Готові списки джерел за темами / Non linear hydrodynamic

Добірка наукової літератури з теми "Non linear hydrodynamic"

Автор: Grafiati
Опубліковано: 14 березня 2023

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Статті в журналах з теми "Non linear hydrodynamic"

1

Kalliadasis, Serafim. "Non-linear Mass Transfer and Hydrodynamic Stability." Chemical Engineering Journal 84, no. 3 (December 2001): 608–9. http://dx.doi.org/10.1016/s1385-8947(01)00168-1.

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2

Osipov, A. I., and A. V. Uvarov. "Non-linear hydrodynamic waves in a non-equilibrium gas." Chemical Physics Letters 145, no. 3 (April 1988): 247–50. http://dx.doi.org/10.1016/0009-2614(88)80188-x.

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3

Kristiansen, D., and O. M. Faltinsen. "Non-linear wave-induced motions of cylindrical-shaped floaters of fish farms." Proceedings of the Institution of Mechanical Engineers, Part M: Journal of Engineering for the Maritime Environment 223, no. 3 (June 12, 2009): 361–75. http://dx.doi.org/10.1243/14750902jeme147.

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This paper addresses the two-dimensional hydrodynamical problem of a floating circular cylinder in waves by means of model tests and numerical simulations. The problem is relevant for floaters of fish farms. Dedicated model tests and computational fluid dynamics (CFD)-simulations, using a presently developed numerical wave tank are presented. Large amplitude sway motion of the cylinder at a wave frequency equal to half the natural sway frequency was observed, both experimentally and numerically. This is argued to be associated with non-linear hydrodynamic effects and instabilities. Further, linear potential flow theory is shown to overpredict the sway motion at resonance of about 500 per cent compared with experiments and simulations. This discrepancy is explained to be mainly attributable to viscous damping caused by flow separation. Higher-order harmonic components of the hydrodynamic forces are significant and should be considered in fatigue life analyses of fish farms.
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4

Ande, Raghu, Stefanie Gutschmidt, and Mathieu Sellier. "Non-linear finite-amplitude oscillations of the large beam arrays oscillating in viscous fluids." Journal of Applied Physics 132, no. 17 (November 7, 2022): 174904. http://dx.doi.org/10.1063/5.0106293.

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Over the past decade, several studies have been conducted on a single and multiple oscillating thin cantilever beams in an unbounded viscous fluid. With an increase in the applications of large array oscillators in a fluid environment for fields like medicine, biology, and energy harvesting devices, it is crucial to understand the nature of the surrounding fluid dynamics. In this present study, we perform a two-dimensional computational fluid dynamics (CFD) analysis of an array of beams oscillating in an unbounded viscous fluid. The two-dimensional Navier Stokes and continuity equations are solved to investigate the hydrodynamic forces exerted on the array members from interaction with the fluid environment. A complex hydrodynamic function is proposed here to represent the distributed hydrodynamic loading experienced by the oscillating beams. Results suggest that there is an increase in viscous damping with an increase in the size of the array. In addition, the nonlinearities become dominant when an array of beams is subjected to large amplitude oscillations. The number of beams in an array determines the overall hydrodynamics and the array effect. CFD analysis can predict the non-linearities unlike boundary integral method (BIM) approach, which is limited for low amplitudes. The results from the full Navier–Stokes simulations compared favorably with results using the BIM for the time-harmonic linearized Stokes equations.
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5

Rajesh, S. R. "Weakly non-linear stability of a hydrodynamic accretion disc." Monthly Notices of the Royal Astronomical Society 414, no. 1 (March 24, 2011): 691–701. http://dx.doi.org/10.1111/j.1365-2966.2011.18435.x.

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6

Sviličić, Šimun, and Smiljko Rudan. "Modelling Manoeuvrability in the Context of Ship Collision Analysis Using Non-Linear FEM." Journal of Marine Science and Engineering 11, no. 3 (February 25, 2023): 497. http://dx.doi.org/10.3390/jmse11030497.

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Ship collisions are rare events that may have a significant impact on the safety of people, ships, and other marine structures, as well as on the environment. Because of this, they are extensively studied but events that just precede collision are often overlooked. To rationally assess collision risks and consequences, a ship’s trajectory, and consequently the velocity and collision angle, should be known. One way to achieve this is through accurate modelling of ship manoeuvrability in collision analysis using non-linear FEM (NFEM). The Abkowitz manoeuvring model is implemented in the LS-Dyna software code and is therefore coupled with FEM calculations. Hydrodynamic forces are calculated in each time step of the LS-Dyna calculation and added to the FE model continuously through calculation. The accuracy of the calculations depends on the choice of and values of hydrodynamic derivatives from the Abkowitz model. Abkowitz’s model derives hydrodynamic forces in the Taylor expansion series to provide hydrodynamic derivatives. The application of the procedure is sensitive on higher-order Taylor series members. This article reviews different sets of hydrodynamic derivatives available for the KVLCC2 ship. Each of them is incorporated into the LS-Dyna NFEM solver by a user-made Fortran subroutine, with standard Zigzag and turning manoeuvres simulated and results compared with the experimental tests. As a result, the optimal selection of hydrodynamic derivatives is determined, laying a foundation for assessing the risk of ship collision due to different ship manoeuvres prior to the collision itself.
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7

Smolec, R. "Survey of non-linear hydrodynamic models of type-II Cepheids." Monthly Notices of the Royal Astronomical Society 456, no. 4 (January 14, 2016): 3475–93. http://dx.doi.org/10.1093/mnras/stv2868.

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8

Moshchuk, N., R. A. Ibrahim, and R. Khasminskii. "Response statistics of ocean structures to non-linear hydrodynamic loading." Journal of Sound and Vibration 184, no. 4 (July 1995): 681–701. http://dx.doi.org/10.1006/jsvi.1995.0341.

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9

Abbasov, A. A., E. M. Abbasov, Sh Z. Ismayilov, and A. A. Suleymanov. "Waterflooding efficiency estimation using capacitance-resistance model with non-linear productivity index." SOCAR Proceedings, no. 3 (September 30, 2021): 45–53. http://dx.doi.org/10.5510/ogp20210300528.

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A modified Capacitive Resistive Model (CRM), with a non-linear Productivity Index (PI), has been suggested to evaluate efficiency of waterflooding in heterogeneous reservoirs. CRM model is based on continuity equation between production and injection, and has several additional advantages. The technique does not require sophisticated geological and hydrodynamics numerical simulation modeling, which would require expensive computing time and based on actual hydrodynamic data. The model adequately describes depletion process and can be used for production forecasting and waterflooding mechanism. Capacitance-resistance model with non-linear productivity index has been tested against numerical model as well as actual production data. Additionally, non-linear productivity index based CRM model was compared against the CRM model with linear productivity index function. The calculations algorithm does not require building static geological models and running dynamic simulations, nor it demands extensive computational resources and time, thanks to using production and injection history only, therefore it can be deployed easily. Keywords: waterflooding; capacitance-resistance model; non-linear productivity index; efficiency; monitoring; forecast.
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10

Dratler, D. I., and W. R. Schowalter. "Dynamic simulation of suspensions of non-Brownian hard spheres." Journal of Fluid Mechanics 325 (October 25, 1996): 53–77. http://dx.doi.org/10.1017/s0022112096008038.

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In this work, we investigate the suitability of models based solely on continuum hydrodynamics for Stokesian Dynamics simulations of sheared suspensions of non-Brownian hard spheres. The suspensions of interest consist of monolayers of uniform rigid spheres subjected to a linear shear field. Areal fractions ranged from ϕa = 0.2 to 0.6. For these suspensions, two sets of Stokesian Dynamics simulations were performed. For the first set, particle interactions were assumed to be strictly hydrodynamic in nature. These simulations are analogous to those of Brady & Bossis (1985) and Chang & Powell (1993). For the second set of simulations, particles were subjected to both hydrodynamic and short-range repulsive forces. The repulsion serves as a qualitative model of non-hydrodynamic effects important when particle separation distances are small. Results from both sets of simulations were found to be within the range of established experimental data for viscosities of suspensions. However, simulations employing the pure hydrodynamic model lead to very small separation distances between particles. These small separations give rise to particle overlaps that could not be eliminated by time-step refinement. The instantaneous number of overlaps increased with density and typically exceeded the number of particles at the highest densities considered. More critically, for very dense suspensions the simulations failed to approach a long-time asymptotic state. For simulations employing a short-range repulsive force, these problems were eliminated. The repulsion had the effect of preventing extremely small separations, thereby eliminating particle overlaps. At high concentrations, viscosities computed using the two methods are significantly different. This suggests that the dynamics of particles near contact have a significant impact on bulk properties. Furthermore, the results suggest that a critical aspect of the physics important at small particle separation distances is missing from the pure hydrodynamic model, making it unusable for computing microstructures of dense suspensions. In contrast, simulations employing a short-range repulsive force appear to produce more realistic microstructures, and can be performed even at very high densities.
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Більше джерел

Дисертації з теми "Non linear hydrodynamic"

1

Bhinder, Majid. "3D non-linear numerical hydrodynamic modelling of floating wave energy converters." Ecole centrale de Nantes, 2013. http://www.theses.fr/2013ECDN0028.

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Dans cette thèse, on cherche à quantifier l’impact des effets d’origine visqueuse sur la dynamique et la production d’énergie des systèmes houlomoteurs. A l’heure actuelle, l’état de l’art pour évaluer la production d’énergie des houlomoteurs repose sur des approches en théorie linéarisée des écoulements potentiels (codes BEM) car la CFD (Computational Fluid Dynamics) est encore trop coûteuse en terme de temps de calcul. Cependant, l’approche potentielle est limité par les hypothèses de linéarité sur laquelle elle repose. Ces limitations doivent être comprises et des améliorations apportées. En particulier, une piste d’amélioration est l’ajout de correction visqueuse via l’ajout de terme quadratique à la Morison dans l’équation du mouvement. Cette correction dépend d’un coefficient de trainée qui doit être estimé avant de pouvoir réaliser la simulation. Une possibilité est d’interpoler la valeur de ce coefficient à partir des données expérimentales que l’on peut trouver dans la littérature, ou bien utiliser la CFD. Dans ce travail, on s’est intéressé à la faisabilité de cette seconde approche. Deux houlomoteurs académiques ont été modélisés. Le premier est une bouée pilonnante de forme cylindrique, à bouchains vifs. Le second est un volet oscillant en cavalement. Des calculs CFD des efforts exercés sur ces géométries ont été réalisés dans un écoulement oscillant. L’effort mesuré est lissé conformément à la formule de Morison en utilisant la méthode des moindres carrés pour déterminer les coefficients de trainée et de masse d’eau ajoutée. Ensuite, le coefficient de trainée est implémentée dans l’équation du mouvement du houlomoteur correspondant. L’absorption d’énergie avec et sans la prise en compte des effets visqueux est alors évaluée, qui met en évidence l’importance de leur prise en compte
The impact of the viscous and vortex forces in the context of floating wave energy devices has been studied in this work. At present the state of the art tools to assess the efficiency of the WECs (Wave Energy Converters) comprise the BEM (boundary element method) codes based on the potential linear approach whereas CFD (computational fluid dynamics) is still considered to be computationally expensive. However the former has its limits regarding linearity restrictions and hence needs further inspections and improvements. A possibility for improvement is to account for viscous damping via additional Morison-like quadratic damping term. The intensity of this additional damping term depends on a coefficient which needs to be estimated prior to the calculations. One can interpolate this coefficient from the many previously published experimental results or imagine using CFD. In this study, the applicability of the latter option is investigated for WEC application. Two generic devices such as a heaving cylinder with sharp corners and a surging flap type WEC are considered. CFD computations of the forces on the buoy in an oscillatory flow are performed. This CFD-force is then fitted by the Morison’s equation using least square approach, which gives estimation of the viscous damping coefficient. This coefficient is implemented in the equation of motion of the WEC. The energy absorption with and without taking into account the viscous damping is then derived, which shows the importance of its appropriate modelling
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2

Pettersson, Johan. "Development of a non-linear hydrodynamic maneuvereing model of a diver delivery vehicle." Thesis, KTH, Marina system, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-211163.

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The SEAL Carrier is a marine hybrid craft with capacity to travel both on the surface and completely submerged with main objective to transport a group of divers. The craft is developed for transporting a unit of combat divers in and out the of area of operation where the high speed at surface and low signature when submerged are key features. In order to reduce the workload for the pilots during longer transports in submerged mode the manufacturer James Fisher Defence (JFD) has instigated two master theses with the aim to develop an automated depth control.This thesis concerns the ÿrst part in this project and describes the development of a hydrodynamic model of the craft. The main purpose of the model is to re°ect the behavior of the craft with focus on depth maneuvers so it can be used as a tool for the development of such a controller.Initially the fundamental theory that this mathematical model is established from is presented and explained. From how positions and motion of an underwater craft is expressed with well established methods the six equa-tions of motion necessary to fully describe these are derived. For estimating the external forces acting on the craft a semi-empirical approach is presented in order to obtain expressions and estimations of these. With these results a platform for the model have been established in the programming environment MATLAB/SIMULINK. With this platform as basis a procedure for manipulating the external forces in order to achieve a better repre-sentation of the real craft is presented.The developed model experiences some di˝culties to capture the motion of the real craft during maneuvers in depth. The cause for this is considered to be because of the methods used for expressing the hydrodynamic forces developed by the hull. The function of the model to serve as a tool for the development of a depth controller is still to be veriÿed and tests are planned. The developed model has a modular design that enables simple modiÿcations of the implemented theory as well as structural modiÿcations for future development and improvements.
SEAL Carrier är en marin hybridfarkost med kapacitet att färdas i både yt- och undervattensläge. Farkosten är utvecklad för att transportera en grupp attackdykare till och från arbetsområden då farkostens hastighet på ytan och låga signatur vid undervattensläge utnyttjas. För att minska arbetsbördan för piloterna vid längre transporter i undervattensläge har tillverkaren James Fisher Defence (JFD) utlyst två examensarbeten med huvudsakligt syfte att ta fram en automatiserad djuphållare.Denna avhandling berör den första delen i detta projekt och beskriver utvecklingen av en hydrodynamisk modell av farkosten. Det huvudsakliga syftet med modellen är att lyckas representera farkostens beteende så att denna modell kan användas som verktyg vid utvecklingen av en sådan djuphållare.Inledningsvis beskrivs den fundamentala teori som denna matematiska modell är etablerad utifrån. Med ut-gångspunkt i hur position och rörelser beskrivs enligt etablerade metoder för en undervattensfarkost härleds de sex rörelseekvationerna som är nödvändiga för att fullständigt uttrycka dessa. För uppskattning av de externa krafterna som verkar på farkosten beskrivs hur semi-empiriska metoder utnyttjats för att på ett e˛ektivt sätt erhålla uttryck och uppskattningar av dessa. Utifrån dessa resultat beskrivs hur en plattform för modellen ut-vecklats i programmeringsmiljön MATLAB/SIMULINK. Vidare presenteras en metod för att justera de externa krafterna för att fånga farkostens rörelsemönster i modellen.Den utvecklade modellen uppvisar vissa svårigheter att efterlikna den riktiga farkostens rörelsemönster vid djupmanövrar. Orsaken till detta anses vara metoden som utnyttjas för att modellera de hydrodynamiska skrov-krafterna. Modellens funktion som verktyg för utvecklingen av den tilltänkta djuphållaren återstår att veriÿera och tester är planerade. Den utvecklade modellen har en modulär design vilket på ett e˛ektivt sätt möjliggör enkla förändringar av den implementerade teorin samt strukturella förändringar för vidare utveckling och för-bättring.
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3

Baheti, Sanjay K. "Non-linear finite element thermo-hydrodynamic analysis of oil ring seals used in high pressure centrifugal compressors." Diss., This resource online, 1995. http://scholar.lib.vt.edu/theses/available/etd-06062008-164027/.

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4

Van, der Fort Zareer. "A numerical investigation of the linear hydrodynamic stability of Newtonian and weakly non-Newtonian channel flows as described by the Orr-Sommerfeld equation." Master's thesis, University of Cape Town, 2009. http://hdl.handle.net/11427/4940.

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Анотація:
Includes abstract.
Includes bibliographical references (leaves 106-112).
The Orr-Sommerfeld equation describes the growth of infinitesimal disturbances to laminar solutions of the Newtonaian Navier-Stokes equations. In this dissertation we consides in part idealised flows between two parallel planes of infinite extent and a finite distance apart. They are referred to as closed channel flows.
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5

Vidmar, Rodrigo. "Formulação hidrodinâmica para a equação de Schrödinger não-linear e não-local em condensados de Bose-Einstein." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2017. http://hdl.handle.net/10183/163724.

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Será explorada a versão hidrodinâmica da equação de Schrödinger não-linear e não-local, descrevendo condensados de Bose-Einstein com auto-interações de longo alcance. Tais sistemas têm despertado interesse tendo em vista a busca da realização da condensação de Bose-Einstein sem necessidade de um potencial externo confinante e nos quais as interações atômicas locais não são suficientes. Para obter a descrição hidrodinâmica, a transformação de Madelung para a função de onda será utilizada, reduzindo o problema a uma equação da continuidade e a uma equação de transporte de momentum. Esta última é similar à equação de Euler em fluidos ideais, porém contendo um potencial quântico efetivo e um termo não local, o qual advém da interação atômica. Tais equações de fluido traduzem, respectivamente, a conservação da probabilidade e do momentum total. O método hidrodinâmico permitirá o estudo de excitações elementares, entre os quais os modos de Bogoliubov, segundo uma abordagem macroscópica.
The hydrodynamic version of the Schrödinger equation nonlinear and nonlocal will be explored, describing Bose-Einstein condensates with long-range self-interactions. Such systems have aroused interest with a view to pursuing the realization of Bose-Einstein condensation without an external confining potential and in which local atomic interactions are not enough. For the hydrodynamic description, the eikonal decomposition of the wave function is used, reducing the problem to one equation of continuity and to a transport of momentum equation. The latter is similar to the Euler equation in ideal fluid but containing an effective quantum potential and a nonlocal term, which comes from the atomic interaction. Such fluid equations translate, respectively, conservation of probability and total momentum. The hydrodynamic method will allow the study of elementary excitations, including Bogoliubov modes according to a macroscopic approach.
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6

Crudu, Monica. "Étude expérimentale et numérique des joints hydrauliques." Thesis, Poitiers, 2012. http://www.theses.fr/2012POIT2283/document.

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Ce travail est une contribution à l'étude du comportement des joints en translation. Un modèle numérique, basé sur la théorie inverse, est développé pour en prédire les performances. La principale contribution consiste dans le traitement des effets hydrodynamiques liés à la région d'entrée du contact. Les résultats numériques sont ensuite validés par comparaison avec lesmesures expérimentales. Ces dernières sont obtenues sur un dispositif original, conçu et réalisé au laboratoire INOE 2000 IHP de Bucarest. Ce banc reproduit les conditions réelles de fonctionnement d'un joint hydraulique et permet de mesurer la force de frottement à pression et vitesse constantes. La comparaison des résultats numériques et expérimentaux a été effectuéepour un joint de tige en forme de "U" à des pressions de service comprises entre 4 MPa et 20 MPa et pour deux vitesses de translation. Dans un premier temps, on a idéalisé le problème en considérant que les surfaces en contact tige-joint sont lisses. Si l'épaisseur du film est supérieure à la rugosité de la tige, les résultats numériques qu'on a obtenus sont en bonne corrélation avecles résultats expérimentaux. Dans le cas contraire, le modèle doit être amélioré. Cette amélioration a été entreprise de manière originale. En effet, la théorie inverse est appliquée à la distribution de pression statique du contact obtenue à partir de la simulation par éléments finis de l'assemblage d'un joint rugueux et d'un arbre lisse. La rugosité moyenne (Ra) de la surface dujoint en contact avec la tige a été choisie égale à la rugosité moyenne mesurée du joint étudié. Les résultats ainsi obtenus améliorent sensiblement la corrélation avec les mesures e
This work is a contribution to the study of reciprocating seals behavior. A numerical model, based on the inverse hydrodynamic lubrication theory, is developed to predict their performances. The main contribution consists in the treatment of the hydrodynamic effects in the entry region of contact. The numerical results are validated by comparison with experimentalones, obtained on an original experimental device, design and conceived in the laboratory INOE 2000 IHP of Bucharest. This bench reproduces actual operating conditions of a hydraulic seal and measures the friction force at constant pressure and speed. The comparison of experimental and numerical results was carried out for a "U" type rod seal at different operating pressuresvarying from 4 MPa up to 20 MPa and for two reciprocating speeds. Initially, we idealized the problem by assuming that the surfaces in contact are smooth. The numerical results obtained are in good correlation with experimental ones if the film thickness is greater than the rod roughness. Otherwise, the model must be improved. This improvement was undertaken in an original way. The inverse lubrication theory is applied to the dry frictionless contact pressure distribution, obtained from a FEM simulation of a rough seal and a smooth rod assembly. The average roughness (Ra) of the seal surface in contact with the rod is chosen equal to the measured average roughness of the studied seal. The results obtained significantly improve the correlationwith experimental measurements. The roughness distribution on the entry region of contact appears to have an important influence on the numerical results
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7

Cerello, Chapchap Alberto. "Unstructured MEL modelling of non linear 3D ship hydrodynamics." Thesis, University of Southampton, 2015. https://eprints.soton.ac.uk/386206/.

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In the present work the investigations of non linear effects, in the context of potential flow theory, are investigated. These effects are caused by three main reasons, namely: the changes of the wetted geometry of the floating body, the water line dynamics and the fully non linear nature of the free surface boundary conditions. In order to understand the importance of tackling the non linear effects, a three dimensional frequency study of the S175 conteinership is carried out, at different Froude numbers, using linear frequency domain methods and a partly non linear time domain method. A time domain analysis, with the aid of an unstructured mixed Eulerian Lagrangian (MEL) description of the fluid flow, is implemented aiming in exploring potential low non linear effects. In this framework, the mixed boundary value problem of the Eulerian phase of the MEL scheme is tackled by means of a Boundary Element Method using constant elements (or a direct Rankine panel method). At given time step, on Neumann boundaries the impervious boundary condition is specified whereas, on Dirichlet boundaries, the potential on the free surface is prescribed. The solution of the Boundary Value problem yields the potential on the Neumann boundaries and its normal derivative on Dirichlet boundaries. In the Lagrangian phase, the free surface boundary conditions are then integrated in time. This method was used to solve the linear time domain radiation, i.e by applying linearized free surface boundary conditions on the exact free surface and solving the mixed boundary value problem on the mean undisturbed free surface, for the case of forced motions of a hemisphere and a Wigley hull. In addition, the linear time domain method is also extended to the unified hydroelastic analysis in time domain for the cases of 2 and 3 nodes bending. Results are presented for the the Wigley hull, undergoing prescribed forced oscillations for both rigid and exible mode shapes. The extension of the MEL scheme to a numerical tool capable of addressing several degrees of non linearities (from body nonlinear to fully nonlinear) is also discussed. In this context, two numerical formulations to calculate the time derivative of the velocity potential are implemented, namely: a backward finite scheme and an exact calculation based in the time harmonic property of the velocity potential. In latter case, a second boundary value problem is constructed and solved for the time derivative of the potential on Neumann boundaries and for the normal acceleration on Dirichlet boundaries. Results of both approaches are compared for the case of a sphere undergoing force oscillations in heave are compared to results obtained by other time domain methods. Moreover, after the boundary value problem is solved, a radial basis function representation of the velocity potential and free surface elevation is constructed, this approach allows for the estimation of the gradient of the velocity potential (body nonlinear and fully nonlinear simulations) and free surface steepness (fully nonlinear simulations). The results of the body non linear analysis, for large amplitude of oscillation in heave, are presented for the both the sphere and Wigley hull. For the latter, body non linear results of the coupling between heave into the first distortion mode (2-node) are also presented. The results of the fully non linear simulations are presented for the case of a sphere. An investigation of the suitability of two unstructured meshing libraries is also performed in the context of the MEL simulation scheme. Practical issues related to (re)meshing at each time step, the representation of ship like geometries, free surface evolution and numerical stability are highlighted for both libraries.
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8

Bengana, Yacine. "Simulations numériques pour la prédiction de fréquences par champs moyens." Thesis, Paris Sciences et Lettres (ComUE), 2018. http://www.theses.fr/2018PSLET032.

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Les écoulements fluides jouent un rôle important dans de nombreux phénomènes naturels ainsi que dans de nombreux secteurs industriels. On s’intéresse dans cette thèse aux écoulements instationnaires oscillants provenant d’une bifurcation de Hopf.L’écoulement affleurant une cavité carrée ouverte présente deux cycles limites séparés par un état quasi-périodique instable. Nous avons décrit en détail ce scénario au moyen de simulations numériques directes, de l’analyse de stabilité linéaire et de l’analyse de Floquet. La bifurcation de Hopf dans la geometry de Taylor-Couette donne naissance à deux solutions, les spirals (ondes progressives) et les rubans (ondes stationnaires dans la direction axiale). Nous avons découvert que la branche des rubans est suivie de deux cycles hétéroclines consécutifs avec deux états axisymétriques comme point d’ancrage.L’analyse de stabilité linéaire autour des solutions stationnaires permet d’obtenir le seuil de bifurcation. Une autre approche, est la linéarisation autour du champ moyen. Cette approche permet d’obtenir des fréquences très proches des fréquences non linéaires et montre dans la plupart des cas un taux de croissance proche de zéro. Nous avons montré que les spirales, les rubans, la cavité entrainée ainsi que l’écoulement autour d’un objet prismatique vérifient cette propriété.Dans la convection thermosolutal, la linéarisation autour du champ moyen des ondes stationnaires ne permet pas d’obtenir les fréquences non linéaires et le taux de croissance est loin d’être zéro, par contre pour les ondes progressives cette propriété est pleinement satisfaite. Nous avons étudié la validité d’un modèle auto-cohérent dans le cas de ces ondes progressives. En effet, si l’écoulement vérifie la propriété du champ moyen, ce modèle est supposé calculer le champ moyen, la fréquence nonlinear ainsi que l’amplitude. Ce modèle est constitué de l’équation gouvernant le champ moyen couplé avec l’équation linéarisé au travers le mode le plus instable et des contraintes de Reynolds. Nous avons montré que dans le cas des ondes progressives ce modèle permet de prédire la fréquence non linéaire seulement très proche du seuil. La prédiction est améliorée significativement en considérant les ordres supérieurs dans le terme des contraintes de Reynolds
Fluid flows play an important role in many natural phenomena as well as in many industrial applications. In this thesis, we are interested in oscillating flows origins from a Hopf bifurcation.The open shear-driven square cavity has two limit cycles separated by an unsteady quasi-periodic state. We have described this scenario in detail by using direct numerical simulations, linear stability analysis, and Floquet analysis. The Hopf bifurcation in Taylor-Couette flow gives rise to two solutions, spirals (traveling waves) and ribbons (standing waves in the axial direction). We discovered that the ribbons branch is followed by two consecutive heteroclinic cycles connecting two pairs of axisymmetric vortices. We studied in detail these two heteroclinic cycles.The linear stability analysis about the stationary solution is used to compute the threshold of the bifurcations. Another approach is the linearization about the mean field. This approach gives frequencies very close to that of the nonlinear system and shows in most cases a nearly zero growth rate. We have shown that spirals, ribbons, the lid-driven cavity and the flow around a prismatic object verify this property.In the thermosolutal convection, the frequencies obtained by the linearization about the mean field of the standing waves do not match the nonlinear frequencies and the growth rate is far from zero, on the other hand for the traveling waves this property is fully satisfied. We studied the validity of a self-consistent model in the case of the traveling waves. The self-consistent model consists of the mean field governing equation coupled with the linearized Navier-Stokes equation through the most unstable mode and the Reynolds stress term. This model calculates the mean field, the nonlinear frequency, and the amplitude without time integration. The self-consistent model is assumed to be valid for flows that satisfy the property of the mean field. We have shown that in this case, this model predicts the nonlinear frequency only very close to the threshold. We have improved significantly the predictions by considering higher orders in the Reynolds stress term
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Tachil, Alexandra. "Lineare Stabilitätsanalyse selbstgravitierenderAkkretionsscheiben." [S.l. : s.n.], 2007. http://nbn-resolving.de/urn:nbn:de:bsz:16-opus-81823.

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Benali, Abdelkader. "Comportement dynamique des butées hydrodynamiques." Poitiers, 1988. http://www.theses.fr/1988POIT2011.

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Книги з теми "Non linear hydrodynamic"

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Boi͡adzhiev, Khristo. Non-linear mass transfer and hydrodynamic stability. Amsterdam: Elsevier, 2000.

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Donley, M. G. Dynamic analysis of non-linear structures by the method of statistical quadratization. Berlin: Springer-Verlag, 1990.

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Non-Linear Mass Transfer and Hydrodynamic Stability. Elsevier, 2000. http://dx.doi.org/10.1016/b978-0-444-50428-9.x5000-5.

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Non-Linear Mass Transfer and Hydrodynamic Stability. Elsevier Science, 2000.

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Boyadjiev, C. B., and V. N. Babak. Non-Linear Mass Transfer and Hydrodynamic Stability. Elsevier Science & Technology Books, 2000.

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Oraevsky, V. N. Non-Linear Instabilities in Plasmas and Hydrodynamics. CRC Press LLC, 2017.

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Non-Linear Instabilities in Plasmas and Hydrodynamics. Routledge, 2017. http://dx.doi.org/10.1201/9780203745557.

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Non-Linear Instabilities in Plasmas and Hydrodynamics. CRC Press LLC, 2017.

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Oraevsky, V. N. Non-Linear Instabilities in Plasmas and Hydrodynamics. CRC Press LLC, 2017.

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Oraevsky, V. N. Non-Linear Instabilities in Plasmas and Hydrodynamics. CRC Press LLC, 2017.

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Частини книг з теми "Non linear hydrodynamic"

1

Hooft, J. P., and H. A. Quadvlieg. "Non-linear hydrodynamic hull forces derived from segmented model tests." In Marine Simulation and Ship Manoeuvrability, 399–409. London: Routledge, 2021. http://dx.doi.org/10.1201/9780203748077-50.

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Janardhanan, Sheeja, and Parameswaran Krishnankutty. "Determination of Linear and Non-linear Hydrodynamic Derivatives of a Surface Ship in Manoeuvring Using CFD Method." In Lecture Notes in Mechanical Engineering, 95–121. Singapore: Springer Singapore, 2019. http://dx.doi.org/10.1007/978-981-13-9806-3_4.

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3

Timman, R., A. J. Hermans, and G. C. Hsiao. "Irregular and Non-Linear Waves." In Water waves and ship hydrodynamics, 33–62. Dordrecht: Springer Netherlands, 1985. http://dx.doi.org/10.1007/978-94-017-3657-2_3.

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Hermans, A. J. "Irregular and Non-linear Waves." In Water Waves and Ship Hydrodynamics, 103–23. Dordrecht: Springer Netherlands, 2011. http://dx.doi.org/10.1007/978-94-007-0096-3_7.

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5

Taylor, R. Eatock. "Analysis of Non-Linear Wave-Body Interactions Using Finite Elements." In Waves and Nonlinear Processes in Hydrodynamics, 51–62. Dordrecht: Springer Netherlands, 1996. http://dx.doi.org/10.1007/978-94-009-0253-4_4.

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Pauwels, Ine S., Jeffrey Tuhtan, Johan Coeck, David Buysse, and Raf Baeyens. "Archimedes Screw—An Alternative for Safe Migration Through Turbines?" In Novel Developments for Sustainable Hydropower, 125–33. Cham: Springer International Publishing, 2022. http://dx.doi.org/10.1007/978-3-030-99138-8_11.

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AbstractFish passing downstream through hydraulic structures and turbines may risk dying or getting injured. Archimedes screw turbines are frequently considered more “fishfriendly” than conventional turbines. However, to date only a handful of studies assess the impact of Archimedes screws. Within the FIThydro project, we investigated injury and mortality on 2700 bream, roach and eel, including passive barotrauma sensors passing a large Archimedes hydrodynamic screw (10 m head, 22 m length) on three rotational speeds of 30, 40 and 48 Hz. The sensors measured total water pressure, linear acceleration, rotation rate, magnetic field intensity and absolute orientation. They indicated that passage is a chaotic event, and that barotrauma-related injury and mortality are indeed unlikely. Nonetheless, substantial mortality of fish was observed, specifically for bream (42%) and roach (18%) but not for eel (1%). No straightforward relation was found between rotational speeds and fish injury and mortality. The study indicates generally lower mortality and injury rates compared to conventional turbine types. However, fish can still get heavily injured or die, depending on the fish species. Therefore, we stress the need for further studies on Archimedes screws to identify the causes of the observed species-specific injury and mortality rates.
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Albeverio, S., Ph Blanchard, and R. Høegh-Krohn. "Reduction of non linear problems to Schrödinger or heat equations: Formation of kepler orbits, singular solutions for hydrodynamical equations." In Stochastic Aspects of Classical and Quantum Systems, 189–206. Berlin, Heidelberg: Springer Berlin Heidelberg, 1985. http://dx.doi.org/10.1007/bfb0101545.

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Kan, Jinyu, Lizheng Wang, Jialun Liu, Xuming Wang, and Bing Han. "Numerical Investigation of an Inland 64 TEU Container Vessel in Restricted Waters." In Lecture Notes in Civil Engineering, 516–28. Singapore: Springer Nature Singapore, 2023. http://dx.doi.org/10.1007/978-981-19-6138-0_45.

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AbstractCompared with sea-going ships, inland vessels mostly sail in restricted waters, which may cause resistance and ship motions to change greatly. To ensure the safety of navigation, it is of great importance to study the hydrodynamic performance of inland vessels navigating in restricted waters. A 64 Twenty-feet Equivalent Unit (TEU) container vessel is numerically simulated at different speeds and water depth draft ratios (water depth/draft = 2, 2.5, 3, 4, 5, 16). The numerical methods are firstly verified and then applied to systematic simulations. The resistance components, ship motions, and details of flow fields are calculated and analyzed. Generally, the total, frictional and residual resistance coefficients increase with a decrease of water depth as expected. However, at relatively low speeds (Fr = 0.1129 and 0.1135) of h/T = 2, 2.5, 3, the resistance components change conversely that they decrease as the water depth gets shallower. This special phenomenon may be caused by the design of the ship hull or the use of the turbulence model that may not be appropriate. The residual resistance has the same trend as the total resistance and the lines are nearly parallel, which shows that the residual resistance is dominant in the component of total resistance. The ship squat phenomenon happens but is not severe in the shallowest condition (h/T = 2). With the water depth decreasing, the wave amplitude becomes larger and the wave crests near the ship bow and stern also increase, while the troughs change slightly at different water depths.
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Boyadjiev, Chr B., and V. N. Babak. "Non-Linear Mass Transfer and Hydrodynamic Stability." In Non-Linear Mass Transfer and Hydrodynamic Stability, vi. Elsevier, 2000. http://dx.doi.org/10.1016/b978-0-444-50428-9.50012-0.

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Boyadjiev, Christo Boyanov, and Vladislav Nikolaevich Babak. "Non-Stationary Interphase Mass Transfer with Chemical Reactions." In Non-Linear Mass Transfer and Hydrodynamic Stability, 225–387. Elsevier, 2000. http://dx.doi.org/10.1016/b978-044450428-9/50005-3.

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Тези доповідей конференцій з теми "Non linear hydrodynamic"

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Szeri, Andras Z. "Non-Linear Lubricant Behavior in Concentrated Contacts." In ASME 2001 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2001. http://dx.doi.org/10.1115/imece2001/fed-24919.

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Abstract Elastohydrodynamic lubrication (EHL) is the name given to hydrodynamic lubrication when it is applied to solid surfaces of low geometric conformity (counterformal contacts) that are capable of, and are subject to, elastic deformation. In bearings relying on EHL principles, the residence time of the fluid is less than 1 ms, the pressures are up to 4 GP, the film is thin, down to 0.1 μm, and shear rates are up to 108 s−1 — under such conditions lubricants exhibit material behavior that is distinctly different from their behavior in bulk at normal temperature and pressure. In fact, without taking into account the viscosity-pressure characteristics of the liquid lubricant and the elastic deformation of the bounding solids, hydrodynamic theory is unable to explain the existence of continuous lubricant films in highly loaded gears and rolling contact bearings.
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Ko, Hyung-Jong, and George S. Dulikravich. "A Fully Non-Linear Theory of Electro-Magneto-Hydrodynamics." In ASME 1998 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 1998. http://dx.doi.org/10.1115/imece1998-0462.

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Abstract A number of analytical models exist for both electro-hydrodynamics (EHD), the study of fluid flows containing electric charges under the influence of an electric field and negligible magnetic field, and magneto-hydrodynamics (MHD), the study of fluid flows containing no free electric charges that are under the influence of a magnetic field and no electric field. At the present, there are no practical yet consistent models for the combined electro-magneto-hydrodynamic (EMHD) effects which most often occur in actual situations. This work represents an attempt to develop such a fully consistent analytical model for multi-dimensional, steady and unsteady, compressible and incompressible flows of electrically conducting fluids under the simultaneous or separate influence of externally applied and internally generated steady or unsteady electric and magnetic fields. The approach is based on the fundamental laws of continuum mechanics and thermodynamics with all assumptions clearly stated and consistently applied. The resulting second order EMHD model allows for non-linear polarization and magnetization of the medium. The new model is therefore superior to the existing EMHD models and represents a tractable set of equations suitable for detailed numerical discretization and integration.
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Dutta, Suman, M. P. Mathew, and D. Venkata Aditya. "Trajectory simulation of a ship and a submarine (using linear and non-linear hydrodynamic derivatives) using MATLAB." In OCEANS 2022 - Chennai. IEEE, 2022. http://dx.doi.org/10.1109/oceanschennai45887.2022.9775304.

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Liew, A., N. S. Feng, and E. J. Hahn. "Application of Transfer Matrices to Non-Linear Rotor Bearing Systems." In ASME 1999 Design Engineering Technical Conferences. American Society of Mechanical Engineers, 1999. http://dx.doi.org/10.1115/detc99/vib-8263.

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Abstract To obtain the steady state unbalance response of rotor bearing systems, it is common to linearise the hydrodynamic bearing forces about their static equilibrium position. Such linearisation is increasingly approximate with increasing unbalance as it ignores the possibility of typical non-linear phenomena such as sub- and super-harmonic response and multi-stable response. Even in the case of mono-stable synchronous response, the amplitudes are differently attenuated as a result of non-linear effects. This paper shows how the transfer matrix approach, traditionally applied to linear systems, can be extended to evaluate the steady state response of non-linear systems, using harmonic balance to accommodate the various response harmonics. The technique is illustrated using a hydrodynamic journal bearing and a squeeze film damper as the non linear elements.
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Heilskov, Nicolai F., and Ole Svenstrup Petersen. "Non-Linear 3D Hydrodynamics of Floating Wind Turbine Compared Against Wave Tank Tests." In ASME 2016 35th International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/omae2016-55090.

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Assessment of wave-structure interaction in terms of combined hydrodynamic stability and structural survivability is paramount in extreme wave conditions. Components of CFD methodologies needed for accurately capturing the detailed motion of a floating wind turbine (FWT) in survival sea-state is the focus of the study. Physical wave tank tests of a Tension Leg Platform (TLP) concept with four moorings are applied as a first validation, due to its simplicity from a CFD point of view. Two different codes have been objects of study, namely the open source code OpenFOAM® with a flexible mesh approach and the commercial CFD code StarCCM+ with the overset mesh method. The influence of the surface capturing algorithm (VOF method) and the two-way coupling of the six degrees-of-freedom body motion solver and the hydrodynamic solver have been identified as the crucial components in CFD simulation of the FWT. A major advantage of StarCCM+ was that it does not suffer from the same sensitivity as OpenFOAM to the fact that motion of the floating body is strongly coupled to the solution of the hydrodynamics (a stiff FSI problem) which led to instability of the numerical solution. The results obtained with StarCCM+ are comparable with the measured motion of and tension forces on the TLP in both in regular waves and irregular waves.
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Shinkarenko, Alexey, Yuri Kligerman, and Izhak Etsion. "The Effect of Laser Surface Texturing on Soft Elasto-Hydrodynamic Lubrication Considering Non-Linear Elasticity." In ASME 2008 9th Biennial Conference on Engineering Systems Design and Analysis. ASMEDC, 2008. http://dx.doi.org/10.1115/esda2008-59017.

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A non-linear theoretical model is presented to study the effect of laser surface texturing (LST) on the load carrying capacity in soft elasto-hydrodynamic lubrication (SEHL). Both geometrical and physical non-linearity of the elastomer is considered by using a logarithmic strain and the Mooney-Rivlin constitutive law, respectively. The results of the present non-linear model are compared with those of a previous linear one over a wide range of operating conditions. It is found that the two models predict the same optimum LST parameters for maximum load capacity but the non-linear model gives load capacity that is up to 10% lower than that obtained from the linear model.
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Suzuki, Takuya, and Hassan Mahfuz. "Non-Linear Modeling of Ocean Current Turbine Blades Under Large Deflection." In ASME 2016 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/imece2016-66802.

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This paper presents a non-linear modeling approach for large-scale ocean current turbine (OCT) blades. During the operation, OCT blades are subjected to a hydrodynamic load that has fluid density 800 times higher than that of air. The fluid load on OCT blades are sufficient to cause large deflection; therefore, a method that couples the blade’s deflection and the hydrodynamic load is required. For this purpose, we developed a non-linear model for turbine blades based on blade element momentum (BEM) theory. The newly developed method considers interplay between blade’s deflection and the hydrodynamic load. In addition, geometric non-linearity is also considered in the analysis, which provides a more accurate prediction of the structural response. For validation purposes, the developed method and a set of existing National Renewable Energy Laboratory (NREL) codes were used to calculate the deflection of the OCT blade. A comparison of flap-wise and edge-wise deflections given by both methods were determined and the results showed a good correlation between the two methods. This comparison was made only for small deflection since NREL codes cannot account for large deflection. In the next step, to investigate the effect of non-linearity, both linear and non-linear analyses were performed for a large-scale OCT blade where deflection was indeed large. In this study, we analyzed a flexible blade made of E-glass/epoxy composite. The difference in deflection was about 11% for the flexible blade since the fluid-structure interaction was significant as the blade deflection was large.
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Zang, J., R. Gibson, P. H. Taylor, R. Eatock Taylor, and C. Swan. "Non-Linear Wave Diffraction Around a Moored Ship." In ASME 2004 23rd International Conference on Offshore Mechanics and Arctic Engineering. ASMEDC, 2004. http://dx.doi.org/10.1115/omae2004-51589.

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The objective of this research, part of the FP5 REBASDO Programme, is to examine the effects of directional wave spreading on the nonlinear hydrodynamic loads and the wave run-up around the bow of a floating vessel (FPSO) in random seas. In this work, the non-linear wave scattering problem is solved by employing a quadratic boundary element method. An existing scheme (DIFFRACT developed in Oxford) has been extended to deal with uni-directional and directional bi-chromatic input wave systems, calculating second-order wave diffraction under regular waves and focused wave groups. The second order wave interaction with a floating vessel in a unidirectional focused wave group is presented in this paper. Comparison of numerical results and the experimental measurements conducted at Imperial College shows excellent agreement. The second-order free surface components at the bow of the ship are very significant, and cannot be neglected if one requires accurate prediction of the wave-structure interaction; otherwise a major underestimation of the wave impact on the structure could occur.
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Song, Jiajun, Ossama Abdelkhalik, and Shangyan Zou. "Genetic Optimization of Shape and Control of Non-Linear Wave Energy Converters." In ASME 2020 39th International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2020. http://dx.doi.org/10.1115/omae2020-19156.

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Abstract This paper presents an optimization approach to design ax-isymmetric wave energy converters (WECs) based on a nonlinear hydrodynamic model. This paper shows optimal nonlinear shapes of buoy can be generated by combing basic shapes in an optimal sense. The time domain non-linear Froude-Krylov force can be computed for a complex buoy shape, by adopting analytical formulas of its basic shape components. The time domain Forude-Krylov force is decomposed into its dynamic and static components, and then contribute to the calculation of the excitation force and the hydrostatic force. A non-linear control is assumed in the form of the combination of linear and nonlinear damping terms. A variable size genetic algorithm (GA) optimization tool is developed to search for the optimal buoy shape along with the optimal control coefficients simultaneously. Chromosome of the GA tool is designed to improve computational efficiency and to leverage variable size genes to search for the optimal non-linear buoy shape. Different criteria of wave energy conversion can be implemented by the variable size GA tool. Simulation results presented in this paper show that it is possible to find non-linear buoy shapes and non-linear controllers that take advantage of non-linear hydrodynamics to improve energy harvesting efficiency with out adding reactive terms to the system.
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Jagite, George, Hervé le Sourne, Patrice Cartraud, Šime Malenica, Fabien Bigot, Jérôme de Lauzon, and Quentin Derbanne. "A New Approach to Compute the Non-Linear Whipping Response Using Hydro-Elastoplastic Coupling." In ASME 2020 39th International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2020. http://dx.doi.org/10.1115/omae2020-18200.

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Abstract In the last ten years, the importance of whipping on the extreme hull girder loads has received much attention, but its consequence on the hull girder’s collapse is still unclear. The most common practice is to consider the structural behavior as linear-elastic in the hydro-elastic coupling, and as non-linear elasto-plastic in the ultimate strength evaluation. In order to investigate the influence of the non-linear structural behavior on the hydro-structure interaction responses, a new hydro-elastoplastic model is proposed to compute the non-linear whipping response. The structural part is modeled as two beams connected by a non-linear hinge, which follows the collapse behavior of a ship’s hull girder. The hydrodynamic problem is solved using the three-dimensional boundary element method, and the exact coupling between the structural model and the hydrodynamic one is made by making use of the shape function approach. Finally, the fully-coupled hydro-elastoplastic problem is solved directly in time-domain by numerical integration.
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Звіти організацій з теми "Non linear hydrodynamic"

1

Riveros, Guillermo, Felipe Acosta, Reena Patel, and Wayne Hodo. Computational mechanics of the paddlefish rostrum. Engineer Research and Development Center (U.S.), September 2021. http://dx.doi.org/10.21079/11681/41860.

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Purpose – The rostrum of a paddlefish provides hydrodynamic stability during feeding process in addition to detect the food using receptors that are randomly distributed in the rostrum. The exterior tissue of the rostrum covers the cartilage that surrounds the bones forming interlocking star shaped bones. Design/methodology/approach – The aim of this work is to assess the mechanical behavior of four finite element models varying the type of formulation as follows: linear-reduced integration, linear-full integration, quadratic-reduced integration and quadratic-full integration. Also presented is the load transfer mechanisms of the bone structure of the rostrum. Findings – Conclusions are based on comparison among the four models. There is no significant difference between integration orders for similar type of elements. Quadratic-reduced integration formulation resulted in lower structural stiffness compared with linear formulation as seen by higher displacements and stresses than using linearly formulated elements. It is concluded that second-order elements with reduced integration and can model accurately stress concentrations and distributions without over stiffening their general response. Originality/value – The use of advanced computational mechanics techniques to analyze the complex geometry and components of the paddlefish rostrum provides a viable avenue to gain fundamental understanding of the proper finite element formulation needed to successfully obtain the system behavior and hot spot locations.
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