Дисертації з теми "Phenomenological fluid-structure interaction model"
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TEUMA-MELAGO, Eric. "A FLUID STRUCTURE INTERACTION MODEL OF INTRACORONARY ATHEROSCLEROTIC PLAQUE RUPTURE." Doctoral diss., University of Central Florida, 2006. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/2359.
Повний текст джерелаPh.D.
Department of Mechanical, Materials and Aerospace Engineering;
Engineering and Computer Science
Mechanical Engineering
Ferria, Hakim. "Experimental Campaign on a Generic Model for Fluid-Structure Interaction Studies." Thesis, KTH, Kraft- och värmeteknologi, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-48975.
Повний текст джерелаHao, Qing. "Modeling of Flow in an In Vitro Aneurysm Model: A Fluid-Structure Interaction Approach." Scholarly Repository, 2010. http://scholarlyrepository.miami.edu/oa_dissertations/508.
Повний текст джерелаVenkataraman, Siddharth. "Analytic, Simulation and Experimental Analysis of Fluid-Pipe Systems." Thesis, KTH, MWL Marcus Wallenberg Laboratoriet, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-249996.
Повний текст джерелаEn analytisk lösning för egenfrekvenser och egenmoder för en icke-viskös fluid inuti ett tunt rörsystem är först framtagen med användning av en modbaserad modell för interaktion mellan fluid och struktur som randvillkor. Idealiserad randvillkor används för att jämföra och validera analytiska resultat med simulationer i COMSOL Multiphysics. Effekten av viskositet jämförs också med hjälp av en Newtonsk fluidmodell. Experiment genomförs med simpel rörgeometri samt fluid för att mäta acceleransen som är analyserad för till att få ut mo-der i omkretsled upp till fjärde ordningen; detta i sin tur används för att jämföra och validera de experimentella resultaten med simulering-ar. Det erhålls bra korrelation mellan de analytiska-, simulerade- samt experimentella resultaten. Undantaget för n=0 grundmoder då krävs modifikation av differentialekvationerna till att inkorporera kompressibilitetseffekter
Tenaud, Philippe. "Analyse expérimentale des mécanismes de coercitivité dans les aimants Nd-Fe-B frittés." Grenoble 1, 1988. http://www.theses.fr/1988GRE10092.
Повний текст джерелаVARELLO, ALBERTO. "Advanced higher-order one-dimensional models for fluid-structure interaction analysis." Doctoral thesis, Politecnico di Torino, 2013. http://hdl.handle.net/11583/2517517.
Повний текст джерелаMowat, Andrew Gavin Bradford. "Modelling of non-linear aeroelastic systems using a strongly coupled fluid-structure-interaction methodology." Diss., University of Pretoria, 2011. http://hdl.handle.net/2263/30521.
Повний текст джерелаDissertation (MEng)--University of Pretoria, 2011.
Mechanical and Aeronautical Engineering
unrestricted
Hosein, Falahaty. "Enhanced fully-Lagrangian particle methods for non-linear interaction between incompressible fluid and structure." Kyoto University, 2018. http://hdl.handle.net/2433/235070.
Повний текст джерелаLemmon, Jack David Jr. "Three-dimensional computational modeling of fluid-structure interaction : study of diastolic function in a thin-walled left heart model." Diss., Georgia Institute of Technology, 1998. http://hdl.handle.net/1853/15912.
Повний текст джерелаBERTAGLIA, Giulia. "1D augmented fluid-structure interaction systems with viscoelasticity: from water pipelines to blood vessels." Doctoral thesis, Università degli studi di Ferrara, 2020. http://hdl.handle.net/11392/2488143.
Повний текст джерелаOggigiorno, modelli matematici e simulazioni numeriche sono ampiamente utilizzati nell’intero campo della ricerca fluidodinamica. Essi rappresentano una potente risorsa per comprendere meglio i fenomeni e i processi e per ridurre significativamente i costi che sarebbero altrimenti necessari per la realizzazione di esperimenti di laboratorio (a volte anche per ottenere utili dati che non potrebbero essere raccolti mediante misurazioni). Attualmente esistono molte importanti industrie di sistemi idraulici che, per la corretta analisi del comportamento dei sistemi progettati, richiedono l’uso preventivo di un accurato modello matematico, in grado di descrivere l’andamento delle proprietà del fluido nelle tubazioni. D’altra parte, la disponibilità di strumenti matematici robusti ed efficienti, insieme al know-how ingegneristico nel settore della fluidodinamica, rappresenta uno strumento inestimabile per un supporto costante anche negli studi emodinamici, fornendo approcci pratici per la quantificazione delle variabili coinvolte nella fluidodinamica cardiovascolare. La corretta caratterizzazione delle interazioni tra il fluido e la parete che ne circoscrive il moto, è un aspetto fondamentale in tutti i contesti di condotte deformabili, che richiede la massima attenzione in ogni fase dello sviluppo dello schema di calcolo e della interpretazione dei risultati e nella loro applicazione a casi di interesse pratico. In questa Tesi di Dottorato vengono presentati innovativi modelli matematici in grado di prevedere il comportamento del meccanismo di interazione fluido-struttura che sta alla base della dinamica dei flussi in diverse condotte deformabili. Partendo dal settore dell’ingegneria puramente civile, con lo studio di condotte idrauliche in plastica, l’applicazione finale dello strumento proposto è legata al campo della ricerca medica, per riprodurre la meccanica del flusso sanguigno sia nelle arterie che nelle vene. A tal fine, sono stati applicati ed estesi diversi modelli viscoelastici lineari, dai più semplici ai più sofisticati, per ottenere sistemi aumentati di interazione fluido-struttura in cui l’equazione costitutiva del materiale è direttamente inserita nel sistema come equazione alle derivate parziali. Questi sistemi sono risolti ricorrendo a Metodi ai Volumi Finiti al secondo ordine che tengono conto della recente evoluzione della letteratura computazionale dei sistemi iperbolici di leggi di bilancio. I modelli sono stati ampiamente validati attraverso diversi tipi di casi test, evidenziando i vantaggi dell’utilizzo del sistema di equazioni in forma aumentata. I risultati numerici sono stati confrontati con soluzioni quasi esatte di problemi ideali dipendenti dal tempo per situazioni vicine alla realtà o con valori di riferimento ottenuti con schemi numerici adottati solitamente nello specifico campo di ricerca indagato. Inoltre, sono stati presi in considerazione confronti con dati sperimentali sia per lo scenario delle condotte idriche che per la modellazione del flusso sanguigno, ricorrendo a misurazioni in-vivo ad hoc per quest’ultimo. Sono state effettuate analisi di accuratezza ed efficienza in diversi contesti, nonché un’analisi di sensitività per quanto riguarda la parte finale del progetto, relativa ad uno studio più applicativo sull’ipertensione arteriosa.
Gao, Haotian. "POD-Galerkin based ROM for fluid flow with moving boundaries and the model adaptation in parametric space." Diss., Kansas State University, 2018. http://hdl.handle.net/2097/38776.
Повний текст джерелаDepartment of Mechanical and Nuclear Engineering
Mingjun Wei
In this study, a global Proper Orthogonal Decomposition (POD)-Galerkin based Reduced Order model (ROM) is proposed. It is extended from usual fixed-domain problems to more general fluid-solid systems with moving boundaries/interfaces. The idea of the extension is similar to the immersed boundary method in numerical simulations which uses embedded forcing terms to represent boundary motions and domain changes. This immersed boundary method allows a globally defined fixed domain including both fluid and solid, where POD-Galerkin projection can be directly applied. However, such a modified approach cannot get away with the unsteadiness of boundary terms which appear as time-dependent coefficients in the new Galerkin model. These coefficients need to be pre-computed for prescribed periodic motion, or worse, to be computed at each time step for non-prescribed (e.g. with fluid-structure interaction) or non-periodic situations. Though computational time for each unsteady coefficient is smaller than the coefficients in a typical Galerkin model, because the associated integration is only in the close neighborhood of moving boundaries. The time cost is still much higher than a typical Galerkin model with constant coefficients. This extra expense for moving-boundary treatment eventually undermines the value of using ROMs. An aggressive approach is to decompose the moving boundary/domain to orthogonal modes and derive another low-order model with fixed coefficients for boundary motion. With this domain decomposition, an approach including two coupled low-order models both with fixed coefficients is proposed. Therefore, the new global ROM with decomposed approach is more efficient. Though the model with the domain decomposition is less accurate at the boundary, it is a fair trade-off for the benefit on saving computational cost. The study further shows, however, that the most time-consuming integration in both approaches, which come from the unsteady motion, has almost negligible impact on the overall dynamics. Dropping these time-consuming terms reduces the computation cost by at least one order while having no obvious effect on model accuracy. Based on this global POD-Galerkin based ROM with forcing term, an improved ROM which can handle the parametric variation of body motions in a certain range is also presented. This study shows that these forcing terms not only represent the moving of the boundary, but also decouple the moving parameters from the computation of model coefficients. The decoupling of control parameters provides the convenience to adapt the model for the prediction on states under variation of control parameters. An improved ROM including a shit mode seems promising in model adaptation for typical problems in a fixed domain. However, the benefit from adding a shit mode to model diminishes when the method is applied to moving-boundary problems. Instead, a combined model, which integrates data from a different set of parameters to generate the POD modes, provides a stable and accurate ROM in a certain range of parametric space for moving-boundary problems. By introducing more data from a different set of parameters, the error of the new model can be further reduced. This shows that the combined model can be trained by introducing more and more information. With the idea of the combined model, the improved global ROM with forcing terms shows impressive capability to predict problems with different unknown moving parameters, and can be used in future parametric control and optimization problems.
Douglas, Steven. "Numerical Modeling of Extreme Hydrodynamic Loading and Pneumatic Long Wave Generation: Application of a Multiphase Fluid Model." Thesis, Université d'Ottawa / University of Ottawa, 2015. http://hdl.handle.net/10393/34076.
Повний текст джерелаMagal, Rithvik. "Development and validation of a mathematical model for a monotube automotive damper." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2021. http://amslaurea.unibo.it/22951/.
Повний текст джерелаNusser, Katrin [Verfasser], Stefan [Akademischer Betreuer] Becker, and Stefan [Gutachter] Becker. "Investigation of the Fluid-Structure-Acoustics Interaction on a Simplified Car Model / Katrin Nusser ; Gutachter: Stefan Becker ; Betreuer: Stefan Becker." Erlangen : Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), 2019. http://d-nb.info/1200637534/34.
Повний текст джерелаMudrich, Jaime. "Development of a Coupling Model for Fluid-Structure Interaction using the Mesh-free Finite Element Method and the Lattice Boltzmann Method." FIU Digital Commons, 2013. http://digitalcommons.fiu.edu/etd/964.
Повний текст джерелаKondratyuk, Anastasia [Verfasser], Michael [Akademischer Betreuer] Schäfer, and Suad [Akademischer Betreuer] Jakirlić. "Investigation of the Very Large Eddy Simulation Model in the Context of Fluid-Structure Interaction / Anastasia Kondratyuk ; Michael Schäfer, Suad Jakirlic." Darmstadt : Universitäts- und Landesbibliothek Darmstadt, 2017. http://d-nb.info/1135385971/34.
Повний текст джерелаCampbell, Ian 1982. "A study of coronary flow in the presence of geometric and mechanical abnormalities in a fluid-structure interaction model of the aortic valve /." Thesis, McGill University, 2007. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=111522.
Повний текст джерелаJanousek, Miroslav, and Thibault Burnotte. "A Study of a Volvo CE Articulated Hauler’s Hydraulic Tank : Validation of a Finite-Element Model Taking the Fluid-Structure Interaction into Account." Thesis, Linnéuniversitetet, Institutionen för maskinteknik (MT), 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:lnu:diva-76542.
Повний текст джерелаChin, David 1982. "Wall shear patterns of a 50% asymmetric stenosis model using photochromic molecular flow visualization." Thesis, McGill University, 2008. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=111613.
Повний текст джерелаPauthenet, Martin. "Macroscopic model and numerical simulation of elastic canopy flows." Thesis, Toulouse, INPT, 2018. http://www.theses.fr/2018INPT0072/document.
Повний текст джерелаWe study the turbulent flow of a fluid over a canopy, that we model as a deformable porous medium. This porous medium is more precisely a carpet of fibres that bend under the hydrodynamic load, hence initiating a fluid-structure coupling at the scale of a fibre's height (honami). The objective of the thesis is to develop a macroscopic model of this fluid-structure interaction in order to perform numerical simulations of this process. The volume averaging method is implemented to describe the large scales of the flow and their interaction with the deformable porous medium. An hybrid approach is followed due to the non-local nature of the solid phase; While the large scales of the flow are described within an Eulerian frame by applying the method of volume averaging, a Lagrangian approach is proposed to describe the ensemble of fibres. The interface between the free-flow and the porous medium is handle with a One-Domain- Approach, which we justify with the theoretical development of a mass- and momentum- balance at the fluid/porous interface. This hybrid model is then implemented in a parallel code written in C$++$, based on a fluid- solver available from the \openfoam CFD toolbox. Some preliminary results show the ability of this approach to simulate a honami within a reasonable computational cost. Prior to implementing a macroscopic model, insight into the small-scale is required. Two specific aspects of the small-scale are therefore studied in details; The first development deals with the inertial deviation from Darcy's law. A geometrical parameter is proposed to describe the effect of inertia on Darcy's law, depending on the shape of the microstructure of the porous medium. This topological parameter is shown to efficiently characterize inertia effects on a diversity of tested microstructures. An asymptotic filtration law is then derived from the closure problem arising from the volume averaging method, proposing a new framework to understand the relationship between the effect of inertia on the macroscopic fluid-solid force and the topology of the microstructure of the porous medium. A second research axis is then investigated. As we deal with a deformable porous medium, we study the effect of the pore-scale fluid-structure interaction on the filtration law as the flow within the pores is unsteady, inducing time-dependent fluidstresses on the solid- phase. For that purpose, we implement pore-scale numerical simulations of unsteady flows within deformable pores, focusing for this preliminary study on a model porous medium. Owing to the large displacements of the solid phase, an immersed boundary approach is implemented. Two different numerical methods are compared to apply the no-slip condition at the fluid-solid interface: a diffuse interface approach and a sharp interface approach. The objective is to find the proper method to afford acceptable computational time and a good reliability of the results. The comparison allows a cross-validation of the numerical results, as the two methods compare well for our cases. This numerical campaign shows that the pore-scale deformation has a significant impact on the pressure drop at the macroscopic scale. Some fundamental issues are then discussed, such as the size of a representative computational domain or the form of macroscopic equations to describe the momentum transport within a soft deformable porous medium
Jedouaa, Meriem. "Une méthode efficace de capture d'interface pour la simulation de suspensions d'objets rigides et de vésicules immergées dans un fluide." Thesis, Université Grenoble Alpes (ComUE), 2017. http://www.theses.fr/2017GREAM042/document.
Повний текст джерелаIn this work, we propose a method to efficiently capture an arbitrary number of fluid/solid or fluid/fluid interfaces, in a level-set framework. This technique, borrowed from image analysis, is introduced in the context of the interaction of several bodies immersed in a fluid. A configuration of the bodies in the fluid/structure domain is described by three label maps providing the first and second neighbours, and their associated distance functions. Only one level set function captures the union of all interfaces and is transported with the fluid velocity or with a global velocity field which takes into account the velocity of each structure. A multi-label fast marching method is then performed in a narrow-band around the interfaces allowing to update the label and distance functions. Within this framework, the numerical treatment of contacts between the structures is achieved by a short-range repulsive force depending on the distance between the closest bodies.The method is validated through the simulation of a dense suspension of rigid bodies immersed in an incompressible fluid. A global penalization model uses the label maps to follow the solid bodies altogether without a separate computation of each body velocity. Consequently, the method shows its efficiency when dealing with a large number of rigid bodies. We also investigate the numerical simulation of vesicle suspensions for which a computation of elastic and bending forces on membranes is required. In the present model, only one elastic and bending force is computed for the whole set of membranes according to the level set function and the label maps
Nasar, Abouzied. "Eulerian and Lagrangian smoothed particle hydrodynamics as models for the interaction of fluids and flexible structures in biomedical flows." Thesis, University of Manchester, 2016. https://www.research.manchester.ac.uk/portal/en/theses/eulerian-and-lagrangian-smoothed-particle-hydrodynamics-as-models-for-the-interaction-of-fluids-and-flexible-structures-in-biomedical-flows(507cd0db-0116-4258-81f2-8d242e8984fa).html.
Повний текст джерелаLiu, Yujie. "Contribution à la vérification et à la validation d'un modèle diphasique bifluide instationnaire." Phd thesis, Aix-Marseille Université, 2013. http://tel.archives-ouvertes.fr/tel-00864567.
Повний текст джерелаLecuyer-Le, Bris Romain. "Modélisation numérique et expérimentale de la captation d'énergie houlomotrice : application aux essais à échelle réduite en bassin." Thesis, Brest, 2022. http://theses-scd.univ-brest.fr/2022/These-2022-SML-Mecanique_genie_mecanique_mecanique_des_fluides_et_energetique-LECUYER_LE_BRIS_Romain.pdf.
Повний текст джерелаThe behaviour of wave energy converters (WEC) is non-linear and complex to model accurately, especially due to the fluid–structure interaction and the randomness of the wave. The ability of a WEC to recover some of the wave energy depends on the control strategy used and the reliability of the behaviour model. Numerical computation time must remain reasonable in order to allow real–time control. In this context, perfect fluid calculations are used to model the fluid-structure interaction at first order. This diffraction–radiation approach highlights the delay functions of the system, a detailed analysis of which has been carried out in this work and illustrated on a reference case. This thesis proposes to establish a method applicable to the modelling of any type of multi-body WEC. The formulation of the hydrodynamic forces resulting from the assumptions of perfect fluid is then supplemented with semi–empirical terms in order to take into account non–linear effects. The viscous forces represented are particularly influential in the vicinity of the motion resonances. This method also allows the integration of experimental data into the numerical model. Experimental work was therefore carried out in order to understand, quantify and integrate the effects observed experimentally for an anchored body into the numerical model. Finally, elements in favor of an experimental campaign for a two-body system are presented
El, Maani Rabii. "Étude basée sur l’optimisation fiabiliste en aérodynamique." Thesis, Rouen, INSA, 2016. http://www.theses.fr/2016ISAM0017/document.
Повний текст джерелаThe domain of the fluid-structure interaction includes the study of all phenomena presenting the coupling of the motion of a structure with the one of a fluid. The range of the phenomena being studied is very extensive, going from the study of vibrating cylinders in the flow as is the case in the nuclear industry, to vibrating structures in turbulent flows, through the free surface phenomena in reservoirs. However, the complexity of the phenomena studied is reflected by the cost of the prohibitive calculations, which leads us to look for models with the computation time would be more realistic. In this thesis, we will present different models of fluid-structure interaction and we will put forward the model adopted in our study. Reducing the model as well as the optimization of the structures will be introduced into a coupling setting. By introducing uncertainties, the reliability study as well as an optimization based reliability approach will be proposed. The different methodologies adopted will be validated numerically and experimentally compared
Remillieux, Marcel C. "Development of a Model for Predicting the Transmission of Sonic Booms into Buildings at Low Frequency." Diss., Virginia Tech, 2010. http://hdl.handle.net/10919/27543.
Повний текст джерелаPh. D.
Divaret, Lise. "U-RANS Simulation of fluid forces exerted upon an oscillating tube array." Thesis, KTH, Farkost och flyg, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-32747.
Повний текст джерелаGineau, Audrey Nathalie. "Modélisation multi-échelle de l'interaction fluide-structure dans les systèmes tubulaires." Thesis, Paris 6, 2015. http://www.theses.fr/2015PA066651/document.
Повний текст джерелаVibration of tubes arrays is a matter of safety assessments of nuclear reactor cores or steam generators. Such systems count up thousands of slender-bodies immersed in viscous flow, involving multi-physics mechanisms caused by nonlinear dynamic interactions between the fluid and the solid materials. Direct numerical simulations for predicting these phenomena could derive from continuum mechanics, but require expensive computing resources. Therefore, one alternative to the costly micro-scale simulations consists in describing the interstitial fluid dynamics at the same scale as the structures one. Such approach rely on homogenization techniques intended to model mechanics of multi-phase systems. Homogenization results in coupled governing equations for the fluid and solid dynamics, whose solution provides individual tubes displacements and average fluid fields for each periodic unit cell. An hydrodynamic force term arises from the formulation within this set of homogenized equations: it depends on the micro-scale flow in the vicinity of a given tube-wall, but needs to be estimated as a function of the macro-scale fields in order to close the homogenized problem. The fluid force estimation relies on numerical micro-scale solutions of fluid-solid interactions over a tube array of small size. The multi-scale model is assessed for arrays made up of hundreds tubes, and is compared with solutions coming from the numerical micro-scale simulations. The macro-scale solution reproduces with good agreement the averaged solution of the micro-scale simulation, indicating that the homogenization method and the hydrodynamic force closure are suitable for such tube array configurations
Pomarède, Marie. "Investigation et application des méthodes d'ordre réduit pour les calculs d'écoulements dans les faisceaux tubulaires d'échangeurs de chaleur." Thesis, La Rochelle, 2012. http://www.theses.fr/2012LAROS355/document.
Повний текст джерелаThe objective of this thesis is to study the ability of model reduction for investigations of flow-induced vibrations in heat exchangers tube bundle systems.These mechanisms are a cause of major concern because heat exchangers are key elements of nuclear power plants and on-board stoke-holds.In a first part, we give a recall on heat exchangers functioning and on vi-bratory problems to which they are prone. Then, complete calculations leaded with the CFD numerical code Code_Saturne are carried out, first for the flow around a single circular cylinder (fixed then elastically mounted) and then for the case of a tube bundle system submitted to cross-flow. Reduced-order method POD is ap-plied to the flow resolution with fixed structures. The obtained results show the efficiency of this technique for such configurations, using stabilization methods for the dynamical system resolution in the tube-bundle case.Multiphase-POD, which is a method enabling the adaptation of POD to fluid-structure interactions, is applied. Large displacements of a single cylinder elastically mounted under cross-flow, corresponding to the lock-in phenomenon,are well reproduced with this reduction technique. In the same way, large displace-ments of a confined moving tube in a bundle are shown to be faithfully recon-structed.Finally, the use of model reduction is extended to parametric studies. First,we propose to use the method which consists in projecting Navier-Stokes equations for several values of the Reynolds number on to a unique POD basis. The resultsobtained confirm the fact that POD predictability is limited to a range of parameter values. Then, a basis interpolation method, constructed using Grassmann mani-folds and allowing the construction of a POD basis from other pre-calculated basis,is applied to basic cases
Beltzung, Thibaud. "Simulation et modélisation des interactions fluide-structure en écoulements diphasiques Parallel geothermal numerical model with fractures and multi-branch wells." Thesis, Université Paris-Saclay (ComUE), 2019. http://www.theses.fr/2019SACLV052.
Повний текст джерелаSteam generators are a key component of nuclear power reactors, and an in-depth knowledge of their mechanisms is a major industrial challenge for the designer AREVA-NP and the operator EDF. Vibration of tube bundles induced by cross-flow is one of the problems encountered by the designer, thus needing to assess the vibration response to the excitation generated by the flow. The critical region is the U shape of the bundle (upper part of the steam generator), where two-phase cross-flow occurs with an important void fraction. In order to measure excitation induced by flow fluctuations on the tube bundle, some physical parameters have to be identified. For single-phase flows, it seems possible to link load on tubular structure to turbulence intensity of the flow, thanks to experimental data reduction methods together with numerical simulation methods. For two-phase flows, it is believed that forces induced on the tubes by the flow have other origins, and might be connected to dynamic contribution of each phase together with interfacial transfers. Nevertheless, relevant physical parameters which could predict the amplitude of the forces remain a subject of debate (void fraction, flow regime, etc.) and physical processes not yet fully understood. In order to study mechanical instabilities in two-phase flows, some analytic experiments a have been and continue to be conducted at CEA. These analytic experiments focuses on isolated tube or tube bundles (rigid or flexible), and on a large regime flow range (AMOVI and DIVA mockups at CEA). They aim to describe these mechanical instabilities (forces measurement on the obstacle) based upon average parameters of the flow (gas and liquid flow rates, "mean" void fraction, etc.), but also local parameters (local void fraction, bubble size, gas velocity, etc.). These measured or locally estimated parameters are used to conduct relevant nondimensionalization, both on the random excitation forces (two-phase excitation spectrum on a rigid tube) and the fluid-elastic coupling forces (single flexible tube or flexible bundle). Nonetheless, some dispersion remains on the results, physical mechanisms are not well understood, and the nondimensionalization process remains dependent on metrology. The aim of this PhD thesis is to conduct numerical simulations with front tracking in configurations close to the experiments conducted at CEA in order to expand the knowledge on phenomena leading to vibration of tube bundle in steam generators
Bosco, Elisa. "Développement d'une nouvelle méthodologie pour l'intéraction fluide structure nonlinéaire : concepts et validation." Thesis, Toulouse, ISAE, 2017. http://www.theses.fr/2017ESAE0032/document.
Повний текст джерелаAn innovative method for numerical simulating complex problems of fluid structure interaction, such as non-linear transients, characterized by good performances and high precision is presented in this manuscript. To cut down the simulation time, reduced order models are used for both the aerodynamic and structural modules. High fidelity industrial models have been used. A technique of dynamic condensation is employed to reduce the size of the finite element model while the technique of Proper Orthogonal Decomposition is used on a database of aerodynamic pressures built from CFD simulations. Structural non-linearities are reintroduced a posteriori. Different interpolation techniques such as the classic spline interpolation, interpolation on a Grassmann Manifold with more innovative methods of statistical learning have been compared. In order to validate the developed methodology a test campaign has been designed to reproduce a simplified mechanism of interaction inspired by a flap track fairing in take-off configuration. A plate whose stiffness depends on the springs at its attachment to the wind tunnel test section floor is immersed in a mixing layer. In parallel to the test activities a numerical model of the test rig has been developed. The validation of the methodology of fluid structure interaction is done through direct comparison between test data and simulation results. The testing activities have granted a deeper comprehension of the vibratory phenomenon that has led to recurrent fatigue problems on the impacted structures. The methodology is ultimately applied to an industrial problem: the load prediction on flap track fairings excited by engine exhaust
Rubio, Jose E. "Modal Characterization and Structural Dynamic Response of a Crane Fly Forewing." ScholarWorks@UNO, 2014. http://scholarworks.uno.edu/td/1941.
Повний текст джерелаBénéfice, Guillaume. "Développement d'une méthode de couplage partitionné fort en vue d'une application aux turbomachines." Thesis, Ecully, Ecole centrale de Lyon, 2015. http://www.theses.fr/2015ECDL0050/document.
Повний текст джерелаTo increase turbomachinery design, manufacturers have to comprehend complex aeroelastic phenomena involving compressors like fluid-structure interaction limit cycles of fans. The understanding and the modeling of these phenomena involve developing complex solvers coupling techniques and validating these techniques with bench tests. The bench test of the CREATE compressor is instrumented to study the coupling between aerodynamic instabilities and structure vibration, in particular on the first stage rotor, and allows to validate numerical techniques. The flow modeling upstream to the first stage with the Turb’Flow flow solver (targeting turbomachinery applications) shows that, to have accurate results, inlet limit conditions must take into account. The ingestion of non-homogeneous flow upstream to the inlet guide vane is accurately modeled. This phenomenon can appear upstream to fans and interact with structure Eigen-modes. Explicit partitioned strong coupling considered in time domain was implemented in a Turb’Flow flow solver. As there is a risk of time shift at the fluid-structure interface, careful attention should be paid to energy conservation at the interface. This conservation is crucial when displacements are large and when strong non-linear behaviors occur in both fluid and structure domains, namely shock waves, flow separations and non-linear structural damping. In parallel with coupling technique development, the three-order implicit Runge-Kutta scheme (RKI-3) was implemented and validated on a structure dynamic case (transonic turbine blade vibration) and on a case of shock waves propagation. The RKI-3 scheme allows increasing the time step of one order of magnitude with the same accuracy. There is a CPU time gain for structure dynamics simulations, but no for URANS simulations. However, the RKI-3 scheme can be to use for fluid-structure coupling simulations. The coupling technique was validated on a test case involving tube in which the shock wave impinges on a cross flow flexible panel, initially at rest. This case allows modeling an interaction between sonic flow and a panel movement with a tip clearance. Some numerical simulations were carried out with different temporal schemes. The RKI-3 scheme has no influence on results (compared with Gear and/or Newmark scheme) on the energy conservation at the fluid-structure interface. Compared to experimental results, pressure is in fairly good ix Liste des publications agreement. The analysis of numerical results highlighted that a vertical shock tube with up and down waves creates pressure fluctuation. Frequency is under predicted and amplitude is not in fairly good agreement. The panel root modeling might be questionable
Rumpler, Romain. "Efficient finite element approach for structural-acoustic applicationns including 3D modelling of sound absorbing porous materials." Phd thesis, Conservatoire national des arts et metiers - CNAM, 2012. http://tel.archives-ouvertes.fr/tel-00726915.
Повний текст джерелаRumpler, Romain. "Efficient Finite Element Approach for Structural-Acoustic Applications including 3D modelling of Sound Absorbing Porous Materials." Doctoral thesis, KTH, MWL Numerisk akustik, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-90335.
Повний текст джерелаDans le contexte de lutte contre les nuisances sonores, cette thèse porte sur le développement de méthodes de résolution efficaces par éléments finis, pour des problèmes de vibroacoustique interne avec interfaces dissipatives, dans le domaine des basses fréquences. L’étude se limite à l’utilisation de solutions passives telles que l’intégration de matériaux poreux homogènes et isotropes, modélisés par une approche fondée sur la théorie de Biot-Allard. Ces modèles étant coûteux en terme de résolution, un des objectifs de cette thèse est de proposer une approche modale pour la réduction du problème poroélastique, bien que l’adéquation d’une telle approche avec le comportement dynamique des matériaux poreux soit à démontrer.Dans un premier temps, la résolution de problèmes couplés élasto-poro-acoustiques par sous-structuration dynamique des domaines acoustiques et poreux est établie. L’approche modale originale proposée pour les milieux poroélastiques, ainsi qu’une procédure de sélection des modes significatifs, sont validées sur des exemples 1D à 3D.Une deuxième partie présente une méthode combinant l’utilisation des modèles réduits précédemment établis avec une procédure d’approximation de solution par approximants de Padé. Il est montré qu’une telle combinaison offre la possibilité d’accroître les performances de la résolution (allocation mémoire et ressources en temps de calcul).Un chapitre dédié aux applications permet d’évaluer et comparer les approches sur un problème académique 3D, mettant en valeur leurs performances encourageantes. Afin d’améliorer les méthodes établies dans cette thèse, des perspectives à ces travaux de recherche sont apportées en conclusion.
QC 20120224
FP6 Marie-Curie Smart Structures
FP7 Marie-Curie Mid-Frequency
Khalifé, Maya. "Mesure de pression non-invasive par imagerie cardiovasculaire et modélisation unidimensionnelle de l’aorte." Thesis, Paris 11, 2013. http://www.theses.fr/2013PA112325/document.
Повний текст джерелаMagnetic Resonance Imaging (MRI) is used to measure blood flow. It allows assessing not only dynamic images of the heart and the large arteries, but also functional velocity images by means of Phase Contrast. This promising technique is important for studying fluid dynamics and characterizing the arteries, especially the large systemic arteries that play a prominent role in the blood circulation. One of the parameters used for determining the cardiac function and the vascular behavior is the arterial pressure. The reference technique for measuring the aortic pressure is catheterism, but several methods combining imaging and mathematical modeling have been proposed in order to non-invasively estimate a pressure gradient. This work proposes to measure pressure in an aortic segment through a simplified 1D model using MRI measured flow and 0D model representing the peripheral vascular system as boundary conditions. To adapt the model to the aorta of a patient, a pressure law was used forming a relation between the aortic section area and pressure, based on compliance, which is linked to pulse wave velocity (PWV) estimated on MRI measured flow waves.Scan duration was optimized, as it is often a limitation during image acquisition. Velocity and acceleration sequences require a long time and may cause artifacts. Hence, they are acquired during apnea to avoid respiratory motion. However, for such acquisitions, a subject would have to hold their breath for more than 25 seconds which can pose difficulties for some patients. A technique that allows dynamic acquisition time optimization through field of view reduction was proposed and studied. The technique unfolds fold-over regions by complex difference of two images, one of which is motion encoded and the other acquired without an encoding gradient. By implementing this method, we decrease the acquisition time by more than 25%
Mansouri, Mohamed. "Etude mécano-fiabiliste et réduction du modèle des problèmes vibro-acoustiques à paramètres aléatoires." Phd thesis, INSA de Rouen, 2013. http://tel.archives-ouvertes.fr/tel-00845562.
Повний текст джерелаSpühler, Jeannette Hiromi. "Patient-Specific Finite Element Modeling of the Blood Flow in the Left Ventricle of a Human Heart." Doctoral thesis, KTH, Beräkningsvetenskap och beräkningsteknik (CST), 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-215277.
Повний текст джерелаQC 20171006
Bruckner, Michael. "Biofluid Mechanics Of Embryo Transfer." Thesis, Lyon 1, 2013. http://www.theses.fr/2013LYO10159.
Повний текст джерелаThis thesis focuses on the study of the hydrodynamic behavior of an embryo during the transfer process following the in vitro fertilization. Worldwide, one in six couples experiences infertility problems. Today, 5 millions babies are born from an in-vitro fertilization since the first one in 1978. In 2009, 1.5 millions Assisted Reproductive Technology cycles have been started, resulting in 350 000 births. The total number of cycles per year is constantly increasing (from 5 to 10 %), and the number of ART cycles is believed to reach 4 millions per year in 2020. Although the fertilization step is now fairly mastered with a 80% success rate, the final stage consisting in the embryo transfer into the uterine cavity remains a critical step, since only 25% of the cycles lead to a live birth. Even though every cycle is expensive, no specific, optimized and operator-independent protocol has been developed yet. In this thesis, we first demonstrate the interest and the feasibility of a bio-engineering approach. Indeed, although the issue of the transfer depends on numerous chemical and physiological factors, this crucial step can also be studied from a fluid mechanical point of view. This step can be divided in several sub-steps : introduction of the catheter in the intra-uterine cavity, injection of the medium fluid containing one or several embryos, and the withdrawal of the catheter. One can identify several important parameters such as fluids viscosity, injections speeds, catheter withdrawal speed, catheter loading scheme and the geometries of the uterine cavity and the catheter. In a second part, we focus on the fluid ow patterns inside the uterine cavity during the injection. The influence of the system parameters is studied thanks to a computational solving of the Navier-Stokes equations in an idealized three-dimensional uterine cavity. A study of the potential trajectories of the embryos is also conducted and confronted against the location of optimal implantation zones but also risky zones. As the outcome of these computations, we are able to propose recommendations for physicians practicing embryo transfers. In the last part of the thesis, we discuss numerical methods for the fluid{structure interaction study of embryo transfer. The embryo is indeed submitted to potentially destructive stress constraints at injection time that we are not capable of defining precisely at the scale of the uterine cavity. With the aim of developing a mechanical model for the blastocyst to determine system parameters minimizing the constraints, we present the implementation of two Eulerian numerical methods. The first one is a fluid-structure level set method in a finite volume code benefiting from an automatic mesh refinement feature. The second one addresses a phase field method based on a Discontinuous Galerkin finite element formalism
Alleau, Thibaut. "Development of a numerical platform to model the mitral valve." Thesis, Compiègne, 2021. http://www.theses.fr/2021COMP2649.
Повний текст джерелаMitral insufficiency is the first valvular disease worldwide, with a 2% prevalence. When open-heartsurgery is impossible for the patient, surgeons use percutaneous devices to help the mitral leaflets coapt. However, the only device currently available is based on the edge-to-edge mitral valve repair technique. This type of implant is not adapted for patients suffering from functional mitral insufficiency, where the ventricle is responsible for the lack of coaptation of the leaflets. This thesis aims to provide a numerical platform to help the development of a mitral valve implant adapted for those patients. Several mitral valve geometries were created from a parametric model using anatomical measurements. Finite element simulations of the mitral valve were performed using ADINA to determine the valve closure under constant pressure. Several material models were developed in large strain and large deformation to model the valve closure accurately. Pathological behaviour such as annulus dilatation and chordae rupture were modelled, and several methods were tested to implement medical devices. Fluid-structure interaction of a 2D mitral valve was obtained using an ALE description and a monolithic coupling approach. Both the systole and the diastole were reproduced and studied, and the hermetic seal of the valve was detailed. The numerical platform developed is suited to model mitral valve function and can be used to help the development of mitral implants. In addition, the parametric geometry model and the anisotropic material model will be useful to depict with realism the valve function. A 3D fluid-structure interaction of the mitral valve could be developed
Hoareau, Christophe. "Vibrations hydroélastiques de réservoirs élastiques couplés à un fluide interne incompressible à surface libre autour d’un état précontraint." Thesis, Paris, CNAM, 2019. http://www.theses.fr/2019CNAM1241/document.
Повний текст джерелаThis doctoral thesis focuses on the calculation by the finite element method of the dynamic behavior of prestressed elastic tanks containing an internal liquid with a free surface. We consider that the hydrostatic pressure exerted by the incompressible internal fluid on the flexible walls of the tank causes large displacements, thus leading to a geometric non-linear equilibrium state. The change of stiffness related to this prestressed state induces a shift in the resonance frequencies of the coupled linear vibration problem. The main objective of the work is therefore to estimate, through precise and efficient numerical approaches, the influence of geometric nonlinearities on the hydroelastic behavior of the reservoir/internal liquid system around different equilibrium configurations. The methodology developed is carried out in two stages. The first one consists in calculating the non-linear static state by a total Lagrangian finite element approach.The action of the fluid on the structure is modelled here by hydrostatic following forces. The second step is the calculation of linearized coupled vibrations. In particular, an original reduced order model is proposed to limit the calculation costs associated with the estimation of the added mass effect. Finally, various examples are proposed and compared with results from the literature (from numerical simulations or experimental tests) to show the effectiveness and validity of the different numerical approaches developed in this work
Tran, Quang Thinh. "Modélisation de la dynamique non linéaire d'un train de tiges de forage immergé dans un puits de trajectoire 3D." Thesis, Lyon, 2019. http://www.theses.fr/2019LYSEI082.
Повний текст джерелаThis research work is a part of the Labcom DrilLab, a joint laboratory between the LaMCoS UMR 5259 - INSA Lyon and the SME DrillScan, in the framework of the ANR-SME program. DrilLab’s objective is to develop the nonlinear models to simulate the dynamic behavior of drillstring for the oil extraction and geothermal exploitation. Understanding and controlling the vibratory behavior of the rotating elements improves the rate of penetration and reduces the mean time between two failures. In this thesis, the drillstring is modeled with straight Timoshenko beam finite element accounting axial-flexion and torsion -flexion couplings, drillstring-well and fluid-structure interactions. The effect of the 3D trajectory of the well causing the initial pre-loaded state of the drillstring is considered by the path calculation: the drillstring in vertical initial position is forced to correspond to the borehole axis using the co-rotational formulation. The quasi-static equilibrium position of drillstring confined in the well under the actions of gravity, weight and torque on bit, pulsed fluid and contact reactions is obtained by the iterative method Newton-Raphson. Modal analysis, Campbell's diagram, and non-linear dynamic responses are investigated from this initial equilibrium position of the drillstring in the well. The developed fluid model is adapted to the 3D curve of the drillstring and considers the eccentric annular drillstring-well clearance. Dynamic responses under different excitation sources (unbalance, harmonic, asynchronous, transient, etc.) can be obtained by solving the system of non-linear dynamic equations using the Runge-Kutta numerical scheme of order 4 with an adaptive time step to significantly reduce the calculation time. In order to follow the dynamic behavior of the entire drillstring that can actually reach a few kilometers in length, the Craig-Bampton reduction technique is implemented. Thus, the dynamic simulation speed of the proposed model in this thesis is much improved. The developed modeling has been implemented in the developed computer code DrillSim - Drilling Simulation. Finally several well configurations are simulated for predicting their nonlinear statics and dynamics responses
Kassab, Souha. "Formation de voies vibroacoustique pour la détection d'une source monopolaire dans une coque cylindrique remplie de fluide lourd : Développements numériques et expérimentaux." Thesis, Lyon, 2018. http://www.theses.fr/2018LYSEI047/document.
Повний текст джерелаThe safety of nuclear reactors represents a necessary and vital condition for the exploitation of nuclear plants with liquid-cooled cores. This safety passes by the ability to detect and anticipate the earliest stages of a water leak into sodium within the heat generator. The study detailed in this manuscript has been initiated in a framework aiming to develop nonintrusive detection techniques for sodium water chemical reactions. Its main goal is to uncover the signal of a water leak into sodium, based on the measurements of the vibratory field recorded by the means of accelerometers externally mounted on the heat generator shell. However, such a spectrum is masked by the plant general background noise, especially that generated by heavy fluid flow (i.e. sodium flow) during actual operating times of the power plant. In order to increase the signal-to-noise ratio of the leak, beamforming technique for the acceleration measurements of the mechanical system is considered. The aforementioned system is characterized by a strong non-linear coupling between the the heat generator’s cylindrical shell and the heavy fluid in motion. In particular, fluid motion and the acoustic emission of the leak seem to excite some eigen modes of the cylinder, at these same frequencies where the acoustic signature of the leak is at its highest amplitude. For the purpose of our study, a cylindrical mock-up connected by some very rigid links to a hydraulic circuit is considered. A hydrophone emission excites the mock-up from within and is being accounted for the acoustic leak. Water flows inside the cylinder at turbulent Reynolds number. An array of twenty-five accelerometers is mounted on the mock-up shell using ceramic insulators. The main goal is to combine the twenty-five signals in such a way that allows the increase of the SNR for the acoustic source while rejecting water flow noise. Two beamforming techniques are applied and compared: classical Bartlett beamforming as well as optimized beamforming for SNR maximization (Max SN
Fouchet-Incaux, Justine. "Modélisation, analyse numérique et simulations autour de la respiration." Thesis, Paris 11, 2015. http://www.theses.fr/2015PA112043.
Повний текст джерелаIn this thesis, we study the modelling of the human mecanical ventilation and the numerical analysis of linked systems. Direct simulations of air flow in the whole airways are impossible (complex geometry, unavailable meshes). Then a reduced area of interest can be considered, working with reduced geometries and artificial boundaries. One can also use reduced models, simple but realistic. If one try to make 3D numerical simulations where the fluid flow is described by the Navier-Stokes equations, various issues are raised:- If we consider that ventilation is the result of pressure drops, the associated boundary conditions are Neumann conditions. It leads to theoretical questions in terms of existence and uniqueness of solution and numerical issues in terms of scheme choice and appropriate numerical methods.- When working in a truncated domain, it may be necessary to take into account non-described phenomena with appropriate models. Here we consider 0D models. These 3D/0D couplings imply numerical instabilities that we mathematically and numerically study in this thesis.Furthermore, when we focus on forced breathing, linear usual models are invalidated by experiments. In order to observe the differences between the experimental and numerical results, it is necessary to take into account several types of non-linearities, such as deformation of the domain or the Bernoulli phenomenon. A reduced model approach is adopted in this work. Finally, we sought to validate the obtained models by comparing numerical and experimental results in the context of interdisciplinary work.Achieving model and simulate these flows allow to better understand phenomena and parameters that come into play in diseases (asthma, emphysema ...). A medium-term objective is to study the influence of helium-oxygen mixture in the aerosol deposition. In the longer term, the application of these models to pathological situations could afford to build decision support tools in the medical field (understanding of pathology, therapy optimization ...)
Abbas, Fatima. "Modélisation et simulation numérique de la déformation et la rupture de la plaque d'athérosclérose dans les artères." Thesis, Normandie, 2019. http://www.theses.fr/2019NORMLH05/document.
Повний текст джерелаThis thesis is devoted to the mathematical modeling of the blood flow in stenosed arteries due to atherosclerosis. Atherosclerosis is a complex vascular disease characterized by the build up of a plaque leading to the narrowing of the artery. It is responsible for heart attacks and strokes. Regardless of the many risk factors that have been identified- cholesterol and lipids, pressure, unhealthy diet and obesity- only mechanical and hemodynamic factors can give a precise cause of this disease. In the first part of the thesis, we introduce the three dimensional mathematical model describing the blood-wall setting. The model consists of coupling the dynamics of the blood flow given by the Navier-Stokes equations formulated in the Arbitrary Lagrangian Eulerian (ALE) framework with the elastodynamic equations describing the elasticity of the arterial wall considered as a hyperelastic material modeled by the non-linear Saint Venant-Kirchhoff model as a fluid-structure interaction (FSI) system. Theoretically, we prove local in time existence and uniqueness of solution for this system when the fluid is assumed to be an incompressible Newtonian homogeneous fluid and the structure is described by the quasi-incompressible non-linear Saint Venant-Kirchhoff model. Results are established relying on the key tool; the fixed point theorem. The second part is devoted for the numerical analysis of the FSI model. The blood is considered to be a non-Newtonian fluid whose behavior and rheological properties are described by Carreau model, while the arterial wall is a homogeneous incompressible material described by the quasi-static elastodynamic equations. Simulations are performed in the two dimensional space R^2 using the finite element method (FEM) software FreeFem++. We focus on investigating the pattern of the viscosity, the speed and the maximum shear stress. Further, we aim to locate the recirculation zones which are formed as a consequence of the existence of the stenosis. Based on these results we proceed to detect the solidification zone where the blood transits from liquid state to a jelly-like material. Next, we specify the solidified blood to be a linear elastic material that obeys Hooke's law and which is subjected to an external surface force representing the stress exerted by the blood on the solidification zone. Numerical results concerning the solidified blood are obtained by solving the linear elasticity equations using FreeFem++. Mainly, we analyze the deformation of this zone as well as the wall shear stress. These analyzed results will allow us to give our hypothesis to derive a rupture model
Fillon, Blandine. "Développement d'un outil statistique pour évaluer les charges maximales subies par l'isolation d'une cuve de méthanier au cours de sa période d'exploitation." Thesis, Poitiers, 2014. http://www.theses.fr/2014POIT2337/document.
Повний текст джерелаThis thesis focuses on statistical tools for the assessment of maxima sloshing loads in LNG tanks. According to ship features, tank cargo and sailing conditions, a sloshing phenomenon is observed inside LNG tanks. The determination of sloshing loads supported by the tank structure is derived from impact pressure measurements performed on a test rig. Pressure maxima per impact, extracted from test measurements, are investigated. Test duration is equivalent to 5 hours in full scale. This duration is not sufficient to determine pressure maxima associated with high return periods (40 years). It is necessary to use a probabilistic model in order to extrapolate pressure maxima. Usually, a Weibull model is used. As we focus on extreme values from samples, fittings are also performed with the generalized extreme value distribution and the generalized Pareto distribution using block maximum method and peaks over threshold method.The originality of this work is based on the use of an alternate measurement system which is more relevant than usual measurement system to get pressure maxima and a 480 hours measured data available for same test conditions. This provides a reference distribution for pressure maxima which is used to assess the relevance of the selected probabilistic models. Particular attention is paid to the assessment of fittings quality using statistical tests and to the quantification of uncertainties on estimated values.The provided methodology has been implemented in a software called Stat_R which makes the manipulation and the treatment of results easier
Boubehziz, Toufik. "Simulation en quasi temps réel d’une capsule sous écoulement grâce à des Modèles d’Ordre Réduit." Thesis, Compiègne, 2022. http://www.theses.fr/2022COMP2678.
Повний текст джерелаThe motion of a liquid-filled microcapsule flowing in a microchannel is a complex problem tosimulate. Two innovative reduced-order data-driven models are proposed to replace the Fluid Structure Interaction (FSI) model using a collected database from high-fidelity simulations. The objective is to replace the existing Full Order Model (FOM) with a fast-simulation model that can simulate the capsule deformation in flow at a low cost in terms of time and calculation. The first model consists in building from a space-time-parameter datacube a reduced model to simulate the deformation of the microcapsule for any admissible configuration of parameters. Time evolution of the capsule deformation is treated by identifying the nonlinear low-order manifold of the reduced variables. Then, manifold learning is applied using the Diffuse Approximation (DA) method to predict capsule deformation for a query configuration of parameters and a chosen time discretization. The second model is based on rewriting the FSI model under the form of a reduced-order dynamic system. In this latter, the spectral displacement and velocity coefficients are related through a dynamic operator to be identified. To determine this operator, we suggest the use of a dynamic mode decomposition approach. Numerical validations prove the reliability and stability of the two new models compared to the high order model. A software application has been developed to explore the capsule deformation evolution for any couple of admissible parameters
Hadžalić, Emina. "Analysis of pore pressure influence on failure mechanisms in structural systems." Thesis, Compiègne, 2019. http://www.theses.fr/2019COMP2502.
Повний текст джерелаThis thesis studies the issue of the overall safety of structures built of heterogeneous and pore-saturated materials under extreme loads in application to fluid-structure interaction problems, such as the dam-reservoir interaction. We propose a numerical model of interaction capable of predicting main tendencies and overall behavior of pore-saturated dam structure interacting with the reservoir in failure analyses of practical interest. The proposed numerical model is first presented in two-dimensional (2D) framework and later extended to three-dimensional (3D) framework. We consider the structure built of porous cohesive material. We assume that the external fluid in interaction with the structure acts as a source of pore saturation. We model the response of the pore-saturated structure with the coupled discrete beam lattice model based on Voronoi cell representation of domain with inelastic Timoshenko beam finite elements enhanced with additional kinematics in terms of embedded strong discontinuities acting as cohesive links. The coupling between the solid phase and the pore fluid is handled with Biot’s porous media theory, and Darcy’s law governing the pore fluid flow. The numerical consideration of internal coupling results with an additional pressure-type degree of freedom placed at each node of the Timoshenko beam finite element, which is later used at the fluidstructure interface. The confined conditions met for external fluid placed in the reservoir enable the modeling of external fluid motion with the acoustic wave theory. For the numerical representation of the external fluid limited to small (irrotational) motion, we choose a Lagrangian formulation and the mixed displacement/pressure based finite element approximation. The end result are the displacement and pressure degrees of freedom per node of external fluid finite elements, which allows for the issue of the fluid-structure interface to be solved in an efficient and straightforward manner by directly connecting the structure and external fluid finite elements at common nodes. As a result, all computations can be performed in a fully monolithic manner. All numerical implementations and computations are performed with the research version of the computer code FEAP (Finite Element Analysis Program). The proposed numerical models of structure, external fluid and ultimately numerical model of interaction are validated in the linear elastic regime of structure response by comparing computed results against reference values obtained either with analytical solutions or continuum models. The numerical simulations in the nonlinear regime of structure response are performed with the aim to demonstrate the proposed coupled discrete beam lattice model capabilities to capture complete macro-scale response and failure mechanisms in pore-saturated structures. Finally, the proposed numerical model of interaction ability to deal with the progressive localized failure of a dam structure built of porous cohesive material under damreservoir interaction for a particular loading program was tested. To account for the temperature effects, the thermal coupling is introduced in the numerical model of the structure
Buczkowski, Daniel. "Coupled fluid-structure interaction numerical model of the shock absorber valve." Rozprawa doktorska, 2021. https://repolis.bg.polsl.pl/dlibra/docmetadata?showContent=true&id=72843.
Повний текст джерелаBuczkowski, Daniel. "Coupled fluid-structure interaction numerical model of the shock absorber valve." Rozprawa doktorska, 2021. https://delibra.bg.polsl.pl/dlibra/docmetadata?showContent=true&id=72843.
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