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Auswahl der wissenschaftlichen Literatur zum Thema „Keulegan-Carpenter“
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Zeitschriftenartikel zum Thema "Keulegan-Carpenter"
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Tumer, Irem Y., Raul G. Longoria und Kristin L. Wood. „Signal Analysis Using Karhunen-Loe`ve Transformation: Application to Hydrodynamic Forces“. Journal of Offshore Mechanics and Arctic Engineering 122, Nr. 3 (07.02.2000): 208–13. http://dx.doi.org/10.1115/1.1286923.
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This paper describes a signal analysis method using the Karhunen-Loe`ve (KL) transform, and applies the method to the analysis of hydrodynamic force data collected from controlled laboratory experiments. To demonstrate feasibility, the study focuses on inline forces induced on fixed cylinders exposed to oscillatory flows, with increasing Keulegan-Carpenter numbers. This preliminary example illustrates how this force makes a transition from the inertia-dominated region at low Keulegan-Carpenter numbers up into higher Keulegan-Carpenter numbers where the nonlinear effects of the flow-structure interaction can be observed through the increased influence of clearly defined modes. [S0892-7219(00)00603-8]
2
Hudspeth, Robert T. „Significance of Keulegan‐Carpenter Parameter“. Journal of Hydraulic Engineering 117, Nr. 12 (Dezember 1991): 1626–38. http://dx.doi.org/10.1061/(asce)0733-9429(1991)117:12(1626).
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3
Tatsuno, M., und P. W. Bearman. „A visual study of the flow around an oscillating circular cylinder at low Keulegan–Carpenter numbers and low Stokes numbers“. Journal of Fluid Mechanics 211 (Februar 1990): 157–82. http://dx.doi.org/10.1017/s0022112090001537.
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The structures of the flow induced by a circular cylinder performing sinusoidal oscillations in a fluid at rest are investigated by means of flow visualization. The experiments are carried out at Keulegan–Carpenter numbers between 1.6 and 15 and at Stokes numbers between 5 and 160. Above a certain value of Keulegan–Carpenter number, depending on the Stokes number, some asymmetry appears in the flow separation and the associated vortex development behind the cylinder. The two vortices that are developed in a half cycle differ in strength and may be convected in different directions. This results in a fascinating set of flow patterns. Eight different regimes of flow can be identified within the ranges of Keulegan–Carpenter number and Stokes number studied. Furthermore, most of the resulting flows show a three-dimensional instability along the axis of the cylinder. Measurements of the wavelength of these disturbances are presented.
4
Nath, J. H. „On Wave Force Coefficient Variability“. Journal of Offshore Mechanics and Arctic Engineering 109, Nr. 4 (01.11.1987): 295–306. http://dx.doi.org/10.1115/1.3257023.
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Wave force coefficient variability for cylinders, from wave to wave in a train of periodic waves, has been shown to be dependent on the phase of the force record relative to the ambient flow. The phase varies due to vortex shedding, but the maximum force is approximately constant as seen from this work and the work of other investigators. Thus, the maximum force coefficient is tightly organized according to the Keulegan-Carpenter number and scatter is seen in the phase angle versus Keulegan-Carpenter number. On the other hand, both Cd and Cm have scatter due to these phase differences from wave to wave. For unknown reasons, even when averaged over several wave cycles there is scatter in the results for Cd and Cm. This investigation shows that the maximum force coefficients for a heavily roughened vertical cylinder are tightly arranged according to the Keulegan-Carpenter number and the period parameter. Furthermore, the phase angle is similarly much more organized than for the smooth cylinder.
5
Zdravkovich, M. M. „Inadequacy of a Conventional Keulegan-Carpenter Number for Wave and Current Combination“. Journal of Offshore Mechanics and Arctic Engineering 118, Nr. 4 (01.11.1996): 309–11. http://dx.doi.org/10.1115/1.2833922.
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The physical consideration, taken as a starting point, has been based on the change of duration of each wave half-cycle by the superposition of a current. The Keulegan-Carpenter number could reflect that feature if the wave plus current velocity replaces the wave velocity as the reference velocity. It is also argued that the ratio of current to wave velocity is a more appropriate parameter than the reduced velocity. The modified Keulegan-Carpenter numbers separate different observed flow regimes in a coherent manner in drag coefficient and current-to-wave velocity plane.
6
Longoria, R. G., J. J. Beaman und R. W. Miksad. „An Experimental Investigation of Forces Induced on Cylinders by Random Oscillatory Flow“. Journal of Offshore Mechanics and Arctic Engineering 113, Nr. 4 (01.11.1991): 275–85. http://dx.doi.org/10.1115/1.2919931.
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Results are presented from experiments investigating hydrodynamic forces induced on fixed circular cylinders by random oscillatory flows. The oscillatory flow was generated in a water tunnel and the inline and transverse forces induced on the cylinders were measured simultaneously. Analysis of the measured forces shows that significant differences exist when comparing drag and inertia coefficients to those measured under sinusoidal flow conditions, particularly in the inertia/ drag regime of the Keulegan-Carpenter number. The comparison of results for random versus sinusoidal flow conditions generated in the same experimental apparatus quantifies the difference in the physical mechanisms, specifically the vortex shedding and pairing, which influence the induced forces. A study is also made of the dependence of measured force power spectral densities on the statistical Keulegan-Carpenter number, Reynold’s number and on the spectral width of the flow velocity auto-power spectrum.
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Chaplin, J. R., K. Subbiah und M. Irani. „Loading on a Vertical Cylinder in Multidirectional Waves“. Journal of Offshore Mechanics and Arctic Engineering 117, Nr. 3 (01.08.1995): 151–58. http://dx.doi.org/10.1115/1.2827083.
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This paper presents laboratory measurements of local and total loading on an isolated vertical cylinder in irregular unidirectional and multidirectional waves. Maximum Keulegan-Carpenter numbers in individual waves were about 16, and maximum Reynolds numbers about 3 × 104. It is shown that in these conditions, existing theoretical and numerical models underestimate the reduction in loading on a cylinder due to wave spreading. Besides the changes that are predicted when Morison’s equation is used with constant coefficients, there are hydrodynamic influences that contribute further force reductions. Comparisons with Dean’s (1977) hybrid approach suggest that in the present conditions these reductions are in the region of 3 and 6 percent for a spreading function cos2s θ, with s = 8 and s = 2, respectively. Larger reductions can be expected at higher Keulegan-Carpenter numbers, though scale effects are likely to become more important in the drag-dominated regime.
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Sumer, B. M., und J. Fredso̸e. „Transverse Vibrations of an Elastically Mounted Cylinder Exposed to an Oscillating Flow“. Journal of Offshore Mechanics and Arctic Engineering 110, Nr. 4 (01.11.1988): 387–94. http://dx.doi.org/10.1115/1.3257077.
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This study reports the results of an experimental work carried out with an elastically mounted rigid cylinder exposed to an oscillating flow. To facilitate comparison, the steady current case is included in the test program as well. The oscillatory flow as well as the steady current conditions are created by the so-called carriage technique. The present study covers the Keulegan-Carpenter number range 5 ≤ KC ≤ 100. The range of the reduced velocity is from 0 to approximately 16 in most of the cases. The tests have been conducted for different combinations of spring stiffness and mass of cylinder. The present results shed considerable light into the understanding of the various vibrational response patterns obtained for different ranges of KC number. The response characteristics of the cylinder have been shown to vary extensively, depending on Keulegan-Carpenter number as well as on the reduced velocity.
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Duggal, A. S., und J. M. Niedzwecki. „Dynamic Response of a Single Flexible Cylinder in Waves“. Journal of Offshore Mechanics and Arctic Engineering 117, Nr. 2 (01.05.1995): 99–104. http://dx.doi.org/10.1115/1.2827070.
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A large-scale experimental study to investigate the dynamic response of a single flexible cylinder in waves is presented. The cylinder was designed to exhibit the dynamic characteristics of a TLP riser or tendon in approximately 1000 m of water. Instrumentation provided detailed information on the inline and transverse curvature along the length of the cylinder. Wave loading mechanisms and the resulting response were investigated and compared with previous studies of rigid cylinders in oscillating flow. It was found that the complicated multifrequency response at large Keulegan-Carpenter numbers could be explained by introducing the depth dependence of the Keulegan-Carpenter number. The predicted inline response was shown to be reasonable for the wave frequency component of the measured inline response. Similarities between the measured transverse response and the high-frequency inline response were also shown. Probability density functions of the measured curvature were non-Gaussian, leading to significantly higher probabilities of curvature than would be predicted based on assuming a Gaussian process.
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Bearman, P. W., M. J. Downie, J. M. R. Graham und E. D. Obasaju. „Forces on cylinders in viscous oscillatory flow at low Keulegan-Carpenter numbers“. Journal of Fluid Mechanics 154 (Mai 1985): 337–56. http://dx.doi.org/10.1017/s0022112085001562.
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This paper presents a comparison between theory and experiment for the in-line forces on cylinders of general cross-section in planar oscillatory flows of small amplitude. The theoretical analysis evaluates corrections to the standard inviscid inertial force at low Keulegan-Carpenter numbers which arise from the presence of viscous laminar boundary layers and from the development of vortex shedding. The boundary-layer contribution due to both skin friction and displacement effects is calculated to first order in the Stokes parameter β−½. The contribution to the in-line force from separation and vortex shedding, for which the results presented only apply to sharp-edged bodies, is taken from previous work on vortex shedding from isolated edges using the discrete vortex modelling technique. The resulting force has components both in phase with the fluid acceleration (inertia) and in phase with the velocity (drag).The theoretical results are compared to measurements taken in a [xcup ]-tube water channel on a number of cylinders of different cross-section including circular cylinders and sharp-edged sections. The comparisons suggest that the theory is valid for Keulegan–Carpenter numbers below about 3 and for moderately high values of the β parameter.
Dissertationen zum Thema "Keulegan-Carpenter"
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Jarno-Druaux, Armelle. „Nteraction houle-cylindre horizontal à faible nombre de Keulegan-Carpenter“. Le Havre, 1989. http://www.theses.fr/1990LEHA0004.
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Les cylindres horizontaux soumis à la houle, places en dehors de l'influence directe de la surface libre et du fond, dans des conditions telles que le nombre de Keulegan-Carpenter (KC) est de l'ordre de 2, subissent des efforts plus faibles que prédits par la théorie potentielle. L'étude expérimentale permet de faire apparaitre KC=2. 3 comme une valeur critique pour le phénomène de détachement de tourbillon. L'analyse fine du champ cinématique mesure par vélocimétrie doppler a laser, dans ce cas, met en évidence près du cylindre, l'existence d'une circulation de fluide, d'intensité relativement constante durant toute la période et dirigée dans le sens du mouvement orbital. La force induite par cet effet, calculée en généralisant la formule de Kutta-Joukowski à la houle, et ajoutée au modèle de Morison, conduit à une réduction du coefficient d'inertie telle que les efforts ainsi prédits, sont plus proches des efforts mesures. Ce résultat valide l'hypothèse de Chaplin. La comparaison entre les cas KC=2. 3 et KC=3. 1, des énergies cinétiques moyenne et fluctuante, du rotationnel, des positions des points d'arrêt et des différents termes du développement de la forme intégrale de l'équation de Navier-stokes, montre en quoi les caractéristiques de l'écoulement sont fondamentalement modifiées par la présence du cylindre dans le cas KC=3. 1
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Longo, Lorenzo. „Experimental characterization of PWR fuel assemblies mechanical behavior under hydrodynamic and seismic-like loads“. Electronic Thesis or Diss., Ecole centrale de Marseille, 2023. http://www.theses.fr/2023ECDM0002.
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Les assemblages de combustible nucléaire dans le cœur d’un réacteur à eau pressurisée(REP) sont immergés dans un écoulement axial. Cet écoulement exerce une charge hydrodynamique sur les assemblages et est responsable de leur couplage et de leurs vibrations. De plus, lors d’un tremblement de terre ou d’un événement LOCA (Loss Of CoolantAccident), les assemblages de combustible sont soumis à de fortes oscillations. La charge hydrodynamique peut déformer les assemblages, générant une déformation arquée, tandis que des oscillations plus fortes, comme lors d’un événement sismique,peuvent être à l’origine d’impacts sur les assemblages. Afin de garantir l’intégrité et la sûreté du cœur du réacteur, les industries nucléaires souhaitent améliorer la connaissance phénoménologique des interactions fluide-structure à l’intérieur du cœur d’un réacteur à eau pressurisée. Les ingénieurs ont donc besoin de modèles numériques pour le comportement mécanique et de campagnes expérimentales pour les valider et définir leurs limites.L’étude présentée dans ce document est principalement divisée en trois campagnes expérimentales visant à étudier : les effets d’oscillation de l’assemblage dans un fluide au repos, les phénomènes de traînée sur les assemblages de combustible en régime permanent sous un écoulement et le comportement des oscillations des assemblages lorsqu’ils sont immergés dans un écoulement. Deux installations expérimentales sont utilisées :SBF (Shaking Bundle Facility) et Eudore. SBF accueille un assemblage fictif de pleine hauteur soumis à un écoulement axial sur une table vibrante. Grâce à des techniques optiques, le champ de vitesse du fluide et le mouvement de l’assemblage peuvent être mesurés. L’installation Eudore utilise trois assemblages réduits en ligne, soumis à un écoulement axial, avec la possibilité d’appliquer une excitation sismique à l’ensemble de la section d’essai. L’instrumentation développée sur Eudore permet de mesurer les déplacements des assemblages, le champ de vitesse du fluide et les forces d’impact.Les expériences réalisées sur Eudore sont simulées à l’aide d’un outil de calcul numérique développé au CEA, nommé FSCORE, basé sur une approche en milieu poreux. Cette approche permet d’accéder à un modèle de fluide équivalent et à un modèle de structure équivalent définis sur l’ensemble du domaine à partir de l’intégration spatiale d’équations locales. Les équations de mouvement du fluide équivalent et de la structure équivalente sont établies séparément, pour fournir un modèle couplé fluide-structure prenant en compte les contacts entre les assemblages.A l’aide d’un modèle analytique, les résultats expérimentaux obtenus sur Eudore sont utilisés pour retrouver le coefficient de traînée présent dans FSCORE. Les résultats expérimentaux et numériques sont largement discutés et montrent un bon accordNuclear fuel assemblies in Pressurized Water Reactor (PWR) core are immersed in anaxial flow. This flow exerts a hydrodynamic load on the assemblies, and it is responsible fortheir coupling and vibrations. Furthermore, during an earthquake or a LOCA event (LossOf Coolant Accident), fuel assemblies are subjected to strong oscillation amplitudes. The hydrodynamic load can deform the assemblies, generating assembly bow, while strongeroscillations, such in a seismic event, can be responsible for assemblies impacts. In order to ensure the reactor core integrity and safety, nuclear industries want to improve thephenomenological knowledge of fluid-structure interactions inside a PWR core. Thus, engineersneed numerical models for mechanical behavior of fuel assemblies and experimentalcampaigns to validate them and define their limits.The study presented in this document is mainly divided in three experimental campaignsand aim to investigate: the assembly oscillation effects in fluid at rest, the dragphenomena on steady state fuel assemblies under a flow and the assemblies oscillationsbehavior when immersed in a flow. Two experimental facilities are used: SBF (ShakingBundle Facility) and Eudore. SBF hosts one full-height surrogate assembly under axialflow on a vibrating table. By using optical technique, the velocity field of the fluid andassembly motion can be measured. Eudore facility uses three reduced assemblies in line,under axial flow with the possibility of applying seismic excitation to the entire test section.The instrumentation developed on Eudore makes it possible to measure the displacementsof the assemblies, velocity field of the fluid and the impact forces.The experiments performed on Eudore are simulated with a numerical calculation tooldeveloped at CEA, named FSCORE, based on a porous medium approach. This approachprovides access to an equivalent fluid model and an equivalent structure model defined overthe entire domain from the spatial integration of local equations. The equations of motionof the equivalent fluid and of the equivalent structure are established separately, to providea coupled model taking into account the contacts between assemblies.With the help of an analytical model, the experimental results obtained on Eudoreare used to retrieve the drag coefficient present in FSCORE. Experimental and numericalresults are widely discussed and show good agreement
3
Duclercq, Marion. „Étude de l'interaction entre un fluide et une structure oscillante : régimes d'écoulement et de forces, du cylindre isolé au réseau de cylindres“. Phd thesis, Ecole Polytechnique X, 2010. http://pastel.archives-ouvertes.fr/pastel-00545937.
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Cette thèse porte sur l'étude numérique et physique de la dynamique d'un fluide réel incompressible initialement au repos, mis en mouvement par les oscillations rectilignes transversales forcées d'un cylindre. Ce système est décrit par deux nombres adimensionnels. Le nombre de Reynolds (Re) compare les forces d'inertie aux forces de viscosité, et le nombre de Keulegan-Carpenter (KC) mesure l'amplitude des oscillations du cylindre par rapport à son diamètre. L'objectif est de déterminer l'influence de ces deux paramètres sur les forces de traînée et de portance exercées par le fluide sur la structure, en lien avec la dynamique de l'écoulement. Les équations de Navier-Stokes sont résolues numériquement par une méthode d'éléments finis. Les résultats de ces calculs pour l'écoulement et les forces permettent d'abord d'identifier différents modes de comportement du système sur un cycle d'oscillation du cylindre. Les propriétés de symétrie de l'écoulement et les trajectoires des tourbillons sont corrélées aux signaux temporels des forces. Puis l'analyse de la réponse du système sur des temps longs devant la période d'oscillation du cylindre met en évidence des domaines de stabilité des modes dans le plan (KC, Re). Dans certains régimes, les forces présentent des fluctuations d'amplitude. Elles sont interprétées notamment à l'aide des spectres des forces et des instabilités observées dans l'écoulement. Enfin, le passage du problème d'un seul cylindre à un réseau carré de 25 cylindres est étudié. Une approche énergétique est proposée pour caractériser l'influence de KC et Re sur le comportement global du système, dans le cas du cylindre isolé et celui du réseau.
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Yuen, Nathan Q. S. „Oscillating flow about circular cylinders at low Keulegan-Carpenter numbers“. Thesis, 1985. http://hdl.handle.net/10945/21477.
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The in-line force and the resulting drag and inertia
coefficients for smooth and rough circular cylinders
immersed in a sinusoidally oscillating flow at low Keulegan-
Carpenter numbers (K) have been determined experimentally
and compared with those obtained theoretically by Stokes and
Wang. In addition, flow visualization experiments were
carried out with oscillating cylinders in a water table and
the stability of the flow was investigated. The results
have shown that for very low values of K, the flow about the
cylinder is laminar, attached, and stable and the drag
coefficient is nearly identical to that predicted theoretically. At a critical K, the flow becomes unstable to
Taylor-Gortler vortices and the drag coefficient jumps to a
higher value. Subsequently, the flow separates, becomes
turbulent and results in a minimum drag coefficient. The
subsequent increases in drag are attributed to vortex
shedding. The inertia coefficient agrees with that obtained
theoretically in the range where the flow in laminar.
Bücher zum Thema "Keulegan-Carpenter"
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Yuen, Nathan Q. S. Oscillating flow about circular cylinders at low Keulegan-Carpenter numbers. 1985.
Den vollen Inhalt der Quelle findenKonferenzberichte zum Thema "Keulegan-Carpenter"
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Derouich, D. Hamel. „Wave Forces on Rectangular Cylinders at Low Keulegan-Carpenter Numbers“. In Offshore Technology Conference. Offshore Technology Conference, 1991. http://dx.doi.org/10.4043/6520-ms.
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2
Dalton, Charles, Xiaohua Sun, Jianfeng Zhang und Lixian Zhuang. „Computation Of Hydrodynamic Damping Coefficients At Low Keulegan Carpenter Numbers“. In Offshore Technology Conference. Offshore Technology Conference, 1993. http://dx.doi.org/10.4043/7235-ms.
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3
Anagnostopoulos, P., A. Koutras und S. A. Seitanis. „Numerical Study of Oscillatory Flow Past a Pair of Cylinders in a Side-by-Side Arrangement“. In ASME 2005 24th International Conference on Offshore Mechanics and Arctic Engineering. ASMEDC, 2005. http://dx.doi.org/10.1115/omae2005-67225.
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The results of a numerical study of the viscous oscillating flow around a pair of circular cylinders are presented herein, for a constant frequency parameter, β, equal to 50, and Keulegan-Carpenter numbers, KC, ranging between 0.2 and 10. The cylinders were placed side-by-side to the oncoming flow, for a pitch to diameter ratio, P/D, equal to 2. The finite-element method was employed for the solution of the Navier-Stokes equations, in the formulation where the stream function and the vorticity are the field variables. The vorticity contours generated from the solution were used mainly for the flow visualization, whereas the stream-lines and isobars are shown in some cases. At low values of the Keulegan-Carpenter number the flow remains symmetrical with respect to the horizontal axis of symmetry of the solution domain. As the Keulegan-Carpenter number is increased asymmetries appear in the flow, which are eventually amplified and lead finally to more complicated vortex-shedding patterns. These asymmetries generate an aperiodic flow configuration at consecutive cycles, which becomes almost chaotic as KC grows larger. For the various Keulegan-Carpenter numbers examined the time-histories of the hydrodynamic forces are presented, and the r.m.s. values of the hydrodynamic forces and the coefficients of the in-line force were evaluated.
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Anagnostopoulos, P., A. Koutras und S. A. Seitanis. „Numerical Study of Oscillatory Flow Past a Pair of Cylinders at Low Reynolds and Keulegan-Carpenter Numbers“. In ASME 2002 International Mechanical Engineering Congress and Exposition. ASMEDC, 2002. http://dx.doi.org/10.1115/imece2002-32178.
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The results of a numerical study of the viscous oscillating flow around a pair of circular cylinders are presented herein, for a constant frequency parameter, β, equal to 50, and Keulegan-Carpenter numbers, KC, ranging between 0.2 and 10. The cylinders were placed side-by-side to the oncoming flow, for a pitch to diameter ratio, P/D, equal to 1.2. The finite-element method was employed for the solution of the Navier-Stokes equations, in the formulation where the stream function and the vorticity are the field variables. The streamlines and vorticity contours generated from the solution were used for the flow visualization. At low values of the Keulegan-Carpenter number the flow remains symmetrical with respect to the horizontal axis of symmetry of the domain. As the Keulegan-Carpenter number is increased asymmetries appear in the flow, which are eventually amplified and lead finally to more complicated vortex-shedding patterns. These asymmetries generate an aperiodic flow configuration at consecutive cycles, which becomes almost chaotic as KC grows larger. For the various Keulegan-Carpenter numbers examined the traces of the hydrodynamic forces are presented, and the r.m.s. values of the hydrodynamic forces and the coefficients of the in-line force were evaluated.
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Sha, Yong, Yongxue Wang und Lee M. Pearson. „Experimental Investigation on Dynamic Response of Submarine Pipeline Over Flat Beds in Waves“. In ASME 2007 26th International Conference on Offshore Mechanics and Arctic Engineering. ASMEDC, 2007. http://dx.doi.org/10.1115/omae2007-29088.
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Model tests have been conducted on flexible submarine pipelines over flat beds in both regular and irregular waves and the second order effect induced by waves are concerned within the certain range of Keulegan-Carpenter numbers and Reynolds numbers. The tests were conducted in the wave flume with 55m in length, 4m in width and 2.5m in depth. The pipelines were made by flexible pipe with 60mm in diameter and placed at various distances from a flat bed. Gap to diameter ratio varies from 0.4 to 0.8 when the pipelines are not sagging. The wave period in the model tests is in the range from 0.8 to 2.0 and water depth is 0.4m. The Keulegan-Carpenter numbers are less than 8.0 and the Reynolds numbers are in the subcritical regime. Bending strain was measured by strain gauges bonded on the inner surface of the pipeline. The strain amplitudes and second order effect are analyzed and discussed against various Keulegan-Carpenter numbers and gaps between the pipeline and the flat bed.
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Fechhelm, Stuart, und Li P. Sung. „Hydrodynamics of Heaving Oscillating Water Columns in Low Keulegan-Carpenter Flow Regimes“. In OCEANS 2023 - Limerick. IEEE, 2023. http://dx.doi.org/10.1109/oceanslimerick52467.2023.10244441.
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Turner, Matthew, Lu Wang, Krish Thiagarajan und Amy Robertson. „Heave Plate Hydrodynamic Coefficients for Floating Offshore Wind Turbines – A Compilation of Data“. In ASME 2023 5th International Offshore Wind Technical Conference. American Society of Mechanical Engineers, 2023. http://dx.doi.org/10.1115/iowtc2023-119414.
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Abstract The National Renewable Energy Laboratory’s OpenFAST software is utilized by academics and industry professionals alike to simulate offshore wind turbines. The software’s modeling of hydrodynamic loads on heave plates attached to these structures relies on user-specified hydrodynamic coefficients. To guide the proper selection of these coefficients and potentially develop a new functionality within OpenFAST that automatically prescribes and/or adjusts the heave-plate hydrodynamic coefficients, we review past literature to examine the dependence of the added mass, damping, and drag coefficients on various relevant nondimensional parameters, including the Keulegan-Carpenter number, the frequency parameter, and the plate thickness ratio. Existing data in the literature show strong dependence of the hydrodynamic coefficients on the Keulegan-Carpenter number. We observe consistent trends across a range of different plate geometry, plate porosity, and flow conditions. Secondary dependence of the coefficients on the frequency parameter and plate thickness ratio is also present.
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Anagnostopoulos, P., Ch Dikarou und S. A. Seitanis. „Numerical Study of Oscillatory Flow Past Four Cylinders in Square Arrangement for Pitch Ratio Equal to 4“. In ASME 2011 30th International Conference on Ocean, Offshore and Arctic Engineering. ASMEDC, 2011. http://dx.doi.org/10.1115/omae2011-49578.
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The results of a numerical study of the viscous oscillating flow around four circular cylinders are presented herein, for a constant frequency parameter, β, equal to 50, and Keulegan-Carpenter numbers, KC, ranging between 0.2 and 10. The cylinders were placed on the vertices of a square, whose two sides were perpendicular and two parallel to the oncoming flow, for a pitch ratio, P/D, equal to 4. The finite-element method was employed for the solution of the Navier-Stokes equations, in the formulation where the stream function and the vorticity are the field variables. The streamlines and the vorticity contours generated from the solution were used for the flow visualization. When the Keulegan-Carpenter number is lower than 4, the flow remains symmetrical with respect to the horizontal axis of symmetry of the solution domain and periodic at consecutive cycles. As KC increases to 4 the flow becomes aperiodic in different cycles, although symmetry with respect to the horizontal central line of the domain is preserved. For KC equal to 5 asymmetries appear intermittently in the flow, which are eventually amplified as KC increases still further. These asymmetries, in association with the aperiodicity at different cycles, lead to an almost chaotic configuration, as KC grows larger. For characteristic cases the flow pattern and the traces of the hydrodynamic forces are presented. In addition, the mean and r.m.s. values of the in-line and transverse forces and the hydrodynamic coefficients of the inline force were evaluated for the entire range of Keulegan-Carpenter numbers examined.
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Mohammad Beigi Kasvaei, M., M. H. Kazeminezhad und A. Yeganeh-Bakhtiary. „Numerical Investigation on Wave Induced Vortex Dynamics Around Cylindrical Pile With Considering Varying Keulegan-Carpenter Number“. In ASME 2017 36th International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/omae2017-61948.
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Three-dimensional numerical simulation of regular waves passing over cylindrical monopile has been conducted to investigate the vortex dynamics. To do so the rectangular wave flume and monopile is modeled on a solver, available in the open-source CFD toolkit OpenFOAM®. The solver applied RANS equations with VOF method for tracking free surface. Model validation has been done by comparison numerical results with the experimental ones and admissible agreement has been seen. Computations have been done for three cases with different pile diameters consequently for different Keulegan-Carpenter numbers (KC). The vorticity field around the pile was investigated as well as vortices by means of Q criterion. It was seen that by increasing KC number, horseshoe vortices will be formed and vortex shedding will be happened. Moreover, Bed shear stress around the pile has been extracted and it has been seen that, the bed shear stress is influenced by KC value which result of existence of horseshoe vortices and vortex shedding.
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Hover, F. S., O̸ Smogeli, J. A. Harper und M. S. Triantafyllou. „Low Damping of Cylinders Vibrating in Still Water“. In ASME 2002 21st International Conference on Offshore Mechanics and Arctic Engineering. ASMEDC, 2002. http://dx.doi.org/10.1115/omae2002-28161.
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We performed laboratory tests of a smooth rigid cylinder oscillating in still water, with L/D in the range 3.3–26.2, Keulegan-Carpenter numbers KC = 2 − 7, and β = 1000 − 6000. Within these ranges, drag coefficients are seen to increase with increasing KC, decrease with increasing β, and decrease with increasing L/D. The values, especially with high L/D, are somewhat lower than those reported by Sarpkaya.
Berichte der Organisationen zum Thema "Keulegan-Carpenter"
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Bryant, Mary, Duncan Bryant, Leigh Provost, Nia Hurst, Maya McHugh, Anna Wargula und Tori Tomiczek. Wave attenuation of coastal mangroves at a near-prototype scale. Engineer Research and Development Center (U.S.), September 2022. http://dx.doi.org/10.21079/11681/45565.
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A physical model study investigating the dissipation of wave energy by a 1:2.1 scale North American red mangrove forest was performed in a large-scale flume. The objectives were to measure the amount of wave attenuation afforded by mangroves, identify key hydrodynamic parameters influencing wave attenuation, and provide methodologies for application. Seventy-two hydrodynamic conditions, comprising irregular and regular waves, were tested. The analysis related the dissipation to three formulations that can provide estimates of wave attenuation for flood risk management projects considering mangroves: damping coefficient β, drag coefficient C𝐷, and Manning’s roughness coefficient 𝑛. The attenuation of the incident wave height through the 15.12 m long, 1:2.1 scale mangrove forest was exponential in form and varied from 13%–77%. Water depth and incident wave height strongly influenced the amount of wave attenuation. Accounting for differences in water depth using the sub-merged volume fraction resulted in a common fit of the damping coefficient as a function of relative wave height and wave steepness. The drag coefficient demonstrated a stronger relationship with the Keulegan–Carpenter number than the Reynolds number. The linear relationship between relative depth and Manning’s 𝑛 was stronger than that between Manning’s 𝑛 and either relative wave height or wave steepness.