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1

Johnson, Blair A., and Edwin A. Cowen. "Turbulent boundary layers absent mean shear." Journal of Fluid Mechanics 835 (November 27, 2017): 217–51. http://dx.doi.org/10.1017/jfm.2017.742.

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We perform an experimental study to investigate the turbulent boundary layer above a stationary solid glass bed in the absence of mean shear. High Reynolds number $(Re_{\unicode[STIX]{x1D706}}\sim 300)$ horizontally homogeneous isotropic turbulence is generated via randomly actuated synthetic jet arrays (RASJA – Variano & Cowen J. Fluid Mech. vol. 604, 2008, pp. 1–32). Each of the arrays is controlled by a spatio-temporally varying algorithm, which in turn minimizes the formation of secondary mean flows. One array consists of an $8\times 8$ grid of jets, while the other is a $16\times 16$
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2

Thole, K. A., and D. G. Bogard. "High Freestream Turbulence Effects on Turbulent Boundary Layers." Journal of Fluids Engineering 118, no. 2 (1996): 276–84. http://dx.doi.org/10.1115/1.2817374.

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High freestream turbulence levels significantly alter the characteristics of turbulent boundary layers. Numerous studies have been conducted with freestreams having turbulence levels of 7 percent or less, but studies using turbulence levels greater than 10 percent have been essentially limited to the effects on wall shear stress and heat transfer. This paper presents measurements of the boundary layer statistics for the interaction between a turbulent boundary layer and a freestream with turbulence levels ranging from 10 to 20 percent. The boundary layer statistics reported in this paper inclu
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3

Fontaine, Ryan A., Gregory S. Elliott, Joanna M. Austin, and Jonathan B. Freund. "Very near-nozzle shear-layer turbulence and jet noise." Journal of Fluid Mechanics 770 (March 27, 2015): 27–51. http://dx.doi.org/10.1017/jfm.2015.119.

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One of the principal challenges in the prediction and design of low-noise nozzles is accounting for the near-nozzle turbulent mixing layers at the high Reynolds numbers of engineering conditions. Even large-eddy simulation is a challenge because the locally largest scales are so small relative to the nozzle diameter. Model-scale experiments likewise typically have relatively thick near-nozzle shear layers, which potentially hampers their applicability to high-Reynolds-number design. To quantify the sensitivity of the far-field sound to nozzle turbulent-shear-layer conditions, a family of diame
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4

Pei, Binbin, FangBo Li, Zhengyuan Luo, Liang Zhao, and Bofeng Bai. "Dynamics of mixing flow with double-layer density stratification: Enstrophy and vortical structures." Physics of Fluids 34, no. 10 (2022): 104107. http://dx.doi.org/10.1063/5.0121554.

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Previous studies on stratified shear layers involving two streams with different densities have been conducted under the Boussinesq approximation, while the combined effect of stratified instability and mean shear in relation to multi-layer density stratification induced by scalar fields remains an unresolved fundamental question. In this paper, the shear-driven mixing flow involving initial double-layer density interfaces due to the compositional differences are numerically investigated, in which the mean shear interacts with Rayleigh–Taylor instability (RTI). Since its critical role in dynam
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5

Sleath, J. F. A. "Coastal Bottom Boundary Layers." Applied Mechanics Reviews 48, no. 9 (1995): 589–600. http://dx.doi.org/10.1115/1.3023147.

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Turbulent boundary layers in oscillatory flow are reviewed. These boundary layers show a thin inner layer with similar characteristics to wall layers in steady flow. Above this, there is an outer layer which has some characteristics which are the same as those of steady flow outer layers and other characteristics which are different. One difference is that the defect velocity profile does not scale on the shear velocity alone. Also, over rough beds, the turbulence intensity in the outer layer falls off with height in a similar way to oscillating grid turbulence. Transition from laminar to turb
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6

Watanabe, Tomoaki, Carlos B. da Silva, and Koji Nagata. "Non-dimensional energy dissipation rate near the turbulent/non-turbulent interfacial layer in free shear flows and shear free turbulence." Journal of Fluid Mechanics 875 (July 18, 2019): 321–44. http://dx.doi.org/10.1017/jfm.2019.462.

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The non-dimensional dissipation rate $C_{\unicode[STIX]{x1D700}}=\unicode[STIX]{x1D700}L/u^{\prime 3}$, where $\unicode[STIX]{x1D700}$, $L$ and $u^{\prime }$ are the viscous energy dissipation rate, integral length scale of turbulence and root-mean-square of the velocity fluctuations, respectively, is computed and analysed within the turbulent/non-turbulent interfacial (TNTI) layer using direct numerical simulations of a planar jet, mixing layer and shear free turbulence. The TNTI layer that separates the turbulent and non-turbulent regions exists at the edge of free shear turbulent flows and
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7

Muppidi, Suman, and Krishnan Mahesh. "Direct numerical simulations of roughness-induced transition in supersonic boundary layers." Journal of Fluid Mechanics 693 (January 6, 2012): 28–56. http://dx.doi.org/10.1017/jfm.2011.417.

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AbstractDirect numerical simulations are used to study the laminar to turbulent transition of a Mach 2.9 supersonic flat plate boundary layer flow due to distributed surface roughness. Roughness causes the near-wall fluid to slow down and generates a strong shear layer over the roughness elements. Examination of the mean wall pressure indicates that the roughness surface exerts an upward impulse on the fluid, generating counter-rotating pairs of streamwise vortices underneath the shear layer. These vortices transport near-wall low-momentum fluid away from the wall. Along the roughness region,
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8

Gan, X., M. Kilic, and J. M. Owen. "Flow Between Contrarotating Disks." Journal of Turbomachinery 117, no. 2 (1995): 298–305. http://dx.doi.org/10.1115/1.2835659.

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The paper describes a combined experimental and computational study of laminar and turbulent flow between contrarotating disks. Laminar computations produce Batchelor-type flow: Radial outflow occurs in boundary layers on the disks and inflow is confined to a thin shear layer in the midplane; between the boundary layers and the shear layer, two contrarotating cores of fluid are formed. Turbulent computations (using a low-Reynolds-number k–ε turbulence model) and LDA measurements provide no evidence for Batchelor-type flow, even for rotational Reynolds numbers as low as 2.2 × 104. While separat
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9

CARSTENSEN, STEFAN, B. MUTLU SUMER, and JØRGEN FREDSØE. "Coherent structures in wave boundary layers. Part 1. Oscillatory motion." Journal of Fluid Mechanics 646 (March 8, 2010): 169–206. http://dx.doi.org/10.1017/s0022112009992825.

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This work concerns oscillatory boundary layers over smooth beds. It comprises combined visual and quantitative techniques including bed shear stress measurements. The experiments were carried out in an oscillating water tunnel. The experiments reveal two significant coherent flow structures: (i) Vortex tubes, essentially two-dimensional vortices close to the bed extending across the width of the boundary-layer flow, caused by an inflectional-point shear layer instability. The imprint of these vortices in the bed shear stress is a series of small, insignificant kinks and dips. (ii) Turbulent sp
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10

Molinari, John, Patrick Duran, and David Vollaro. "Low Richardson Number in the Tropical Cyclone Outflow Layer." Journal of the Atmospheric Sciences 71, no. 9 (2014): 3164–79. http://dx.doi.org/10.1175/jas-d-14-0005.1.

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Abstract Dropsondes from the NOAA G-IV aircraft were used to examine the presence of low bulk Richardson numbers RB in tropical cyclones. At least one 400-m layer above z = 7.5 km exhibited RB < 1 in 96% of the sondes and RB ≤ 0.25 in 35% of the sondes. The latter represent almost certain turbulence. Sondes from major Hurricane Ivan (2004) were examined in detail. Turbulent layers fell into three broad groups. The first was found below cloud base near the edge of the central dense overcast (CDO) where relative humidity fell below 40%. Near-zero static stability existed within the turbul
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11

Elsinga, G. E., and C. B. da Silva. "How the turbulent/non-turbulent interface is different from internal turbulence." Journal of Fluid Mechanics 866 (March 5, 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
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12

Watanabe, Tomoaki, and Koji Nagata. "Energetics and vortex structures near small-scale shear layers in turbulence." Physics of Fluids 34, no. 9 (2022): 095114. http://dx.doi.org/10.1063/5.0099959.

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Vortices and kinetic energy distributions around small-scale shear layers are investigated with direct numerical simulations of isotropic turbulence. The shear layers are examined with the triple decomposition of a velocity gradient tensor. The shear layers subject to a biaxial strain appear near vortices with rotation, which induce energetic flow that contributes to the shear. A similar configuration of rotating motions near the shear layers is observed in a multi-scale random velocity field, which is free from the dynamics of turbulence. Therefore, the mechanism that sustains shearing motion
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13

Mislevy, S. P., and T. Wang. "The Effects of Adverse Pressure Gradients on Momentum and Thermal Structures in Transitional Boundary Layers: Part 2—Fluctuation Quantities." Journal of Turbomachinery 118, no. 4 (1996): 728–36. http://dx.doi.org/10.1115/1.2840928.

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The effects of adverse pressure gradients on the thermal and momentum characteristics of a heated transitional boundary layer were investigated with free-stream turbulence ranging from 0.3 to 0.6 percent. Boundary layer measurements were conducted for two constant-K cases, K1 = −0.51 × 10−6 and K2 = −1.05 × 10−6. The fluctuation quantities, u′, ν′, t′, the Reynolds shear stress (uν), and the Reynolds heat fluxes (νt and ut) were measured. In general, u′/U∞, ν′/U∞, and νt have higher values across the boundary layer for the adverse pressure-gradient cases than they do for the baseline case (K =
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14

KIT, E. L. G., E. J. STRANG, and H. J. S. FERNANDO. "Measurement of turbulence near shear-free density interfaces." Journal of Fluid Mechanics 334 (March 10, 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 in
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15

Brown, Garry L., and Anatol Roshko. "Turbulent shear layers and wakes." Journal of Turbulence 13 (January 2012): N51. http://dx.doi.org/10.1080/14685248.2012.723805.

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16

Volino, R. J., and T. W. Simon. "Boundary Layer Transition Under High Free-Stream Turbulence and Strong Acceleration Conditions: Part 2—Turbulent Transport Results." Journal of Heat Transfer 119, no. 3 (1997): 427–32. http://dx.doi.org/10.1115/1.2824115.

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Measurements from heated boundary layers along a concave-curved test wall subject to high (initially 8 percent) free-stream turbulence intensity and strong (K = (ν/U∞2 dU∞/dx, as high as 9 × 10−6) acceleration are presented and discussed. Conditions for the experiments were chosen to simulate those present on the downstream half of the pressure side of a gas turbine airfoil. Turbulence statistics, including the turbulent shear stress, the turbulent heat flux, and the turbulent Prandtl number are presented. The transition zone is of extended length in spite of the high free-stream turbulence le
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17

Watanabe, Tomoaki, James J. Riley, Koji Nagata, Keigo Matsuda, and Ryo Onishi. "Hairpin vortices and highly elongated flow structures in a stably stratified shear layer." Journal of Fluid Mechanics 878 (September 4, 2019): 37–61. http://dx.doi.org/10.1017/jfm.2019.577.

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Turbulent structures in stably stratified shear layers are studied with direct numerical simulation. Flow visualization confirms the existence of hairpin vortices and highly elongated structures with positive and negative velocity fluctuations, whose streamwise lengths divided by the layer thickness are $O(10^{0})$ and $O(10^{1})$, respectively. The flow at the wavelength related to these structures makes a large contribution to turbulent kinetic energy. These structures become prominent in late time, but with small buoyancy Reynolds numbers indicating suppression of turbulent mixing. Active t
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18

Park, Seung-Bu, Jong-Jin Baik, and Beom-Soon Han. "Role of Wind Shear in the Decay of Convective Boundary Layers." Atmosphere 11, no. 6 (2020): 622. http://dx.doi.org/10.3390/atmos11060622.

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The role of wind shear in the decay of the convective boundary layer (CBL) is systematically investigated using a series of large-eddy simulations. Nine CBLs with weak, intermediate, and strong wind shear are simulated, and their decays after stopping surface heat flux are investigated. After the surface heat flux is stopped, the boundary-layer-averaged turbulent kinetic energy (TKE) stays constant for almost one convective time scale and then decreases following a power law. While the decrease persists until the end of the simulation in the buoyancy-dominated (weak-shear) cases, the TKE in th
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19

Umlauf, Lars. "The Description of Mixing in Stratified Layers without Shear in Large-Scale Ocean Models." Journal of Physical Oceanography 39, no. 11 (2009): 3032–39. http://dx.doi.org/10.1175/2009jpo4006.1.

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Abstract Large-scale geophysical flows often exhibit layers with negligible vertical shear and infinite gradient Richardson number Ri. It is well known that these layers may be regions of active mixing, even in the absence of local shear production of turbulence because, among other processes, turbulence may be supplied by vertical turbulent transport from neighboring regions. This observation is contrasted by the behavior of most turbulence parameterizations used in ocean climate modeling, predicting the collapse of mixing of mass and matter if the Richardson number exceeds a critical thresho
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20

Ji (季索清), Suoqing, S. Peng Oh, and Phillip Masterson. "Simulations of radiative turbulent mixing layers." Monthly Notices of the Royal Astronomical Society 487, no. 1 (2019): 737–54. http://dx.doi.org/10.1093/mnras/stz1248.

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ABSTRACTRadiative turbulent mixing layers should be ubiquitous in multi-phase gas with shear flow. They are a potentially attractive explanation for the high ions such as O vi seen in high-velocity clouds and the circumgalactic medium (CGM) of galaxies. We perform 3D magnetohydrohynamics (MHD) simulations with non-equilibrium (NEI) and photoionization modelling, with an eye towards testing simple analytic models. Even purely hydrodynamic collisional ionization equilibrium (CIE) calculations have column densities much lower than observations. Characteristic inflow and turbulent velocities are m
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21

Barrett, Michael J., and D. Keith Hollingsworth. "On the Calculation of Length Scales for Turbulent Heat Transfer Correlation." Journal of Heat Transfer 123, no. 5 (2000): 878–83. http://dx.doi.org/10.1115/1.1391277.

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Turbulence length scale calculation methods were critically reviewed for their usefulness in boundary layer heat transfer correlations. Using the variance of the streamwise velocity and the dissipation spectrum, a rigorous method for calculating an energy-based integral scale was introduced. A principal advantage of the new method is the capability to calculate length scales in a low-Reynolds-number turbulent boundary layer. The method was validated with data from grid-generated, free-shear-layer, and wall-bounded turbulence. Length scales were calculated in turbulent boundary layers with mome
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22

MacKinnon, J. A., and M. C. Gregg. "Spring Mixing: Turbulence and Internal Waves during Restratification on the New England Shelf." Journal of Physical Oceanography 35, no. 12 (2005): 2425–43. http://dx.doi.org/10.1175/jpo2821.1.

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Abstract Integrated observations are presented of water property evolution and turbulent microstructure during the spring restratification period of April and May 1997 on the New England continental shelf. Turbulence is shown to be related to surface mixed layer entrainment and shear from low-mode near-inertial internal waves. The largest turbulent diapycnal diffusivity and associated buoyancy fluxes were found at the bottom of an actively entraining and highly variable wind-driven surface mixed layer. Away from surface and bottom boundary layers, turbulence was systematically correlated with
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23

Johnston, J. P., and K. A. Flack. "Review—Advances in Three-Dimensional Turbulent Boundary Layers With Emphasis on the Wall-Layer Regions." Journal of Fluids Engineering 118, no. 2 (1996): 219–32. http://dx.doi.org/10.1115/1.2817367.

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Current information concerning three-dimensional turbulent boundary layers is discussed. Several topics are presented including (i) a detailed description of eleven experiments published since 1990. In nine cases cross flows are controlled by pressure gradients imposed from the freestream, but in two cases the cross flows are wall-shear-driven. The other topics include (ii) an examination of state of the art in measurement techniques; (iii) a look at some issues and ideas in turbulence modeling; and (iv) an introduction to new work on the visualization and description of quasicoherent structur
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24

Perera, M. J. A. M., H. J. S. Fernando, and D. L. Boyer. "Turbulent mixing at an inversion layer." Journal of Fluid Mechanics 267 (May 25, 1994): 275–98. http://dx.doi.org/10.1017/s0022112094001187.

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A series of laboratory experiments was carried out to examine the interaction between stratification and turbulence at an inversion layer, with the objective of gaining insight into certain wave–turbulence encounters in the atmosphere. A three-layer stratified fluid system, consisting of a (thick) strongly stratified inversion layer, sandwiched between an upper turbulent layer and a lower non-turbulent weakly stratified layer, was employed. Oscillating-grid-induced shear-free turbulence was used in the upper layer. During the experiments, a fourth (interfacial) layer developed in the region be
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25

Gat, Ilana, Georgios Matheou, Daniel Chung, and Paul E. Dimotakis. "Incompressible variable-density turbulence in an external acceleration field." Journal of Fluid Mechanics 827 (August 24, 2017): 506–35. http://dx.doi.org/10.1017/jfm.2017.490.

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Dynamics and mixing of a variable-density turbulent flow subject to an externally imposed acceleration field in the zero-Mach-number limit are studied in a series of direct numerical simulations. The flow configuration studied consists of alternating slabs of high- and low-density fluid in a triply periodic domain. Density ratios in the range of $1.05\leqslant R\equiv \unicode[STIX]{x1D70C}_{1}/\unicode[STIX]{x1D70C}_{2}\leqslant 10$ are investigated. The flow produces temporally evolving shear layers. A perpendicular density–pressure gradient is maintained in the mean as the flow evolves, wit
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26

Lyn, D. A., and W. Rodi. "The flapping shear layer formed by flow separation from the forward corner of a square cylinder." Journal of Fluid Mechanics 267 (May 25, 1994): 353–76. http://dx.doi.org/10.1017/s0022112094001217.

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The turbulent shear layer and the associated recirculation region on the sidewall formed in flow separation from the forward corner of a square cylinder have been studied with one-component laser-Doppler velocimetry. Because of vortex shedding, the flow is approximately periodic, and is treated as a separated flow undergoing largeamplitude forcing at the shedding frequency. Phase (ensemble)-averaged velocities and turbulence intensities were obtained, and a close relationship in phase and amplitude between phase-averaged turbulence intensities and gradients of phase-averaged velocity is found
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27

Hunt, J. C. R. "Studying turbulence using direct numerical simulation: 1987 Center for Turbulence Research NASA Ames/Stanford Summer Programme." Journal of Fluid Mechanics 190 (May 1988): 375–92. http://dx.doi.org/10.1017/s0022112088001363.

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This paper is an account of a summer programme for the study of the ideas and models of turbulent flows, using the results of direct numerical stimulations of the Navier-Stokes equations. These results had been obtained on the computers and stored as accessible databases at the Center for Turbulence Research (CTR) of NASA Ames Research Center and Stanford University. At this first summer programme, some 32 visiting researchers joined those at the CTR to test hypotheses and models in five aspects of turbulence research: turbulence decomposition, bifurcation and chaos; two-point closure (or k-sp
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28

Gu, Li, Hang Yuan, Qiu Lan Li, Zi Nan Jiao, and Lan Lan Wang. "Section Turbulent Distribution of the Stratified Shear Flow in the Braided River." Applied Mechanics and Materials 665 (October 2014): 459–63. http://dx.doi.org/10.4028/www.scientific.net/amm.665.459.

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The turbulent characteristics of stratified shear flow in braided rivers with different velocities in upper and lower layers are not clear at present. The physical model of a typical braided river was conducted to study its sectional turbulence intensity distribution. The model has a mid-bar between two symmetrical anabranches. The transverse distribution, the vertical distribution and the whole section distribution of turbulent intensity were analyzed. The strong turbulent intensity occurred in the interface of upper and lower layers and the boundary zone of the high velocity and low velocity
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29

Baysal, Selman, and V. S. Ozgur Kirca. "Numerical Investigation of Transitional Oscillatory Boundary Layers: Turbulence Quantities." Fluids 10, no. 6 (2025): 143. https://doi.org/10.3390/fluids10060143.

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This study investigates the organized flow structures and turbulence quantities in a transitional oscillatory boundary-layer flow over a smooth bed using a DNS model set up by the open-source framework Nektar++ (v5.2.0). The present model was validated against the results of a previous study involving a bypass transition mechanism in the intermittently turbulent regime. To trigger the initial perturbations, a roughness element was placed on the bed and removed at the very moment a two-dimensional vortex tube, caused by an inflectional-point shear-layer instability, was observed on it. Then, th
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30

Volino, Ralph J., and Terrence W. Simon. "Spectral Measurements in Transitional Boundary Layers on a Concave Wall Under High and Low Free-Stream Turbulence Conditions." Journal of Turbomachinery 122, no. 3 (1997): 450–57. http://dx.doi.org/10.1115/1.1303075.

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The relationship between free-stream turbulence and boundary layer behavior has been investigated using spectral measurements. The power spectral densities of turbulence quantities in transitional and fully turbulent boundary layers were computed and compared to the power spectra of the same quantities measured in the free stream. Comparisons were made using the “transfer function.” The transfer function is the ratio of two spectra at each frequency in the spectra. Comparisons were done in flows with low (0.6 percent) and high (8 percent) free-stream turbulence intensities. Evidence was gather
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31

Schetz, Joseph A. "Turbulent Shear Layers in Supersonic Flow." AIAA Journal 36, no. 5 (1998): 879–80. http://dx.doi.org/10.2514/2.455.

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32

Benham, Graham P., Alfonso A. Castrejon-Pita, Ian J. Hewitt, Colin P. Please, Rob W. Style, and Paul A. D. Bird. "Turbulent shear layers in confining channels." Journal of Turbulence 19, no. 6 (2018): 431–45. http://dx.doi.org/10.1080/14685248.2018.1459630.

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33

Jović, Srba. "Recovery of reattached turbulent shear layers." Experimental Thermal and Fluid Science 17, no. 1-2 (1998): 57–62. http://dx.doi.org/10.1016/s0894-1777(97)10049-8.

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34

Alboussière, T., V. Uspenski, and R. Moreau. "Quasi-2D MHD turbulent shear layers." Experimental Thermal and Fluid Science 20, no. 1 (1999): 19–24. http://dx.doi.org/10.1016/s0894-1777(99)00023-0.

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35

WONG, A. B. D., R. W. GRIFFITHS, and G. O. HUGHES. "Shear layers driven by turbulent plumes." Journal of Fluid Mechanics 434 (May 10, 2001): 209–41. http://dx.doi.org/10.1017/s002211200100355x.

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A turbulent plume from a continuous source of buoyancy in a long tank is shown to generate a series of quasi-steady counterflowing horizontal shear layers throughout the tank. Both the horizontal flow velocity and the depth of the shear layers are observed to decrease with distance above/below the plume outflow. The shear layers are supported by the stable density stratification produced by the plume and are superimposed on the vertical advection and entrainment inflow that make up the so-called ‘filling box’ circulation. Thus, at some depths, the surrounding water flows away from the plume in
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36

Geurts, Bernard J. "Mixing efficiency in turbulent shear layers." Journal of Turbulence 2 (January 2001): N17. http://dx.doi.org/10.1088/1468-5248/2/1/017.

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37

Naqavi, Iftekhar Z., James C. Tyacke, and Paul G. Tucker. "Direct numerical simulation of a wall jet: flow physics." Journal of Fluid Mechanics 852 (August 8, 2018): 507–42. http://dx.doi.org/10.1017/jfm.2018.503.

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A direct numerical simulation (DNS) of a plane wall jet is performed at a Reynolds number of $Re_{j}=7500$. The streamwise length of the domain is long enough to achieve self-similarity for the mean flow and the Reynolds shear stress. This is the highest Reynolds number wall jet DNS for a large domain achieved to date. The high resolution simulation reveals the unsteady flow field in great detail and shows the transition process in the outer shear layer and inner boundary layer. Mean flow parameters of maximum velocity decay, wall shear stress, friction coefficient and jet spreading rate are c
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38

WU, XIAOHUA, and KYLE D. SQUIRES. "Numerical investigation of the turbulent boundary layer over a bump." Journal of Fluid Mechanics 362 (May 10, 1998): 229–71. http://dx.doi.org/10.1017/s0022112098008982.

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Large-eddy simulation (LES) has been used to calculate the flow of a statistically two-dimensional turbulent boundary layer over a bump. Subgrid-scale stresses in the filtered Navier–Stokes equations were closed using the dynamic eddy viscosity model. LES predictions for a range of grid resolutions were compared to the experimental measurements of Webster et al. (1996). Predictions of the mean flow and turbulence intensities are in good agreement with measurements. The resolved turbulent shear stress is in reasonable agreement with data, though the peak is over-predicted near the trailing edge
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39

Baysal, Selman, V. S. Özgür Kirca, and B. Mutlu Sumer. "LAMINAR-TO-TURBULENT TRANSITION IN OSCILLATORY WAVE BOUNDARY LAYERS." Coastal Engineering Proceedings, no. 38 (May 29, 2025): 100. https://doi.org/10.9753/icce.v38.waves.100.

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The orbital motion of water particles under a progressive wave in shallow waters becomes a straight line parallel to the bottom, i.e., oscillatory motion, at the seabed. A new time-dependent boundary layer develops over the seabed for each half-cycle of this motion. The turbulent oscillatory wave boundary layer is of great importance in many engineering applications, especially in coastal engineering. Even though both laminar and turbulent regimes have been considered in oscillatory boundary layers, of particular interest is the transitional regime. The laminar-to-turbulent transition first oc
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Womack, Kristofer M., Charles Meneveau, and Michael P. Schultz. "Comprehensive shear stress analysis of turbulent boundary layer profiles." Journal of Fluid Mechanics 879 (September 27, 2019): 360–89. http://dx.doi.org/10.1017/jfm.2019.673.

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Motivated by the need for accurate determination of wall shear stress from profile measurements in turbulent boundary layer flows, the total shear stress balance is analysed and reformulated using several well-established semi-empirical relations. The analysis highlights the significant effect that small pressure gradients can have on parameters deduced from data even in nominally zero pressure gradient boundary layers. Using the comprehensive shear stress balance together with the log-law equation, it is shown that friction velocity, roughness length and zero-plane displacement can be determi
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Ali, Sk Zeeshan, and Subhasish Dey. "Origin of the scaling laws of developing turbulent boundary layers." Physics of Fluids 34, no. 7 (2022): 071402. http://dx.doi.org/10.1063/5.0096255.

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In this Perspective article, we seek the origin of the scaling laws of developing turbulent boundary layers over a flat plate from the perspective of the phenomenological theory of turbulence. The scaling laws of the boundary-layer thickness and the boundary shear stress in rough and smooth boundary-layer flows are established. In a rough boundary-layer flow, the boundary-layer thickness (scaled with the boundary roughness) and the boundary shear stress (scaled with the dynamic pressure) obey the “2/(1− σ)” and “(1+ σ)/(1− σ)” scaling laws, respectively, with the streamwise distance (scaled wi
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Williams, Owen, Tristen Hohman, Tyler Van Buren, Elie Bou-Zeid, and Alexander J. Smits. "The effect of stable thermal stratification on turbulent boundary layer statistics." Journal of Fluid Mechanics 812 (January 11, 2017): 1039–75. http://dx.doi.org/10.1017/jfm.2016.781.

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The effects of stable thermal stratification on turbulent boundary layers are experimentally investigated for smooth and rough walls. For weak to moderate stability, the turbulent stresses are seen to scale with the wall shear stress, compensating for changes in fluid density in the same manner as done for compressible flows. This suggests little change in turbulent structure within this regime. At higher levels of stratification turbulence no longer scales with the wall shear stress and turbulent production by mean shear collapses, but without the preferential damping of near-wall motions obs
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Beresh, Steven J., Justin L. Wagner, and Katya M. Casper. "Compressibility effects in the shear layer over a rectangular cavity." Journal of Fluid Mechanics 808 (October 26, 2016): 116–52. http://dx.doi.org/10.1017/jfm.2016.540.

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The influence of compressibility on the shear layer over a rectangular cavity of variable width has been studied in a free stream Mach number range of 0.6–2.5 using particle image velocimetry data in the streamwise centre plane. As the Mach number increases, the vertical component of the turbulence intensity diminishes modestly in the widest cavity, but the two narrower cavities show a more substantial drop in all three components as well as the turbulent shear stress. This contrasts with canonical free shear layers, which show significant reductions in only the vertical component and the turb
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DEY, SUBHASISH, TUSHAR K. NATH, and SUJIT K. BOSE. "Submerged wall jets subjected to injection and suction from the wall." Journal of Fluid Mechanics 653 (April 27, 2010): 57–97. http://dx.doi.org/10.1017/s0022112010000182.

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This paper presents an experimental study on turbulent flow characteristics in submerged plane wall jets subjected to injection (upward seepage) and suction (downward seepage) from the wall. The vertical distributions of time-averaged velocity components, turbulence intensity components and Reynolds shear stress at different horizontal distances are presented. The horizontal distributions of wall shear stress determined from the Reynolds shear stress profiles are also furnished. The flow field exhibits a decay of the jet velocity over a horizontal distance. The wall shear stress and the rate o
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Briggs, D. A., J. H. Ferziger, J. R. Koseff, and S. G. Monismith. "Entrainment in a shear-free turbulent mixing layer." Journal of Fluid Mechanics 310 (March 10, 1996): 215–41. http://dx.doi.org/10.1017/s0022112096001784.

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Results from a direct numerical simulation of a shear-free turbulent mixing layer are presented. The mixing mechanisms associated with the turbulence are isolated. In the first set of simulations, the turbulent mixing layer decays as energy is exchanged between the layers. Energy spectra with E(k) ∼ k2 and E(k) ∼ k4 dependence at low wavenumber are used to initialize the flow to investigate the effect of initial conditions. The intermittency of the mixing layer is quantified by the skewness and kurtosis of the velocity fields: results compare well with the shearless mixing layer experiments of
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Mashayek, A., C. P. Caulfield, and W. R. Peltier. "Role of overturns in optimal mixing in stratified mixing layers." Journal of Fluid Mechanics 826 (August 8, 2017): 522–52. http://dx.doi.org/10.1017/jfm.2017.374.

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Turbulent mixing plays a major role in enabling the large-scale ocean circulation. The accuracy of mixing rates estimated from observations depends on our understanding of basic fluid mechanical processes underlying the nature of turbulence in a stratified fluid. Several of the key assumptions made in conventional mixing parameterizations have been increasingly scrutinized in recent years, primarily on the basis of adequately high resolution numerical simulations. We add to this evidence by compiling results from a suite of numerical simulations of the turbulence generated through stratified s
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Schultz, Michael P. "Turbulent Boundary Layers on Surfaces Covered With Filamentous Algae." Journal of Fluids Engineering 122, no. 2 (2000): 357–63. http://dx.doi.org/10.1115/1.483265.

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Turbulent boundary layer measurements have been made on surfaces covered with filamentous marine algae. These experiments were conducted in a closed return water tunnel using a two-component, laser Doppler velocimeter (LDV). The mean velocity profiles and parameters, as well as the axial and wall-normal turbulence intensities and Reynolds shear stress, are compared with flows over smooth and sandgrain rough walls. Significant increases in the skin friction coefficient for the algae-covered surfaces were measured. The boundary layer and integral thickness length scales were also increased. The
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Fortova, S. V. "Numerical Simulation of Turbulence Flows in Shear Layer." Archives of Metallurgy and Materials 59, no. 3 (2014): 1155–58. http://dx.doi.org/10.2478/amm-2014-0201.

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Abstract For various problems of continuum mechanics described by the equations of hyperbolic type, the comparative analysis of scenarios of development of turbulent flows in shear layers is carried out. It is shown that the development of the hydrodynamic instabilities leads to a vortex cascade that corresponds to the development stage of the vortices in the energy and the inertial range during the transition to the turbulent flow stage. It is proved that for onset of turbulence the spatial problem definition is basic. At the developed stage of turbulence the spectral analysis of kinetic ener
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Wu, Xuesong, and Xiuling Zhuang. "Nonlinear dynamics of large-scale coherent structures in turbulent free shear layers." Journal of Fluid Mechanics 787 (December 16, 2015): 396–439. http://dx.doi.org/10.1017/jfm.2015.646.

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Fully developed turbulent free shear layers exhibit a high degree of order, characterized by large-scale coherent structures in the form of spanwise vortex rollers. Extensive experimental investigations show that such organized motions bear remarkable resemblance to instability waves, and their main characteristics, including the length scales, propagation speeds and transverse structures, are reasonably well predicted by linear stability analysis of the mean flow. In this paper, we present a mathematical theory to describe the nonlinear dynamics of coherent structures. The formulation is base
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Thorpe, S. A. "Layers and internal waves in uniformly stratified fluids stirred by vertical grids." Journal of Fluid Mechanics 793 (March 16, 2016): 380–413. http://dx.doi.org/10.1017/jfm.2016.121.

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Laboratory experiments in which uniformly stratified fluids are stirred by horizontally moving vertical grids, or arrays of vertical rods, are reviewed to examine their consistency and to compare their findings, particularly those relating to the generation of layers. Selected experiments are of three types, those in which (a) turbulence spreads from a horizontally confined region where it is continuously generated by an oscillating grid; (b) grid stirring is maintained throughout a rectangular tank; or (c) a ‘cloud’ of turbulence decays after a short period of horizontally localized grid mixi
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