Готові списки джерел за темами / Wake structures

Добірка наукової літератури з теми "Wake structures"

Автор: Grafiati
Опубліковано: 7 липня 2024
Оновлено: 7 липня 2024

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Зміст

  1. Статті в журналах
  2. Дисертації
  3. Книги
  4. Частини книг
  5. Тези доповідей конференцій
  6. Звіти організацій

Статті в журналах з теми "Wake structures":

1

Steiner, T. R., and A. E. Perry. "Large-scale vortex structures in turbulent wakes behind bluff bodies. Part 2. Far-wake structures." Journal of Fluid Mechanics 174 (January 1987): 271–98. http://dx.doi.org/10.1017/s0022112087000120.

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An investigation of a selection of high-Reynolds-number bluff-body flows was conducted. Here in Part 2 phase-averaged velocity-field results will be presented for several far-wake flows generated by nominally two-dimensional and three-dimensional bodies. In these far-wake flows the shed vortices have approached a nearly constant convection velocity. Some mean velocity and phase-averaged and global Reynoldsstress measurements are also presented. The turbulent wake of a lift-producing three-dimensional body has been examined. Also included are the phase-averaged wake patterns behind a flapping flag and a windmill. The topological structure of these patterns is discussed and a preliminary classification of wake patterns is presented.
2

Hickey, Jean-Pierre, Fazle Hussain, and Xiaohua Wu. "Role of coherent structures in multiple self-similar states of turbulent planar wakes." Journal of Fluid Mechanics 731 (August 22, 2013): 312–63. http://dx.doi.org/10.1017/jfm.2013.315.

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AbstractWe study the nature of archetypal, incompressible, planar splitter-plate wakes, specifically the effects of the exit boundary layer state on multiple approximate self-similarity. Temporally developing direct numerical simulations, at a Reynolds number of 1500 based on the volume-flux defect, are performed to investigate three distinct wake evolution scenarios: Kelvin–Helmholtz transition, bypass transition in an asymmetric wake, and an initially fully turbulent wake. The differences in the evolution and far-wake statistics are analysed in detail. The individual approximately self-similar states exhibit a relative variation of up to 48 % in the spread rate, in second-order statistics, and in peak values of the energy budget terms. The multiplicity of self-similar states is tied to the non-universality of the large-scale coherent structures. These structures maintain the memory of the initial conditions. In the far wake, two distinct spanwise-coherent motions are identified: (i) staggered, segregated spanwise rollers on either side of the centreplane, dominant in wakes transitioning via anti-symmetric instability modes; and, (ii) larger spanwise rollers spanning across the centreplane, emerging in the absence of a near-wake characteristic length scale. The latter structure is characterized by strong spanwise coherence, cross-wake velocity correlations and a larger entrainment rate caused by deep pockets of irrotational fluid within the folds of the turbulent/non-turbulent interface. The mid-sized structures, primarily vortical rods, are generic for all initial conditions and are inclined at ∼$\pm 3{3}^{\circ } $ to the downstream, shallower than the preferential $\pm 4{5}^{\circ } $ inclination of the vorticity vector. The spread rate is driven by the inner-wake dynamics, more specifically the advective flux of spanwise vorticity across the centreplane, which depends on the large-scale coherent structures.
3

Wheeler, Andrew P. S., Robert J. Miller, and Howard P. Hodson. "The Effect of Wake Induced Structures on Compressor Boundary-Layers." Journal of Turbomachinery 129, no. 4 (July 31, 2006): 705–12. http://dx.doi.org/10.1115/1.2720499.

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The interaction of a convected wake with a compressor blade boundary layer was investigated. Measurements within a single-stage compressor were made using an endoscopic PIV system, a surface mounted pressure transducer, hotfilms and hotwire traverses, along with CFD simulations. The wake/leading-edge interaction was shown to lead to the formation of a thickened laminar boundary-layer, within which turbulent spots formed close to the leading edge. The thickened boundary-layer became turbulent and propagated down the blade surface, giving rise to pressure perturbations of 7% of the inlet dynamic head in magnitude. The results indicate that wake/leading-edge interactions have a crucial role to play in the performance of compressor blades in the presence of wakes.
4

Bodini, Nicola, Dino Zardi, and Julie K. Lundquist. "Three-dimensional structure of wind turbine wakes as measured by scanning lidar." Atmospheric Measurement Techniques 10, no. 8 (August 14, 2017): 2881–96. http://dx.doi.org/10.5194/amt-10-2881-2017.

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Abstract. The lower wind speeds and increased turbulence that are characteristic of turbine wakes have considerable consequences on large wind farms: turbines located downwind generate less power and experience increased turbulent loads. The structures of wakes and their downwind impacts are sensitive to wind speed and atmospheric variability. Wake characterization can provide important insights for turbine layout optimization in view of decreasing the cost of wind energy. The CWEX-13 field campaign, which took place between June and September 2013 in a wind farm in Iowa, was designed to explore the interaction of multiple wakes in a range of atmospheric stability conditions. Based on lidar wind measurements, we extend, present, and apply a quantitative algorithm to assess wake parameters such as the velocity deficits, the size of the wake boundaries, and the location of the wake centerlines. We focus on wakes from a row of four turbines at the leading edge of the wind farm to explore variations between wakes from the edge of the row (outer wakes) and those from turbines in the center of the row (inner wakes). Using multiple horizontal scans at different elevations, a three-dimensional structure of wakes from the row of turbines can be created. Wakes erode very quickly during unstable conditions and can in fact be detected primarily in stable conditions in the conditions measured here. During stable conditions, important differences emerge between the wakes of inner turbines and the wakes of outer turbines. Further, the strong wind veer associated with stable conditions results in a stretching of the wake structures, and this stretching manifests differently for inner and outer wakes. These insights can be incorporated into low-order wake models for wind farm layout optimization or for wind power forecasting.
5

Zhang, Can, Jisheng Zhang, Athanasios Angeloudis, Yudi Zhou, Stephan C. Kramer, and Matthew D. Piggott. "Physical Modelling of Tidal Stream Turbine Wake Structures under Yaw Conditions." Energies 16, no. 4 (February 9, 2023): 1742. http://dx.doi.org/10.3390/en16041742.

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Tidal stream turbines may operate under yawed conditions due to variability in ocean current directions. Insight into the wake structure of yawed turbines can be essential to ensure efficient tidal stream energy extraction, especially for turbine arrays where wake interactions emerge. We studied experimentally the effects of turbines operating under varying yaw conditions. Two scenarios, including a single turbine and a set of two turbines in alignment, were configured and compared. The turbine thrust force results confirmed that an increasing yaw angle results in a decrease in the turbine streamwise force and an increase in the turbine spanwise force. The velocity distribution from the single turbine scenario showed that the wake deflection and velocity deficit recovery rate increased at a rate proportional to the yaw angle. The two-turbine scenario results indicated that the deployment of an upstream non-yawed turbine significantly limited the downstream wake steering (i.e., the wake area behind the downstream turbine). Interestingly, a yawed downstream turbine was seen to influence the steering of both the upstream and the downstream wakes. These systematically derived data could be regarded as useful references for the numerical modelling and optimisation of large arrays.
6

Sørensen, Jens N., Robert F. Mikkelsen, Dan S. Henningson, Stefan Ivanell, Sasan Sarmast, and Søren J. Andersen. "Simulation of wind turbine wakes using the actuator line technique." Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 373, no. 2035 (February 28, 2015): 20140071. http://dx.doi.org/10.1098/rsta.2014.0071.

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The actuator line technique was introduced as a numerical tool to be employed in combination with large eddy simulations to enable the study of wakes and wake interaction in wind farms. The technique is today largely used for studying basic features of wakes as well as for making performance predictions of wind farms. In this paper, we give a short introduction to the wake problem and the actuator line methodology and present a study in which the technique is employed to determine the near-wake properties of wind turbines. The presented results include a comparison of experimental results of the wake characteristics of the flow around a three-bladed model wind turbine, the development of a simple analytical formula for determining the near-wake length behind a wind turbine and a detailed investigation of wake structures based on proper orthogonal decomposition analysis of numerically generated snapshots of the wake.
7

Yang, Xiaolei, and Fotis Sotiropoulos. "A Review on the Meandering of Wind Turbine Wakes." Energies 12, no. 24 (December 11, 2019): 4725. http://dx.doi.org/10.3390/en12244725.

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Meandering describes the large-scale, low frequency motions of wind turbine wakes, which could determine wake recovery rates, impact the loads exerted on turbine structures, and play a critical role in the design and optimal control of wind farms. This paper presents a comprehensive review of previous work related to wake meandering. Emphasis is placed on the origin and characteristics of wake meandering and computational models, including both the dynamic wake meandering models and large-eddy simulation approaches. Future research directions in the field are also discussed.
8

Fleming, Paul, Jennifer Annoni, Matthew Churchfield, Luis A. Martinez-Tossas, Kenny Gruchalla, Michael Lawson, and Patrick Moriarty. "A simulation study demonstrating the importance of large-scale trailing vortices in wake steering." Wind Energy Science 3, no. 1 (May 14, 2018): 243–55. http://dx.doi.org/10.5194/wes-3-243-2018.

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Abstract. In this paper, we investigate the role of flow structures generated in wind farm control through yaw misalignment. A pair of counter-rotating vortices is shown to be important in deforming the shape of the wake and in explaining the asymmetry of wake steering in oppositely signed yaw angles. We also demonstrate that vortices generated by an upstream turbine that is performing wake steering can deflect wakes of downstream turbines, even if they are themselves aligned. We encourage the development of improvements to control-oriented engineering models of wind farm control, to include the effects of these large-scale flow structures. Such a new model would improve the predictability of control-oriented models. Further, we demonstrate that the vortex structures created in wake steering can lead to greater impact on power generation than currently modeled in control-oriented models. We propose that wind farm controllers can be made more effective if designed to take advantage of these effects.
9

Fu, Jiawei, Junhui Wang, Jifei Wu, Ke Xu, and Shuling Tian. "Investigation of the Influence of Wake Field Characteristic Structures on Downstream Targets Using the POD Method." Aerospace 10, no. 9 (September 21, 2023): 824. http://dx.doi.org/10.3390/aerospace10090824.

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This research investigated the impact of complex low-speed wake flow structures on the aerodynamic characteristics of objects downstream. It employed the proper orthogonal decomposition (POD) method and the domain precursor simulation method to compare traditional methods and validate this approach. The study generated several flow structures of parallel dual-cylinder wakes with different scales and spacing. The variations in the aerodynamic coefficient of three downstream objects at various times passing through wakes of varying scales were appropriately compared and analyzed. The study established that the wake with a cylinder spacing of G = 1.5 has a more compact and concentrated modal structure than that with a cylinder spacing of G = 0.35. Smaller objects were more responsive to the wake flow structure with a spacing of G = 1.5, whereas larger objects responded more to the flow structure with a spacing of G = 0.35. The achieved results also revealed that the aerodynamic force coefficients of objects passing through the wakefield at different times were closely related to the temporal characteristics of the wake flow structure with different scales.
10

Wang, Lianzhou, Xinyu Liu, Nian Wang, and Mijian Li. "Modal analysis of propeller wakes under different loading conditions." Physics of Fluids 34, no. 6 (June 2022): 065136. http://dx.doi.org/10.1063/5.0096307.

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Propeller wakes under different loading conditions obtained by the improved delayed detached eddy simulation method were studied based on the flow decomposition technique. The sparsity-promoting dynamic mode decomposition was used to study the flow physics in the wake of a propeller, with particular emphasis placed on identifying the underlying temporal and spatial scales that play important roles in the onset of propeller wake instabilities. The morphology of flow structures of different modes selected by the sparsity-promoting algorithm at different frequencies characterizes the instability process of the wake system. It shows that the circumferential diffusion of tip vortex structures promotes the approaching of adjacent tip vortices, enhancing the interaction of the vortex pairs, which plays an important role in the instability triggering mechanism of the propeller wake, especially the mutual inductance between neighboring tip vortices. The present study further extends knowledge of propeller wake instability inception mechanisms under different loading conditions.
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Статті в журналах Дисертації Книги

Дисертації з теми "Wake structures":

1

Lam, Fung. "Induced drag and wake structures behind wings." Thesis, University of Cambridge, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.316745.

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2

Muld, Tomas W. "Analysis of Flow Structures in Wake Flows for Train Aerodynamics." Licentiate thesis, KTH, Mechanics, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-12746.

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Train transportation is a vital part of the transportation system of today anddue to its safe and environmental friendly concept it will be even more impor-tant in the future. The speeds of trains have increased continuously and withhigher speeds the aerodynamic effects become even more important. One aero-dynamic effect that is of vital importance for passengers’ and track workers’safety is slipstream, i.e. the flow that is dragged by the train. Earlier ex-perimental studies have found that for high-speed passenger trains the largestslipstream velocities occur in the wake. Therefore the work in this thesis isdevoted to wake flows. First a test case, a surface-mounted cube, is simulatedto test the analysis methodology that is later applied to a train geometry, theAerodynamic Train Model (ATM). Results on both geometries are comparedwith other studies, which are either numerical or experimental. The comparisonfor the cube between simulated results and other studies is satisfactory, whiledue to a trip wire in the experiment the results for the ATM do not match.The computed flow fields are used to compute the POD and Koopman modes.For the cube this is done in two regions of the flow, one to compare with a priorpublished study Manhart & Wengle (1993) and another covering more of theflow and especially the wake of the cube. For the ATM, a region containing theimportant flow structures is identified in the wake, by looking at instantaneousand fluctuating velocities. To ensure converged POD modes two methods toinvestigate the convergence are proposed, tested and applied. Analysis of themodes enables the identification of the important flow structures. The flowtopologies of the two geometries are very different and the flow structures arealso different, but the same methodology can be applied in both cases. For thesurface-mounted cube, three groups of flow structures are found. First groupis the mean flow and then two kinds of perturbations around the mean flow.The first perturbation is at the edge of the wake, relating to the shear layerbetween the free stream and the disturbed flow. The second perturbation isinside the wake and is the convection of vortices. These groups would then betypical of the separation bubble that exists in the wake of the cube. For theATM the main flow topology consists of two counter rotating vortices. Thiscan be seen in the decomposed modes, which, except for the mean flow, almostonly contain flow structures relating to these vortices.


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3

Ryan, Kris. "The analysis of wake structures behind stationary, freely oscillating and tethered cylinders." Monash University, Dept. of Mechanical Engineering, 2004. http://arrow.monash.edu.au/hdl/1959.1/9605.

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4

Muld, Tomas W. "Slipstream and Flow Structures in the Near Wake of High-Speed Trains." Doctoral thesis, KTH, Farkost och flyg, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-94182.

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Train transportation is a vital part of the transportation system of today. Asthe speed of the trains increase, the aerodynamic effects become more impor-tant. One aerodynamic effect that is of vital importance for passengers’ andtrack workers’ safety is slipstream, i.e. the induced velocities by the train.Safety requirements for slipstream are regulated in the Technical Specificationsfor Interoperability (TSI). Earlier experimental studies have found that forhigh-speed passenger trains the largest slipstream velocities occur in the wake.Therefore, in order to study slipstream of high-speed trains, the work in thisthesis is devoted to wake flows. First a test case, a surface-mounted cube, issimulated to test the analysis methodology that is later applied to two differ-ent train geometries, the Aerodynamic Train Model (ATM) and the CRH1.The flow is simulated with Delayed-Detached Eddy Simulation (DDES) andthe computed flow field is decomposed into modes with Proper Orthogonal De-composition (POD) and Dynamic Mode Decomposition (DMD). The computedmodes on the surface-mounted cube compare well with prior studies, whichvalidates the use of DDES together with POD/DMD. To ensure that enoughsnapshots are used to compute the POD and DMD modes, a method to inves-tigate the convergence is proposed for each decomposition method. It is foundthat there is a separation bubble behind the CRH1 and two counter-rotatingvortices behind the ATM. Even though the two geometries have different flowtopologies, the dominant flow structure in the wake in terms of energy is thesame, namely vortex shedding. Vortex shedding is also found to be the mostimportant flow structure for slipstream, at the TSI position. In addition, threeconfigurations of the ATM with different number of cars are simulated, in orderto investigate the effect of the size of the boundary layer on the flow structures.The most dominant structure is the same for all configurations, however, theStrouhal number decreases as the momentum thickness increases. The velocityin ground fixed probes are extracted from the flow, in order to investigate theslipstream velocity defined by the TSI. A large scatter in peak position andvalue for the different probes are found. Investigating the mean velocity atdifferent distances from the train side wall, indicates that wider versions of thesame train will create larger slipstream velocities.

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5

Krueger, Matthew J. "Three-dimensional vortical structures in the wake of a flexible flapping foil." Thesis, Massachusetts Institute of Technology, 2005. http://hdl.handle.net/1721.1/32950.

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Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2005.
Includes bibliographical references (leaf 22).
This project aims to gain a qualitative view of the three-dimensional vortical structures of a flexible flapping foil at Reynolds number 164. Flexible foils were fabricated, coated with fluorescent dye, and towed with heave and pitch in a large glass tank. The foil cross section is a NACA 0030 foil shape, and the foil has an aspect ratio of 3. Pictures where taken of the vortical structures from planform, wingtip, and isometric views over a range of Strouhal number and kinematic parameters. Results are compared to previous experimental and numerical studies.
by Matthew J. Krueger.
S.B.
6

Zhong, Shan. "An interferometric study of organized structures in compressible turbulent flows." Thesis, University of Cambridge, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.319551.

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7

Karunakaran, Arvind. "Truce structures : examining cross-professional coordination in the wake of technological and institutional change." Thesis, Massachusetts Institute of Technology, 2018. http://hdl.handle.net/1721.1/118004.

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Thesis: Ph. D., Massachusetts Institute of Technology, Sloan School of Management, 2018.
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Includes bibliographical references.
This research examines the structures, processes, and mechanisms that facilitate cross-professional coordination during periods of technological and institutional change. My study draws on a 24-month ethnographic study, combined with historical data and quantitative analysis, of 911 emergency management organizations in the United States. In Chapter 2, I focus on the mechanisms to facilitate cross-professional coordination in conditions that are marked by protracted jurisdictional conflicts. My findings articulate the importance of truce structures - an ensemble of truce roles and organizational forms - that are intended to address protracted jurisdictional conflicts among symmetrical professions such as police officers and firefighters. I further find that the coevolution of truce roles and organizational forms resulted in the emergence of a specific truce profession - in this case, that of 911 Public Safety Telecommunicators. The truce profession serves to triage, direct, and channel contested tasks among the conflicting professions without bringing those professions into direct contact with each during the initial stages of coordination when the "definition of the situation" is getting worked out. In Chapter 3, I turn to examining how the truce professionals navigate what I call status-authority asymmetry in order to effectively coordinate with the focal professionals. Conducting within-shift comparisons of coordination encounters between 911 dispatchers and police officers, I identify that the bounded publicization tactic performed via the open radio channel allows dispatchers to generate peer knowledge about individual non-compliance. Through this process, dispatchers navigate the status-authority asymmetry and orchestrate effective cross-professional coordination. My focus in Chapter 4 shifts to examining how truce professionals respond to the public's increased digital scrutiny, and consider the consequences for organizational accountability. My findings suggest that the public's increased use of mobile phones and social media to monitor and report on organizations and their workers can, under some conditions, end up worsening accountability. I unpack the processes that generate this paradox of public accountability, showing how these processes reshape the work of truce professionals and produce a vicious cycle of coordination that worsens organizational accountability. I end with a concluding chapter that discusses the implications of my dissertation for research on cross-professional coordination, accountability, and technological change.
by Arvind Karunakaran.
Ph. D.
8

Carmer, Carl Friedrich v. "Shallow turbulent wake flows momentum and mass transfer due to large-scale coherent vortical structures /." Karlsruhe : Univ.-Verl, 2005. http://deposit.d-nb.de/cgi-bin/dokserv?idn=976439034.

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9

Sutkowy, Mark Louis Jr. "Relationship between Rotor Wake Structures and Performance Characteristics over a Range of Low-Reynolds Number Conditions." The Ohio State University, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=osu1534768619864476.

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10

Sönmez, Nurcan. "Investigating Wind Data and Configuration of Wind Turbines for a Turning Floating Platform." Thesis, KTH, Mekanik, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-148957.

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Wake interactions on a floating platform for offshore wind energy applications were investigated.The study is performed in collaboration with Hexicon AB which has a patent family for innovative floating platforms, which are able to turn automatically. The Jensen model is used for wake effect calculations and the simulations were performed in MATLAB. The present study starts with wind speed and wind direction data analysis for the specific site that Hexicon AB plans to construct its first platform. Data analysis is followed by wake interaction studies for H4-24MW type Hexicon AB platform. Wake interaction simulations were performed for three different cases. Fixed turbine and platform, Nacelle yawing and fixed platform and Nacelle yawing and turned platform. Different cases were investigated in order to see wake interactions for different wind directions. Wind direction effect on wake interactions were performed between _90_ and 90_ with an increment of 10_. After having the simulation results for Nacelle yawing and turned platform case the results were compared with ANSYS - CFX simulations results. The results didn’t match exactly but they were very close, which is an indicator to the validity of the Jensen Model. After finding out the possible behavior of wake interactions for different wind directions, power calculations were performed for the same three cases. In order to perform the power calculations the wake interactions for different wind directions were taken into account. In case of platform turning it was assumed that power losses were caused both by wake interactions and in case of thrusters activation. The losses that would be caused by different thrust forces on the turbine blades were not included. The last study was performed to suggest different layouts. In the second case, Nacelle yawing and fixed platform, it was found out that nacelle yawing for most of the angles is not possible because it creates wake regions in front of the rotor area. It was decided to propose new turbine configurations on the platform which are tolerant to different nacelle yawing angles. The simulations were run without considering any constructions limitations, meaning that the availability of platform structure was not included. The study is ended by performing some probabilistic results for platform turning behavior.
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Книги з теми "Wake structures":

1

Hiroshima Daigaku. Bungaku Kenkyūka. Miura Kenkyūshitsu. Kyū Ōkuni-ke jūtaku chōsa kenkyū hōkokusho: Okayama-ken shitei jūyō bunkazai. [Wake-chō]: Wake-chō, 2003.

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2

Lawlor, Mairead. Wage bargaining structures. Dublin: University College Dublin, 1991.

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3

Doyle, James F. Wave Propagation in Structures. New York, NY: Springer New York, 1997. http://dx.doi.org/10.1007/978-1-4612-1832-6.

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4

Doyle, James F. Wave Propagation in Structures. New York, NY: Springer US, 1989. http://dx.doi.org/10.1007/978-1-4684-0344-2.

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5

Doyle, James F. Wave Propagation in Structures. Cham: Springer International Publishing, 2021. http://dx.doi.org/10.1007/978-3-030-59679-8.

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6

Haq, Qureshi A., and United States. National Aeronautics and Space Administration., eds. Review of slow-wave structures. [Washington, DC]: National Aeronautics and Space Administration, 1994.

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7

Sarpkaya, Turgut. Wave forces on offshore structures. New York: Cambridge University Press, 2010.

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8

Sarpkaya, Turgut. Wave forces on offshore structures. Cambridge: Cambridge University Press, 2010.

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9

Sarpkaya, Turgut. Wave forces on offshore structures. Cambridge: Cambridge University Press, 2010.

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10

Haq, Qureshi A., and United States. National Aeronautics and Space Administration., eds. Review of slow-wave structures. [Washington, DC]: National Aeronautics and Space Administration, 1994.

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Частини книг з теми "Wake structures":

1

Ivanell, Stefan. "Wake Structures." In Handbook of Wind Energy Aerodynamics, 915–26. Cham: Springer International Publishing, 2022. http://dx.doi.org/10.1007/978-3-030-31307-4_48.

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Ivanell, Stefan. "Wake Structures." In Handbook of Wind Energy Aerodynamics, 1–12. Cham: Springer International Publishing, 2021. http://dx.doi.org/10.1007/978-3-030-05455-7_48-1.

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Provansal, Michel. "Wake Instabilities Behind Bluff Bodies." In Dynamics of Spatio-Temporal Cellular Structures, 179–202. New York, NY: Springer New York, 2006. http://dx.doi.org/10.1007/978-0-387-25111-0_10.

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Zsolnay, Ilona. "DO DIVINE STRUCTURES OF GENDER MIRROR MORTAL STRUCTURES OF GENDER?" In In the Wake of Tikva Frymer-Kensky, edited by Steven Holloway, JoAnn Scurlock, and Richard H. Beal, 103–20. Piscataway, NJ, USA: Gorgias Press, 2009. http://dx.doi.org/10.31826/9781463219185-010.

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Dong, Xiangrui, and Chaoqun Liu. "Micro-Ramp Wake Structures Identified by Liutex." In Liutex and Third Generation of Vortex Definition and Identification, 279–88. Cham: Springer International Publishing, 2021. http://dx.doi.org/10.1007/978-3-030-70217-5_18.

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Antonia, R. A., L. W. B. Browne, and D. K. Bisset. "Topology of Organised Structures in a Turbulent Plane Wake." In Advances in Turbulence, 337–45. Berlin, Heidelberg: Springer Berlin Heidelberg, 1987. http://dx.doi.org/10.1007/978-3-642-83045-7_38.

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Zurek, W. H., and Y. Hoffman. "Large Scale Streaming in the Wake of a Loop of Cosmic String." In Large Scale Structures of the Universe, 568. Dordrecht: Springer Netherlands, 1988. http://dx.doi.org/10.1007/978-94-009-2995-1_121.

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Hernández, R. H., M. Vial, L. Bellon, and C. Baudet. "Resonant behavior of the wake of a flat plate: Hot wire and sound scattering measurements." In Instabilities and Nonequilibrium Structures IX, 195–205. Dordrecht: Springer Netherlands, 2004. http://dx.doi.org/10.1007/978-94-007-0991-1_11.

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Jeong, J., F. F. Grinstein, F. Hussain, and N. Albanis. "Eduction of Coherent Structures in a Numerically Simulated Plane Wake." In Eddy Structure Identification in Free Turbulent Shear Flows, 65–75. Dordrecht: Springer Netherlands, 1993. http://dx.doi.org/10.1007/978-94-011-2098-2_7.

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Grinstein, F. F., F. Hussain, and J. P. Boris. "Dynamics and Topology of Coherent Structures in a Plane Wake." In Advances in Turbulence 3, 34–41. Berlin, Heidelberg: Springer Berlin Heidelberg, 1991. http://dx.doi.org/10.1007/978-3-642-84399-0_4.

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Тези доповідей конференцій з теми "Wake structures":

1

Karpel, Mordechay, Alexander Shousterman, Hector Climent, and Manuel Reyes. "Dynamic Response to Wake Encounter." In 54th AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics, and Materials Conference. Reston, Virginia: American Institute of Aeronautics and Astronautics, 2013. http://dx.doi.org/10.2514/6.2013-1921.

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Nagabhushanam, J., G. Gaonkar, J. Nagabhushanam, and G. Gaonkar. "Hingeless-rotor aeromechanical stability in hover and forward flight with wake dynamics." In 38th Structures, Structural Dynamics, and Materials Conference. Reston, Virigina: American Institute of Aeronautics and Astronautics, 1997. http://dx.doi.org/10.2514/6.1997-1286.

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Selph, Frank. "Wake fields in 1 cm structures." In AIP Conference Proceedings Volume 156. AIP, 1987. http://dx.doi.org/10.1063/1.36440.

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Correa, Manoela, Donizeti de Andrade, Manoela Correa, and Donizeti de Andrade. "Generalized dynamic wake model applied to rigid blade equations for helicopter rotor in hover." In 38th Structures, Structural Dynamics, and Materials Conference. Reston, Virigina: American Institute of Aeronautics and Astronautics, 1997. http://dx.doi.org/10.2514/6.1997-1281.

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Quackenbush, Todd R., Alan J. Bilanin, and Robert M. McKillip, Jr. "Vortex wake control via smart structures technology." In 1996 Symposium on Smart Structures and Materials, edited by C. Robert Crowe. SPIE, 1996. http://dx.doi.org/10.1117/12.239160.

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Wheeler, Andrew P. S., Robert J. Miller, and Howard P. Hodson. "The Effect of Wake Induced Structures on Compressor Boundary-Layers." In ASME Turbo Expo 2006: Power for Land, Sea, and Air. ASMEDC, 2006. http://dx.doi.org/10.1115/gt2006-90892.

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The interaction of a convected wake with a compressor blade boundary-layer was investigated. Measurements within a single-stage compressor were made using an endoscopic PIV system, a surface mounted pressure transducer, hotfilms and hotwire traverses, along with CFD simulations. The wake/leading-edge interaction was shown to lead to the formation of a thickened laminar boundary-layer, within which turbulent spots formed close to the leading-edge. The thickened boundary-layer became turbulent and propagated down the blade surface, giving rise to pressure perturbations of 7% of the inlet dynamic head in magnitude. The results indicate that wake/leading-edge interactions have a crucial role to play in the performance of compressor blades in the presence of wakes.
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Quackenbush, Todd R., Alan J. Bilanin, P. F. Batcho, Robert M. McKillip, Jr., and Bernie F. Carpenter. "Implementation of vortex wake control using SMA-actuated devices." In Smart Structures and Materials '97, edited by Janet M. Sater. SPIE, 1997. http://dx.doi.org/10.1117/12.274657.

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Wang, S. S., H. Li, and H. S. Tzou. "Wake Structures of a Cantilever Beam Excited by Piezoelectric Actuators." In ASME 2013 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/imece2013-64306.

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In this paper, the wake structures of a cantilever beam in axial flows under the excitations of piezoelectric actuators are studied. It is assumed that the dynamic response of the cantilever beam is relatively small (i.e., linear) and the beam is modeled as an Euler-Bernoulli beam. The total force is divided into two parts: 1) the hydrodynamic loading, which changes beam’s natural frequencies and damping ratios and 2) the piezoelectric induced part, which is the excitation force. Furthermore, the hydrodynamic loading can be separated into an added mass term and a fluid damping term and they are obtained with the hydrodynamic function; the excitation force induced by the converse piezoelectric effect is calculated with Love’s control operator. In order to maximize wake generations, two specific types of piezoelectric actuators (i.e., modal actuators and segmented actuators) are used in this study. It is assumed that the mode shapes of the cantilever beam remain unchanged in fluids and the dynamic responses of the cantilever beam can be calculated by the modal expansion method. Once the dynamic responses of the cantilever beam are known, the panel method free-wake model is adopted to simulate the wake structures. In case studies, the wake structures excited by modal actuators and segmented actuators of the first four modes are compared. The effects of applied voltage and flow velocity to the wakes are also studied. Distinct wake roll-up phenomenon is observed in all simulation results. Higher applied voltage and lower flow speed make the wake easier to roll-up.
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Chabalko, Christopher, Richard Snyder, Philip Beran, and Michael Ol. "Study of Deflected Wake Phenomena by 2D Unsteady Vortex Lattice." In 50th AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics, and Materials Conference. Reston, Virigina: American Institute of Aeronautics and Astronautics, 2009. http://dx.doi.org/10.2514/6.2009-2475.

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Dong, Xiangrui, Sita Charkrit, Xuan Truong, and Chaoqun Liu. "POD Study on vortex Structures in MVG wake." In AIAA Scitech 2019 Forum. Reston, Virginia: American Institute of Aeronautics and Astronautics, 2019. http://dx.doi.org/10.2514/6.2019-1136.

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Звіти організацій з теми "Wake structures":

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Rahmani, Mehran, and Manan Naik. Structural Identification and Damage Detection in Bridges using Wave Method and Uniform Shear Beam Models: A Feasibility Study. Mineta Transportation Institute, February 2021. http://dx.doi.org/10.31979/mti.2021.1934.

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This report presents a wave method to be used for the structural identification and damage detection of structural components in bridges, e.g., bridge piers. This method has proven to be promising when applied to real structures and large amplitude responses in buildings (e.g., mid-rise and high-rise buildings). This study is the first application of the method to damaged bridge structures. The bridge identification was performed using wave propagation in a simple uniform shear beam model. The method identifies a wave velocity for the structure by fitting an equivalent uniform shear beam model to the impulse response functions of the recorded earthquake response. The structural damage is detected by measuring changes in the identified velocities from one damaging event to another. The method uses the acceleration response recorded in the structure to detect damage. In this study, the acceleration response from a shake-table four-span bridge tested to failure was used. Pairs of sensors were identified to represent a specific wave passage in the bridge. Wave velocities were identified for several sensor pairs and various shaking intensities are reported; further, actual observed damage in the bridge was compared with the detected reductions in the identified velocities. The results show that the identified shear wave velocities presented a decreasing trend as the shaking intensity was increased, and the average percentage reduction in the velocities was consistent with the overall observed damage in the bridge. However, there was no clear correlation between a specific wave passage and the observed reduction in the velocities. This indicates that the uniform shear beam model was too simple to localize the damage in the bridge. Instead, it provides a proxy for the overall extent of change in the response due to damage.
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Torres, Marissa, Michael-Angelo Lam, and Matt Malej. Practical guidance for numerical modeling in FUNWAVE-TVD. Engineer Research and Development Center (U.S.), October 2022. http://dx.doi.org/10.21079/11681/45641.

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This technical note describes the physical and numerical considerations for developing an idealized numerical wave-structure interaction modeling study using the fully nonlinear, phase-resolving Boussinesq-type wave model, FUNWAVE-TVD (Shi et al. 2012). The focus of the study is on the range of validity of input wave characteristics and the appropriate numerical domain properties when inserting partially submerged, impermeable (i.e., fully reflective) coastal structures in the domain. These structures include typical designs for breakwaters, groins, jetties, dikes, and levees. In addition to presenting general numerical modeling best practices for FUNWAVE-TVD, the influence of nonlinear wave-wave interactions on regular wave propagation in the numerical domain is discussed. The scope of coastal structures considered in this document is restricted to a single partially submerged, impermeable breakwater, but the setup and the results can be extended to other similar structures without a loss of generality. The intended audience for these materials is novice to intermediate users of the FUNWAVE-TVD wave model, specifically those seeking to implement coastal structures in a numerical domain or to investigate basic wave-structure interaction responses in a surrogate model prior to considering a full-fledged 3-D Navier-Stokes Computational Fluid Dynamics (CFD) model. From this document, users will gain a fundamental understanding of practical modeling guidelines that will flatten the learning curve of the model and enhance the final product of a wave modeling study. Providing coastal planners and engineers with ease of model access and usability guidance will facilitate rapid screening of design alternatives for efficient and effective decision-making under environmental uncertainty.
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Zhu, Minjie, and Michael Scott. Two-Dimensional Debris-Fluid-Structure Interaction with the Particle Finite Element Method. Pacific Earthquake Engineering Research Center, University of California, Berkeley, CA, April 2024. http://dx.doi.org/10.55461/gsfh8371.

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In addition to tsunami wave loading, tsunami-driven debris can cause significant damage to coastal infrastructure and critical bridge lifelines. Using numerical simulations to predict loads imparted by debris on structures is necessary to supplement the limited number of physical experiments of in-water debris loading. To supplement SPH-FEM (Smoothed Particle Hydrodynamics-Finite Element Method) simulations described in a companion PEER report, fluid-structure-debris simulations using the Particle Finite Element Method (PFEM) show the debris modeling capabilities in OpenSees. A new contact element simulates solid to solid interaction with the PFEM. Two-dimensional simulations are compared to physical experiments conducted in the Oregon State University Large Wave Flume by other researchers and the formulations are extended to three-dimensional analysis. Computational times are reported to compare the PFEM simulations with other numerical methods of modeling fluid-structure interaction (FSI) with debris. The FSI and debris simulation capabilities complement the widely used structural and geotechnical earthquake simulation capabilities of OpenSees and establish the foundation for multi-hazard earthquake and tsunami simulation to include debris.
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Melby, Jeffrey, Thomas Massey, Abigail Stehno, Norberto Nadal-Caraballo, Shubhra Misra, and Victor Gonzalez. Sabine Pass to Galveston Bay, TX Pre-construction, Engineering and Design (PED) : coastal storm surge and wave hazard assessment : report 1 – background and approach. Engineer Research and Development Center (U.S.), September 2021. http://dx.doi.org/10.21079/11681/41820.

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The US Army Corps of Engineers, Galveston District, is executing the Sabine Pass to Galveston Bay Coastal Storm Risk Management (CSRM) project for Brazoria, Jefferson, and Orange Counties regions. The project is currently in the Pre-construction, Engineering, and Design phase. This report documents coastal storm water level and wave hazards for the Port Arthur CSRM structures. Coastal storm water level (SWL) and wave loading and overtopping are quantified using high-fidelity hydrodynamic modeling and stochastic simulations. The CSTORM coupled water level and wave modeling system simulated 195 synthetic tropical storms on three relative sea level change scenarios for with- and without-project meshes. Annual exceedance probability (AEP) mean values were reported for the range of 0.2 to 0.001 for peak SWL and wave height (Hm0) along with associated confidence limits. Wave period and mean wave direction associated with Hm0 were also computed. A response-based stochastic simulation approach is applied to compute AEP runup and overtopping for levees and overtopping, nappe geometry, and combined hydrostatic and hydrodynamic fluid pressures for floodwalls. CSRM structure crest design elevations are defined based on overtopping rates corresponding to incipient damage. Survivability and resilience are evaluated. A system-wide hazard level assessment was conducted to establish final recommended system-wide CSRM structure elevations.
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Hite, John, Robert Ebeling, and Barry White. Hydraulic load definitions for use in Load and Resistance Factor Design (LRFD) analysis, including probabilistic load characterization, of 10 hydraulic steel structures : report number 1. Engineer Research and Development Center (U.S.), May 2024. http://dx.doi.org/10.21079/11681/48610.

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In the past, allowable stress design (ASD) was used to design steel structures. The allowable stresses used were determined from previous practice, with limited understanding of the reliability and risk performance provided by the structure. Engineering methods based on Load and Resistance Factor Design (LRFD) provide more accurate lifetime models of structures by providing risk-based load factors. Besides improved safety, cost savings can be provided through improved performance and, in some cases, by delaying rehabilitation. This research project develops LRFD-based engineering procedures for the evaluation and design of hydraulic steel structures (HSS). Hydraulic loads are a key element to the LRFD analysis. This report identifies the primary hydraulic loads and describes procedures that can be used to determine these hydraulic loads. Existing design guidance for HSS is described and presented in the individual chapters. The appendixes to the report provide examples of the procedures used to compute the hydrostatic, wave, and hydrodynamic loads. A new approach for determining wind-induced wave loads was developed. Design guidance for computing the hydrodynamic load was limited for many of the HSS. Additional research is recommended to improve capabilities for computing hydraulic loads. Details on these recommendations can be found in this report.
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Ter-Minassian, Teresa. Structural Reforms in Brazil: Progress and Unfinished Agenda. Inter-American Development Bank, May 2012. http://dx.doi.org/10.18235/0008417.

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This paper discusses Brazil's structural reforms since the 1990s and areas where work remains to be done. Reforms of the 1990s included the containment of inflation, the adoption of a comprehensive Fiscal Responsibility Law, a successful debt restructuring program for subnational governments, the reduction of trade barriers, a wave of privatizations, and the expansion of health and education programs. Reforms of the 2000s included strengthening welfare programs, rapidly increasing the minimum wage, and reforming the financial sector to increase access to credit among lower income groups. Political opposition and other factors, however, have prevented reforms in the tax and pension systems and in the labor market. Brazil's recent strong economic performance owes more to generally sound macroeconomic management, and to a favorable external environment, than to a comprehensive and sustained structural reform effort. Doubts remain about the country's ability to sustain high growth rates while keeping inflation low.
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Allen, Steven. Technology and the Wage Structure. Cambridge, MA: National Bureau of Economic Research, April 1996. http://dx.doi.org/10.3386/w5534.

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Muhlestein, Michael, and Carl Hart. Numerical analysis of weak acoustic shocks in aperiodic array of rigid scatterers. Engineer Research and Development Center (U.S.), October 2020. http://dx.doi.org/10.21079/11681/38579.

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Nonlinear propagation of shock waves through periodic structures have the potential to exhibit interesting phenomena. Frequency content of the shock that lies within a bandgap of the periodic structure is strongly attenuated, but nonlinear frequency-frequency interactions pumps energy back into those bands. To investigate the relative importance of these propagation phenomena, numerical experiments using the Khokhlov-Zabolotskaya-Kuznetsov (KZK) equation are carried out. Two-dimensional propagation through a periodic array of rectangular waveguides is per-formed by iteratively using the output of one waveguide as the input for the next waveguide. Comparison of the evolution of the initial shock wave for both the linear and nonlinear cases is presented.
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Williams, James H., and Jr. Wave Propagation and Dynamics of Lattice Structures. Fort Belvoir, VA: Defense Technical Information Center, October 1987. http://dx.doi.org/10.21236/ada190037.

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Williams, James H., and Jr. Wave Propagation and Dynamics of Lattice Structures. Fort Belvoir, VA: Defense Technical Information Center, October 1987. http://dx.doi.org/10.21236/ada190611.

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