the linear distance (Pitch) between the jets.
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Jets have been the topic of extensive research for the past many decades since it has been the basic element in the study of free shear flow. Jets form the basic flow module in many industrial applications especially in Heating Ve...
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Jets have been the topic of extensive research for the past many decades since it has been the basic element in the study of free shear flow. Jets form the basic flow module in many industrial applications especially in Heating Ventilating and Air Conditioning. Multiple jet modules of different shapes and configurations form the basic structure of the air distribution systems. The merging and mixing characteristics of the shear layer and potential core of the individual jets plays a major role in the formation of a combined jet of desired qualities. The combined jet characteristics are a strong function of basic configuration of the jet orifices. The size and the distance between orifices (Pitch) have strong influence on the behavior of the combined jet. The present study focuses on explaining the merging characteristics of identical triple jet (three jets of same diameter) configuration for different diameters and pitch values by modeling and analyzing with the help of CFD tools.
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The characterisation of the jet substructure can give insight into the microscopic nature of the modification induced on high-momentum partons by the Quark-Gluon Plasma that is formed in ultra-relativistic heavy-ion collisions. Th...
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The characterisation of the jet substructure can give insight into the microscopic nature of the modification induced on high-momentum partons by the Quark-Gluon Plasma that is formed in ultra-relativistic heavy-ion collisions. This modification of parton-to-jet fragmentation and of the parton virtuality, induced by the QGP, can be studied using jet shapes, in particular using jet energy redistribution, intra-jet broadening or collimation. Results of a selected set of jet shapes are presented for p-Pb collisions at root S-NN = 5.02 TeV and for Pb-Pb collisions at root S-NN = 2.76 TeV. Results are also compared with PYTHIA Perugia 11 calculations and models that include in-medium energy loss.
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Direct numerical simulation of incompressible, spatially developing round and square jets at a Reynolds number of 1,000 is performed. The effect of two types of inlet perturbation on the flow structures is analyzed. First, dual-mo...
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Direct numerical simulation of incompressible, spatially developing round and square jets at a Reynolds number of 1,000 is performed. The effect of two types of inlet perturbation on the flow structures is analyzed. First, dual-mode excitation, which is a combination of axisymmetric perturbation at preferred mode frequency and helical perturbation at sub-harmonic frequency is used, having a disturbance frequency ratio equal to R_f = 2. It is observed that the circular and square jets bifurcate and spread on one of the orthogonal planes forming a Y-shape jet in the downstream while no spreading is visible on the other plane. The second type of perturbation is a flapping excitation at a sub-harmonic frequency, St_F = 0.2. It leads to a Y-shape bifurcation for both square and circular jets. On the other hand, for flapping excitation at the preferred mode frequency, namely, St_F = 0.4, a circular jet bifurcates into a Ψ-shape whereas the square jet reveals simple spreading.
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The present study investigates the impact of a droplet onto a deep pool of immiscible liquid for a wide range of drop impact Froude numbers (10 < Fr < 1075) to characterize the crater and jet dynamics. The radial expansion of the crater is followed by contraction of its sidewalls before the inception of vertical retraction at low drop impact Froude numbers (Fr < 400), whereas the gravity-induced buoyant force of displaced liquid resulted in the simultaneous horizontal and vertical retraction of deeper cavities at high Froude numbers (Fr > 400). Four different jet regimes such as short jet, singular jet, slender jet, and co...
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The present study investigates the impact of a droplet onto a deep pool of immiscible liquid for a wide range of drop impact Froude numbers (10 < Fr < 1075) to characterize the crater and jet dynamics. The radial expansion of the crater is followed by contraction of its sidewalls before the inception of vertical retraction at low drop impact Froude numbers (Fr < 400), whereas the gravity-induced buoyant force of displaced liquid resulted in the simultaneous horizontal and vertical retraction of deeper cavities at high Froude numbers (Fr > 400). Four different jet regimes such as short jet, singular jet, slender jet, and compound thin thick jet are observed and their formation is associated with specific flow behaviors around the retracting crater. The short, singular, and slender jets are observed when retraction of the crater is capillary dominant. The compound thin thick jets are mainly attributed to gravity dominant deeper cavities.
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It is well known that initial conditions significantly affect the flow field and the evolution characteristics of the jets. In the present study, experiments on twin pipe jets were performed to understand the effect of developing ...
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It is well known that initial conditions significantly affect the flow field and the evolution characteristics of the jets. In the present study, experiments on twin pipe jets were performed to understand the effect of developing length on the twin-jet characteristics. The developing length was varied in the range of 4收起
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Nanofibers are known to have incredible properties and applications in diverse field such as defense, energy, aerospace, filtration, and biotechnology, to name a few. Forcespinning (FS) is a new experimental process that can produ...
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Nanofibers are known to have incredible properties and applications in diverse field such as defense, energy, aerospace, filtration, and biotechnology, to name a few. Forcespinning (FS) is a new experimental process that can produce nanoscale fibers under the action of rotating forces. In the usual FS process, a mesoscale fluid jet is forced through an orifice of a rotating spinneret, where the ambient fluid is air. This leads to the formation of a jet with a curved centerline. In this study we apply multiscale and perturbation techniques to investigate rotating fiber jets and their stabilities in the presence of aerodynamic drag force due to the ambient air that is known to exist experimentally in the FS process. First, we calculate numerically the expressions for the leading-order steady solutions for jet quantities such as radius, speed, and trajectory versus arc length, and we determine, in particular, the results for such quantities and their variations in the presence of aerodynamic effect. Next, we calculate the stability of the fiber jet versus temporally growing, spatially growing, or spatiotemporally growing perturbations and determine the results for the growth rates of the effective perturbations versus jet flow parameters.
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On the basis of available knowledge, it is shown that different mechanisms may have control in different jet flows or in different regions of a jet flow. In free jet flows, the downstream region is dominated by turbulence structur...
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On the basis of available knowledge, it is shown that different mechanisms may have control in different jet flows or in different regions of a jet flow. In free jet flows, the downstream region is dominated by turbulence structure whereas coherent eddy-structure can have a strong influence on the near field, particularly for low-Reynolds number jet flows. At present, however, it has become a common belief that coherent-eddy structures determine, to a large degree, the evolution and dynamics of turbulent jet flows. The following article is an attempt to review the current information on round turbulent jet flows. In so doing, the influence of the jet origin (initial conditions) and the boundary conditions (presence or absence of endplate, side walls, and/or jet enclosure) on the jet flow structure is considered.
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The striking suppression and modification patterns that are observed in jet observables measured in heavy-ion collisions with respect to the proton-proton baseline have the potential to constrain the spatio-temporal branching proc...
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The striking suppression and modification patterns that are observed in jet observables measured in heavy-ion collisions with respect to the proton-proton baseline have the potential to constrain the spatio-temporal branching process of energetic partons in a dense QCD medium. The mechanism of jet energy loss is intricately associated with medium resolution of jet substructure fluctuations. This naturally affects the behavior of the suppression of jets at high-p(T), inducing an explicit dependence on jet scales. In this contribution, we review recent work on using the insight from multi-parton quenching to calculate leading-logarithmic corrections to the single-inclusive jet spectrum, and discuss its impact on a wide range of observables, including jet substructure.
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