Dissertations / Theses on the topic 'Fluid-solid'
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Valkov, Boris Ivanov. "A blurred interface formulation of The Reference Map Technique for Fluid-Solid Interactions and Fluid-Solid-Solid Interactions." Thesis, Massachusetts Institute of Technology, 2014. http://hdl.handle.net/1721.1/92123.
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Thesis: S.M., Massachusetts Institute of Technology, Department of Mechanical Engineering, 2014.Cataloged from PDF version of thesis.
Includes bibliographical references (pages 143-144).
In this work we present a blurred interface method for Fluid-Solid Interactions (FSI) and multiple solids immersed in a fluid or FSSI (Fluid-Solid-Solid Interactions) based on the reference map technique as presented by Kamrin and Rycroft. I will follow the chain of thought which lead from the initial sharp interface technique to the newer blurred interface one. We will present its capabilities of doing fully-coupled simulations of a compressible Navier-Stokes fluid and highly non-linear solid undergoing large deformations all performed on a single Eulerian grid with no Lagrangian particles whatsoever. The Reference Map Technique (RMT) provides an Eulerian simulation framework allowing to compute fully coupled fluid/soft-solid interactions. However, due to the extrapolations inherent to the Ghost Fluid Method (GFM) for fluid/fluid interactions, on which the RMT is based, numerical artifacts get created in the resulting pressure and velocity fields whenever the levelset defining the interface crosses a gridpoint from the fixed cartesian grid utilized in this method. We will therefore follow the creation and propagation of these artifacts as well as analyze how the blurred technique solves or avoids these problems.
by Boris Ivanov Valkov.
S.M.
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Illingworth, Justin Barrett. "Fluid-solid heat transfer coupling." Thesis, University of Sussex, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.430954.
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This thesis documents the application of a computer code developed by the author which makes possible the coupling of heat transfer between fluid and solid thermal models. The code was written using FORTRAN and couples the commercial computational fluid dynamics (CFD) software FLUENT with the Rolls-Royce finite element analysis program, SC03. The thermal modelling of a solid domain bounded by a fluid typically uses heat transfer correlations to define the heat flux at those boundaries. Considerable engineering judgement is required to appropriately select and apply these correlations, so that they accurately model the flow and geometry being considered. The objective of the coupling code is to replace the correlations with a CFD model of the fluid. The coupling is achieved by extracting metal temperatures determined from the finite element solver, using them to define CFD boundary conditions, and passing heat fluxes from the resulting CFD solution back to the finite element model. The finite element model then solves the newly defined problem and the process is repeated until a converged solution is obtained. The coupling code was evaluated through its application to two test cases. The first was an axisymmetric representation of a compressor stator well rig, the experimental apparatus or which comprised a two stage axial compressor, driven by a single stage axial turbine. The coupling code was used to model a temperature transient generated in the rig by injecting liquid nitrogen into the mainstream annulus, upstream of the compressor stages. For the second test case, an industrial application was chosen with real engine geometry. Using an axisymmetric finite element whole engine model of the Rolls-Royce Trent 500 aero-engine the code was employed to couple both axisymmetric and three dimensional representations of the fluid domain surrounding the pre-swirl system. Following the successful completion of these two test cases, the coupling code (now known as SC89) was production released by Rolls-Royce in July 2004 and is now available to their engineering community, as a design tool worldwide.
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Wang, Gerald J. (Gerald Jonathan). "Atomistic engineering of fluid Structure at the fluid-solid interface." Thesis, Massachusetts Institute of Technology, 2019. https://hdl.handle.net/1721.1/121850.
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Thesis: Ph. D. in Mechanical Engineering and Computation, Massachusetts Institute of Technology, Department of Mechanical Engineering, 2019Cataloged from PDF version of thesis.
Includes bibliographical references (pages 131-141).
Under extreme confinement, fluids exhibit a number of remarkable effects that cannot be predicted using macroscopic fluid mechanics. These phenomena are especially pronounced when the confining length scale is comparable to the fluid's internal (molecular) length scale. Elucidating the physical principles governing nanoconfined fluids is critical for many pursuits in nanoscale engineering. In this thesis, we present several theoretical and computational results on the structure and transport properties of nanoconfined fluids. We begin by discussing the phenomenon of fluid layering at a solid interface. Using molecular-mechanics principles and molecular-dynamics (MD) simulations, we develop several models to characterize density inhomogeneities in the interfacial region. Along the way, we introduce a non-dimensional number that predicts the extent of fluid layering by comparing the effects of fluid-solid interaction to thermal energy.
We also present evidence for a universal scaling relation that relates the density enhancement of layered fluid to the non-dimensional temperature, valid for dense-fluid systems. We then apply these models of fluid layering to the problem of anomalous fluid diffusion under nanoconfinement. We show that anomalous diffusion is controlled by the degree of interfacial fluid layering; in particular, layered fluid exhibits restricted diffusive dynamics, an effect whose origins can be traced to the (quasi-) two dimensionality and density enhancement of the fluid layer. We construct models for the restricted diffusivity of interfacial fluid, which enables accurate prediction of the overall diffusivity anomaly as a function of confinement length scale. Finally, we use these earlier developments to tackle the notorious problem of dense fluid slip at a solid interface.
We propose a molecular-kinetic theory that formulates slip as a series of thermally activated hops performed by interfacial fluid molecules, under the influence of the bulk fluid shear stress, within the corrugated energy landscape generated by the solid. This theory linearizes to the Navier slip condition in the limit of low shear rate, captures the central features of existing models, and demonstrates excellent agreement with MD simulation as well as experiments.
by Gerald J. Wang.
Ph. D. in Mechanical Engineering and Computation
Ph.D.inMechanicalEngineeringandComputation Massachusetts Institute of Technology, Department of Mechanical Engineering
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De, La Peña-Cortes Jesus Ernesto. "Development of fluid-solid interaction (FSI)." Thesis, University of Manchester, 2018. https://www.research.manchester.ac.uk/portal/en/theses/development-of-fluidsolid-interaction-fsi(b22b29e2-0349-44a9-ab18-eeb0717d18c8).html.
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This work extends a previously developed finite-volume overset-grid fluid flow solver to enable the characterisation of rigid-body-fluid interaction problems. To this end, several essential components have been developed and blended together. The inherent time-dependent nature of fluid-solid interaction problems is captured through the laminar transient incompressible Navier-Stokes equations for the fluid, and the Euler-Newton equations for rigid-body motion. First and second order accurate time discretisation schemes have been implemented for the former, whereas second and third order accurate time discretisation schemes have been made available for the latter. Without doubt the main advantage the overset-grid method offers regarding moving entities is the avoidance of the time consuming grid regeneration step, and the resulting grid distortion that can often cause numerical stability problems in the solution of the flow equations. Instead, body movement is achieved by the relative motion of a body fitted grid over a suitable background mesh. In this case, the governing equations of fluid flow are formulated using a Lagrangian, Eulerian, or hybrid flow description via the Arbitrary Lagrangian-Eulerian method. This entails the need to guarantee that mesh motion shall not disturb the flow field. With this in mind, the space conservation law has been hard-coded. The compliance of the space conservation law has the added benefit of preventing spurious mass sources from appearing due to mesh deformation. In this work, two-way fluid-solid interaction problems are solved via a partitioned approach. Coupling is achieved by implementing a Picard iteration algorithm. This allows for flexible degree of coupling specificationby the user. Furthermore, if strong coupling is desired, three variants of interface under-relaxation can be chosen to mitigate stability issues and to accelerate convergence. These include fixed, or two variants of Aitkenâs adaptive under-relaxation factors. The software also allows to solve for one-way fluid-solid interaction problems in which the motion of the solid is prescribed. Verification of the core individual components of the software is carried out through the powerful method of manufactured solutions (MMS). This purely mathematically based exercise provides a picture of the order of accuracy of the implementation, and serves as a filter for coding errors which can be virtually impossible to detect by other means. Three instances of one-way fluid-solid interaction cases are compared with simulation results either from the literature, or from the OpenFOAM package. These include: flow within a piston cylinder assembly, flow induced by two oscillating cylinders, and flow induced by two rectangular plates exhibiting general planar motion. Three cases pertaining to the class of two-way fluid-interaction problems are presented. The flow generated by the free fall of a cylinder under the action of gravity is computed with the aid of an intermediate âmotion trackingâ grid. The solution is compared with the one obtained using a vorticity based particle solver for validation purposes. Transverse vortex induced vibrations (VIV) of a circular cylinder immersed in a fluid, and subject to a stream are compared with experimental data. Finally, the fluttering motion of a rectangular plate under different scenarios is analysed.
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Wilkinson, E. T. "Stochastic models for certain solid classification and solid fluid separation processes." Thesis, University of Manchester, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.384086.
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Smith, Vicky S. "Solid-fluid equilibria in natural gas systems." Diss., Georgia Institute of Technology, 1995. http://hdl.handle.net/1853/10095.
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Kolumban, Jozsef. "Control issues for some fluid-solid models." Thesis, Paris Sciences et Lettres (ComUE), 2018. http://www.theses.fr/2018PSLED012/document.
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L'analyse du comportement d'un solide ou de plusieurs solides à l'intérieur d'un fluide est un problème de longue date, que l'on peut voir décrit dans de nombreux manuels classiques d'hydrodynamique. Son étude d'un point de vue mathématique a suscité une attention croissante, en particulier au cours des 15 dernières années. Ce projet de recherche vise à mettre l'accent sur plusieurs aspects de cette analyse mathématique, en particulier sur le contrôle et les problèmes asymptotiques. Un modèle simple d'évolution fluide-solide est celui d'un seul corps rigide entouré d'un fluide incompressible parfait. Le fluide est modelé par les équations d'Euler, tandis que le solide évolue selon la loi de Newton et est influencé par la pression du fluide sur la limite. L'objectif de cette thèse de doctorat consisterait en diverses études dans cette branche et, en particulier, étudierait les questions de contrôlabilité de ce système, ainsi que des modèles de limite pour les solides minces qui convergent vers une courbe. Nous souhaitons également étudier le système de contrôle Navier-Stokes / solid d'une manière similaire au problème de contrôlabilité du système Euler / solid. Une autre direction pour ce projet de doctorat est d'obtenir une limite lorsque le solide se concentre dans une courbe. Est-il possible d'obtenir un modèle simplifié d'un objet mince évoluant dans un fluide parfait, de la même manière que des modèles simplifiés ont été obtenus pour des objets qui sont petits dans toutes les directions? Cela pourrait ouvrir la voie à des recherches futures sur la dérivation des flux de cristaux liquides comme limite du système décrivant l'interaction entre le fluide et un filet de tubes solides lorsque le diamètre des tubes converge à zéroThe analysis of the behavior of a solid or several solids inside a fluid is a long-standing problem, that one can see described in many classical textbooks of hydrodynamics. Its study from a mathematical viewpoint has attracted a growing attention, in particular in the last 15 years. This research project aims at focusing on several aspect of this mathematical analysis, in particular on control and asymptotic issues. A simple model of fluid-solid evolution is that of a single rigid body surrounded by a perfect incompressible fluid. The fluid is modeled by the Euler equations, while the solid evolves according to Newton’s law, and is influenced by the fluid’s pressure on the boundary. The goal of this PhD thesis would consist in various studies in this branch, and in particular would investigate questions of controllability of this system, as well as limit models for thin solids converging to a curve. We would also like to study the Navier-Stokes/solid control system in a similar manner to the previously discussed controllability problem for the Euler/solid system. Another direction for this PhD project is to obtain a limit when the solid concentrates into a curve. Is it possible to obtain a simplified model of a thin object evolving in a perfect fluid, in the same way as simplified models were obtained for objects that are small in all directions? This could open the way to future investigations on derivation of liquid crystal flows as the limit of the system describing the interaction between the fluid and a net of solid tubes when the diameter of the tubes is converging to zero
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Obadia, Benjamin. "A multimaterial Eulerian approach for fluid-solid interaction." Thesis, Cranfield University, 2012. http://dspace.lib.cranfield.ac.uk/handle/1826/7270.
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This thesis is devoted to understanding and modeling multimaterial interactions, and to develop accordingly a robust scheme taking into account the largest variety of those, with a particular interest in resolving solid/fluid configurations. This very general frame of studies can be tackled with numerous different approaches as several issues arise and need to be addressed before attempting any modelisation of these problems. A first questioning should be the frame of reference to be used for the materials considered. Eulerian shock-capturing schemes have advantages for modeling problems involving complex non-linear wave structures and large deformations. If originally reserved mostly to fluids components, recent work has focused on extending Eulerian schemes to other media such as solid dynamics, as long as the set of equations employed is written under a hyperbolic system of conservation laws. Another matter of interest when dealing with multiple immiscible materials it the necessity to include some means of tracking material boundaries within a numerical scheme. Interface tracking methods based on the use of level set functions are an attractive alternative for problems with sliding interfaces since it allows discontinuous velocity profiles at the material boundaries whilst employing fixed grids. However, its intrinsic lack of variables conservation needs to be circumvented by applying an appropriate fix near the interface, where cells might comprise multiple components. Another requirement is the ability to correctly predict the physical interaction at the interface between the materials. For that purpose, the Riemann problem corresponding to the interfacial conditions needs to be formulated and solved. This implies in turn the need of appropriate Riemann solvers; if they are largely available when the materials are identical (i.e. governed by the same set of equations), a specific Riemann solver will be developed to account for fluid/solid interaction. Eventually, these newly developed methods will be tested on a wide range of different multimaterial problems, involving several materials undergoing large deformations. The materials used, whether modelling fluid/fluid or solid/fluid interactions, will be tested using various initial conditions from both sides of the interface, to demonstrate the robustness of the solver and its flexibility. These testcases will be carried out in 1D, 2D and 3D frames, and compared to exact solutions or other numerical experiments conducted in previous studies.
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Heneghan, Peter. "fluid -solid-chemical interactions of the nucleus pulposus." Thesis, University of Strathclyde, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.488795.
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Rogoff, Zigmund M. "Diffraction of acoustic waves at fluid-solid boundaries." Thesis, University of Nottingham, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.319952.
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Khodabakhshi, Goodarz. "Computational modelling of fluid-porous solid interaction systems." Thesis, Loughborough University, 2007. https://dspace.lboro.ac.uk/2134/35182.
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Deformation of a porous medium due to the pressure applied by an interacting fluid passing through it is a phenomenon which occurs in a number of applications such as filtration and membrane separation processes. Mathematical modelling of these systems using porous medium theory has proved to be beneficial in the design of experiments and equipments as well as gaining better insight about multi-physics phenomenon such as combined fluid flow and solid deformation regimes. In the present work the interaction of fluid and porous solid medium has been studied.
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Pouillot, Frederic. "Thermodynamic and spectroscopic investigations of solid-supercritical fluid equilibrium." Diss., Georgia Institute of Technology, 1995. http://hdl.handle.net/1853/11120.
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Dear, J. P. "The fluid mechanics of high-speed liquid/solid impact." Thesis, University of Cambridge, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.354324.
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Pitt-Francis, Joseph M. "Dynamics of solid bodies in a rotating viscous fluid." Thesis, University of Oxford, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.386716.
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Burk, Robert C. (Robert Charles) Carleton University Dissertation Chemistry. "Supercritical fluid extraction of trace organics from solid matrices." Ottawa, 1990.
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Mellema, Garfield Richard. "Subcritical acoustic scattering across a rough fluid-solid interface /." Thesis, Connect to this title online; UW restricted, 1999. http://hdl.handle.net/1773/6098.
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Pan, Kai Ph D. Massachusetts Institute of Technology. "Simulating fluid-solid interaction using smoothed particle hydrodynamics method." Thesis, Massachusetts Institute of Technology, 2017. http://hdl.handle.net/1721.1/109642.
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Thesis: Ph. D., Massachusetts Institute of Technology, Department of Civil and Environmental Engineering, 2017.Cataloged from PDF version of thesis.
Includes bibliographical references (pages 97-102).
The fluid-solid interaction (FSI) is a challenging process for numerical models since it requires accounting for the interactions of deformable materials that are governed by different equations of state. It calls for the modeling of large deformation, geometrical discontinuity, material failure, including crack propagation, and the computation of flow induced loads on evolving fluid-solid interfaces. Using particle methods with no prescribed geometric linkages allows high deformations to be dealt with easily in cases where grid-based methods would introduce difficulties. Smoothed Particle Hydrodynamics (SPH) method is one of the oldest mesh-free methods, and it has gained popularity over the last decades to simulate initially fluids and more recently solids. This dissertation is focused on developing a general numerical modeling framework based on SPH to model the coupled problem, with application to wave impact on floating offshore structures, and the hydraulic fracturing of rocks induced by fluid pressure. An accurate estimate of forces exerted by waves on offshore structures is vital to assess potential risks to structural integrity. The dissertation first explores a weakly compressible SPH method to simulate the wave impact on rigid-body floating structures. Model predictions are validated against two sets of experimental data, namely the dam-break fluid impact on a fixed structure, and the wave induced motion of a floating cube. Following validation, this framework is applied to simulation of the mipact of large waves on an offshore structure. A new numerical technique is proposed for generating multi-modal and multi-directional sea waves with SPH. The waves are generated by moving the side boundaries of the fluid domain according to the sum of Fourier modes, each with its own direction, amplitude and wave frequency. By carefully selecting the amplitudes and the frequencies, the ensemble of wave modes can be chosen to satisfy a real sea wave spectrum. The method is used to simulate an extreme wave event, with generally good agreement between the simulated waves and the recorded real-life data. The second application is the modeling of hydro-fracture initiation and propagation in rocks. A new general SPH numerical coupling method is developed to model the interaction between fluids and solids, which includes non-linear deformation and dynamic fracture initiation and propagation. A Grady-Kipp damage model is employed to model the tensile failure of the solid and a Drucker-Prager plasticity model is used to predict material shear failures. These models are coupled together so that both shear and tensile failures can be simulated within the same scheme. Fluid and solid are treated as a single system for the entire domain, and are computed using the same stress representation within a uniform SPH framework. Two new stress coupling approaches are proposed to maintain the stress continuity at the fluid-solid interface, namely, a continuum approach and stress-boundary-condition approach. A corrected form of the density continuity equation is implemented to handle the density discontinuity of the two phases at the interface. The method is validated against analytic solutions for a hydrostatic problem and for a pressurized borehole in the presence of in-situ stresses. The simulation of hydro-fracture initiation and propagation in the presence of in-situ stresses is also presented. Good results demonstrate that SPH has the potential to accurately simulate the hydraulic-fracturing phenomenon in rocks.
by Kai Pan.
Ph. D.
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Mohd, Razip Wee Farhan. "Solid-fluid interaction in a pillar based phononic crystal." Thesis, Bourgogne Franche-Comté, 2017. http://www.theses.fr/2017UBFCD055.
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Les cristaux phononiques (CP) sont des structures constituées de motifs élémentaires périodisés qui sont conçus et dimensionnés de manière à obtenir une propagation d’ondes acoustiques ou élastiques très différente de la propagation naturelle dans un matériau non structuré. C’est un moyen très efficace pour façonner la propagation des ondes acoustiques grâce notamment à la présence de bandes interdites liées à la périodicité des motifs élémentaires ou liées à leurs résonances intrinsèques. Ces mécanismes de contrôle de la propagation d’ondes constituent un énorme potentiel technologique dans diverses applications (filtre, multiplexeur, guide d’onde, résonateur et capteur). De nombreux travaux ont permis le développement de dispositifs à ondes acoustiques de surface (SAW) intégrant des CP pour le contrôle d’ondes à haute fréquence. Néanmoins, de tels dispositifs devant fonctionner en présence d’un liquide en contact avec le CP présentent des difficultés de conception liées à l’affaiblissement des ondes à l’interface solide-fluide à cause de la radiation vers le fluide des ondes à composantes hors plan. Dans le cas particulier d’un usage au titre d’un capteur, les performances d’un tel dispositif sont souvent insuffisantes.L’objectif de l’étude menée dans le cadre de cette thèse est de remédier à ce problème en utilisant les résonances localisées de cristaux phononiques constitués de piliers pour concevoir des dispositifs opérationnels en milieu liquide.Dans un premier temps, des outils numériques basés sur la méthode des éléments finis ont été développés et validés pour la modélisation de cellules élémentaires d’un CP à base de piliers. Cela nous a permis de démontrer que la présence de résonances localisées de piliers judicieusement dimensionnés permet de ralentir la vitesse de l’onde Scholte-Stoneley à l’interface solide-fluide. Les modèles de dispositifs à base de CP ont été implémentés et utilisés pour valider les résultats retenus du modèle unitaire, dans un deuxième temps. Quant à la partie expérimentale, elle nous a permis de valider la persistance en milieu liquide des bandes interdites à résonances localisées qui est attribuée au fait qu’à la résonance des piliers, l’énergie reste confinée dans ces derniers empêchant ainsi sa radiation dans le fluide. Ces résultats nous ont permis de concevoir des guides d’ondes persistantes en milieu liquide par l’intégration au sein du CP de défauts géométriques sous forme d’une chaine de piliers ayant des dimensions différentes du reste des piliers du CP.L’étude théorique a montré que les ondes guidées que l'on peut engendrer en utilisant les deux types de bandes interdites (Bragg et résonances localisées) ont des propriétés proches d’une onde de surface de Rayleigh. Les résultats obtenus dans ce travail ont permis d’élucider et d'expliciter les mécanismes à l’origine de la persistance des modes propagatifs dans les CP à résonances localisées. Cela devrait permettre d'ouvrir un champ d’investigation visant à développer des capteurs SAW phononiques pour des applications en micro-fluidique, notamment des dispositifs de type lab-on-chipPhononic crystal(PC) can be defined as an artificial structure built from periodical unit cell which could achieve interesting acoustic and elastic propagation thanks to the presence of phononic bandgap(PnBg) related to the periodicity and its intrinsic resonance of the unit cell. These mechanisms to control the wave’s propagation illustrate a huge potential that could led to several promising applications (filtering, waveguiding, resonator and sensor). Many works proposed the integration of surface acoustic wave(SAW) with PC with the purpose to manipulate the wave’s propagation at high frequency(UHF-VHF range). Nevertheless, the presence of liquid on the surface of such device induces an attenuation of the wave at the interface of solid-fluid due to the out-of-plane displacement which radiate into the fluid. For the development of such device as a sensor, its performance is usually degraded and not sufficient compared to the current state of art. The objective of this thesis is to provide a solution to the above problem through the utilization of locally-resonant mechanism in PC composed of an array of pillars to design a device which could operate in the liquid environment. First, we developed a theoretical model based on Finite Element Method (FEM) simulation for a unit cell of pillar-based structure embedded with a liquid medium. We demonstrated that local resonances of pillars with optimized dimension could decrease the phase velocity of Scholte-Stoneley wave, to produce a slow wave at the solid/fluid interface. For the experimental part, we showed the conservation of locally-resonant bandgap when the fabricated device is loaded with liquid. This conservation is attributed to the local resonance of pillars that confine the energy inside the pillar to prevent radiation of energy into the fluid. The obtained results allow us to design a waveguide persistent under liquid medium by the integration of geometrical defect in the PC in the form of a chain of pillars with a different dimension compared to the rest. Furthermore, the theoretical studies indicated also that the waveguide induced in the both type of band gap(Bragg and locally-resonant) has a close appearance as a Rayleigh SAW. The results from this study could elucidate the mechanism of the persistence of the propagation mode of locally-resonant PC. This could open a new perspective for a further investigation to develop SAW phononic especially in the in a microfluidic and lab on chip application
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Reisner, Timo T. [Verfasser], Holger [Akademischer Betreuer] Steeb, and Ioana [Akademischer Betreuer] Luca. "Fluid compressibility in a solid-fluid mixture flow / Timo T. Reisner. Gutachter: Holger Steeb ; Ioana Luca." Bochum : Ruhr-Universität Bochum, 2016. http://d-nb.info/1082425397/34.
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Nordsletten, David. "Fluid-solid coupling for the simulation of left ventricular mechanics." Thesis, University of Oxford, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.510199.
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Aharonov, Einat. "Solid-fluid interactions in porous media : processes that form rocks." Thesis, Massachusetts Institute of Technology, 1996. http://hdl.handle.net/1721.1/53026.
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Zhang, Dingan. "Solid-supercritical fluid phase equilibria of binary and ternary mixtures." Thesis, University of Ottawa (Canada), 1990. http://hdl.handle.net/10393/5611.
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Experimental investigation of phase equilibria at supercritical fluid conditions was carried out for four binary mixtures and two ternary mixtures consisting of supercritical carbon dioxide and aromatic compounds (naphthalene, biphenyl, m-terphenyl and phenanthrene). A new technique, the first freezing point method, was developed in this study to determine the pressure-temperature (P-T) projection of the solid-liquid-gas (S-L-G) three-phase coexistence curves for binary and ternary mixtures at supercritical fluid conditions. In addition, the equilibrium liquid compositions along the three-phase coexistence curves were also determined. A temperature minimum in the P-T projection of the three-phase coexistence curve was observed for each of the binary mixtures. The liquid-gas (L = G) critical loci of two binary mixtures consisting of super-critical carbon dioxide and a solid (naphthalene or biphenyl) were determined. The bubble-point pressures along three isotherms as well as the solubilities of carbon dioxide in liquid naphthalene and biphenyl were also measured. By means of the intersection method, the upper critical end points (UCEP) were established to be 333.4 K, 25.9 MPa and 0.16 mole fraction of naphthalene for naphthalene-carbon dioxide mixture and 328.5 K, 48.5 MPa and 0.18 mole fraction of biphenyl for biphenyl-carbon dioxide mixture. A "crossover region" was found in the study of isothermal solubilities of super-critical CO$\sb2$ in liquid biphenyl at a pressure of about 36 MPa. Below the crossover region pressure, an increase in temperature caused a decrease in solubility of carbon dioxide in the liquid phase, while above the crossover region pressure the opposite effect occurs. A rational explanation was given. The P-T projection of the solid 1-solid 2-liquid gas (S$\sb1$-S$\sb2$-L-G) four-phase coexistence curve of two ternary mixtures--naphthalene-biphenyl-carbon dioxide and naphthalene-phenanthrene-carbon dioxide--were determined. The results indicate that the assumption of an unchanged eutectic composition of the solids with pressure may lead to a not negligible error in the measurements. The freezing point depression of the solid under the pressure of a supercritical solvent and the solubility behaviour in the vicinity of the lower critical end point (LCEP) and the UCEP were explored and discussed. The slopes of the depression curves at the triple points of the solids were predicted. Two different approaches, based respectively on the compressed gas model (equation of state) and the expanded liquid model (activity coefficient model), were developed to describe the S-L-G three-phase equilibria and the solubilities of supercritical carbon dioxide in the melted solids. Using the Peng-Robinson equation of state with the modified correction factors, $\alpha$, together with the composition-dependent mixing rules, the correlations of the experimental results were accomplished with satisfactory accuracy. The merits of these two approaches in the representation of the S-L-G three-phase equilibria were compared.
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Zhang, Yonghao. "Particle-gas interactions in two-fluid models of gas-solid flows." Thesis, University of Aberdeen, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.367375.
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Modelling gas-solid two-phase flows using a two-fluid approach has two main difficulties: formulating constitutive laws for the particulate stresses and modelling the gas turbulence modulation. Due to the complex nature of the gas-particle interactions, there is no universal model covering every flow regime. In this thesis, three flow regimes with distinctive characteristics are studied, i.e. the very dense regime where the solid volume fraction, v2>5%, the dense flow regime where 5%≥1%, and the relatively dilute regime where 1%≥v2>0.1%. In the very dense flow regime, where the interstitial gas is normally neglected, the gas flow is assumed laminar and causes a viscous energy dissipation in the particulate phase. Numerical results for granular materials flowing down an inclined chute show that the interstitial gas may have a considerable effect in these flows. In the dense regime, where the inter-particle collisions are very important, a fluctuational energy transfer rate between the two phases is postulated, similar to that in a dilute Stokes flow. Consequently, the numerical solutions relax the restriction of elastic inter-particle collisions and show good agreement with experimental measurements. In the above two regimes, the kinetic theory of dry granular flow is adopted for the particulate stresses because the inter-particle collisions dominate the flows. The interstitial gas influence on the constitutive flow behaviour of the particulate phase is considered in the relatively dilute flow regime also, and a k-equation with a prescribed turbulent length scale is first used to address the gas turbulence modulation. Numerical results show that the gas turbulence has a significant effect on the microscopic flow behaviour of the particulate phase. The k-equation of Crowe & Gillandt (1998) has the best performance in predicting the experimentally observed phenomena. Finally, the influence of the particles on the k-Ε model coefficients are studied and the turbulent motion is considered to be restricted by the particles, thereby reducing the turbulent length scale directly. The simulation results indicate that these coefficients should be modified in order to incorporate the effect of particles.
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Denissenko, Petr Valerievich. "Asymmetric flows driven by a rotating solid in a fluid layer." Thesis, University of Hull, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.397078.
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Cook, Benjamin Koger 1965. "A numerical framework for the direct simulation of solid-fluid systems." Thesis, Massachusetts Institute of Technology, 2001. http://hdl.handle.net/1721.1/8231.
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Thesis (Sc. D.)--Massachusetts Institute of Technology, Dept. of Civil and Environmental Engineering, 2001.Includes bibliographical references (p. 129-136).
Our understanding of solid-fluid dynamics has been severely limited by the nonexistence of a high-fidelity modeling capability for these multiphase systems. Continuum modeling approaches overlook the microscale solid-fluid interactions from which macroscopic system properties emerge, while experimental inquiries have been plagued by high costs and limited resolution. One promising numerical alternative is to simulate solid-fluid systems at the grain-scale, fully resolving the interaction of individual solid particles with other solid particles and the surrounding fluid. Until recently, the direct simulation of these systems has proven computationally intractable. In this thesis an accurate, efficient, and robust modeling capability for the direct simulation of solid-fluid systems is formulated and implemented. The coupled equations of motion governing both the fluid phase and the individual particles comprising the solid phase are solved using a highly efficient numerical scheme based on the discrete-element (DEM) and the lattice-Boltzmann (LB) methods. Particle forcing mechanisms represented in the model to at least the first order include dynamic fluid-induced forces, buoyancy forces, and intergranular forces from particle collisions, static formation stresses, and intergranular bonding. Coupling is realized with an immersed moving boundary scheme that has been thoroughly validated.
(cont.) For N solid bodies under simulation, the coupled DEM-LB numerical scheme scales roughly as O(N), and is highly parallelizable due to the local and explicit nature of the underlying algorithms. The coupled method has been implemented into a generalized modeling environment for the seamless definition, simulation, and analysis of two-dimensional solid-fluid physics. Extensive numerical testing of the model has demonstrated its accuracy and robustness over a wide range of dynamical regimes. Various fundamental phenomena have been reproduced in simulations, including drafting-kissing-tumbling interactions between settling particles, and the saltating transport regime of bed erosion.
by Benjamin Koger Cook.
Sc.D.
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Yurko, James Andrew 1975. "Fluid flow behavior of semi-solid aluminum at high shear rates." Thesis, Massachusetts Institute of Technology, 2001. http://hdl.handle.net/1721.1/8451.
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Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 2001."June 2001."
Includes bibliographical references (leaves 119-127).
The rheological behavior and microstructure of semi-solid aluminum alloys were studied using a novel apparatus, the Drop Forge Viscometer (DFV). The viscometer determines force from the curvature of displacement data allowing calculations of viscosities at shear rates in excess of 1000 s-1. Alternatively, the DFV can be operated like a conventional parallel-plate compression viscometer, attaining shear rates as low as 10-5 s-1. Durations of an experiment range between approximately 5 ms and 24 hours. Most rapid compression tests resulted in periods of first rapidly increasing shear rate followed by rapidly decreasing shear rate. Viscosity during the increasing shear rate period decreased by 1-2 orders of magnitude. The viscosity during the decreasing shear rate was an order of magnitude smaller (relative to another experiment) when it achieved a 75% greater maximum shear rate. The DFV was used to calculate viscosity as a function of shear rate for Al-Si and Al-Cu alloys that were rheocast with the commercial SIMA and MHD processes, as well as the recently developed MIT method. Experiments were conducted between fractions solid of 0.44 and 0.67. Viscosity of A357 produced by the three processing routes all had similar viscosities, ranging from 300 Pas at 120 s-1 to 2.2 Pas at 1500 s-1. The final height of compressed Al-Cu was always greater than Al-Si for a given set of experimental conditions. Segregation was not observed in rapid compression experiments shorter than 10 ms, either visually or with EDS characterization. At low compression velocities, segregation was observed and increased with the amount of strain.
by James Andrew Yurko.
Ph.D.
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Gobal, Koorosh. "High-Fidelity Multidisciplinary Sensitivity Analysis for Coupled Fluid-Solid Interaction Design." Wright State University / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=wright1483614152174005.
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Behera, Narayana. "On the solutions of fluid flow and solid deformation interaction problems /." The Ohio State University, 1992. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487777901658103.
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Mindel, Julian Eduardo. "Interface Tracking and Solid-Fluid Coupling Techniques with Coastal Engineering Applications." Thesis, Imperial College London, 2008. http://hdl.handle.net/10044/1/4376.
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Multi-material physics arise in an innumerable amount of engineering problems. A broadlyscoped numerical model is developed and described in this thesis to simulate the dynamic interactionof multi-fluid and solid systems. It is particularly aimed at modelling the interactionof two immiscible fluids with solid structures in a coastal engineering context; however it canbe extended to other similar areas of research. The Navier Stokes equations governing thefluids are solved using a combination of finite element (FEM) and control volume finite element(CVFE) discretisations. The sharp interface between the fluids is obtained through thecompressive transport of material properties (e.g. material concentration). This behaviour isachieved through the CVFE method and a conveniently limited flux calculation scheme basedon the Hyper-C method by Leonard (1991). Analytical and validation test cases are provided,consisting of steady and unsteady flows. To further enhance the method, improve accuracy, andexploit Lagrangian benefits, a novel moving mesh method is also introduced and tested. It isessentially an Arbitrary Lagrangian Eulerian method in which the grid velocity is defined bysemi-explicitly solving an iterative functional minimisation problem. A multi-phase approach is used to introduce solid structure modelling. In this approach,solution of the velocity field for the fluid phase is obtained using Model B as explained byGidaspow (1994, page 151). Interaction between the fluid phase and the solids is achievedthrough the means of a source term included in the fluid momentum equations. The interactingforce is calculated through integration of this source term and adding a buoyancy contribution. The resulting force is passed to an external solid-dynamics model such as the Discrete ElementMethod (DEM), or the combined Finite Discrete Element Method (FEMDEM).The versatility and novelty of this combined modelling approach stems from its ability tocapture the fluid interaction with particles of random size and shape. Each of the three maincomponents of this thesis: the advection scheme, the moving mesh method, and the solid interactionare individually validated, and examples of randomly shaped and sized particles areshown. To conclude the work, the methods are combined together in the context of coastal engineeringapplications, where the complex coupled problem of waves impacting on breakwateramour units is chosen to demonstrate the simulation possibilities. The three components developedin this thesis significantly extend the application range of already powerful tools, suchas Fluidity, for fluids-modelling and finite discrete element solids-modelling tools by bringingthem together for the first time.
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Hajishafiee, Alireza. "Finite-volume CFD modelling of fluid-solid interaction in EHL contacts." Thesis, Imperial College London, 2013. http://hdl.handle.net/10044/1/32100.
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Classically in an elastohydrodynamic (EHD) problem, the Reynolds equation is the most widely used PDE to describe the behaviour of lubricants in high-pressure non-conforming contacts, and elastic deformation is usually calculated using the Hertzian theory of elastic contacts. This thesis outlines the development of a new method for modelling of fluid-solid interactions in elastohydrodynamic lubrication (EHL) contact based on Finite Volume (FV) techniques. A Computational Fluid Dynamics (CFD) approach to solve the Navier-Stokes equations is implemented to model lubrication in roller bearings using the open-source package OpenFOAM. This has first been applied to simulate full film hydrodynamic lubrication (HL), enabling an accurate description of the flow within the entire domain surrounding the contact region. The rheology is assumed to be non-Newtonian and shear-thinning. The phenomenon of cavitation is modelled by implementing a homogenous equilibrium cavitation model, which maintains specified lubricant saturation pressure in cavitating region. The current fluid solver involves the solution of the full momentum and energy equations, and satisfying continuity. The aim is firstly to demonstrate the range of applicability and the limitations of traditional formulations of the Reynolds equation and secondly to highlight areas where Navier-Stokes based approaches are necessary for accurate solution of lubrication problems. Subsequently, a finite volume solid solver is fully coupled with the fluid solver in a forward iterative manner to take into account elastic deflection effects using Navier-Lamé equation. The advantage of using a single numerical tool enables an internal transfer of information at the fluid-solid interface through one common data structure. The stability of the model, in the presence of high contact pressures, is enhanced by incorporation of multigrid method, implicit coupling and improved mesh adaption and motion techniques. The developed model has been applied to a series of lubricated metal on metal smooth line contact with slide to roll ratios ranging from 0 to 2 and is stable for a wide range of industrial operating conditions (pressures up to 4 GPa). The model is further improved to account for time-dependent transient behaviour of an EHL rough contact. The results for a travelling ridge, dent and sinusoidal wave through EHL conjunction are presented.
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Franci, Alessandro. "Unified Lagrangian formulation for fluid and solid mechanics, fluid-structure interaction and coupled thermal problems using the PFEM." Doctoral thesis, Universitat Politècnica de Catalunya, 2015. http://hdl.handle.net/10803/291562.
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The objective of this thesis is the derivation and implementation of a unified Finite Element formulation for the solution of uid and solid mechanics, Fluid-Structure Interaction (FSI) and coupled thermal problems.
The unified procedure is based on a stabilized velocity-pressure Lagrangian formulation. Each time step increment is solved using a two-step Gauss-Seidel scheme: first the linear momentum equations are solved for the velocity increments, next the continuity equation is solved for the pressure in the updated configuration.
The Particle Finite Element Method (PFEM) is used for the fluid domains, while the Finite Element Method (FEM) is employed for the solid ones. As a consequence, the domain is remeshed only in the parts occupied by the fluid. Linear shape functions are used for both the velocity and the pressure fields. In order to deal with the incompressibility of the materials, the formulation has been stabilized using an updated version of the Finite Calculus (FIC) method. The procedure has been
derived for quasi-incompressible Newtonian fluids. In this work, the FIC stabilization procedure has been extended also to the analysis of quasi-incompressible hypoelastic solids. Specific attention has been given to the study of free surface flow problems. In particular, the mass preservation feature of the PFEM-FIC stabilized procedure has been deeply studied with the help of several numerical examples. Furthermore, the conditioning of the problem has been analyzed in detail describing the effect of the bulk modulus on the numerical scheme. A strategy based on the use of a pseudo bulk modulus for improving
the conditioning of the linear system is also presented. The unified formulation has been validated by comparing its numerical results to experimental tests and other numerical solutions for fluid and solid mechanics, and FSI problems. The convergence of the scheme has been also analyzed for most of the problems presented. The unified formulation has been coupled with the heat tranfer problem using a staggered scheme. A simple algorithm for simulating phase change problems is also described. The numerical solution of several FSI problems involving the temperature is given. The thermal coupled scheme has been used successfully for the solution of an industrial problem. The objective of study was to analyze the damage of a nuclear power plant pressure vessel induced by a high viscous fluid at high temperature, the corium. The numerical study of this industrial problem has been included in the thesis.El objectivo de la presente tesis es la derivación e implementación de una formulación unificada con elementos finitos para la solución de problemas de mecánica de fluidos y de sólidos, interacción fluido-estructura (Fluid-Structure Interaction (FSI)) y con acoplamiento térmico. El método unificado està basado en una formulación Lagrangiana estabilizada y las variables incognitas son las velocidades y la presión. Cada paso de tiempo se soluciona a través de un esquema de dos pasos de tipo Gauss-Seidel. Primero se resuelven las ecuaciones de momento lineal por los incrementos de velocidad, luego se calculan las presiones en la configuración actualizada usando la ecuación de continuidad. Para los dominios fluidos se utiliza el método de elementos finitos de partículas (Particle Finite Element Method (PFEM)) mientras que los sólidos se solucionan con el método de elementos finitos (Finite Element Method (FEM)). Por lo tanto, se ramalla sólo las partes del dominio ocupadas por el fluido. Los campos de velocidad y presión se interpolan con funciones de forma lineales. Para poder analizar materiales incompresibles, la formulación ha sido estabilizada con una nueva versión del método Finite Calculus (FIC). La técnica de estabilización ha sido derivada para fluidos Newtonianos casi-incompresibles. En este trabajo, la estabilización con FIC se usa también para el análisis de sólidos hipoelásticos casi-incompresibles. En la tesis se dedica particular atención al estudio de flujo con superficie libre. En particular, se analiza en profundidad el tema de las pérdidas de masa y se muestra con varios ejemplos numéricos la capacidad del método de garantizar la conservación de masa en problemas de flujos en supeficie libre. Además se estudia con detalle el condicionamiento del esquema numérico analizando particularmente el efecto del módulo de compresibilidad. Se presenta también una estrategia basada en el uso de un pseudo módulo de compresibilidad para mejorar el condicionamiento del problema. La formulación unificada ha sido validada comparando sus resultados numéricos con pruebas de laboratorio y resultados numéricos de otras formulaciones. En la mayoría de los ejemplos también se ha estudiado la convergencia del método. En la tesis también se describe una estrategia segregada para el acoplamiento de la formulación unificada con el problema de transmisión de calor. Además se presenta una simple estrategia para simular el cambio de fase. El esquema acoplado ha sido utilizado para resolver varios problemas de FSI donde se incluye la temperatura y su efecto. El esquema acoplado con el problema térmico ha sido utilizado con éxito para resolver un problema industrial. El objetivo del estudio era la simulación del daño y la fusión de la vasija de un reactor nuclear provocados por el contacto con un fluido altamente viscoso y a gran temperatura. En la tesis se describe con detalle el estudio numérico realizado para esta aplicación industrial
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Price, Andrew D. "Surface anchoring of a nematic liquid crystal at solid and fluid interfaces." Connect to online resource, 2007. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:3288881.
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Micheletti, Martina. "Study of fluid velocity and mixing characteristics in stirred solid-liquid suspensions." Thesis, King's College London (University of London), 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.483567.
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Pham, Thanh Tung. "Multiscale modelling and simulation of slip boundary conditions at fluid-solid interfaces." Phd thesis, Université Paris-Est, 2013. http://tel.archives-ouvertes.fr/tel-00980155.
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In most applications concerning a fluid flowing over a solid surface, the no-slip velocity condition was widely used because it is simple and produces the results in agreement with experiments. However, this dynamical boundary condition is not appropriate when the flow under consideration is at a micro or nano length scale.In order to model this effect at the macroscopic scale, the Navier boundary conditions have been introduced, with the slip length as a parameter. When the fluid is a gas, this length is related to the tangential momentum accommodation coefficient (TMAC) and the mean free path, according to the Maxwell model. The aim of this work is to systematically address this model using a multi-scale approach and to extend it by incorporating both the morphology and the anisotropy of a surface. The thesis consists of five chapters. In Chapter 1, the basics of the kinetic theory of gases, the Boltzmann equation and related solutions (Navier-Stokes-Fourier, Burnett, Grad, Direct Simulation Monte Carlo ...) are briefly presented. The models of gas-wall interaction and slip models introduced in the fluid mechanics are also recalled. The chapter ends with a description of the computational method used for the molecular dynamics simulations performed in this work. Chapter 2 is dedicated to the development of a simple technique to simulate the pressure driven flows. The principle is to rely on the atomistic formulas of the stress tensor (Irving Kirkwood, Method of Plane, Virial Stress) and to modify the periodic conditions by maintaining the difference between the kinetic energy of the ingoing and outgoing particles of the simulation domain. Several types of channels are studied with this technique. The results (temperature, velocity ...) are discussed and compared. Chapter 3 deals with the study of the gas-wall interaction potential by the ab-initio method. The code CRYSTAL 09 is used to obtain the potential between an atom of argon (Ar) and a surface of platinum (Pt) <111> as a function of distance. Then the gas-wall potential is decomposed into binary potential and approached by an analytic function. This function is then implemented in a MD code to simulate the gas-wall collisions and determine the TMAC coefficient. In Chapter 4, the effect of morphology is studied. The multi-body Quantum Sutton Chen (QSC) potential is used for Pt <100> solid and the binary potential proposed in the previous chapter for the Ar-Pt couple is employed. The QSC potential is needed to reproduce the surface effects that affect the final results. Different surfaces are treated : smooth, nanostructured surface and, random surface obtained by Chemical vapor deposition (CVD). The TMAC is determined using a generalized approach, i.e. depending on the angle of incident flux of gas atoms on the surface. The surface anisotropy and the scattering kernel are also examined. In Chapter 5, we propose a model of anisotropic slip for fluids based on accommodation tensor. The model is obtained by the analytical approximate calculations developed in the framework of the kinetic theory. We thus generalize Maxwell's equation by showing that the slip length tensor is directly related to the accommodation tensor. The model is in good agreement with the MD results. Thanks to our MD simulations, we develop a suitable technique for reproducing the anisotropy of the accommodation tensor. The thesis ends with a conclusion section in which we suggest some perspectives for a continuation of this work
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Michelin, Sébastien Honoré Roland. "Falling, flapping, flying, swimming,... high-Re fluid-solid interactions with vortex shedding /." Diss., [La Jolla] : University of California, San Diego, 2009. http://wwwlib.umi.com/cr/ucsd/fullcit?p3369655.
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Thesis (Ph. D.)--University of California, San Diego, 2009.Title from first page of PDF file (viewed September 17, 2009). Available via ProQuest Digital Dissertations. Vita. Includes bibliographical references (p. 200-210).
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Ting, Wupao. "A fluid and solid inclusion study of the Sukulu carbonatite complex, Uganda." Thesis, Kingston University, 1994. http://eprints.kingston.ac.uk/20577/.
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The thesis consists of 8 chapters. The first Chapter gives an introduction to carbonatites and outlines the general aims of this study. The general geology of Sukulu, the methodology used in this research, and previous work are presented in Chapter 2. Detailed descriptions and analytical results on the principal minerals are given in Chapter 3. Chapters 4 and 5 focus on aqueous and solid inclusions in apatite, and detailed descriptions, microthermometric results and interpretations are presented. Determination of oxygen and carbon stable isotope compositions and their interpretations are covered in Chapter 6. Chapter 7 describes geothermometric and geobarometric investigations and the calculation of oxygen fugacities during the deposition of apatite and carbonate. The final chapter discusses evolution of the fluids in the Sukulu carbonatite complex and presents a petrogenetic model. Aqueous inclusions in apatite from the Sukulu carbonatite consist essentially of three types: CO[sub]2-bearing, H[sub]2 0-rich and CH[sub]4-bearing. The CO[sub]2- and CH[sub]4-bearing inclusions, in general, are not present together in individual apatite crystals. It is considered that these compositionally discrete inclusions represent different fluids trapped during different stages of apatite crystallisation. The CO[sub]2-bearing fluid probably formed from an originally H[sub]2 0-rich fluid containing significant CO[sub]2 by immiscible separation under high pressure and temperature. This precursor H[sub]2 0-CO[sub]2 fluid was probably derived from a carbonatite melt, also by a possible process of liquid immiscibility. The CH[sub]4-bearing inclusions were probably formed by late stage hydrothermal processes under different P-T conditions. Many solid inclusions occur in apatite of the Sukulu carbonatite, of which the most abundant are carbonate. They can be classified into Mg-calcite. (primary) and calcite (secondary) inclusions based on their morphology, texture and chemical composition. Although such carbonate inclusions are ubiquitous in carbonatite apatite and have been described by many other workers, this study provides new insight into their genesis and petrogenetic significance. Carbon and oxygen stable isotopic composition from fluid inclusions, in both apatite and matrix carbonate, suggest that the CO[sub]2-bearing fluid was equilibrated with carbonate fluids at an early stage, but it evolved along a different path. The CO[sub]2-bearing fluids which has a stable isotopic composition close to upper-mantle values, evolved in a closed-system after being trapped by apatite, but the carbonate fluid evolved in an open-system and its isotopic composition was elevated by assimilation and contamination during ascent. The results also reveal that post-magmatic processes played an important role in the development of the Sukulu carbonatite. P-T-X isochores calculated for each type of fluid indicate that their evolution was probably from a CO[sub]2-bearing fluid, through a moderate to highly saline one, to a CH[sub]4-bearing one, and took place under temperatures and pressures varying from >1000°C and >7.4kb, through >560°C and >5kb, to about 500°C and <3 kb. This trend represents evolution of the carbonatite from a deep magmatic (carbonate melt) environment towards a shallow level hydrothermal system. This study confirms that both apatite and carbonate-can be precipitated over a wide range of temperatures and melt fluid compositions. The present findings indicate that the compositions of the fluids associated with the Sukulu carbonatite complex appear to have evolved chemically from a Mg-bearing calcite melt, through aqueous CO[sub]2-bearing and bicarbonate-rich melts (NaHC0[sub]3 daughters) to a final aqueous CH[sub]4-bearing fluid.
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Lee, Emma-Jane. "Forensic sample analysis using supercritical fluid extraction coupled with solid phase microextraction." Thesis, University of South Wales, 2007. https://pure.southwales.ac.uk/en/studentthesis/forensic-sample-analysis-using-supercritical-fluid-extraction-coupled-with-solid-phase-microextraction(0159ef22-bb14-433f-a50f-2bd2773ef937).html.
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A third of adults in the UK admit to using controlled substances at least once hi their lives and the most commonly abused drug was found to be cannabis, followed by the opiates and ecognine derivatives. Forensic laboratories are continually trying to reduce the turnaround time for samples submitted for analysis, to less than the current time of four days. One of the main aims of this work was to reduce the time taken to prepare, extract and analyse hair for target analytes. A new method combining supercritical fluid extraction and solid phase micro-extraction (SFE/SPME) is introduced. This coupled procedure utilises the advantages of using supercritical carbon dioxide as an extraction solvent and collecting the extract on a selected SPME fibre. Together the combined techniques provide a method that is solvent-free and highly selective, whilst reducing sample preparation to a minimum. Digested hair samples are examined by SEM to find the best method. Alkali hydrolysis and enzyme digestion using proteinase K were found to be the most effective pre-extraction methods. Solid hair samples with the addition of a derivatization reagent (BSTFA) gave the best results using the coupled technique. After optimisation and validation, the extraction from both real and spiked samples resulted in recoveries between 60% to 80% for the target analytes A9 -tetrahydrocannabinol (A9- THC) , cannabinol (CBN) and cannabidiol (CBD). Other forensic applications such as the extraction of polycyclic aromatic hydrocarbons and pesticides from environmental and food samples and the examination of fire debris for the presence of accelerants are also carried out. PAH could easily be extracted from complex matrices to give recoveries of up to 97% for some analytes at the optimized conditions of 90°C at 4500 psi over a 10 minute dynamic extraction period. Pesticide extraction gave recoveries of 60 - 80% while the extraction of accelerants from fire debris clearly showed that accelerants such as diesel can be identified over the coincidental PAH and hydrocarbon peaks found in burnt debris. The coupling of SFE to SPME provides an exciting technique that has a wide range of applications and creates potential for a fully automated on-line system.
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Mutch, Greg Alexander. "Carbon capture and storage optimisation in solid oxides : understanding surface-fluid interactions." Thesis, University of Aberdeen, 2016. http://digitool.abdn.ac.uk:80/webclient/DeliveryManager?pid=231044.
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To decrease carbon dioxide emissions into the atmosphere for climate change mitigation it is necessary to modify existing practices in processes where greenhouse gases are emitted. Due to the extremely large volumes of carbon dioxide produced globally, it is generally accepted that although carbon dioxide conversion and utilisation will contribute in the long term, in the short to medium term it will be necessary to capture and store carbon dioxide emissions to progress towards a low carbon future. Current industrial capture processes incur large energy and thus economic penalties. Storage in geological formations requires robust confidence in storage security to be publically accepted. Therefore the objective of this work was to study carbon dioxide capture and storage in processes directly confronting these two major challenges. Carbon dioxide adsorption on oxide materials for advanced carbon capture processes with lower energetic and economic penalties was investigated. Water was shown to play a crucial role in determining the presence of reactive sites, the speciation of carbonates formed and increased sorbent utilisation. A high surface area oxide with specifically exposed facets was prepared and the impact of these facets on carbon dioxide uptake performance was assessed. Volumetric gas adsorption and isotherm modelling supported the presence of two distinct adsorption sites. To enhance confidence in storage security it is necessary to understand storage processes that result in stable products. An apparatus capable of obtaining geological storage conditions was developed and carbonate formation and surface hydration at high pressure was investigated. By locating individual reactive cations on the surface of silica, silicate mineral analogues were prepared. It was shown that carbonate speciation was dependent on the reactive cation and the presence or absence of water.
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Shui, Pei. "Novel immersed boundary method for direct numerical simulations of solid-fluid flows." Thesis, University of Edinburgh, 2015. http://hdl.handle.net/1842/10050.
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Solid-fluid two-phase flows, where the solid volume fraction is large either by geometry or by population (as in slurry flows), are ubiquitous in nature and industry. The interaction between the fluid and the suspended solids, in such flows, are too strongly coupled rendering the assumption of a single-way interaction (flow influences particle motion alone but not vice-versa) invalid and inaccurate. Most commercial flow solvers do not account for twoway interactions between fluid and immersed solids. The current state-of-art is restricted to two-way coupling between spherical particles (of very small diameters, such that the particlediameter to the characteristic flow domain length scale ratio is less than 0.01) and flow. These solvers are not suitable for solving several industrial slurry flow problems such as those of hydrates which is crucial to the oil-gas industry and rheology of slurries, flows in highly constrained geometries like microchannels or sessile drops that are laden with micro-PIV beads at concentrations significant for two-way interactions to become prominent. It is therefore necessary to develop direct numerical simulation flow solvers employing rigorous two-way coupling in order to accurately characterise the flow profiles between large immersed solids and fluid. It is necessary that such a solution takes into account the full 3D governing equations of flow (Navier-Stokes and continuity equations), solid translation (Newton’s second law) and solid rotation (equation of angular momentum) while simultaneously enabling interaction at every time step between the forces in the fluid and solid domains. This thesis concerns with development and rigorous validation of a 3D solid-fluid solver based on a novel variant of immersed-boundary method (IBM). The solver takes into account full two-way fluid-solid interaction with 6 degrees-of-freedom (6DOF). The solid motion solver is seamlessly integrated into the Gerris flow solver hence called Gerris Immersed Solid Solver (GISS). The IBM developed treats both fluid and solid in the manner of “fluid fraction” such that any number of immersed solids of arbitrary geometry can be realised. Our IBM method also allows transient local mesh adaption in the fluid domain around the moving solid boundary, thereby avoiding problems caused by the mesh skewness (as seen in common mesh-adaption algorithms) and significantly improves the simulation efficiency. The solver is rigorously validated at levels of increasing complexity against theory and experiment at low to moderate flow Reynolds number. At low Reynolds numbers (Re 1) these include: the drag force and terminal settling velocities of spherical bodies (validating translational degrees of freedom), Jeffrey’s orbits tracked by elliptical solids under shear flow (validating rotational and translational degrees of freedom) and hydrodynamic interaction between a solid and wall. Studies are also carried out to understand hydrodynamic interaction between multiple solid bodies under shear flow. It is found that initial distance between bodies is crucial towards the nature of hydrodynamic interaction between them: at a distance smaller than a critical value the solid bodies cluster together (hydrodynamic attraction) and at a distance greater than this value the solid bodies travel away from each other (hydrodynamic repulsion). At moderately high flow rates (Re O(100)), the solver is validated against migratory motion of an eccentrically placed solid sphere in Poisuelle flow. Under inviscid conditions (at very high Reynolds number) the solver is validated against chaotic motion of an asymmetric solid body. These validations not only give us confidence but also demonstrate the versatility of the GISS towards tackling complex solid-fluid flows. This work demonstrates the first important step towards ultra-high resolution direct numerical simulations of solid-fluid flows. The GISS will be available as opensource code from February 2015.
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Ramirez, Carmen Hernandez. "Enhancement of the rate of solution of relatively insoluble drugs from solid-solid systems prepared by supercritical fluid technology." Columbus, Ohio : Ohio State University, 2007. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1179928429.
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Zitoun, Khaled Bechir. "Continuous flow of solid-liquid food mixtures during ohmic heating : fluid interstitial velocities, solid area fraction, orientation and rotation /." The Ohio State University, 1996. http://rave.ohiolink.edu/etdc/view?acc_num=osu148794066543593.
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Scholtz, Kelly Burchell. "Optimisation of solid rocket motor blast tube and nozzle assemblies using computational fluid dynamics." Thesis, Cape Peninsula University of Technology, 2017. http://hdl.handle.net/20.500.11838/2487.
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Thesis (MTech (Mechanical Engineering))--Cape Peninsula University of Technology, 2017.A framework for optimising a tactical solid rocket motor nozzle is established and investigated within the ANSYS Workbench environment. Simulated results are validated against thrust measurements from the static bench firing of a full-scale rocket. Grid independence is checked and achieved using inflation based meshing. A rocket nozzle contour is parametrized using multiple control points along a spline contour. The design of experiments table is populated by a central composite design method and the resulting response surfaces are used to find a thrust optimised rocket nozzle geometry. CFD results are based on Favre-mass averaged Navier-Stokes equations with turbulence closure implemented with the Menter SST model. Two optimisation algorithms (Shifted Hammersley Sampling and Nonlinear Programming by Quadratic Lagrangian) are used to establish viable candidates for maximum thrust. Comparisons are made with a circular arc, Rao parabolic approximation and conical nozzle geometries including the CFD simulation there-off. The effect of nozzle length on thrust is simulated and optimised within the framework. Results generally show increased thrust as well as demonstrating the framework's potential for further investigations into nozzle geometry optimisation and off-design point characterisation.
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Evola, Salvatore. "Modelling of the sedimentation phenomenon of solid particles immersed in a turbulent fluid." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2020. http://amslaurea.unibo.it/20077/.
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Settling phenomenon of solid particles immersed in a turbulent fluid has been investigated, in a condition of free-stream turbulence.
Since structures formed onto this condition are complex, it is difficult to predict exactly how particles move. It is thus appropriate to conduct deepen studies of the phenomenon and carry out simulations to describe particles’ settling velocity.
In order to define a new correlation for the evaluation of particles’ settling velocity, different literature correlations and parameters have been exploited.
Langevin dynamics has been used to describe fluid’s motion, and by considering several forces acting on particles (buoyancy, drag, gravitational and virtual mass), it has been possible to evaluate their settling velocity, through a computational approach. Data have been obtained by varying characteristic properties, such as kinetic energy, its rate of dissipation, and physical properties of fluid and particles.
Aiming to find a reliable correlation which best explains the settling phenomenon, results in output from simulations have been compared with that deriving from proposed correlation. Encouraging results have been obtained over the range of operating conditions examined.
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Dann, Martin Richard. "Experimental study of two dimensional fluid and solid '3He adsorbed on preplated graphite." Thesis, Royal Holloway, University of London, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.325525.
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The heat capacity of 3He adsorbed on Grafoil (exfoilated graphite) preplated with four layers of 4He was measured between 1 and 50mK. The heat capacity was found to be linear up to 4OmK. At 3He surface densities below 4nm-2 two dimensional Fermi liquid behaviour was found and values of the hydrodynamic effective mass and Landau parameter Ff inferred. Subsequent steps in the heat capacity as a function of coverage were taken as evidence of independent 2D Fermi fluids. A low field DC SQUID pulsed NMR spectrometer was developed for future studies of magnetic order in 2D solid 3He films at ultralow temperatures
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Zhao, Shunzi. "The numerical study of fluid-solid interactions for modelling blood flow in arteries." Thesis, City University London, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.312951.
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Mahabadian, Mohammadreza Ameri. "Solid-fluid equilibria modelling in wax, hydrate and combined wax-hydrate forming systems." Thesis, Heriot-Watt University, 2016. http://hdl.handle.net/10399/3331.
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Waxes and hydrates formation are two major flow assurance challenges, imposing considerable costs for prevention and, in worst case scenario, pipeline blockage removal and deferred production. Employing remediation and prevention schemes for hydrate and wax related problems necessitates knowledge of their formation conditions as well as their amount. The main focus of this work is thermodynamic modelling of phase equilibria in systems prone to waxes, hydrates and combined wax−hydrate formation. Study of these complex mixtures requires the development of a robust multiphase flash calculation algorithm capable of identifying the correct number and nature of the phases in equilibrium. Such an algorithm is devised in this work based on the Gibbs free energy minimization concept. The algorithm is first applied to complex hydrate forming systems and then extended to combined wax-hydrate forming mixtures, enabling investigation of the mutual interactions between hydrates and waxes from the thermodynamics viewpoint. The new algorithm is fast and is capable of showing complex behaviours in hydrate and wax forming systems including stability of several wax phases or more than one hydrate structure at equilibrium conditions. In this work, an integrated thermodynamic model coupling three highly accurate schemes, i.e., the cubic plus association equation of state, UNIQUAC activity coefficient model and van der Waals and Platteeuw approach−to describe the non-idealities of the fluids, paraffinic solids (waxes) and hydrates, respectively−is implemented. Furthermore, the formation of waxes in high-pressure condition is thoroughly investigated, especially for highly asymmetric condensate-like systems. Accordingly, a modified thermodynamic model is presented for wax formation in high-pressure systems. Comparing with experimental solid-fluid equilibrium data of synthetic mixtures, the integrated model presents excellent agreement which demonstrates the reliability of the approach. Finally, the method available for the extension of the integrated model−which was based on synthetic mixtures−to real oil systems and especially for wax formation, are evaluated. Based on the analysis presented the best model is chosen and used for illustrating the combined wax-hydrate precipitation in a real crude oil.
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Barnhart, Donald H. "Whole-field holographic measurements of three-dimensional displacement in solid and fluid mechanics." Thesis, Loughborough University, 2001. https://dspace.lboro.ac.uk/2134/34516.
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This thesis reports on the development of two, conceptually different, holographic measurement systems for the study of three-dimensional displacement and velocity fields. The first approach reported in this thesis is an intensity correlation-based holographic velocimetry system that employs a reference-multiplexed, off-axis geometry for determining velocity directions using the cross-correlation technique, and a stereo camera geometry for determining three-dimensional fluid velocity fields. The pulsed-laser recording system produces three-dimensional particle images with resolution, signal-to- noise ratio, accuracy and derived velocity fields that are comparable to high-quality two-dimensional photographic PIV (particle image velocimetry). The high image resolution is accomplished by using low f-number optics, a fringe-stabilized processing chemistry, and a phase conjugate play-back geometry that compensates for aberrations in the imaging system. This holographic velocimetry system is then used to successfully measure the volumetric, three-dimensional velocity field of an air nozzle jet flow. In this experiment, more than five million three-dimensional velocity vectors are successfully identified within a single hologram result.
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Sousani, Marina. "Modeling of hydraulic fracturing in rocks : a multiscale and fluid-solid coupling approach." Thesis, University of Leeds, 2015. http://etheses.whiterose.ac.uk/9607/.
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This dissertation investigates the implications of the fluid flow on the behaviour of the particle-scale structure of a porous hard rock, based on the Discrete Element Method (DEM). This project is driven by the need to contribute towards a better understanding of the mechanical behaviour of porous rock formations under intense injection conditions and the influence of natural pre-existing rock damage to the hydraulic fracturing mechanism. The proposed numerical scheme incorporates different methods for computing both the solid and co-existing fluid phases. The solid phase (rock sample) has been characterized as a collection of discrete interacting particles, bound by spring-like contacts according to the DEM. Meanwhile, the fluid phase has been modelled by discretising the Navier-Stokes equations for porous media, utilising the fluid coupling algorithm embedded in the Particle Flow Code (PFC3D) software by Itasca. The outcome of this dissertation suggests that the DEM approach is an advanced computational method that can reproduce accurate rock models, adequately describe the inter-particle dynamics and thus contribute towards direct numerical and experimental comparisons, and interpret the geo-mechanical behaviour of the rock materials. Furthermore, this study identifies the importance of shear cracking in the hydraulic fracturing models, whereas conventional theory relates hydraulic fracturing with tensile cracking. Finally, this study focuses on the influences of various parameters, such as the external stress regime, fluid viscosity and pre-existing fractures, on the mechanical behaviour of the rock material in the particle-scale and the hydraulic fracturing process as a whole. This work is in an early stage and it aims to simulate hydraulic fracturing experiments with the use of a 3D modelling and the DEM approach, and to investigate the micromechanical response of the rock. Further research may include areas such as the 3D modelling of pre-cracked rocks using a larger variety of fracture angles.
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Hunt, Neil Andrew. "A study of the freezing of binary mixtures of hard colloidal spheres." Thesis, University of Bath, 1999. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.311449.
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González, Acedo Ignacio. "Development of a finite volume method for elastic materials and fluid-solid coupled applications." Doctoral thesis, Universitat Politècnica de Catalunya, 2019. http://hdl.handle.net/10803/666790.
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This thesis presents the development of a parallel finite volume numerical method to analyse thermoelastic and hyperelastic materials and applied problems with mutual interaction between a fluid and a structure.
The solid problem follows a cell-centred finite volume formulation for three-dimensional unstructured grids under the same framework that is frequently devoted to computational fluid dynamics. Second-order accurate schemes are used to discretise both in time and space. A direct implicit time integration promotes numerical stability when facing vibration and quasi-static scenarios. The geometrical non-linearities, encountered with the large displacements of both Saint Venant-Kirchhoff and neo-Hookean models, are tackled by means of an updated Lagrangian approach.
Verification of the method is conducted with canonical cases which involve: static equilibrium, thermal stress, vibration, structural damping, large deformations, nearly incompressible materials and high memory usage. Significant savings in computation time are achieved owing to the acceleration strategies implemented within the system resolution, namely a segregated algorithm with Aitken relaxation and a block-coupled system arrangement. The similarities between the block-coupled method and the displacement-based finite element method, with regards to the matrix form of the resulting equations, allow for including Rayleigh viscous damping within a finite volume solver.
The program for structures is to be coupled with the in-house fluid numerical models in order to produce a unified fluid-structure interaction platform, where an arbitrary Lagrangian-Eulerian approach is used to solve the flow in a conforming grid. As a first step, the method for incompressible Newtonian fluids is adapted to deal with structure-coupled problems. To do so, the Lagrangian-Eulerian version of the Navier-Stokes equations is presented, and automatic moving mesh techniques are developed. These techniques are designed to mitigate the mesh quality deterioration and to satisfy the space conservation law. Besides, a semi-implicit coupling algorithm, which only implicitly couples the fluid pressure term to the structure, is implemented. As a result, numerical stability for strongly coupled phenomena at a reduced computational cost is obtained. These new tools are tested on an applied case, consisting of the turbulent flow through self-actuated flexible valves.
Finally, a pioneering coupled numerical model for the thermal and structural analysis of packed-bed thermocline storage tanks is developed. This thermal accumulation system for concentrated solar power plants has attracted the attention of the industry due to the economic advantage compared to the usual two-tank system. Dynamic coupling among the thermoelastic equations for the tank shell and the numerical models for all other relevant elements of the system is considered. After validating the model with experimental results, the commercial viability of the thermocline concept, regarding energetic effectiveness and structural reliability, is evaluated under real operating conditions of the power plants.Esta tesis presenta el desarrollo de un método numérico paralelo basado en volúmenes finitos para analizar materiales termoelásticos e hiperelásticos y problemas con una interacción mutua entre un fluido y una estructura. El problema del sólido sigue una formulación de volúmenes finitos centrada en las celdas para mallas no-estructuradas tridimensionales, bajo el mismo marco que se suele emplear en la dinámica de fluidos computacional. Se utilizan esquemas de segundo orden de precisión para discretizar el tiempo y el espacio. Una integración temporal directa implícita asegura estabilidad numérica al afrontar escenarios casi-estáticos o de vibración. Las no linealidades, que aparecen con los amplios desplazamientos de los modelos de Saint Venant-Kirchhoff y de neo-Hookean, son abordadas con un enfoque Lagrangiano actualizado. La verificación del método se realiza a través de casos canónicos que involucran: equilibrio estático, tensiones térmicas, vibración, amortiguación estructural, grandes deformaciones, materiales casi incompresibles y altos requerimientos de memoria. Se registra un ahorro significativo en el tiempo de cálculo gracias a las estrategias de aceleración implementadas dentro de la resolución del sistema, principalmente un algoritmo segregado con relajación Aitken y una disposición acoplada en bloques del sistema. Las similitudes entre este método acoplado en bloques y el método de los elementos finitos basados en el desplazamiento, con respecto a la forma matricial de las ecuaciones resultantes, permiten incluir la amortiguación viscosa tipo Rayleigh dentro de un solucionador de volúmenes finitos. El programa para estructuras se acoplará con los modelos numéricos internos para fluidos con el objetivo de generar una plataforma unificada de interacción fluido-estructura, donde se usa un enfoque arbitrario Lagrangiano-Euleriano sobre una malla conforme para resolver el fluido. Como primer paso, el método para flujos incompresibles Newtonianos se adapta para lidiar con problemas acoplados a una estructura. Para ello, se presenta la versión Lagrangiana-Euleriana de las ecuaciones de Navier-Stokes y se desarrollan técnicas automáticas de movimiento de malla. El diseño de estas técnicas se centra en mitigar el deterioro de la calidad de la malla y satisfacer la ley de conservación del espacio. Además, se implementa un algoritmo de acoplamiento semi-implícito, que sólo acopla implícitamente el término fluido de presión a la estructura. Como resultado, se obtiene estabilidad numérica para fenómenos fuertemente acoplados a un coste computacional reducido. Estas nuevas herramientas se prueban en un caso aplicado, que consiste el flujo turbulento a través de válvulas flexibles autoactivadas. Finalmente, se desarrolla un modelo numérico acoplado pionero para analizar estructuralmente y térmicamente los tanques termoclina de almacenamiento térmico. Este sistema de acumulación para centrales termosolares ha atraído la atención de la industria debido al ahorro económico comparado con el sistema de doble tanque habitual. Se tiene en cuenta el acoplamiento dinámico entre las ecuaciones gobernantes de la pared del tanque y las de todos los elementos relevantes del sistema. Tras validar el modelo con datos experimentales, se evalúa la viabilidad comercial de estos tanques, en cuanto a rendimiento energético y fiabilidad estructural, bajo condiciones reales de operación de las centrales.