Littérature scientifique sur le sujet « Interface turbulent »

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Articles de revues sur le sujet "Interface turbulent"

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Teixeira, M. A. C., et C. B. da Silva. « Turbulence dynamics near a turbulent/non-turbulent interface ». Journal of Fluid Mechanics 695 (13 février 2012) : 257–87. http://dx.doi.org/10.1017/jfm.2012.17.

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AbstractThe characteristics of the boundary layer separating a turbulence region from an irrotational (or non-turbulent) flow region are investigated using rapid distortion theory (RDT). The turbulence region is approximated as homogeneous and isotropic far away from the bounding turbulent/non-turbulent (T/NT) interface, which is assumed to remain approximately flat. Inviscid effects resulting from the continuity of the normal velocity and pressure at the interface, in addition to viscous effects resulting from the continuity of the tangential velocity and shear stress, are taken into account by considering a sudden insertion of the T/NT interface, in the absence of mean shear. Profiles of the velocity variances, turbulent kinetic energy (TKE), viscous dissipation rate ($\varepsilon $), turbulence length scales, and pressure statistics are derived, showing an excellent agreement with results from direct numerical simulations (DNS). Interestingly, the normalized inviscid flow statistics at the T/NT interface do not depend on the form of the assumed TKE spectrum. Outside the turbulent region, where the flow is irrotational (except inside a thin viscous boundary layer),$\varepsilon $decays as${z}^{\ensuremath{-} 6} $, where$z$is the distance from the T/NT interface. The mean pressure distribution is calculated using RDT, and exhibits a decrease towards the turbulence region due to the associated velocity fluctuations, consistent with the generation of a mean entrainment velocity. The vorticity variance and$\varepsilon $display large maxima at the T/NT interface due to the inviscid discontinuities of the tangential velocity variances existing there, and these maxima are quantitatively related to the thickness$\delta $of the viscous boundary layer (VBL). For an equilibrium VBL, the RDT analysis suggests that$\delta \ensuremath{\sim} \eta $(where$\eta $is the Kolmogorov microscale), which is consistent with the scaling law identified in a very recent DNS study for shear-free T/NT interfaces.
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Hannoun, Imad A., Harindra J. S. Fernando et E. John List. « Turbulence structure near a sharp density interface ». Journal of Fluid Mechanics 189 (avril 1988) : 189–209. http://dx.doi.org/10.1017/s0022112088000965.

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The effects of a sharp density interface and a rigid flat plate on oscillating-grid induced shear-free turbulence were investigated experimentally. A two-component laser-Doppler velocimeter was used to measure turbulence intensities in and above the density interface (with matched refractive indices) and near the rigid flat plate. Energy spectra, velocity correlations, and kinetic energy fluxes were also measured. Amplification of the horizontal turbulent velocity, coupled with a sharp reduction in the vertical turbulent velocity, was observed near both the density interface and the flat plate. These findings are in agreement with some previous results pertaining to shear-free turbulence near rigid walls (Hunt & Graham 1978) and near density interfaces (Long 1978). The results imply that, near the density interface, the turbulent kinetic energy in the vertical velocity component is only a small fraction of the total turbulent kinetic energy and indicate that the effects of the anisotropy created by the density interface or the flat plate are confined to the large turbulence scales.
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Popot, Jean-Lue. « Turbulent interface ». Biochimie 80, no 5-6 (mai 1998) : 355–56. http://dx.doi.org/10.1016/s0300-9084(00)80002-4.

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Elsinga, G. E., et C. B. da Silva. « How the turbulent/non-turbulent interface is different from internal turbulence ». Journal of Fluid Mechanics 866 (5 mars 2019) : 216–38. http://dx.doi.org/10.1017/jfm.2019.85.

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The average patterns of the velocity and scalar fields near turbulent/non-turbulent interfaces (TNTI), obtained from direct numerical simulations (DNS) of planar turbulent jets and shear free turbulence, are assessed in the strain eigenframe. These flow patterns help to clarify many aspects of the flow dynamics, including a passive scalar, near a TNTI layer, that are otherwise not easily and clearly assessed. The averaged flow field near the TNTI layer exhibits a saddle-node flow topology associated with a vortex in one half of the interface, while the other half of the interface consists of a shear layer. This observed flow pattern is thus very different from the shear-layer structure consisting of two aligned vortical motions bounded by two large-scale regions of uniform flow, that typically characterizes the average strain field in the fully developed turbulent regions. Moreover, strain dominates over vorticity near the TNTI layer, in contrast to internal turbulence. Consequently, the most compressive principal straining direction is perpendicular to the TNTI layer, and the characteristic 45-degree angle displayed in internal shear layers is not observed at the TNTI layer. The particular flow pattern observed near the TNTI layer has important consequences for the dynamics of a passive scalar field, and explains why regions of particularly high scalar gradient (magnitude) are typically found at TNTIs separating fluid with different levels of scalar concentration. Finally, it is demonstrated that, within the fully developed internal turbulent region, the scalar gradient exhibits an angle with the most compressive straining direction with a peak probability at around 20$^{\text{o}}$. The scalar gradient and the most compressive strain are not preferentially aligned, as has been considered for many years. The misconception originated from an ambiguous definition of the positive directions of the strain eigenvectors.
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Li, Sicheng, Yanguang Long et Jinjun Wang. « Turbulent/non-turbulent interface for laminar boundary flow over a wall-mounted fence ». Physics of Fluids 34, no 12 (décembre 2022) : 125113. http://dx.doi.org/10.1063/5.0128609.

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The turbulent/non-turbulent interface plays an important role in the exchange of mass, momentum, and energy between turbulent and nonturbulent flows. However, the role played by the interface in the separation and reattachment flow remains poorly understood. This study, thus, investigates the geometrical and dynamic properties of the interface in the separation and reattachment flow induced by a wall-mounted fence by using particle image velocimetry in a water tunnel. The flow undergoes laminar separation, reattachment, and the recovery of the boundary layer. Finally, the fully developed turbulent boundary layer is established. The geometrical and dynamic properties of the interface vary consistently with the vortex structure. The geometrical properties change most quickly above the reattachment point, where the dynamic properties are maximal. Before the reattachment point, the shear motion of the fluid contributes significantly to the interface properties. As a result, the interface thickness does not scale with the size of the nearby vortex until reattachment. Additionally, quasiperiodic shedding vortices significantly affect the interface properties. Remarkable bulges and troughs of the interface form corresponding to the spatial arrangement of the shedding vortices. In addition, the conditional averaged dynamic quantities peak along the interface coordinate as the turbulence intensity is enhanced by the shedding vortex. This study provides a new perspective of the turbulent/non-turbulent interface, improves our understanding of turbulent diffusion in the separation and reattachment flow, and clarifies how the separated flow and shedding vortices affect the interface properties.
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Lee, Jin, Hyung Jin Sung et Tamer A. Zaki. « Signature of large-scale motions on turbulent/non-turbulent interface in boundary layers ». Journal of Fluid Mechanics 819 (18 avril 2017) : 165–87. http://dx.doi.org/10.1017/jfm.2017.170.

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The effect of large-scale motions (LSMs) on the turbulent/non-turbulent (T/NT) interface is examined in a turbulent boundary layer. Using flow fields from direct numerical simulation, the shape of the interface and near-interface statistics are evaluated conditional on the position of the LSM. The T/NT interface is identified using the vorticity magnitude and a streak detection algorithm is adopted to identify and track the LSMs. Two-point correlation and spectral analysis of variations in the interface height show that the spatial undulation of the interface is longer in streamwise wavelength than the boundary-layer thickness, and grows with the Reynolds number in a similar manner to the LSMs. The average variation in the interface height was evaluated conditional on the position of the LSMs. The result provides statistical evidence that the interface is locally modulated by the LSMs in both the streamwise and spanwise directions. The modulation is different when the coherent structure is high- versus low-speed motion: high-speed structures lead to a wedge-shaped deformation of the T/NT interface, which causes an anti-correlation between the angles of the interface and the internal shear layer. On the other hand, low-speed structures are correlated with crests in the interface. Finally, the sudden changes in turbulence statistics across the interface are in line with the changes in the population of low-speed structures, which consist of slower mean streamwise velocity and stronger turbulence than the high-speed counterparts.
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Borrell, Guillem, et Javier Jiménez. « Properties of the turbulent/non-turbulent interface in boundary layers ». Journal of Fluid Mechanics 801 (26 juillet 2016) : 554–96. http://dx.doi.org/10.1017/jfm.2016.430.

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The turbulent/non-turbulent interface is analysed in a direct numerical simulation of a boundary layer in the Reynolds number range$Re_{{\it\theta}}=2800{-}6600$, with emphasis on the behaviour of the relatively large-scale fractal intermittent region. This requires the introduction of a new definition of the distance between a point and a general surface, which is compared with the more usual vertical distance to the top of the layer. Interfaces are obtained by thresholding the enstrophy field and the magnitude of the rate-of-strain tensor, and it is concluded that, while the former are physically relevant features, the latter are not. By varying the threshold, a topological transition is identified as the interface moves from the free stream into the turbulent core. A vorticity scale is defined which collapses that transition for different Reynolds numbers, roughly equivalent to the root-mean-squared vorticity at the edge of the boundary layer. Conditionally averaged flow variables are analysed as functions of the new distance, both within and outside the interface. It is found that the interface contains a non-equilibrium layer whose thickness scales well with the Taylor microscale, enveloping a self-similar layer spanning a fixed fraction of the boundary-layer thickness. Interestingly, the straining structure of the flow is similar in both regions. Irrotational pockets within the turbulent core are also studied. They form a self-similar set whose size decreases with increasing depth, presumably due to breakup by the turbulence, but the rate of viscous diffusion is independent of the pocket size. The raw data used in the analysis are freely available from our web page (http://torroja.dmt.upm.es).
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Ferrey, P., et B. Aupoix. « Behaviour of turbulence models near a turbulent/non-turbulent interface revisited ». International Journal of Heat and Fluid Flow 27, no 5 (octobre 2006) : 831–37. http://dx.doi.org/10.1016/j.ijheatfluidflow.2006.03.022.

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Moeng, C.-H., B. Stevens et P. P. Sullivan. « Where is the Interface of the Stratocumulus-Topped PBL ? » Journal of the Atmospheric Sciences 62, no 7 (1 juillet 2005) : 2626–31. http://dx.doi.org/10.1175/jas3470.1.

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Abstract Various locally defined (not horizontal mean) interfaces between the stratocumulus-topped PBL and the free atmosphere are investigated using a fine-resolution large-eddy simulation with a vertical grid spacing of about 4 m. The local cloud-top height is found to be always below the height where the maximum gradient of the local sounding occurs, and the maximum-gradient height is always below the interface where PBL air can reach via turbulent motions. The distances between these local interfaces are of significant amount, a few tens of meters on average. Air between the cloud-top and maximum-gradient interfaces is fully turbulent, unsaturated, but rather moist. Air between the maximum-gradient and turbulent-mixing interfaces consists of turbulent motions that are intermittent in space and time. The simulated flow shows no clearly defined interface that separates cloudy, turbulent air mass from clear, nonturbulent air above, even locally.
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KIT, E. L. G., E. J. STRANG et H. J. S. FERNANDO. « Measurement of turbulence near shear-free density interfaces ». Journal of Fluid Mechanics 334 (10 mars 1997) : 293–314. http://dx.doi.org/10.1017/s0022112096004442.

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The results of an experimental study carried out to investigate the structure of turbulence near a shear-free density interface are presented. The experimental configuration consisted of a two-layer fluid medium in which the lower layer was maintained in a turbulent state by an oscillating grid. The measurements included the root-mean-square (r.m.s.) turbulent velocities, wavenumber spectra, dissipation of turbulent kinetic energy and integral lengthscales. It was found that the introduction of a density interface to a turbulent flow can strongly distort the structure of turbulence near the interface wherein the horizontal velocity components are amplified and the vertical component is damped. The modification of r.m.s velocities is essentially limited to distances smaller than about an integral lengthscale. Inspection of spectra shows that these distortions are felt only at small wavenumbers of the order of the integral scale and a range of low-wavenumbers of the inertial subrange; the distortions become pronounced as the interface is approached. Comparison of the horizontal velocity data with the rapid distortion theory (RDT) analyses of Hunt & Graham (1978) and Hunt (1984) showed a qualitative agreement near the interface and a quantitative agreement away from the interface. On the other hand, the RDT predictions for the vertical component were in general agreement with the data. The near-interface horizontal velocity data, however, showed quantitative agreement with a model proposed by Hunt (1984) based on nonlinear vortex dynamics near the interface. The effects due to interfacial waves appear to be important for distances less than about 10% of the integral lengthscale. As a consequence of the non-zero energy flux divergence, the introduction of a density interface to oscillating grid turbulence increases the rate of dissipation in the turbulent layer except near the interface, where a sharp drop occurs. The present measurements provide useful information on the structure of turbulence in shear-free boundary layers, such as atmospheric and oceanic convective boundary layers, thus improving modelling capabilities for such flows.
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Thèses sur le sujet "Interface turbulent"

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Cocconi, Giacomo. « Numerical investigation of turbulent/non-turbulent interface ». Master's thesis, Alma Mater Studiorum - Università di Bologna, 2013. http://amslaurea.unibo.it/5237/.

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The subject of this work is the diffusion of turbulence in a non-turbulent flow. Such phenomenon can be found in almost every practical case of turbulent flow: all types of shear flows (wakes, jet, boundary layers) present some boundary between turbulence and the non-turbulent surround; all transients from a laminar flow to turbulence must account for turbulent diffusion; mixing of flows often involve the injection of a turbulent solution in a non-turbulent fluid. The mechanism of what Phillips defined as “the erosion by turbulence of the underlying non-turbulent flow”, is called entrainment. It is usually considered to operate on two scales with different mechanics. The small scale nibbling, which is the entrainment of fluid by viscous diffusion of turbulence, and the large scale engulfment, which entraps large volume of flow to be “digested” subsequently by viscous diffusion. The exact role of each of them in the overall entrainment rate is still not well understood, as it is the interplay between these two mechanics of diffusion. It is anyway accepted that the entrainment rate scales with large properties of the flow, while is not understood how the large scale inertial behavior can affect an intrinsically viscous phenomenon as diffusion of vorticity. In the present work we will address then the problem of turbulent diffusion through pseudo-spectral DNS simulations of the interface between a volume of decaying turbulence and quiescent flow. Such simulations will give us first hand measures of velocity, vorticity and strains fields at the interface; moreover the framework of unforced decaying turbulence will permit to study both spatial and temporal evolution of such fields. The analysis will evidence that for this kind of flows the overall production of enstrophy , i.e. the square of vorticity omega^2 , is dominated near the interface by the local inertial transport of “fresh vorticity” coming from the turbulent flow. Viscous diffusion instead plays a major role in enstrophy production in the outbound of the interface, where the nibbling process is dominant. The data from our simulation seems to confirm the theory of an inertially stirred viscous phenomenon proposed by others authors before and provides new data about the inertial diffusion of turbulence across the interface.
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Er, Sarp. « Structure interne, transfert turbulent et propriétés de cascade de l'interface turbulent/non-turbulent d'un jet turbulent ». Electronic Thesis or Diss., Université de Lille (2022-....), 2023. http://www.theses.fr/2023ULILN048.

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L'interface turbulent/non-turbulent (TNTI) est une couche très fine entre les régions turbulentes et non turbulentes de l'écoulement. Cette étude vise à mieux comprendre le bilan d'énergie cinétique au voisinage de l'interface turbulent/non-turbulent. L'équation de Kármán-Howarth-Monin-Hill (KHMH) est utilisée pour caractériser le bilan énergétique cinétique local, y compris les transferts d'énergie dans l'espace et entre les échelles. L'analyse est effectuée à l'aide de données obtenues par simulation numérique directe (DNS) finement résolue d'un jet plan turbulent se développant avec le temps. Les lois d'échelles de vitesse et de longueur du jet plan turbulent en evolution temporelle sont différentes de celles de son homologue en développement spatial, dans le sens où ces lois sont indépendantes de l'échelle de dissipation turbulente, qu'elle soit à l'équilibre ou hors équilibre. Il est montré que la variation de la vitesse moyenne de propagation à travers l'épaisseur de la TNTI est fonction de la dimension fractale de la surface à chaque position. Une méthodologie basée sur une opération de moyennage le long de la TNTI est utilisée pour l'analyse de l'écoulement local à proximité de la TNTI. L'analyse du vecteur normal associé à l'orientation locale de la TNTI fournit des informations précieuces sur les caractéristiques géométriques prédominantes de l'interface. Les statistiques moyennes de l'interface sont ensuite conditionnées par sa courbure moyenne et sa vitesse de propagation locale afin de caractériser la variation locale de l'écoulement et le bilan de l'équation KHMH dans les différentes couche de l'interface. Il est démontré que l'épaisseur de la TNTI et de ses sous-couches diminuent de manière significative dans les régions de fort entraînement. Les transferts entre échelles et en espace sont décomposés en une partie solénoïdale et une partie irrotationnelle, ce qui montre l'importance, au niveau de la TNTI, des transferts irrotationnels d'énergie cinétique entre échelles et en espace, associés à la corrélation pression-vitesse. Des phénomènes de compression et d'étirement sont observés en moyenne à proximité de la TNTI, dans les directions respectivement normale et tangentielle à l'interface. L'étude du terme de transfert inter-échelles montre la présence d'une cascade directe dans la direction normale et d'une cascade inverse dans la direction tangentielle. Dans les régions d'entraînement inverse, les statistiques locales montrent un étirement dans la direction normale et de la compression dans la direction tangentielle, ce qui contraste avec les statistiques observées pour l'ensemble de la TNTI et les régions d'entraînement locales. Près de la TNTI, du côté turbulent, un équilibre inattendu ressemblant à celui de Kolmogorov est observé entre le transfert inter-échelle et le taux de dissipation pour une large gamme d'échelles. Pour ces échelles, contrairement à l'équilibre de Kolmogorov habituel pour la turbulence homogène, le transfert inter-échelle est constitué uniquement de la partie irrotationnelle qui est directement associée aux corrélations pression-vitesse
The turbulent/non-turbulent interface (TNTI) is a very sharp interface layer between turbulent and non-turbulent regions of the flow. This study aims to gain insight into the kinetic energy balance in the vicinity of the TNTI. The K'arm'an-Howarth-Monin-Hill equation (KHMH) is used to characterize the local kinetic energy balance including interscale/interspace energy transfers. The analysis is conducted by using a data set obtained by highly resolved direct numerical simulation (DNS) of a temporally developing turbulent planar jet. The scalings for the velocity and length scales of the temporally developing turbulent planar jet are shown to be different from its spatially developing counterpart in the sense that these scalings are independent of the turbulent dissipation scaling, whether equilibrium or non-equilibrium. The variation of the mean propagation velocity across the thickness of the TNTI is shown as a function of the fractal dimension of the surface at each location. Furthermore, a methodology based on a TNTI-averaging operation is used for the analysis of the local flow field in the vicinity of the TNTI. The analysis of the normal vector associated with the local facing direction of the TNTI provides valuable insights into the predominant geometric characteristics of the interface. The TNTI-averaged statistics are further conditioned on the mean curvature and the local propagation velocity of the interface, in order to characterize the variation of the local flow field and KHMH balance in various regions of the interface. The thickness of the TNTI and its sublayers are shown to reduce significantly in regions of fast entrainment. The interscale/interspace transfer terms are decomposed into solenoidal/irrotational parts showing the central importance at the TNTI of the irrotational interscale/interspace transfers of kinetic energy associated with pressure-velocity correlation. Compression and stretching are observed on average at the TNTI location, in the normal and tangential directions of the interface respectively. Investigation of the interscale transfer term shows the presence of a forward cascade in the normal direction and an inverse cascade in the tangential direction. In regions of detrainment, the local statistics display stretching in the normal direction and compression in the tangential direction, which is in contrast with the statistics observed for the entire TNTI and the local entrainment regions. Close to the location of TNTI, on the turbulent side, an unexpected Kolmogorov-like balance is observed between the interscale transfer and the dissipation rate for a wide range of scales. For these scales, unlike the usual Kolmogorov balance for homogeneous turbulence, the interscale transfer consists solely of the irrotational part which is directly associated with the pressure-velocity correlations
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Kearney, Dominic. « Turbulent diffusion in channels of complex geometry ». Thesis, Loughborough University, 2000. https://dspace.lboro.ac.uk/2134/7275.

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This thesis examines turbulent diffusion processes in rectangular and compound open channels, with particular attention to the effect of secondary flow and the relationship between eddy viscosity and eddy diffusivity. Three dimensional velocities and concentration were measured using 3 component Laser Doppler Velocimetry (LDV) combined with Laser Induced Fluorescence (LIF) from three laboratory flumes: one rectangular simple channel and a deep and a shallow compound channel. (Continues...).
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Hernandez, Medina Santiago. « Turbulent interface phenomena in a temporally developing boundary layer ». Master's thesis, Alma Mater Studiorum - Università di Bologna, 2017. http://amslaurea.unibo.it/14721/.

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The purpose of the current study was to examine the characteristics and behavior of the turbulent/non-turbulent interface on a temporally developing boundary layer. Flow topology, turbulent statistics, enstrophy budgets and spectral statistics were computed with the purpose of acquiring meaningful results.
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Padovani, Lorenzo. « Enstrophy Analysis of a Turbulent Temporal Plume ». Master's thesis, Alma Mater Studiorum - Università di Bologna, 2021.

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The aim of the present thesis work is to analyse the enstrophy behaviour of a temporal turbulent plume. Several previous works have focused their attention on the role of vorticity or enstrophy in free shear flows, but they mainly concentrate on jets, wakes or mixing layers. The analysis is performed on a temporal turbulent plume at time t = 40 which shows a Reλ= 89. The analyses performed start from a flow general features assessment. It is retrieved that the coherent vorticity structures inside a plume can be divided in Large Vorticity Structures (LVSs) and Intense Vorticity Structures (IVSs) and that the LVSs are responsible for the Turbulent/Non-Turbulent (T/NT) interface geometrical shape. In addition, the sensitivity to the enstrophy detection threshold is tested and verified retrieving a good interface robustness. The characteristics of the T/NT interface are analysed exploiting the traditional mean enstrophy budget equation and the conditional mean enstrophy budget equation.
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Johnstone, Henry Webb 1956. « CONFINED JET-INDUCED MIXING AT A DENSITY INTERFACE (TURBULENT, SHEAR FLOW) ». Thesis, The University of Arizona, 1987. http://hdl.handle.net/10150/292003.

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Lowe, Steven J. « A parametric study of the momentum flux at the air-sea interface ». Thesis, This resource online, 1993. http://scholar.lib.vt.edu/theses/available/etd-06102009-063110/.

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Herlina. « Gas transfer at the air-water interface in a turbulent flow environment ». Karlsruhe : Univ.-Verl, 2005. http://deposit.ddb.de/cgi-bin/dokserv?idn=976595842.

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Carbajal-Gomez, Leopoldo. « Transport in turbulent plasmas at the interface between different levels of description ». Thesis, University of Warwick, 2015. http://wrap.warwick.ac.uk/73926/.

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Energetic ion dynamics play an important role in magnetic confinement fusion (MCF) plasmas, as well as in the solar wind. In the former case, energetic ions such as neutral beam injection (NBI) ions and fusion-born alpha-particles, can interact with global modes in tokamak plasmas leading to instabilities that might result in loss of confinement and energy. In the latter case, ion dynamics must be taken into account in order to explain in situ and remote observations of heating of the solar wind, which show the occurrence of anisotropic heating of ions, as well as magnetohydrodynamics turbulence and intermittency all at the same time. In this thesis we address two scenarios in plasma physics where ion dynamics play a key role modifying the mass and energy transport in the plasma, specifically, ion cyclotron emission (ICE) in MCF plasmas, and preferential ion heating due to intermittent magnetic fields in the solar wind. ICE results from a radiative instability, probably the magnetoacoustic cyclotron instability (MCI), driven by energetic ions in MCF plasmas. Understanding the underlying physics of ICE is important for the exploitation of ICE as a non-perturbative diagnostic for confined and lost alpha-particles in deuterium-tritium (D-T) plasmas in future thermonuclear fusion reactors [McClements et al., Nucl. Fusion, 55, 043013 (2015); Dendy and McClements, Plasma Phys. Controlled Fusion, 57, 044002 (2015)]. On the other hand, preferential ion heating in the solar wind, observed as the occurrence of an ion beam which drifts along the background magnetic field with a velocity close to the local Alfven speed, is still an open problem. Despite the large amount of studies conducted in this issue, none of them included intermittency self-consistently. Therefore, the relationships between preferential ion heating and intermittency have remained unknown, until now. We study in detail the previously mentioned scenarios through numerical simulations using the hybrid approximation for the plasma, which treat ions as kinetic particles and electrons as a neutralizing massless fluid. Our hybrid simulations of the MCI confirm predictions of the analytical theory of the MCI, and recover some features of ICE as observed in D-T plasmas in JET. Furthermore, by going deep into the nonlinear stage of the MCI, we recover additional features of ICE which are not predicted by the linear theory of the MCI but are present in the measured ICE signal, resulting in a good match between our simulation results and the measured ICE intensity in JET. On the other hand, we present the first study of preferential ion heating in the fast solar wind including intermittent electromagnetic fields in a self-consistent way. We find that the temporal and spatial dynamics of the mechanisms driving preferential ion heating in our simulations (gyrobunching and ion trapping by the electric field), the ion temperature anisotropy T=T (perpendicular temperature/parallel temperature), and the degree of correlation between velocity and magnetic field fluctuations, show strong dependence on the level of intermittency in the electromagnetic fields.
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Donnadille, Philippe. « Comportement de gouttes en écoulement turbulent instationnaire : simulation numérique, modélisation, experimentation ». Valenciennes, 1992. https://ged.uphf.fr/nuxeo/site/esupversions/65515773-7bc6-415c-8beb-98e07fbcb3d7.

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Le travail présenté dans cette thèse concerne l'étude de l'influence de fortes instationnarités d'écoulement sur la dispersion de gouttes. Le sujet est abordé selon les trois aspects suivants: simulation numérique, modélisation, expérimentation qui sont appliqués à deux géométries de base: marche descendante, zone de mélange. Des moyens originaux de visualisation, traitement d'image, et mesure sont utilisés pour caractériser l'écoulement: trajectographie de gouttes par vidéo rapide, anemogranulométrie par technique phase doppler. La simulation numérique: approche déterministe instationnaire lagrangienne pour la phase liquide, couplés a un calcul instantané de la phase gazeuse, est validée par l'expérience. Cinq approches stochastiques sont ensuite mises en œuvre pour la phase liquide (couplées à un calcul k-) et comparées aux approches précédentes. Une première analyse relative aux performances de ces différents modèles est présentée.
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Livres sur le sujet "Interface turbulent"

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Komori, Satoru. Turbulence structure and CO₂ transfer at the air-sea interface and turbulent diffusion in thermally-stratified flows. Tsukuba, Japan : Center for Global Environmental Research, National Institute for Environmental Studies, Environment Agency of Japan, 1996.

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Michael, Kelley, et Institute for Computer Applications in Science and Engineering., dir. Tracking a turbulent spot in an immersive environment. Hampton, VA : Institute for Computer Applications in Science and Engineering, NASA Langley Research Center, 1995.

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Michael, Kelley, et Institute for Computer Applications in Science and Engineering., dir. Tracking a turbulent spot in an immersive environment. Hampton, VA : Institute for Computer Applications in Science and Engineering, NASA Langley Research Center, 1995.

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Marcelo J.S. de Lemos. Turbulent Impinging Jets into Porous Materials. Berlin, Heidelberg : Springer Berlin Heidelberg, 2012.

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Carlo, Gualtieri, et Mihailovic Dragutin T, dir. Fluid mechanics of environmental interfaces. London : Taylor & Francis, 2008.

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Woyczyński, W. A. Burgers-KPZ turbulence : Göttingen lectures. Berlin : Springer, 1998.

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Lorencez-González, Carlos Martín. Turbulent momentum transfer at a gas-liquid interface in horizontal stratified flow in a rectangular channel. 1994.

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Lyness, Karen S., et Hilal E. Erkovan. The Changing Dynamics of Careers and the Work–Family Interface. Sous la direction de Tammy D. Allen et Lillian T. Eby. Oxford University Press, 2015. http://dx.doi.org/10.1093/oxfordhb/9780199337538.013.29.

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Although careers are an important part of people’s lives, career constructs have not always been well represented in the work–family (WF) literature. Accordingly, this chapter is written as a resource for WF scholars by providing a concise review of the rich career literature dating back over 100 years to show how conceptualizations of careers have evolved over time, with examples of key psychological and sociological theories that have enriched our understanding of careers. We also draw on the WF literature to illustrate how early career theories and concepts are still being applied to WF issues. We then focus on contemporary career theories and conceptualizations that reflect today’s turbulent work environment, and thus differ from traditional perspectives. In addition, we review the recent WF literature to examine how well these contemporary views of careers are represented, with examples of WF literature that illustrate the insights they offer. The chapter concludes with suggestions for further integration of ideas and constructs from the career literature in future WF research.
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National Aeronautics and Space Administration (NASA) Staff. Aspects of Turbulent / Non-Turbulent Interfaces. Independently Published, 2018.

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Kraus, Eric B., et Joost A. Businger. Atmosphere-Ocean Interaction. Oxford University Press, 1995. http://dx.doi.org/10.1093/oso/9780195066180.001.0001.

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With both the growing importance of integrating studies of air-sea interaction and the interest in the general problem of global warming, the appearance of the second edition of this popular text is especially welcome. Thoroughly updated and revised, the authors have retained the accessible, comprehensive expository style that distinguished the earlier edition. Topics include the state of matter near the interface, radiation, surface wind waves, turbulent transfer near the interface, the planetary boundary layer, atmospherically-forced perturbations in the oceans, and large-scale forcing by sea surface buoyancy fluxes. This book will be welcomed by students and professionals in meteorology, physical oceanography, physics and ocean engineering.
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Chapitres de livres sur le sujet "Interface turbulent"

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Rao, Samrat, G. R. Vybhav, P. Prasanth, S. M. Deshpande et R. Narasimha. « Turbulent/Non-turbulent Interface of a Transient Diabatic Plume ». Dans Lecture Notes in Mechanical Engineering, 355–61. Singapore : Springer Singapore, 2021. http://dx.doi.org/10.1007/978-981-15-5183-3_38.

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Vincent, Stéphane, Jean-Luc Estivalézes et Ruben Scardovelli. « Interface Tracking ». Dans Small Scale Modeling and Simulation of Incompressible Turbulent Multi-Phase Flow, 51–109. Cham : Springer International Publishing, 2022. http://dx.doi.org/10.1007/978-3-031-09265-7_3.

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Zhang, Xinxian. « Direct Numerical Simulation on Turbulent/Non-turbulent Interface in Compressible Turbulent Boundary Layers ». Dans Frontiers of Digital Transformation, 155–68. Singapore : Springer Singapore, 2021. http://dx.doi.org/10.1007/978-981-15-1358-9_10.

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Cocconi, G., A. Cimarelli, B. Frohnapfel et E. De Angelis. « A Numerical Study of the Shear-Less Turbulent/Non-turbulent Interface ». Dans Springer Proceedings in Physics, 37–40. Cham : Springer International Publishing, 2016. http://dx.doi.org/10.1007/978-3-319-29130-7_6.

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Mestayer, Patrice G., James B. Edson, Christofer W. Fairall, Søren E. Larsen et Donald E. Spiel. « Turbulent Transport and Evaporation of Droplets Generated at an Air-Water Interface ». Dans Turbulent Shear Flows 6, 129–47. Berlin, Heidelberg : Springer Berlin Heidelberg, 1989. http://dx.doi.org/10.1007/978-3-642-73948-4_13.

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Jahanbakhshi, Reza, et Cyrus K. Madnia. « Scalar Transport Near the Turbulent/Non-Turbulent Interface in Reacting Compressible Mixing Layers ». Dans Modeling and Simulation of Turbulent Mixing and Reaction, 25–46. Singapore : Springer Singapore, 2020. http://dx.doi.org/10.1007/978-981-15-2643-5_2.

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Sillero, Juan, Guillem Borrell, Javier Jiménez et Robert D. Moser. « Hybrid OpenMP-MPI Turbulent Boundary Layer Code Over 32k Cores ». Dans Recent Advances in the Message Passing Interface, 218–27. Berlin, Heidelberg : Springer Berlin Heidelberg, 2011. http://dx.doi.org/10.1007/978-3-642-24449-0_25.

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Borghi, Roland, et Fabien Anselmet. « Modeling the Mean Gas-Liquid Interface Area per Unit Volume ». Dans Turbulent Multiphase Flows with Heat and Mass Transfer, 165–73. Hoboken, USA : John Wiley & Sons, Inc., 2014. http://dx.doi.org/10.1002/9781118790052.ch7.

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Dixit, Harish N., et Rama Govindarajan. « Instabilities due a vortex at a density interface : gravitational and centrifugal effects ». Dans Seventh IUTAM Symposium on Laminar-Turbulent Transition, 141–46. Dordrecht : Springer Netherlands, 2009. http://dx.doi.org/10.1007/978-90-481-3723-7_21.

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Katul, Gabriel, et John Albertson. « Low Dimensional Turbulent Transport Mechanics Near the Forest-Atmosphere Interface ». Dans Bayesian Inference in Wavelet-Based Models, 361–80. New York, NY : Springer New York, 1999. http://dx.doi.org/10.1007/978-1-4612-0567-8_22.

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Actes de conférences sur le sujet "Interface turbulent"

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Westerweel, Jerry, A. Petracci, Rene Delfos et Julian C. R. Hunt. « THE TURBULENT/NON-TURBULENT INTERFACE OF A COOLED JET ». Dans Fifth International Symposium on Turbulence and Shear Flow Phenomena. Connecticut : Begellhouse, 2007. http://dx.doi.org/10.1615/tsfp5.1640.

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Taveira, Rodrigo M. R., et Carlos B. da Silva. « SCALAR MIXING AT TURBULENT/NON-TURBULENT INTERFACE OF A TURBULENT PLANE JET ». Dans Eighth International Symposium on Turbulence and Shear Flow Phenomena. Connecticut : Begellhouse, 2013. http://dx.doi.org/10.1615/tsfp8.520.

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Kohan, Khashayar F., et Susan Gaskin. « The Turbulent/Non-Turbulent Interface Characteristics in an Axisymmetric Jet ». Dans 7th International Conference on Fluid Flow, Heat and Mass Transfer (FFHMT'20). Avestia Publishing, 2020. http://dx.doi.org/10.11159/ffhmt20.162.

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da Silva, Carlos B., et Rodrigo M. R. Taveira. « CHARACTERISTICS OF THE TURBULENT/NON-TURBULENT INTERFACE AND VISCOUS SUPERLAYER IN TURBULENT PLANAR JETS ». Dans Eighth International Symposium on Turbulence and Shear Flow Phenomena. Connecticut : Begellhouse, 2013. http://dx.doi.org/10.1615/tsfp8.2170.

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Johnson, Blair, et Arefe Ghazi. « Turbulent mixing across a sharp density interface ». Dans Proceedings of the 39th IAHR World Congress From Snow to Sea. Spain : International Association for Hydro-Environment Engineering and Research (IAHR), 2022. http://dx.doi.org/10.3850/iahr-39wc2521711920221238.

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dos Reis, Ricardo J. N., Carlos B. da Silva et Jose C. F. Pereira. « VORTICITY STRUCTURES NEAR THE TURBULENT/NONTURBULENT INTERFACE IN A PLANAR TURBULENT JET ». Dans Seventh International Symposium on Turbulence and Shear Flow Phenomena. Connecticut : Begellhouse, 2011. http://dx.doi.org/10.1615/tsfp7.1040.

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Ghasemi, Abbas, Vesselina Roussinova, Ronald Barron et Ram Balachandar. « Analysis of Entrainment at the Turbulent/Non-Turbulent Interface of a Square Jet ». Dans ASME 2013 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/imece2013-65355.

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Particle image velocimetry measurements are carried out to study the entrainment at the interface between the non-turbulent and turbulent regions in a square jet. Jet Reynolds number based on the hydraulic diameter of the jet is 50,000. Measurements cover up to 25 diameters downstream of the nozzle exit using five horizontal field-of-views in the central plane of the jet. The turbulent/non-turbulent interface is identified using a velocity criterion and a suitable thresholding method. Using vorticity and swirling strength it is shown that the turbulent/non-turbulent interface separates the rotational and irrotational regions of the flow. Instantaneous velocity vector field superimposed with the turbulent/non-turbulent interface are presented. The relation between the vortex cores in the vicinity of the turbulent/non-turbulent interface and the contractions and expansions noticed in the jet velocity field are explained. Entrainment into the jet is evaluated at each axial distance by identifying the points falling inside the turbulent region of the jet. Compared to a round jet, the square jet entrains more ambient fluid. In addition, normal volume fluxes going through the turbulent/non-turbulent interface of the square jet are found to be larger compared to that of a round jet.
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Gampert, Markus, Philip Schaefer, Jonas Boschung et Norbert Peters. « GRADIENT TRAJECTORY ANALYSIS OF THE TURBULENT/NON-TURBULENT INTERFACE IN A JET FLOW ». Dans Eighth International Symposium on Turbulence and Shear Flow Phenomena. Connecticut : Begellhouse, 2013. http://dx.doi.org/10.1615/tsfp8.2180.

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Attili, Antonio, Juan C. Cristancho et Fabrizio Bisetti. « STATISTICS OF THE TURBULENT/NON-TURBULENT INTERFACE IN A SPATIALLY EVOLVING MIXING LAYER ». Dans Eighth International Symposium on Turbulence and Shear Flow Phenomena. Connecticut : Begellhouse, 2013. http://dx.doi.org/10.1615/tsfp8.480.

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De Angelis, V., et S. Banerjee. « Microphysics of Turbulent Transport Processes at Gas-Liquid Interface ». Dans ASME 1997 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 1997. http://dx.doi.org/10.1115/imece1997-0752.

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Abstract Gas and moisture transfer at continuous interfaces between turbulent air and water streams are controlled by layers ∼ O(10−2mm) and ∼ O(1mm) thickness, respectively. This suggests that direct numerical and large eddy simulations could be used to clarify microphysical processes controlling scalar transfer rates, since such scales are resolvable with available computational resources. To this end, numerical procedures using a pseudospectral method, together with a projection algorithm, have been developed and applied to coupled gas-liquid flows. The initial studies focused on flows under conditions where interface deformations were small — a situation corresponding to a series of laboratory experiments where detailed measurements of the near-interface turbulence characteristics were made. The simulations agreed very well with measurements. The next step was to calculate gas flow over wavy solid surfaces, where the wavelengths corresponded to those of capillary waves. The simulation maintained spectral accuracy, and agreed with experimental data, which included waves of sufficient steepness that separation occurred behind the crests. Finally, simulations were conducted for conditions under which capillary waves developed at the interface — the physical properties being those of air and water at atmospheric conditions. The program of simulations, supported, where possible, by experiments, clarified that the scalar transfer rates on each side of the interface were correlated with the sweeps on each side, i.e. fourth-quadrant events which bring high speed fluid close to the interface, forming regions of high shear stress and high scalar transfer rates. Furthermore, the simulations, and experiments indicated that the sweep frequency could be expressed in terms of the frictional drag, but not in terms of the total drag, which includes form drag. From this, using surface renewal theory, it was found that simple parametrizations for the scalar transfer rates could be derived in terms of the frictional drag, with no adjustable parameters. It appeared that capillary wave characteristics affect the scalar transfer rates by affecting the frictional drag, i.e. indirectly, by affecting sweep frequencies, and by affecting the Sc numbere dependency in the case the flow shows recirculation. Parameterizations based on these considerations are in excellent, agreement with large-scale laboratory experiments, some of which were done after the parametrizations were proposed.
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Rapports d'organisations sur le sujet "Interface turbulent"

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Chase, D. M. Turbulent Boundary-Layer Fluctuations at the Solid Interface. Fort Belvoir, VA : Defense Technical Information Center, septembre 1992. http://dx.doi.org/10.21236/ada257253.

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Wilczak, James M., Jr Bedard et Alfred J. Turbulent Pressure Measurements Above the Air-sea Interface. Fort Belvoir, VA : Defense Technical Information Center, septembre 1997. http://dx.doi.org/10.21236/ada629304.

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Tadros, Mariz, Sofya Shabab et Amy Quinn-Graham. Violence and Discrimination Against Women of Religious Minority Backgrounds in Iraq. Institute of Development Studies, décembre 2022. http://dx.doi.org/10.19088/creid.2022.025.

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This volume is part of the Intersections series which explores how the intertwining of gender, religious marginality, socioeconomic exclusion and other factors shape the realities of women and men in contexts where religious inequalities are acute, and freedom of religion or belief is compromised. This volume looks at these intersections in the context of Iraq. Its aim is to amplify the voices of women (and men) whose experiences of religious otherisation have accentuated the impact of the intersections of gender, class, geography and ethnicity. At time of publication, in December 2022, the country is going through a particularly turbulent phase, prompting some to wonder why now? Isn’t it bad timing to focus on the experiences of minorities, let alone inter- and intra-gender dynamics? Iraq is caught in the middle of geo-strategic struggles of tectonic proportions but this is all the more reason to understand the dynamics of micro-politics through a gender-sensitive lens. Doing so sheds light on the interface between global, regional and local power struggles in tangible and concrete ways.
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Monismith, Stephen G., et Robert L. Street. The Structure of Turbulence and Other Motions Beneath an Air-Water Interface. Fort Belvoir, VA : Defense Technical Information Center, août 1997. http://dx.doi.org/10.21236/ada341108.

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