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Journal articles on the topic 'Wake process'

Author: Grafiati

Published: 4 June 2021

Last updated: 16 February 2022

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1

Van Zante, Dale E., John J. Adamczyk, Anthony J. Strazisar, and Theodore H. Okiishi. "Wake Recovery Performance Benefit in a High-Speed Axial Compressor." Journal of Turbomachinery 124, no. 2 (2002): 275–84. http://dx.doi.org/10.1115/1.1445793.

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Rotor wakes are an important source of loss in axial compressors. The decay rate of a rotor wake is largely due to both mixing (results in loss) and stretching (no loss accrual). Thus, the actual loss associated with rotor wake decay will vary in proportion to the amounts of mixing and stretching involved. This wake stretching process, referred to by Smith (1996) as recovery, is reversible and for a 2-D rotor wake leads to an inviscid reduction of the velocity deficit of the wake. It will be shown that for the rotor/stator spacing typical of core compressors, wake stretching is the dominant wa

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2

BANE, K. L. F. "WAKEFIELDS OF SUB-PICOSECOND ELECTRON BUNCHES." International Journal of Modern Physics A 22, no. 22 (2007): 3736–58. http://dx.doi.org/10.1142/s0217751x07037391.

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We discuss wakefields excited by short bunches in accelerators. In particular, we review some of what has been learned in recent years concerning diffraction wakes, roughness impedance, coherent synchrotron radiation wakes, and the resistive wall wake, focusing on analytical solutions where possible. As examples, we apply formulas for these wakes to various parts of the Linac Coherent Light Source (LCLS) project. The longitudinal accelerator structure wake of the SLAC linac is an important ingredient in the LCLS bunch compression process. Of the wakes in the undulator region, the dominant one

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3

Rose, M. G., and N. W. Harvey. "Turbomachinery Wakes: Differential Work and Mixing Losses." Journal of Turbomachinery 122, no. 1 (1999): 68–77. http://dx.doi.org/10.1115/1.555429.

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In this paper the mixing of stator wakes in turbomachinery is considered. An extension is made to the existing model of Denton (1993, ASME J. Turbomach., 115, pp. 621–656) which addresses the effects of acceleration before mixing. Denton showed that if a total pressure wake was accelerated, mixing loss diminished, and vice versa. Here a total temperature wake is shown to exhibit a reverse trend. An attempt is also made to understand better the work transfer process between a stator wake and a rotor. The paper concentrates on axial turbines, but a brief look at compressors is included. It is ar

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4

Zhao, Zhixin, Xudong Xue, and Kun Wang. "Investigation of bubbles interaction and coalescence boiling in the boiling heat transfer process." Thermal Science 23, no. 5 Part A (2019): 2605–11. http://dx.doi.org/10.2298/tsci181126149z.

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This paper presents a new approach to investigate the bubbles movements and their interaction in the boiling heat transfer proess. Based on the study of the wake flow of single rising bubble, the interaction of bubble pairs, such as interaction and coalescenceboiling, is experimentally and numerically simulated. The validity of the numerical simulation was verified by the experimental pictures captured by high-speed CCD camera. The wakes of two bubbles was revealed by obtatined velocity field, and the interaction between two bubbles was analyzed in fluid dynamics. The simulations shows that th

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5

SCHNIPPER, TEIS, ANDERS ANDERSEN, and TOMAS BOHR. "Vortex wakes of a flapping foil." Journal of Fluid Mechanics 633 (August 25, 2009): 411–23. http://dx.doi.org/10.1017/s0022112009007964.

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We present an experimental study of a symmetric foil performing pitching oscillations in a vertically flowing soap film. By varying the frequency and amplitude of the oscillation we visualize a variety of wakes with up to 16 vortices per oscillation period, including von Kármán vortex street, inverted von Kármán vortex street, 2P wake, 2P+2S wake and novel wakes ranging from 4P to 8P. We map out the wake types in a phase diagram spanned by the width-based Strouhal number and the dimensionless amplitude. We follow the time evolution of the vortex formation near the round leading edge and the sh

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6

LaGraff, J. E., D. A. Ashworth, and D. L. Schultz. "Measurement and Modeling of the Gas Turbine Blade Transition Process as Disturbed by Wakes." Journal of Turbomachinery 111, no. 3 (1989): 315–20. http://dx.doi.org/10.1115/1.3262271.

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Heat transfer measurements have been made on a transonic turbine blade undergoing natural transition and with a simulation of the effect of NGV wake interactions. The use of wide bandwidth heat transfer instrumentation permits the tracking of individual unsteady events that were identified as being due to either the impinging wakes or to the turbulent spots occurring within the transition process. Trajectories of these events as seen by the blade surface instrumentation have been measured. Numerical models have been developed for the effects of both types of turbulent activity. The convection

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7

Zhao, Zhi Xin, Jian Hua Niu, Lan Huang, and Huan Ran Wang. "Simulation of the Motion of Two Bubbles in Aluminum Foams Produced Process by Using Level Set Method." Applied Mechanics and Materials 757 (April 2015): 13–17. http://dx.doi.org/10.4028/www.scientific.net/amm.757.13.

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In this paper, the three-dimensional motion of two bubbles in melt Aluminum was simulated by using level set method. Through changing the positions and sizes of two bubbles, the influence of bubbles wake flow and their interaction are considered. Our numerical simulations demonstrate the bubbles characteristic behavior such as distortion, attraction, and repulsion. The velocity field around the bubbles reveals the interaction between the wakes of two bubbles in fluid dynamics. For the two bubbles placed horizontally or vertically, it is found that the coalescence of bubbles may happen when 50%

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8

Dullenkopf, K., A. Schulz, and S. Wittig. "The Effect of Incident Wake Conditions on the Mean Heat Transfer of an Airfoil." Journal of Turbomachinery 113, no. 3 (1991): 412–18. http://dx.doi.org/10.1115/1.2927890.

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The flow phenomena of wakes shed by upstream blade rows is a well-known problem in turbomachinery, which influences blade forces, vibrations, losses, and heat transfer. With respect to the heat load to turbine blades, this problem becomes even more complex because of the interaction between wake, potential flow, and the boundary layer along the surface of the airfoil. Experimentally evaluated mean heat transfer coefficients obtained under different unsteady initial conditions are reported. The heat transfer measurements have been carried out in the cascade test facility at the ITS in Karlsruhe

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9

Yin, Hai Tao, Xin Min Wang, Wen Chao Li, and Rong Xie. "Study of Disturbances Model on Carrier-Based Aircraft Landing Process." Applied Mechanics and Materials 321-324 (June 2013): 824–28. http://dx.doi.org/10.4028/www.scientific.net/amm.321-324.824.

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The disturbances in the landing process of carrier-based aircraft include deck movement and ship wake. To guarantee the security of landing process, the simulation and model are necessary for the disturbances, and the deck movement and ship wake should be analyzed as well. On the basis of analysis of disturbances, the disturbances can be catalogued into two types: deck movement and ship wake. Combining with the relevant instructions in the American Army Standard, the mathematical model of each disturbance is established. The simulations of the deck movement and ship wake are also shown in this

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10

Pellone, C., and A. Rowe. "Effect of Separation on Partial Cavitation." Journal of Fluids Engineering 110, no. 2 (1988): 182–89. http://dx.doi.org/10.1115/1.3243532.

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Partially cavitating flow around a hydrofoil in a confined two-dimensional flow is presented. The calculation method, based on the singularities technique combined with a minimisation method, is adapted to open configurations. With this extension, cavity wakes not necessarily merging with the upper-side of the foil can be treated. In the case of subcavitating flow, a boundary layer calculated is made, indicating a separation point downstream of which the flow becomes separated. In this area, an imaginary streamline (wake) is introduced to simulate the effect of separation. The choice of differ

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11

COULL, JOHN D., and HOWARD P. HODSON. "Unsteady boundary-layer transition in low-pressure turbines." Journal of Fluid Mechanics 681 (July 1, 2011): 370–410. http://dx.doi.org/10.1017/jfm.2011.204.

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This paper examines the transition process in a boundary layer similar to that present over the suction surfaces of aero-engine low-pressure (LP) turbine blades. This transition process is of significant practical interest since the behaviour of this boundary layer largely determines the overall efficiency of the LP turbine. Modern ‘high-lift’ blade designs typically feature a closed laminar separation bubble on the aft portion of the suction surface. The size of this bubble and hence the inefficiency it generates is controlled by the transition between laminar and turbulent flow in the bounda

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12

Lu, Xingen, Yanfeng Zhang, Wei Li, Shuzhen Hu, and Junqiang Zhu. "Effects of periodic wakes on boundary layer development on an ultra-high-lift low pressure turbine airfoil." Proceedings of the Institution of Mechanical Engineers, Part A: Journal of Power and Energy 231, no. 1 (2016): 25–38. http://dx.doi.org/10.1177/0957650916671421.

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The laminar-turbulent transition process in the boundary layer is of significant practical interest because the behavior of this boundary layer largely determines the overall efficiency of a low pressure turbine. This article presents complementary experimental and computational studies of the boundary layer development on an ultra-high-lift low pressure turbine airfoil under periodically unsteady incoming flow conditions. Particular emphasis is placed on the influence of the periodic wake on the laminar-turbulent transition process on the blade suction surface. The measurements were distincti

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13

Wu, Weimin, Xiongfei Liu, Jingcheng Liu, Shunpeng Zeng, Chuande Zhou, and Xiaomei Wang. "Investigation into Yaw Motion Influence of Horizontal-Axis Wind Turbine on Wake Flow Using LBM-LES." Energies 14, no. 17 (2021): 5248. http://dx.doi.org/10.3390/en14175248.

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The dynamic yaw motion of the wind turbine will affect the overall aerodynamic performance of the impeller and the corresponding wake flow, but the current research on this issue is inadequate. Thus, it is very necessary to study the complicated near-wake aerodynamic behaviors during the yaw process and the closely related blade aerodynamic characteristics. This work utilized the multi-relaxation time lattice Boltzmann (MRT-LBM) model to investigate the integral aerodynamic performance characteristics of the specified impeller and the dynamic changes in the near wake under a sine yawing proces

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14

Pan, Jun-Hua, Nian-Mei Zhang, and Ming-Jiu Ni. "The wake structure and transition process of a flow past a sphere affected by a streamwise magnetic field." Journal of Fluid Mechanics 842 (March 7, 2018): 248–72. http://dx.doi.org/10.1017/jfm.2018.133.

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The wake structure and transition process of an incompressible viscous fluid flow past a sphere affected by an imposed streamwise magnetic field are investigated numerically over flow regimes that include steady and unsteady laminar flows at Reynolds numbers up to 300. For cases without a magnetic field, a subregion with the existence of a limit cycle is found in the range $210<Re<270$. The point of division is between $Re=220$ and $Re=230$. For cases with a streamwise magnetic field, five wake patterns are the steady axisymmetric wake with an attached separation bubble, the steady plane

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15

Nylund, Amanda T., Lars Arneborg, Anders Tengberg, Ulf Mallast, and Ida-Maja Hassellöv. "In situ observations of turbulent ship wakes and their spatiotemporal extent." Ocean Science 17, no. 5 (2021): 1285–302. http://dx.doi.org/10.5194/os-17-1285-2021.

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Abstract. In areas of intensive ship traffic, ships pass every 10 min. Considering the amount of ship traffic and the predicted increase in global maritime trade, there is a need to consider all types of impacts shipping has on the marine environment. While the awareness about, and efforts to reduce, chemical pollution from ships is increasing, less is known about physical disturbances, and ship-induced turbulence has so far been completely neglected. To address the potential importance of ship-induced turbulence on, e.g., gas exchange, dispersion of pollutants, and biogeochemical processes, a

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16

Ren, Maosheng, Camilo Rindt, and Anton van Steenhoven. "Lift-up process in a heated-cylinder wake flow." Physics of Fluids 18, no. 1 (2006): 014106. http://dx.doi.org/10.1063/1.2159031.

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17

Hinman, W. Schuyler, and Craig T. Johansen. "Mechanisms in the hypersonic laminar near wake of a blunt body." Journal of Fluid Mechanics 839 (January 25, 2018): 33–75. http://dx.doi.org/10.1017/jfm.2017.902.

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A new theoretical framework, based on the analysis of Navier–Stokes solutions for the hypersonic laminar near wake of two-dimensional and axisymmetric blunt bodies, is presented. A semi-empirical relationship is derived between the free-stream Mach and Reynolds numbers and a characteristic wake Reynolds number. A control volume analysis was performed to assess the validity of some common assumptions used in the literature. Analysis of the momentum and vorticity equations is used to assess the dominant mechanisms of momentum transfer along and across the dividing streamline and centreline which

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18

Wang, Kun, Li Zou, Aimin Wang, Peidong Zhao, and Yichen Jiang. "Wind Tunnel Study on Wake Instability of Twin H-Rotor Vertical-Axis Turbines." Energies 13, no. 17 (2020): 4310. http://dx.doi.org/10.3390/en13174310.

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In recent years, the H-rotor vertical-axis turbine has attracted considerable attention in the field of wind and tidal power generation. After a series of complex spatiotemporal evolutions, the vortex shed from turbine blades forms a turbulent wake with a multi-scale coherent structure. An analysis of the wake characteristics of twin turbines forms the basis of array optimisation. This study aimed to examine the instability characteristics of a twin-turbine wake with two rotational configurations. The dynamic evolution characteristics of coherent structures with different scales in the wake we

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19

Canepa, Edward, Davide Lengani, Alessandro Nilberto, et al. "Flow Coefficient and Reduced Frequency Effects on Wake-Boundary Layer Interaction in Highly Accelerated LPT Cascade." International Journal of Turbomachinery, Propulsion and Power 6, no. 3 (2021): 32. http://dx.doi.org/10.3390/ijtpp6030032.

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The paper presents a detailed analysis of particle image velocimetry (PIV) measurements performed in a turbine cascade representative of highly accelerated low-pressure turbine (LPT) blades. Two cameras have been simultaneously used to observe a great portion of the suction side boundary layer with the highest possible spatial resolution, thus allowing us to solve the interaction process between impinging upstream wakes and the blade boundary layer. Four unsteady inflow conditions, characterized by different incoming wake reduced frequencies and flow coefficients, have been examined at fixed R

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20

Wang, C. T., and C. T. Chen. "Self-Similar Analysis on Vortex Shedding Process." Journal of Mechanics 22, no. 4 (2006): 263–70. http://dx.doi.org/10.1017/s1727719100000915.

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AbstractChaos theory has been seen as an efficient tool for studying the turbulent flow, the findings of attractor were also important and made in the study to investigate the wake flow behind the bluff body. Here, the fractal dimension value would then be found by Hurst analysis. According to the results found, the Hurst empirical formula derived by the self-similar laceration of vortex plane would be applied by self-similar property to decide the band of the frequency variations in the vortex shedding process. The three kinds of flow mode with their individual attractors and characteristics

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21

Serrano González, Javier, Bruno López, and Martín Draper. "Optimal Pitch Angle Strategy for Energy Maximization in Offshore Wind Farms Considering Gaussian Wake Model." Energies 14, no. 4 (2021): 938. http://dx.doi.org/10.3390/en14040938.

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This paper presents a new approach based on the optimization of the blade pitching strategy of offshore wind turbines in order to maximize the global energy output considering the Gaussian wake model and including the effect of added turbulence. A genetic algorithm is proposed as an optimization tool in the process of finding the optimal setting of the wind turbines, which aims to determine the individual pitch of each turbine so that the overall losses due to the wake effect are minimised. The integration of the Gaussian model, including the added turbulence effect, for the evaluation of the

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22

O'Brien, Peter. "Drawing Upon Finnegans Wake." Art/Research International: A Transdisciplinary Journal 3, no. 2 (2018): 196–215. http://dx.doi.org/10.18432/ari29381.

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LOTS OF FUN WITH FINNEGANS WAKE is my six-year project to annotate / illustrate / disrupt the 628 pages of James Joyce’s final book. I’ve been reading Finnegans Wake off and on for about 40 years, and I consider it to be the most multi-layered, protean, and playful collection of words that we have. As a way to explore the book’s circular, recurring, enigmatic pathways, I am involved in the process of transmediation – I am turning some of its words into visual images and some of its linguistic images into words. This project is a way for me to indulge my natural inclination to connect the intel

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23

Simley, Eric, Paul Fleming, and Jennifer King. "Design and analysis of a wake steering controller with wind direction variability." Wind Energy Science 5, no. 2 (2020): 451–68. http://dx.doi.org/10.5194/wes-5-451-2020.

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Abstract. Wind farm control strategies are being developed to mitigate wake losses in wind farms, increasing energy production. Wake steering is a type of wind farm control in which a wind turbine's yaw position is misaligned from the wind direction, causing its wake to deflect away from downstream turbines. Current modeling tools used to optimize and estimate energy gains from wake steering are designed to represent wakes for fixed wind directions. However, wake steering controllers must operate in dynamic wind conditions and a turbine's yaw position cannot perfectly track changing wind direc

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24

Wang, Yong, Yvonne Forrest, and Hanh Pham. "Escalating Chemical Costs A Wake-up Call for Process Optimization." Opflow 36, no. 5 (2010): 14–16. http://dx.doi.org/10.1002/j.1551-8701.2010.tb03017.x.

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25

Hummel, Frank. "Wake–Wake Interaction and Its Potential for Clocking in a Transonic High-Pressure Turbine." Journal of Turbomachinery 124, no. 1 (2001): 69–76. http://dx.doi.org/10.1115/1.1415036.

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Two-dimensional unsteady Navier–Stokes calculations of a transonic single-stage high-pressure turbine were carried out with emphasis on the flow field behind the rotor. Detailed validation of the numerical procedure with experimental data showed excellent agreement in both time-averaged and time-resolved flow quantities. The numerical timestep as well as the grid resolution allowed the prediction of the Ka´rma´n vortex streets of both stator and rotor. Therefore, the influence of the vorticity shed from the stator on the vortex street of the rotor is detectable. It was found that certain vorti

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26

Torsvik, T., I. Didenkulova, T. Soomere, and K. E. Parnell. "Variability in spatial patterns of long nonlinear waves from fast ferries in Tallinn Bay." Nonlinear Processes in Geophysics 16, no. 2 (2009): 351–63. http://dx.doi.org/10.5194/npg-16-351-2009.

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Abstract. High-speed ferries are known to generate wakes with unusually long periods, and occasionally large amplitudes which may serve as a qualitatively new forcing factor in coastal regions that are not exposed to a sea swell. An intrinsic feature of such wakes is their large spatial variation. We analyze the variability of wake conditions for the coasts of Tallinn Bay, the Baltic Sea, a sea area with very intense fast ferry traffic. The modelled ship wave properties for several GPS-recorded ship tracks reasonably match the measured waves in terms of both wave heights and periods. It is sho

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27

Adamczyk, J. J., M. L. Celestina, and Jen Ping Chen. "Wake-Induced Unsteady Flows: Their Impact on Rotor Performance and Wake Rectification." Journal of Turbomachinery 118, no. 1 (1996): 88–95. http://dx.doi.org/10.1115/1.2836611.

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The impact of wake-induced unsteady flows on blade row performance and the wake rectification process is examined by means of numerical simulation. The passage of a stator wake through a downstream rotor is first simulated using a three-dimensional unsteady viscous flow code. The results from this simulation are used to define two steady-state inlet conditions for a three-dimensional viscous flow simulation of a rotor operating in isolation. The results obtained from these numerical simulations are then compared to those obtained from the unsteady simulation both to quantify the impact of the

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28

Kyriakides, N. K., E. G. Kastrinakis, S. G. Nychas, and A. Goulas. "Boundary Layer Transition Induced by a Von Karman Vortex Street Wake." Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering 210, no. 2 (1996): 167–79. http://dx.doi.org/10.1243/pime_proc_1996_210_358_02.

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A study has been made of the process of laminar to turbulent transition induced by a von Karman vortex street wake, in the boundary layer on a flat plate. The boundary layer developed under zero pressure gradient conditions while the vortex street was generated by a cylinder positioned in the free stream. Hot-wire measurements over a range of Strouhal frequencies and free stream velocities were used for the identification of the transition onset. From the analysis of the experimental data, two different transition mechanisms known in the literature as ‘strong’ wake and ‘weak’ wake induced tran

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29

Dai, Jing, Xueqin Liu, Congbing Huang, et al. "Experiment on Pressure Pulsation of Axial Flow Pump System with Different Runaway Head." Processes 9, no. 9 (2021): 1597. http://dx.doi.org/10.3390/pr9091597.

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The runaway condition is a damage condition for pumps and turbines which can induce the wake vortex, reverse flow, and severe pressure pulsation. This study aimed to research the characteristics of pressure pulsation of axial flow pumps under different runaway conditions, and the runaway model test was performed with different blade angles and heads. Moreover, four pressure sensors were uniformly arranged at the impeller inlet section to eliminate the random error. The time domain and frequency domain analysis were the main methods to obtain the change regulations. Results showed that the pres

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30

Sieverding, Claus, and Marcello Manna. "A Review on Turbine Trailing Edge Flow." International Journal of Turbomachinery, Propulsion and Power 5, no. 2 (2020): 10. http://dx.doi.org/10.3390/ijtpp5020010.

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The paper presents a state-of-the-art review of turbine trailing edge flows, both from an experimental and numerical point of view. With the help of old and recent high-resolution time resolved data, the main advances in the understanding of the essential features of the unsteady wake flow are collected and homogenized. Attention is paid to the energy separation phenomenon occurring in turbine wakes, as well as to the effects of the aerodynamic parameters chiefly influencing the features of the vortex shedding. Achievements in terms of unsteady numerical simulations of turbine wake flow charac

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31

Yin, Jiawei, A. Agung Julius, and John T. Wen. "Optimization of light exposure and sleep schedule for circadian rhythm entrainment." PLOS ONE 16, no. 6 (2021): e0251478. http://dx.doi.org/10.1371/journal.pone.0251478.

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The circadian rhythm, called Process C, regulates a wide range of biological processes in humans including sleep, metabolism, body temperature, and hormone secretion. Light is the dominant synchronizer of the circadian rhythm—it has been used to regulate the circadian phase to cope with jet-lag, shift work, and sleep disorder. The homeostatic oscillation of the sleep drive is called Process S. Process C and Process S together determine the sleep-wake cycle in what is known as the two-process model. This paper addresses the regulation of both Process C and Process S by scheduling light exposure

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Liu, Xiaoying, Xinyu Zhang, Xiaochun Zhai, Hongwei Zhang, Bingyi Liu, and Songhua Wu. "Observation of Aircraft Wake Vortex Evolution under Crosswind Conditions by Pulsed Coherent Doppler Lidar." Atmosphere 12, no. 1 (2020): 49. http://dx.doi.org/10.3390/atmos12010049.

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The observation and identification of wake vortex are considered important factors to reduce aviation accidents and increase airport capacity. In addition to aircraft parameters, the evolution process of the wake vortex is strongly related to atmospheric conditions, including crosswind, headwind, atmospheric turbulence, and temperature stratification. Crosswind generally affects the wake vortex trajectories by transporting them to the downwind direction. Additionally, the circulation attenuation of wake vortex is also influenced by crosswind shear or turbulence related to crosswind. This paper

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Miyazaki, Takehiro, Takeshi Kanda, Natsuko Tsujino, et al. "Dynamics of Cortical Local Connectivity during Sleep–Wake States and the Homeostatic Process." Cerebral Cortex 30, no. 7 (2020): 3977–90. http://dx.doi.org/10.1093/cercor/bhaa012.

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Abstract Sleep exerts modulatory effects on the cerebral cortex. Whether sleep modulates local connectivity in the cortex or only individual neural activity, however, is poorly understood. Here we investigated functional connectivity, that is, covarying activity between neurons, during spontaneous sleep–wake states and during and after sleep deprivation using calcium imaging of identified excitatory/inhibitory neurons in the motor cortex. Functional connectivity was estimated with a statistical learning approach glasso and quantified by “the probability of establishing connectivity (sparse/den

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34

Dong, Changming, James C. McWilliams, and Alexander F. Shchepetkin. "Island Wakes in Deep Water." Journal of Physical Oceanography 37, no. 4 (2007): 962–81. http://dx.doi.org/10.1175/jpo3047.1.

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Abstract Density stratification and planetary rotation distinguish three-dimensional island wakes significantly from a classical fluid dynamical flow around an obstacle. A numerical model is used to study the formation and evolution of flow around an idealized island in deep water (i.e., with vertical island sides and surface-intensified stratification and upstream flow), focusing on wake instability, coherent vortex formation, and mesoscale and submesoscale eddy activity. In a baseline experiment with strong vorticity generation at the island, three types of instability are evident: centrifug

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35

Wu, Xiaohua, and Paul A. Durbin. "Boundary Layer Transition Induced by Periodic Wakes." Journal of Turbomachinery 122, no. 3 (1998): 442–49. http://dx.doi.org/10.1115/1.1303076.

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Turbulent wakes swept across a flat plate boundary layer simulate the phenomenon of wake-induced bypass transition. Benchmark data from a direct numerical simulation of this process are presented and compared to Reynolds-averaged predictions. The data are phase-averaged skin friction and mean velocities. The predictions and data are found to agree in many important respects. One discrepancy is a failure to reproduce the skin friction overshoot following transition. [S0889-504X(00)00503-1]

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Koyuncu, A., A. Yava, FE Aslan, and U. Demirkılıç. "COMMUNICATION NEEDS OF CARDIAC SURGERY PATIENTS DURING THEIR WAKE UP PROCESS." Intensive Care Medicine Experimental 3, Suppl 1 (2015): A923. http://dx.doi.org/10.1186/2197-425x-3-s1-a923.

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37

Epifanio, C. C., and R. Rotunno. "The Dynamics of Orographic Wake Formation in Flows with Upstream Blocking." Journal of the Atmospheric Sciences 62, no. 9 (2005): 3127–50. http://dx.doi.org/10.1175/jas3523.1.

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Abstract The development of orographic wakes and vortices is revisited from the dynamical perspective of a three-dimensional (3D) vorticity-vector potential formulation. Particular emphasis is given to the role of upstream blocking in the formation of the wake. Scaling arguments are first presented to explore the limiting form of the 3D vorticity inversion for the case of flow at small dynamical aspect ratio δ. It is shown that in the limit of small δ the inversion is determined completely by the two horizontal vorticity components—that is, the part of the velocity induced by the vertical comp

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Sha, Jin, Xiao-Ming Li, Xue’en Chen, and Tianyu Zhang. "Satellite Observations of Wind Wake and Associated Oceanic Thermal Responses: A Case Study of Hainan Island Wind Wake." Remote Sensing 11, no. 24 (2019): 3036. http://dx.doi.org/10.3390/rs11243036.

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The wind wake on the lee side of Hainan Island in the winter covers the southwest entrance of Beibu Gulf (or Gulf of Tonkin) and is essential to regional ocean dynamics. Using multiple satellite observations including advanced synthetic aperture radar (ASAR), we revisited the wake process during the winter of 2011. Asymmetric oceanic thermal responses were found with a warm band expanding northwestwardly while a cold tongue formed to the southeast. Combining satellite observations, model simulations, and reanalysis data, heat advection terms (ADV) are reconstructed and compared to air-sea heat

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Hu, H., and M. M. Koochesfahani. "Thermal effects on the wake of a heated circular cylinder operating in mixed convection regime." Journal of Fluid Mechanics 685 (October 6, 2011): 235–70. http://dx.doi.org/10.1017/jfm.2011.313.

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AbstractThe thermal effects on the wake flow behind a heated circular cylinder operating in the mixed convection regime were investigated experimentally in the present study. The experiments were conducted in a vertical water channel with the heated cylinder placed horizontally and the flow approaching the cylinder downwards. With such a flow arrangement, the direction of the thermally induced buoyancy force acting on the fluid surrounding the heated cylinder would be opposite to the approach flow. During the experiments, the temperature and Reynolds number of the approach flow were held const

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Pereira, Tassia Penha, Suhas Pol, Arquimedes Ruiz-Columbie, and Carsten Westergaard. "Development of a LIDAR array to study and classify wakes at the U.S. Department of Energy (DOE)/Sandia National Laboratories Scaled Wind Farm Technology (SWiFT) facility." Wind Engineering 43, no. 1 (2018): 26–34. http://dx.doi.org/10.1177/0309524x18818648.

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Wind turbine wake has the wind speed deficit and the increased turbulent flow to the downstream turbines as signatures. Various experiments and simulations have been performed over the years to investigate the wake parameters; however, a statistical characterization of wake states is still to be uncovered. An innovative wake measurement approach that uses five ground-based Spidar Light Detection and Ranging (LIDAR) has been developed in partnership with Texas Tech University (TTU), Sandia National Laboratories, and Pentalum Technologies to develop, test, and validate a system and methodology t

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Wong, Yan Chiew, Szi Hui Tan, Ranjit Singh Sarban Singh, Haoyu Zhang, A. R. Syafeeza, and N. A. Hamid. "Low power wake-up receiver based on ultrasound communication for wireless sensor network." Bulletin of Electrical Engineering and Informatics 9, no. 1 (2020): 21–29. http://dx.doi.org/10.11591/eei.v9i1.1654.

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Wireless sensor network (WSN) consists of base stations and sensors nodes to monitor physical and environmental conditions. Power consumption is a challenge in WSN due to activities of nodes. High power consumption is required for the main transceiver in WSN to receive communication requests all the time. Hence, a low power wake-up receiver is needed to minimize the power consumption of WSN. In this work, a low power wake-up receiver using ultrasound data communication is designed. Wake-up receiver is used to detect wake-up signal to activate a device in WSN. Functional block modelling of the

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Lignarolo, L. E. M., D. Ragni, F. Scarano, C. J. Simão Ferreira, and G. J. W. van Bussel. "Tip-vortex instability and turbulent mixing in wind-turbine wakes." Journal of Fluid Mechanics 781 (September 23, 2015): 467–93. http://dx.doi.org/10.1017/jfm.2015.470.

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Kinetic-energy transport and turbulence production within the shear layer of a horizontal-axis wind-turbine wake are investigated with respect to their influence on the tip-vortex pairwise instability, the so-called leapfrogging instability. The study quantifies the effect of near-wake instability and tip-vortex breakdown on the process of mean-flow kinetic-energy transport within the far wake of the wind turbine, in turn affecting the wake re-energising process. Experiments are conducted in an open-jet wind tunnel with a wind-turbine model of 60 cm diameter at a diameter-based Reynolds number

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He, Yi, Jin Wen Yang, and Feng Bao. "The Instability of a Four-Vortex Wake System in a Water Towing Tank." Advanced Materials Research 756-759 (September 2013): 1484–88. http://dx.doi.org/10.4028/www.scientific.net/amr.756-759.1484.

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A simplified rectangular baseline-airfoil model attached with tailored flaps was designed to study the Rayleigh-Ludwieg instability by tailoring a four-vortex wake system. By means of PIV measurement in a water towing tank, the interaction process and circulation evolution of the wake system were obtained systematically. The circulation remains was reduced to ca. 40% after 43 wingspans which proved the application potentials of this method in alleviating the wake vortex.

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Ma, Tielin, Zhihua Wei, Haibing Chen, and Xiangsheng Wang. "Simulation of the dynamic retrieval process of a towed target system under towing airplane’s wake and atmospheric turbulence." Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering 234, no. 9 (2020): 1518–30. http://dx.doi.org/10.1177/0954410020916292.

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This paper studies the dynamic retrieval process of a towed target system under perturbation by simulating the reel-in operation under the towing airplane’s wake and atmospheric turbulence. To settle the computational problem of cable tension, the constant-length method is proposed to transform this variable-mass problem into a constant-length problem based on a mass-spring model that discretizes the cable. A three-dimensional atmospheric turbulence field is built using a recursive function to model the complex perturbation field along the cable. A horseshoe vortex model is adopted to simulate

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Knechel, W. Robert. "Audit research in the wake of SOX." Managerial Auditing Journal 30, no. 8/9 (2015): 706–26. http://dx.doi.org/10.1108/maj-08-2015-1233.

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Purpose – The purpose of this paper is to summarize the effect that the passage of the Sarbanes–Oxley Act of 2002 (SOX) by the US Congress had on audit research. More specifically, the paper compares the nature of research about auditing conducted before the Act’s passage to the nature of research about audit regulation that dominates the literature since its passage. Design/methodology/approach – The paper builds on an extensive review of the research literature before and after the passage of SOX to suggest and examine potential future research paths that might develop in auditing. The strea

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Brackston, R. D., J. M. García de la Cruz, A. Wynn, G. Rigas, and J. F. Morrison. "Stochastic modelling and feedback control of bistability in a turbulent bluff body wake." Journal of Fluid Mechanics 802 (August 10, 2016): 726–49. http://dx.doi.org/10.1017/jfm.2016.495.

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A specific feature of three-dimensional bluff body wakes, flow bistability, is a subject of particular recent interest. This feature consists of a random flipping of the wake between two asymmetric configurations and is believed to contribute to the pressure drag of many bluff bodies. In this study we apply the modelling approach recently suggested for axisymmetric bodies by Rigaset al.(J. Fluid Mech., vol. 778, 2015, R2) to the reflectional symmetry-breaking modes of a rectilinear bluff body wake. We demonstrate the validity of the model and its Reynolds number independence through time-resol

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Wright, K. H., N. H. Stone, and U. Samir. "A study of plasma expansion phenomena in laboratory generated plasma wakes: preliminary results." Journal of Plasma Physics 33, no. 1 (1985): 71–82. http://dx.doi.org/10.1017/s0022377800002336.

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The plasma expansion into the wake of a large rectangular plate immersed in a single-ion, collisionless, streaming plasma has been investigated in the laboratory. Several characteristics of the process involved in ‘plasma expansion into vacuum’ that have been predicted theoretically were observed, including the creation and motion of a rarefaction wave disturbance; the creation and motion of an expansion front; and the acceleration of ions into the wake at speeds above the ion-acoustic speed. The expansion was limited to early times; i.e. a few ion plasma periods, by the combination of plasma

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Sieverding, Claus H., Davide Ottolia, Carlo Bagnera, Andrea Comadoro, J. F. Brouckaert, and Jean-Michel Desse. "Unsteady Turbine Blade Wake Characteristics." Journal of Turbomachinery 126, no. 4 (2004): 551–59. http://dx.doi.org/10.1115/1.1737783.

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The paper presents an experimental investigation of large coherent structures, commonly referred to as “von Karman vortex street,” in the wake of a turbine blade at high subsonic Mach number M2,is=0.79 and high Reynolds number (RE=2.8×106 and their effect on the steady and unsteady pressure and temperature distribution in the wake. Ultra short smoke visualizations and two interferometric measurement techniques, holographic interferometry and white light differential interferometry provide insight into the vortex formation and shedding process. In addition, the interferometric measurement provi

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Stella, A., G. Guj, F. Di Felice, and M. Elefante. "Experimental Investigation of Propeller Wake Evolution by Means of LDV and Flow Visualizations." Journal of Ship Research 44, no. 03 (2000): 155–69. http://dx.doi.org/10.5957/jsr.2000.44.3.155.

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An experimental investigation of the propeller wake has been performed in a cavitation tunnel using LDV and flow visualizations. The objective is the hydrodynamic and geometrical characterization of the wake flow field and its downstream evolution features. Implications of the physical aspects for wake modeling are also highlighted. The viscous blade wake, originating in the boundary layer on the blade surfaces, the trailing vortex sheets, due to the radial gradient of the bound circulation, as well as the turbulence distribution are identified at the trailing edge and followed. The near-wake

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You, S. M. "Convex Curvature Effect on the Wake Including Recovery from the Curvature." International Journal of Rotating Machinery 1, no. 3-4 (1995): 215–24. http://dx.doi.org/10.1155/s1023621x9500008x.

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Streamwise convex-curvature effect including recovery process is discussed. Previous studies have demonstrated that even mild streamwise curvature has a marked effect on turbulence structure, heat transfer and skin friction coefficient. This effect is further investigated in the present study with Coles wake law. Coles previously reported that flows in or near equilibrium have a constant wake parameter depending on the strength of streamwise pressure gradient. Turbulent boundary layers on the curved and following recovery wall may not be in or near equilibrium and the wake parameter may depend

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