Dissertations / Theses on the topic 'Fluids'
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Vyawahare, Saurabh Scherer Axel. "Manipulating fluids : advances in micro-fluidics, opto-fluidics and fluidic self-assembly /." Diss., Pasadena, Calif. : Caltech, 2006. http://resolver.caltech.edu/CaltechETD:etd-05252006-223101.
Full textYerlett, T. K. "Enthalpies of fluids and fluid mixtures." Thesis, University of Bristol, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.355339.
Full textChen, Wei. "Theoretical study of multi-component fluids confined in porous media." Thesis, Lyon, École normale supérieure, 2011. http://www.theses.fr/2011ENSL0624.
Full textA porous medium or a porous material (called as frame or matrix also) usually consists of two interconnected rejoins: one permeable by a gas or a liquid, i.e., pore or void, and the other impermeable. Many natural substances such as rocks, soils, biological tissues (e.g., bio membranes, bones), and manmade materials such as cements, foams and ceramics are porous materials. Porous materials have important technological applications such as molecular sieve, catalyst, chemical sensor, etc. In recent years, there have been considerable investigations for understanding thoroughly the structure of these materials as well as the behavior of substances confined in them. Much effort (both experimental and theoretical) has been devoted to the study of porous materials. In their pioneering work, a very simple model for the fluid adsorption in random porous media was proposed by Madden and Glandt. The matrix in Madden-Glandt model is made by quenching an equilibrium system. Then, a fluid is adsorbed in such a matrix. Recently, T. Patsahan, M. Holovko and W. Dong have extended the scaled particle theory (SPT) to confined fluids and derived analytical equations of state (EOS) for a hard sphere (HS) fluid in some matrix models. In this thesis, using SPT method, I obtained the equation of state of additive hard-sphere (AHS) fluid mixtures confined in porous media. The contact values of the fluid-fluid and fluid-matrix radial distribution functions (RDF) were derived as well. The results of the contact values of the RDFs and the chemical potentials of different species were assessed against Monte Carlo simulations. Moreover, I analyzed also the fluid-fluid phase separation of non-additive hard sphere (NAHS) fluid confined in porous media. An equation of state is derived by using a perturbation theory with a multi-component fluid reference. The results of this theory are in good agreement with those obtained from semi grand canonical ensemble Monte Carlo simulations
Seed, M. "Electrorheological fluids." Thesis, University of Sheffield, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.321479.
Full textWatson, T. "Electrorheological fluids." Thesis, Cranfield University, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.334815.
Full textGuenther, Gerhard K. "Textured fluids." Diss., This resource online, 1995. http://scholar.lib.vt.edu/theses/available/etd-08272007-163931/.
Full textCardillo, Giulia. "Fluid Dynamic Modeling of Biological Fluids : From the Cerebrospinal Fluid to Blood Thrombosis." Thesis, Institut polytechnique de Paris, 2020. http://www.theses.fr/2020IPPAX110.
Full textIn the present thesis, three mathematical models are described. Three different biomedical issues, where fluid dynamical aspects are of paramount importance, are modeled: i) Fluid-structure interactions between cerebro-spinal fluid pulsatility and the spinal cord (analytical modeling); ii) Enhanced dispersion of a drug in the subarachnoid space (numerical modeling); and iii) Thrombus formation and evolution in the cardiovascular system (numerical modeling).The cerebrospinal fluid (CSF) is a liquid that surrounds and protects the brain and the spinal cord. Insights into the functioning of cerebrospinal fluid are expected to reveal the pathogenesis of severe neurological diseases, such as syringomyelia that involves the formation of fluid-filled cavities (syrinxes) in the spinal cord.Furthermore, in some cases, analgesic drugs -- as well drugs for treatments of serious diseases such as cancers and cerebrospinal fluid infections -- need to be delivered directly into the cerebrospinal fluid. This underscores the importance of knowing and describing cerebrospinal fluid flow, its interactions with the surrounding tissues and the transport phenomena related to it. In this framework, we have proposed: a model that describes the interactions of the cerebrospinal fluid with the spinal cord that is considered, for the first time, as a porous medium permeated by different fluids (capillary and venous blood and cerebrospinal fluid); and a model that evaluates drug transport within the cerebrospinal fluid-filled space around the spinal cord --namely the subarachnoid space--.The third model deals with the cardiovascular system. Cardiovascular diseases are the leading cause of death worldwide, among these diseases, thrombosis is a condition that involves the formation of a blood clot inside a blood vessel. A computational model that studies thrombus formation and evolution is developed, considering the chemical, bio-mechanical and fluid dynamical aspects of the problem in the same computational framework. In this model, the primary novelty is the introduction of the role of shear micro-gradients into the process of thrombogenesis.The developed models have provided several outcomes. First, the study of the fluid-structure interactions between cerebro-spinal fluid and the spinal cord has shed light on scenarios that may induce the occurrence of Syringomyelia. It was seen how the deviation from the physiological values of the Young modulus of the spinal cord, the capillary pressures at the SC-SAS interface and the permeability of blood networks can lead to syrinx formation.The computational model of the drug dispersion has allowed to quantitatively estimate the drug effective diffusivity, a feature that can aid the tuning of intrathecal delivery protocols.The comprehensive thrombus formation model has provided a quantification tool of the thrombotic deposition evolution in a blood vessel. In particular, the results have given insight into the importance of considering both mechanical and chemical activation and aggregation of platelets
CARDILLO, GIULIA. "Fluid Dynamic Modeling of Biological Fluids: From the Cerebrospinal Fluid to Blood Thrombosis." Doctoral thesis, Politecnico di Torino, 2020. http://hdl.handle.net/11583/2845786.
Full textHarris, Rodney Morton. "THE ONSET OF INSTABILITY IN A TRIPLY-DIFFUSIVE FLUID LAYER." Thesis, The University of Arizona, 1985. http://hdl.handle.net/10150/275307.
Full textAndersson, Tomas. "Controlling the fluid dynamics : an analysis of the workflow of fluids." Thesis, University of Gävle, Department of Mathematics, Natural and Computer Sciences, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:hig:diva-155.
Full textA scene containing dynamic fluids can be created in a number of ways. There are two approaches that will highlight the problems and obstacles that might occur. Today’s leading fluid simulator, RealFlow, simulates the fluid dynamics. A comparison between the two approaches will be made and are analyzed. Through experimentation, one of the approaches fails to produce the set requirements in the experiment and furthermore the two approaches differ in efficiency.
Rashid, Abu S. "Compressible magnetorheological fluids." abstract and full text PDF (UNR users only), 2008. http://0-gateway.proquest.com.innopac.library.unr.edu/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:1456488.
Full textBrookes, Sarah. "Fluids in Nanopores." Thesis, Griffith University, 2016. http://hdl.handle.net/10072/365467.
Full textThesis (PhD Doctorate)
Doctor of Philosophy (PhD)
School of Natural Sciences
Science, Environment, Engineering and Technology
Full Text
Holder, Alexander Joseph. "Experimental studies of complex fluids in complex flows." Thesis, Swansea University, 2014. https://cronfa.swan.ac.uk/Record/cronfa42995.
Full textChen, Yng-gwei. "General theory of nonuniform fluids from hard spheres to ionic fluids /." College Park, Md. : University of Maryland, 2004. http://hdl.handle.net/1903/2149.
Full textThesis research directed by: Physics. Title from t.p. of PDF. Includes bibliographical references. Published by UMI Dissertation Services, Ann Arbor, Mich. Also available in paper.
Scrobogna, Stefano. "On some models in geophysical fluids." Thesis, Bordeaux, 2017. http://www.theses.fr/2017BORD0601/document.
Full textIn this thesis we discuss three models describing the dynamics of density-dependent fluids in long lifes pans and on a planetary scale. In such setting the relative displacement induced by various external physical forces, such as the Coriolis force and the stratification buoyancy, is far more relevant than the intrinsic motion generated by the collision of particles of the fluid itself. Such disproportion of balance limits hence the motion, inducing persistent structures in the velocity flow.On a mathematical level one of the main difficulties relies in giving a full description of the perturbations induced by the external forces, which propagate at high speed. This analysis can be performed by the aid of several tools, we chose here to adopt techniques characteristic of harmonic analysis, such as the analysis of the dispersive properties of highly oscillating integrals.All along the thesis we consider boundary-free, three-dimensional domains, and inspecific we study only the case in which the domain in either the whole space or the periodic space . The models we consider are the following ones : primitive equations with comparable Froude and Rossby number and zero vertical diffusivity, density-dependent stratified fluids in low Froude number regime, weakly compressible and fast rotating fluid in a regime in which Mach and Rossbynumber are comparable. We prove that these systems propagate globally-in-time data with low-regularity. Nosmallness assumption is ever made, specific constructive hypothesis are assumed on the initial data when required
Battaglini, Neusa Maria Pavão [UNESP]. "Avaliação do comportamento de impelidores especiais na mistura de fluidos." Universidade Estadual Paulista (UNESP), 1998. http://hdl.handle.net/11449/101864.
Full textFluidos de viscosidade entre 0,874 10-3 e 787 10-3 N m s-2 foram agitados pelos impelidores tipos âncora convencional, âncora modificada, fita helicoidal e parafuso em tanques cilíndricos de fundos reto e toroesférico para determinação da potência requerida e do tempo de mistura. Na agitação efetuada com os impelidores centrados houve o aparecimento de vórtices em algumas rotações. As medidas de potência foram efetuadas na região em que o número de Reynolds (NRe ) variou de 16 a 70.000 com a âncora convencional e modificada. Os diagramas do número de potência( ) P N em função do número de Reynolds, construídos com os dados experimentais, mostraram que, para todos os fluidos usados, ocorreu um desvio na curva quando o vórtice, formado na superfície do fluido, alcançou os impelidores e teve início a dispersão de ar no interior da massa fluida. A presença de bolhas de ar desenvolveu, no tanque, um sistema de duas fases (líquido–gás), alterando as características dos fluidos agitados. Nos cálculos do número de potência e do número de Reynolds foram utilizados os valores de viscosidade e densidade do fluido, e não os correspondentes ao sistema líquido-gás o que provocou, provavelmente, o desvio nas curvas. Na região em que o número de Reynolds fica entre 16 e 300 não houve formação de vórtices acentuados com aeração e a curva foi definida pela correlação ( )a NP A NRe = , onde A é função do tipo de impelidor e das dimensões do vaso e o expoente a, um valor empírico que varia com o número de Reynolds obtendo a relação ( )1,7 Re N = 19.953 N − P . O desempenho dos impelidores na homogeneização foi analisado pela energia requerida para se obter uma mistura de açúcar e água com concentrações correspondentes a 40 e 60o Brix. O método desenvolvido foi baseado na verificação...
Fluids with viscosity between (0,874 and 787 10-3 Nm s-2 were agitated by conventional anchor, modified anchor, helicoidal ribbon and screw impellers in cilindric tanks straight and concave (torospheric) bottoms for the measurement of power and time of mixture. The arisal of vortex occurred when agitation was accomplished with centred impellers and in some rotations. The measures of power were obtained in the interval where the number of Reynolds (NRe) varied from 16 to 70.000 with conventional and modified anchor. The diagrams of number of Reynolds in function of number of Froude constructed with experimental data showed that, to all fluids employed, a deflection in the curve occurred when the vortex formed at the surface of the fluid reached the impellers and the dispersion of air inside the fluid mass started. The presence of air bubbles develops in the tank a system of two phases altering the characteristics of the agitated fluids. In the calculations of the number of Reynolds were used the values of the fluid viscosity and density and not ones corresponding to the liquid-gas system, provoking a deflection in the curves. In the interval where the number of Reynolds remains between 16 and 300 the formation of a well developed vortex with aeration did not occur and the curve was defined by the correlation A N = ANRE Re , where A is function of the type of the impeller and of the dimensions of the tank, and the exponent a, an empirical value, varies with the number of Reynolds. The performance of the impellers in the homogenization was analysed in terms of the energy required in order to obtain a mixture...(Complete abstract click electronic access below)
Steele-MacInnis, Matthew. "Thermodynamics of geologic fluids." Diss., Virginia Tech, 2013. http://hdl.handle.net/10919/22026.
Full textPh. D.
Da, Silva Rui Pitanga Marques. "Organic fluid mixtures as working fluids for the trilateral flash cycle system." Thesis, City University London, 1989. http://openaccess.city.ac.uk/7945/.
Full textLOAIZA, JUAN CARLOS VALDEZ. "SIMULATION OF A REFRIGERATION SYSTEM WORKING WITH NANO-FLUIDS AS SECONDARY FLUID." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2009. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=14553@1.
Full textEstudou-se, numericamente, a utilização de nanofluidos como fluidos secundários em sistemas de refrigeração por compressão de vapor. Foi desenvolvido um modelo de simulação de um sistema água-água com compressor alternativo e condensador e evaporador de tubo duplo reto. O método de multi-zonas foi utilizado na simulação dos trocadores de calor. As zonas bifásicas, por sua vez, foram discretizadas para levar em conta a variação local do coeficiente de transferência de calor. No caso do condensador determinou-se o coeficiente de transferência de calor a partir de um mapa de escoamento bifásico. No evaporador o nanofluido escoa na seção circular (interna) enquanto que o refrigerante escoa na seção anular. Um programa baseado na plataforma EES foi desenvolvido para a solução do sistema de equações algébricas não lineares resultantes do modelo matemático. Os resultados da simulação mostram que, para a mesma capacidade frigorífica, a área de troca de calor no evaporador e a queda de pressão no lado do refrigerante diminuem quando: (i) a concentração volumétrica das nanopartículas e a temperatura do fluido-base aumentam; (ii) o diâmetro das nanopartículas diminui. Observou-se, também, que a queda de pressão do lado do nanofluido e, conseqüentemente, a potência de bombeamento, aumentam com a concentração volumétrica de nanopartículas, mas diminuem para diâmetros das nanopartículas menores e temperaturas mais elevadas do fluido-base. Os resultados para um sistema típico mostraram que o uso de nanofluidos como fluidos secundários pode levar a uma redução de até 6% na área do evaporador, quando comparado com o fluido-base convencional.
The use of nanofluids as secondary coolants in vapor compression refrigeration systems was numerically studied. A simulation model for a liquid-towater heat pump, with reciprocating compressor and straight double-tube condenser and evaporator was studied. The multi-zone method was employed in the modeling of the heat exchangers. By their turn, the two-phase regions of both condenser and evaporator were discretized to take into account the local variation of the refrigerant condensing and boiling heat transfer coefficients. In the condenser two-phase region, the local heat transfer coefficient was determined as a function of the governing two-phase flow regime. The nanofluid was supposed to flow through the inner circular section of the evaporator, while the refrigerant was left to the annular passage. A computational program, based on EES (Engineering Equation Solver) package, was developed to solve the resulting non-linear system of algebraic equations. Different nanoparticles (Cu, Al2O3, CuO and TiO2) were studied for different volumetric concentrations and particle diameters. Simulation results have shown that, for a given refrigerating capacity, evaporator area and refrigerant-side pressure drop are reduced when: (i) the volumetric concentration of nanoparticles and nanofluid temperature increase; (ii) the diameter of nanoparticles decrease. Also, nanofluid-side pressure drop and, consequently, pumping power, increase with nanoparticle volumetric concentration and decrease with nanoparticle diameter and nanofluid temperature. Results from a typical case-study indicated an evaporator area reduction of up to 6%, with the use of nanofluids as secondary coolant, if compared to the conventional base-fluid (H2O).
Giwa, Giwa Solomon Olanrewaju. "Investigation into thermal-fluid properties of hybrid ferrofluids as heat transfer fluids." Thesis, University of Pretoria, 2019. http://hdl.handle.net/2263/77818.
Full textThesis (PhD)--University of Pretoria, 2019.
Mechanical and Aeronautical Engineering
PhD
Unrestricted
Bocchi, Edoardo. "Compressible-incompressible transitions in fluid mechanics : waves-structures interaction and rotating fluids." Thesis, Bordeaux, 2019. http://www.theses.fr/2019BORD0279/document.
Full textThis manuscript deals with compressible-incompressible transitions arising in partial differential equations of fluid mechanics. We investigate two problems: floating structures and rotating fluids. In the first problem, the introduction of a floating object into water waves enforces a constraint on the fluid and the governing equations turn out to have a compressible-incompressible structure. In the second problem, the motion of geophysical compressible fluids is affected by the Earth's rotation and the study of the high rotation limit shows that the velocity vector field tends to be horizontal and with an incompressibility constraint.Floating structures are a particular example of fluid-structure interaction, in which a partially immersed solid is floating at the fluid surface. This mathematical problem models the motion of wave energy converters in sea water. In particular, we focus on heaving buoys, usually implemented in the near-shore zone, where the shallow water asymptotic models describe accurately the motion of waves. We study the two-dimensional nonlinear shallow water equations in the axisymmetric configuration in the presence of a floating object with vertical side-walls moving only vertically. The assumptions on the solid permit to avoid the free boundary problem associated with the moving contact line between the air, the water and the solid. Hence, in the domain exterior to the solid the fluid equations can be written as an hyperbolic quasilinear initial boundary value problem. This couples with a nonlinear second order ODE derived from Newton's law for the free solid motion. Local in time well-posedness of the coupled system is shown provided some compatibility conditions are satisfied by the initial data in order to generate smooth solutions.Afterwards, we address a particular configuration of this fluid-structure interaction: the return to equilibrium. It consists in releasing a partially immersed solid body into a fluid initially at rest and letting it evolve towards its equilibrium position. A different hydrodynamical model is used. In the exterior domain the equations are linearized but the nonlinear effects are taken into account under the solid. The equation for the solid motion becomes a nonlinear second order integro-differential equation which rigorously justifies the Cummins equation, assumed by engineers to govern the motion of floating objects. Moreover, the equation derived improves the linear approach of Cummins by taking into account the nonlinear effects. The global existence and uniqueness of the solution is shown for small data using the conservation of the energy of the fluid-structure system.In the second part of the manuscript, highly rotating fluids are studied. This mathematical problem models the motion of geophysical flows at large scales affected by the Earth's rotation, such as massive oceanic and atmospheric currents. The motion is also influenced by the gravity, which causes a stratification of the density in compressible fluids. The rotation generates anisotropy in viscous flows and the vertical turbulent viscosity tends to zero in the high rotation limit. Our interest lies in this singular limit problem taking into account gravitational and compressible effects. We study the compressible anisotropic Navier-Stokes-Coriolis equations with gravitational force in the horizontal infinite slab with no-slip boundary condition. Both this condition and the Coriolis force cause the apparition of Ekman layers near the boundary. They are taken into account in the analysis by adding corrector terms which decay in the interior of the domain. In this work well-prepared initial data are considered. A stability result of global weak solutions is shown for power-type pressure laws. The limit dynamics is described by a two-dimensional viscous quasi-geostrophic equation with a damping term that accounts for the boundary layers
Obando, Vallejos Benjamin. "Mathematical models for the study of granular fluids." Thesis, Université de Lorraine, 2018. http://www.theses.fr/2018LORR0274/document.
Full textThis Ph.D. thesis aims to obtain and to develop some mathematical models to understand some aspects of the dynamics of heterogeneous granular fluids. More precisely, the expected result is to develop three models, one where the dynamics of the granular material is modeled using a mixture theory approach, and the other two, where we consider the granular fluid is modeled using a multiphase approach involving rigid structures and fluids. More precisely : • In the first model, we obtained a set of equations based on the mixture theory using homogenization tools and a thermodynamic procedure. These equations reflect two essential properties of granular fluids : the viscous nature of the interstitial fluid and a Coulomb-type of behavior of the granular component. With our equations, we study the problem of a dense granular heterogeneous flow, composed by a Newtonian fluid and a solid component in the setting of the Couette flow between two infinite cylinders. • In the second model, we consider the motion of a rigid body in a viscoplastic material. The 3D Bingham equations model this material, and the Newton laws govern the displacement of the rigid body. Our main result is the existence of a weak solution for the corresponding system. • In the third model, we consider the motion of a perfect heat conductor rigid body in a heat conducting Newtonian fluid. The 3D Fourier-Navier-Stokes equations model the fluid, and the Newton laws and the balance of internal energy model the rigid body. Our main result is the existence of a weak solution for the corresponding system. The weak formulation is composed by the balance of momentum and the balance of total energy equation which includes the pressure of the fluid, and it involves a free boundary (due to the motion of the rigid body). To obtain an integrable pressure, we consider a Navier slip boundary condition for the outer boundary and the mutual interface
Cluff, Maryam Ansari. "Microbial Aspects of Shale Flowback Fluids and Response to Hydraulic Fracturing Fluids." The Ohio State University, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=osu1366292190.
Full textZhang, Junfang. "Computer simulation of nanorheology for inhomogenous fluids." Australasian Digital Thesis Program, 2005. http://adt.lib.swin.edu.au/public/adt-VSWT20050620.095154.
Full textA thesis submitted in fulfilment of requirements for the degree of Doctor of Philosophy, Centre for Molecular Simulation, School of Information Technology, Swinburne University of Technology - 2005. Typescript. Bibliography: p. 164-170.
Reich, Thorsten Hendrik Bozzo. "Inhomogeneous hard platelet fluids." [S.l.] : [s.n.], 2006. http://deposit.ddb.de/cgi-bin/dokserv?idn=983423806.
Full textGuigard, Selma. "Solubilities in supercritical fluids." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape8/PQDD_0004/NQ40372.pdf.
Full textDekker, Leendert Johannes Marinus. "Proteomics of body fluids." [S.l.] : Rotterdam : [The Author] ; Erasmus University [Host], 2007. http://hdl.handle.net/1765/10549.
Full textZand, Daniëlle D. van't. "Particles in complex fluids." Thesis, University of Edinburgh, 2010. http://hdl.handle.net/1842/4610.
Full textSu, Wen-Ta. "Electrochemistry in supercritical fluids." Thesis, University of Nottingham, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.537675.
Full textPearc, Daniel John Gaythorne, George Rowlands, and Matthew Simon Turner. "Dynamics in social fluids." Universitätsbibliothek Leipzig, 2015. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-179526.
Full textGibbons, Linda Maria. "Nitration in inert fluids." Thesis, Durham University, 2000. http://etheses.dur.ac.uk/4534/.
Full textBarlow, Stephen J. "Spectroscopy in supercritical fluids." Thesis, University of Nottingham, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.247570.
Full textBarry, Anna M. "Vortex Crystals in Fluids." Thesis, Boston University, 2012. https://hdl.handle.net/2144/31505.
Full textPLEASE NOTE: Boston University Libraries did not receive an Authorization To Manage form for this thesis or dissertation. It is therefore not openly accessible, though it may be available by request. If you are the author or principal advisor of this work and would like to request open access for it, please contact us at open-help@bu.edu. Thank you.
It is common in geophysical flows to observe localized regions of enhanced vorticity. This observation can be used to derive model equations to describe the motion and interaction of these localized regions, or vortices, and which are simpler than the original PDEs. The best known vortex model is derived from the incompressible Euler equations, and treats vortices as points in the plane. A large part of this dissertation utilizes this particular model, but we also survey other point vortex and weakly viscous models. The main focus of this thesis is an object known as the vortex crystal. These remarkable configurations of vortices maintain their basic shapes for long times, while perhaps rotating or translating rigidly in space. We study existence and stability of families of vortex crystals in the special case where N vortices have small and equal circulation and one vortex has large circulation. As the small circulation tends to zero, the weak vortices tend to a circle centered on the strong vortex. A special potential function of this limiting problem can be used to characterize orbits and stability. Whenever a critical point of this function is nondegenerate, we prove that the orbit can be continued via the Implicit Function Theorem, and its linear stability is determined by the eigenvalues of the Hessian matrix of the potential. For general N, we find at least three distinct families of critical points, one of which continues to a linearly stable class of vortex crystals. Because the stable family is most likely to be observed in nature, we study it extensively. Continuation methods allow us to follow these critical points to nonzero weak vortex strength and investigate stability and bifurcations. In the large N limit of this family, we prove that there is a unique one parameter family of distributions which minimize a "generalized" potential. Finally, we use point vortex and weakly viscous vortex models to analyze vortex crystal configurations observed in hurricane eyes and related numerical simulations. We find striking numerical and analytical agreement, thus validating the use of simplified vortex models to describe geophysical phenomena.
2031-01-01
Ramsay, John Andrew. "Mixing of viscoelastic fluids." Thesis, University of Birmingham, 2017. http://etheses.bham.ac.uk//id/eprint/7333/.
Full textIves, Thomas Robert. "Microswimming in complex fluids." Thesis, University of Edinburgh, 2018. http://hdl.handle.net/1842/31225.
Full textPearc, Daniel John Gaythorne, George Rowlands, and Matthew Simon Turner. "Dynamics in social fluids." Diffusion fundamentals 20 (2013) 15, S. 1, 2013. https://ul.qucosa.de/id/qucosa%3A13538.
Full textElwood, Madden Megan Erica. "Fluids in Planetary Systems." Diss., Virginia Tech, 2005. http://hdl.handle.net/10919/28034.
Full textPh. D.
Kang, Kai. "Microfluidics of complex fluids." The Ohio State University, 2003. http://rave.ohiolink.edu/etdc/view?acc_num=osu1064325460.
Full textChilakamarri, Kiran Babu. "Rotating and stratified fluids /." The Ohio State University, 1988. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487584612163036.
Full textSarfraz, Adnan. "Nucleobases in supercritical fluids." Doctoral thesis, Humboldt-Universität zu Berlin, Mathematisch-Naturwissenschaftliche Fakultät I, 2010. http://dx.doi.org/10.18452/16092.
Full textThis work highlights the use of supercritical fluids (SCF) as an analytical tool for the transfer of a group of non-volatile molecules, namely nucleobases, into the gas phase. The most commonly used SCF carbon dioxide was found inefficient in dissolving the nucleobases. Therefore, a mixture of ethylene (p_c = 50.6 bar and T_c = 9.35 C) with a cosolvent was used as the SC solvent. A new bracketing method was developed for detecting the critical point (CP) of pure fluids and diluted mixtures of fluids. The shift in CP of ethylene on addition of ethanol was determined and related to theoretical calculations by using the Soave Redlich Kwong equation of state. Comparing the experimental results to theoretical methods for calculating the CP showed large deviations. The critical temperature shifted by only 5.5 C when the mole fraction of the cosolvent i.e. ethanol was 0.054. Five biologically relevant were dissolved in SC ethylene using 3% of ethanol as cosolvent. The supersonic molecular beam composition of the expanded solution was analyzed quantitatively using a quadrupole mass spectrometer and the ratio of the nucleobases to ethylene in the beam was found to be of the order of 10^-4 to 10^-5. Surface deposition of the nucleobases through SCF solutions was carried out and the morphology was recorded using Atomic Force Microscopy. Remarkable differences were observed while comparing the morphology obtained after deposition using rapid expansion of supercritical solutions (RESS) and drop casting method. These differences are discussed in terms of diffusion, rate of evaporation of the solvent, degree of supersaturation, and the nucleation process.
MARCHISIO, DANIELE. "Precipitation in turbulent fluids." Doctoral thesis, Politecnico di Torino, 2002. http://hdl.handle.net/11583/2550946.
Full textMennad, Abed. "Singular behaviour of Non-Newtonian fluids." Thesis, Peninsula Technikon, 1999. http://hdl.handle.net/20.500.11838/1253.
Full textSince 1996, a team at the Centre for Research in Applied Technology (CRATECH) at Peninsula Technikon, under NRF sponsorship and with industrial co-operation, has been involved in the simulation of Non-Newtonian flow behaviour in industrial processes, in particular, injection moulding of polymers. This study is an attempt to deal with some current issues of Non-Newtonian flow, in small areas, from the viewpoint of computational mechanics. It is concerned with the numerical simulation of Non-Newtonian fluid flows in mould cavities with re-entrant corners. The major complication that exists in this numerical simulation is the singularity of the stresses at the entry of the corner, which is responsible for nonintegrable stresses and the propagation of solution errors. First, the study focuses on the derivation of the equations of motion of the flow which leads to Navier- Stokes equations. Thereafter, the occurrence of singularities in the numerical solution of these equations is investigated. Singularities require special attention no matter what numerical method is used. In finite element analysis, local refinement around the singular point is often employed in order to improve the accuracy. However, the accuracy and the rate of convergence are not, in general, satisfactory. Incorporating the nature of singularity, obtained by an asymptotic analysis in the numerical solution, has proven to be a very effective way to improve the accuracy in the neighborhood of the singularity and, to speed up the rate of convergence. This idea has been successfully adopted in solving mainly fracture mechanics problems by a variety of methods: finite difference, finite elements, boundary and global elements, and spectral methods. In this thesis, the singular finite elements method (SFEM), similar in principle to the crack tip element used in fracture mechanics, is proposed to improve the solution accuracy in the vicinity of the singular point and to speed up the rate of convergence. This method requires minor modifications to standard finite element schemes. Unfortunately, this method could not be implemented in this study due to the difficulty in generating the mesh for the singular element. Only the standard finite element method with mesh refinement has been used. The results obtained are in accordance with what was expected.
Lewerentz, Alexander. "Fluid-induced alteration of metasedimentary rocks in the Scottish Highlands." Doctoral thesis, Stockholms universitet, Institutionen för geologiska vetenskaper, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-146121.
Full textStora volymer H2O och CO2 frigörs som fluider under prograd metamorfos. Metamorfa fluider har lägre densitet än det omgivande berget, varför de stiger genom jordskorpan mot jordytan. Metamorfa fluider kanaliseras i permabla lager, skjuvzoner, veckaxlar, sprickor och andra högflödeszoner. Kanaliserade fluidflöden kan vara flera storleksordningar högre än bakgrundsvärdet för fluidflöde inom en bergart. Metamorfa fluider reagerar under transport med det omgivande berget och bildar fluidomvandlade zoner i anslutning till högflödeskanaler. Fluidomvandlat berg uppvisar texturella, mineralogiska, kemiska och isotopsammansättningsmässiga skillnader i jämförelse med berg som inte utsatts för fluidomvandling. I denna avhandling behandlas reaktioner mellan fluid och berg som studerats i två lokaler i de skotska högländerna: Glen Esk och Islay. Glen Esk är en av de typlokaler som George Barrow (1853-1932) använde för att lägga fram konceptet om metamorfa zoner och metamorfa indexmineral som används för att ungefärligt uppskatta metamorf grad. I flera av de metamorfa zonerna är förekomsten av indexmineral i hög grad beroende av närhet till kvartsådror, vilket visar att bildandet av indexmineral inte bara styrs av tryck och temperatur, utan också av åtkomst till metamorfa fluider. I Glen Esk finns också spår av ett fluidflöde från North Esk-förkastningen, under retrograda metamorfa förhållanden, för vilket mededfluidflödet över tid uppgår till 0.0003 – 0.0126 m3∙m-2∙år-1. Denna fluidflödeshändelse beräknas ha pågått mellan 16 000 och 334 000 år. På ön Islay i de sydvästra högländerna återfinns bergarter, som trots sin låga metamorfa grad i klorit- eller biotitzonen innehåller mineralet kyanit, dvs. temperaturer långt under vad som vanligen associeras med kyanitbildning. Detta förklaras med infiltration av fluider med extremt hög CO2-halt, åtminstone lokalt så högt som XCO2 > 0.7, vid ca. 340°C. Fluidomvandling av dessa bergarter stabiliserade kyanit tillsammans med karbonatmineral. Syre- och kolisotopprofiler över Islayantiklinen påvisar hög kanalisering av fluider längs dess veckaxeln. Förhållandet mellan fluid och berg var mer än fyra gånger så högt i närheten av veckaxeln jämfört lokaler längre ifrån densamma. Påverkan av metakarbonatbergarters isotopförhållanden har skett längs Islayantiklinen, men fluidpåverkan kan inte ensamt förklara de isotopanomalier som observerats under och ovan Port Askaig-tilliten, varför dessa bergarter kan ha bibehållit sin primära paleoklimatologiska isotopsignatur.
At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 2: Submitted. Paper 3: Manuscript.
Anselme, Marc Joseph. "The critical properties of thermally stable and unstable fluids and dilute fluid mixtures." Diss., Georgia Institute of Technology, 1988. http://hdl.handle.net/1853/11778.
Full textGötz, Dario [Verfasser]. "Three topics in fluid dynamics: Viscoelastic, generalized Newtonian, and compressible fluids / Dario Götz." München : Verlag Dr. Hut, 2012. http://d-nb.info/1029400113/34.
Full textIvakhnenko, Oleksandr Petrovych. "Magnetic analysis of petroleum reservoir fluids, matrix mineral assemblages and fluid-rock interactions." Thesis, Heriot-Watt University, 2006. http://hdl.handle.net/10399/140.
Full textBattaglini, Neusa Maria Pavão. "Avaliação do comportamento de impelidores especiais na mistura de fluidos /." Botucatu : [s.n.], 1998. http://hdl.handle.net/11449/101864.
Full textResumo: Fluidos de viscosidade entre 0,874 10-3 e 787 10-3 N m s-2 foram agitados pelos impelidores tipos âncora convencional, âncora modificada, fita helicoidal e parafuso em tanques cilíndricos de fundos reto e toroesférico para determinação da potência requerida e do tempo de mistura. Na agitação efetuada com os impelidores centrados houve o aparecimento de vórtices em algumas rotações. As medidas de potência foram efetuadas na região em que o número de Reynolds (NRe ) variou de 16 a 70.000 com a âncora convencional e modificada. Os diagramas do número de potência( ) P N em função do número de Reynolds, construídos com os dados experimentais, mostraram que, para todos os fluidos usados, ocorreu um desvio na curva quando o vórtice, formado na superfície do fluido, alcançou os impelidores e teve início a dispersão de ar no interior da massa fluida. A presença de bolhas de ar desenvolveu, no tanque, um sistema de duas fases (líquido-gás), alterando as características dos fluidos agitados. Nos cálculos do número de potência e do número de Reynolds foram utilizados os valores de viscosidade e densidade do fluido, e não os correspondentes ao sistema líquido-gás o que provocou, provavelmente, o desvio nas curvas. Na região em que o número de Reynolds fica entre 16 e 300 não houve formação de vórtices acentuados com aeração e a curva foi definida pela correlação ( )a NP A NRe = , onde A é função do tipo de impelidor e das dimensões do vaso e o expoente a, um valor empírico que varia com o número de Reynolds obtendo a relação ( )1,7 Re N = 19.953 N − P . O desempenho dos impelidores na homogeneização foi analisado pela energia requerida para se obter uma mistura de açúcar e água com concentrações correspondentes a 40 e 60o Brix. O método desenvolvido foi baseado na verificação...(Resumo completo, clicar acesso eletrônico abaixo)
Abstract: Fluids with viscosity between (0,874 and 787 10-3 Nm s-2 were agitated by conventional anchor, modified anchor, helicoidal ribbon and screw impellers in cilindric tanks straight and concave (torospheric) bottoms for the measurement of power and time of mixture. The arisal of vortex occurred when agitation was accomplished with centred impellers and in some rotations. The measures of power were obtained in the interval where the number of Reynolds (NRe) varied from 16 to 70.000 with conventional and modified anchor. The diagrams of number of Reynolds in function of number of Froude constructed with experimental data showed that, to all fluids employed, a deflection in the curve occurred when the vortex formed at the surface of the fluid reached the impellers and the dispersion of air inside the fluid mass started. The presence of air bubbles develops in the tank a system of two phases altering the characteristics of the agitated fluids. In the calculations of the number of Reynolds were used the values of the fluid viscosity and density and not ones corresponding to the liquid-gas system, provoking a deflection in the curves. In the interval where the number of Reynolds remains between 16 and 300 the formation of a well developed vortex with aeration did not occur and the curve was defined by the correlation A N = ANRE Re , where A is function of the type of the impeller and of the dimensions of the tank, and the exponent a, an empirical value, varies with the number of Reynolds. The performance of the impellers in the homogenization was analysed in terms of the energy required in order to obtain a mixture...(Complete abstract click electronic access below)
Doutor
Domurath, Jan. "Stress and strain amplification in non-Newtonian fluids filled with spherical and anisometric particles." Thesis, Lorient, 2017. http://www.theses.fr/2017LORIS478/document.
Full textA numerical study of dilute suspensions based on a non-Newtonian matrix fluid and rigid spheroidal particles is performed. A Carreau fluid describes the non-Newtonian matrix. The special case of rigid spherical particles is considered. Here, a uniaxial elongational flow around a sphere is simulated and numerical homogenization is used to obtain the bulk viscosity of the dilute suspension for different applied rates of deformation and different thinning exponents. In the Newtonian regime the well-known Einstein result for the viscosity of a dilute suspension of rigid spherical particles is obtained. In the power-law regime it is found that the intrinsic viscosity depends only on the thinning exponent. Utilizing the simulation results a modification of the Carreau model for dilute suspensions with a non-Newtonian matrix fluid is proposed. To investigate the influence of the particle shape another numerical study is performed. In particular, different flows around spheroidal particles with different orientations are simulated and numerical homogenization is used to obtain the intrinsic viscosity of the suspension as function of applied rate of deformation, thinning exponent and aspect ratio. From the results it is possible to extract the rheological coefficients of the Lipscomb model. In the Newtonian regime the simulation results coincide with Lipscomb’s predictions. In the power-law regime the rheological coefficients depend strongly on the thinning exponent. Furthermore, simulation results indicate that the rheological coefficients additionally depend on the particle orientation in the non-linear regime
Georgeton, Gus Konstantinos. "Group contribution equations of state for complex fluid mixtures." Diss., Georgia Institute of Technology, 1987. http://hdl.handle.net/1853/11772.
Full textDomurath, Jan. "Stress and strain amplification in non-Newtonian fluids filled with spherical and anisometric particles." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2018. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-233044.
Full textUne étude numérique sur des suspensions diluées à base d’un fluide non newtonien et de particules sphéroïdales rigides est réalisée. Le comportement de la matrice est décrit par un fluide de type Carreau. De particules sphériques et rigides est considéré en premier. Un écoulement en élongation uniaxiale autour d’une sphère est simulée. Ensuite, l’homogénéisation numérique est utilisée pour déterminer la viscosité apparente de la suspension pour différents taux de déformation et d’indices pseudoplastiques. Dans le domaine newtonien, le résultat d’Einstein donnant la viscosité d’une suspension diluée de particules sphériques et rigides est obtenu. Dans le régime en loi de puissance on constate que la viscosité intrinsèque dépend uniquement de l’indice pseudoplastique. Une autre étude numérique est effectuée pour investiguer l’influence de la forme des particules. Plusieurs écoulements autour d’une particule sphéroïdale sont simulés pour différentes orientations. Une homogénéisation numérique est ensuite utilisée pour obtenir la viscosité intrinsèque de la suspension en fonction du taux de déformation appliqué, de l’indice d’écoulement et du rapport de forme de la particule. A partir de ces résultats, il est possible d’exprimer les coefficients rhéologiques du modèle de Lipscomb. Dans le régime newtonien, les résultats coïncident avec les prédictions de Lipscomb. Dans le domaine en loi de puissance, les coefficients rhéologiques deviennent fortement dépendent de l’indice pseudoplastique. En outre, les résultats des simulations montrent que ces coefficients rhéologiques dépendent également de l’orientation des particules dans le régime non linéaire
Numerische Untersuchung zu verdünnten Suspensionen basierend auf einer nicht Newtonschen Matrixflüssigkeit und harten spheroidalen Partikeln wurde durchgeführt. Ein Carreau Fluid beschreibt die nicht Newtonsche Matrix. Zuerst wird der Spezialfall harter Kugeln betrachtet. Hierzu wird eine uniaxiale Dehnströmung um eine Kugel simuliert und numerische Homogenisierung wird verwendet um die effektive Viskosität der Suspension für verschieden aufgebrachte Deformationsgeschwindigkeiten und Verdünnungsexponenten zu bestimmen. Im Newtonschen Bereich wird die bekannte Lösung Einsteins für die Viskosität einer verdünnten Suspension harter Kugeln erhalten. Im power-law Bereich ist die intrinsische Viskosität einzig eine Funktion des Verdünnungsexponenten. Unter Nutzung der Simulationsergebnisse wird eine Modifikation des Carreau Modells vorgeschlagen. Um den Einfluss der Partikelform auf die nichtlinearen Eigenschaften zu untersuchen wird eine weitere numerische Simulationen durchgeführt. Dabei werden verschiedene Strömungen um spheroidale Partikel mit unterschiedlicher Orientierung simuliert und numerische Homogenisierung wird verwendet um die intrinsische Viskosität als Funktion der aufgebrachten Deformationsgeschwindigkeit, des Verdünnungsexponenten und des Partikelaspektverhältnisses zu bestimmen. Es ist möglich die rheologischen Parameter des Lipscomb Modells aus den Simulationsergebnissen zu bestimmen. Im Newtonschen Bereich stimmen die numerisch bestimmten Werte mit der Vorhersage Lipscomb‘s überein. Im power-law Bereich hängen die rheologischen Parameter stark vom Verdünnungsexponenten ab. Weiter kann man aus den Ergebnissen auf eine zusätzliche Abhängigkeit der rheologischen Parameter von der Partikelorientierung schließen