Tesis sobre el tema "Non linear hydrodynamic"
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Bhinder, Majid. "3D non-linear numerical hydrodynamic modelling of floating wave energy converters". Ecole centrale de Nantes, 2013. http://www.theses.fr/2013ECDN0028.
Texto completoThe 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
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.
Texto completoSEAL 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.
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/.
Texto completoVan, 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.
Texto completoIncludes 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.
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.
Texto completoThe 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.
Crudu, Monica. "Étude expérimentale et numérique des joints hydrauliques". Thesis, Poitiers, 2012. http://www.theses.fr/2012POIT2283/document.
Texto completoThis 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
Cerello, Chapchap Alberto. "Unstructured MEL modelling of non linear 3D ship hydrodynamics". Thesis, University of Southampton, 2015. https://eprints.soton.ac.uk/386206/.
Texto completoBengana, Yacine. "Simulations numériques pour la prédiction de fréquences par champs moyens". Thesis, Paris Sciences et Lettres (ComUE), 2018. http://www.theses.fr/2018PSLET032.
Texto completoFluid 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
Tachil, Alexandra. "Lineare Stabilitätsanalyse selbstgravitierenderAkkretionsscheiben". [S.l. : s.n.], 2007. http://nbn-resolving.de/urn:nbn:de:bsz:16-opus-81823.
Texto completoBenali, Abdelkader. "Comportement dynamique des butées hydrodynamiques". Poitiers, 1988. http://www.theses.fr/1988POIT2011.
Texto completoDahl, Line J. C. Haakenaasen. "Octabuoy Concept and Spar Buoys: Non Linear Effects and Analysis". Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for marin teknikk, 2012. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-18491.
Texto completoDomino, Lucie. "Contrôle et manipulation d'ondes hydroélastiques". Thesis, Paris Sciences et Lettres (ComUE), 2018. http://www.theses.fr/2018PSLET020.
Texto completoThis thesis deals with waves at the surface of a liquid, and aims at controlling their propagation. We want to show universal results, valid for all waves, using model experiments. We work with hydroelastic waves, obtained with an elastic membrane that covers the liquid surface. The elastic deformation of this membrane couples with the motion of the fluid, so that we can change the propagation of the waves by modifying the properties of the elastic cover. We show that if we locally change the thickness of the elastic cover, we can deviate, reflect or focus the waves. We then periodically structure the membrane and thus unveil effects due to he periodicity and/or the nature of the objects that form the regular array. We use an ensemble of circular perforations of which we vary the diameter, the spacing and the pattern, in order to accurately control the propagation of the waves in this artificial crystal. In particular, we show that there exist band gaps for the waves. Lastly, we re-visit the Faraday instability, known in hydrodynamics, by vertically vibrating a fluid layer covered with an elastic membrane, and we show that this instability also exist for hydroelastic waves
Goh, K. H. M. "Numerical solution of quadratically non-linear boundary value problems using integral equation techniques : with applications to nozzle and wall flows /". Title page, contents and summary only, 1986. http://web4.library.adelaide.edu.au/theses/09PH/09phg614.pdf.
Texto completoHosein, Falahaty. "Enhanced fully-Lagrangian particle methods for non-linear interaction between incompressible fluid and structure". Kyoto University, 2018. http://hdl.handle.net/2433/235070.
Texto completoSrivastava, Shivank. "A Numerical Study in Prediction of Pressure on High-Speed Planing Craft during Slamming Events". ScholarWorks@UNO, 2018. https://scholarworks.uno.edu/td/2494.
Texto completoБеда, Олександр Іванович, Александр Иванович Беда y Oleksandr Ivanovych Beda. "Динамічні характеристики ротора відцентрового насоса з урахуванням особливостей гідродинамічних процесів в шпаринних ущільненнях довільної довжини". Thesis, СумДУ, 2015. http://essuir.sumdu.edu.ua/handle/123456789/41750.
Texto completoВ диссертационной работе предложена уточненная модель щелевого уплотнения с учетом спирального движения рабочей жидкости (модель щелевого уплотнения конечной длины), на основе которой разработан аналитический метод расчета возникающей в щелевом уплотнении радиальной силы. Проанализировано влияние окружных перетоков рабочей жидкости, обусловленных полем давления жидкости в щели, на величину составляющих радиальной силы в зависимости от геометрических размеров уплотнения. Построены диаграммы для безразмерных коэффициентов линеаризованных составляющих радиальной силы, которые дают возможность анализировать влияние геометрии щели на радиальную силу без дополнительных расчетов. В работе исследована нелинейность гидростатической силы, обусловленная радиальным смещением вала в щели. Показано, что данная сила имеет мягкую характеристику жесткости, что ухудшает динамические характеристики ротора. Проведены экспериментальные исследования гидростатической силы у относительно длинных щелевых уплотнениях. Сопоставление данных эксперимента и расчетов свидетельствует о хорошем совпадении результатов. Проведен анализ влияния щелевых уплотнений на критические частоты ротора центробежного насоса типа ПЭ. Расчеты показывают, насколько велико влияние щелевых уплотнений на критические частоты ротора и насколько существенно они снижаются из-за окружных перетоков рабочей жидкости в щели и угловой жесткости гидростатической силы в относительно длинном щелевом уплотнении, которым является цилиндрическая щель системы авторазгрузки.
The dissertation Project offers advanced model of the clearance seal with spiral movement of the fluid. Based on that model, author demonstrates new method to calculate radial force that arises in the seal. The work contains diagrams for dimensionless coefficients of linearized components of the radial force, which allow to analyze an influence of the geometrical shape on the radial force without additional calculus. Next, non linear hydrostatic force analysis is presented. Such forces appear due to radial dislocation of the rotor in the seal, and it is shown that such forces have low hardness’s characteristics, thus lowering dynamic characteristics of the rotor. The work presents experimental results of the nonlinear resilience force in relatively long clearance seals. Comparison of the theoretical and experimental parts proves the consistence of the model.
Meunier, Claude. "Quelques problèmes non-linéaires en hydrodynamique et en physique des plasmas : théorèmes de moyennisation et théorèmes adiabatiques". Paris 6, 1986. http://www.theses.fr/1986PA066126.
Texto completoYau, Her-Terng y 姚賀騰. "Dynamic Analysis of A Flexible Rotor Supported by Non-linear Hydrodynamic Bearings". Thesis, 1996. http://ndltd.ncl.edu.tw/handle/57712863302480388632.
Texto completoLASAPONARA, FRANCESCO. "Two-dimensional and three-dimensional non hydrostatic models for fully non-linear and dispersive hydrodynamic processes". Doctoral thesis, 2017. http://hdl.handle.net/11573/940654.
Texto completoGoh, K. H. M. (Keng Hock Mark). "Numerical solution of quadratically non-linear boundary value problems using integral equation techniques : with applications to nozzle and wall flows / by K.H.M. Goh". 1986. http://hdl.handle.net/2440/20911.
Texto completoiv, 142 leaves : ill ; 30 cm.
Title page, contents and abstract only. The complete thesis in print form is available from the University Library.
Thesis (Ph.D.)--University of Adelaide, 1987
Goh, K. H. M. (Keng Hock Mark). "Numerical solution of quadratically non-linear boundary value problems using integral equation techniques : with applications to nozzle and wall flows / by K.H.M. Goh". Thesis, 1986. http://hdl.handle.net/2440/20911.
Texto completo