Дисертації з теми "Non-Newtonian dynamics"
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BAZZI, MARISA SCHMIDT. "BREAKUP DYNAMICS OF NON-NEWTONIAN THIN LIQUID SHEETS." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2018. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=34574@1.
COORDENAÇÃO DE APERFEIÇOAMENTO DO PESSOAL DE ENSINO SUPERIOR
FUNDAÇÃO DE APOIO À PESQUISA DO ESTADO DO RIO DE JANEIRO
PROGRAMA DE EXCELENCIA ACADEMICA
BOLSA NOTA 10
Filmes finos de líquidos estão presentes em uma gama de aplicações industriais, como processos de atomização e revestimento de substrato. O processo de quebra pode ser divido em duas etapas: o estágio de ruptura, e o estágio de retração. O primeiro, movido pelas forças de van der Waals, ocorre quando uma pequena perturbação cresce e provoca o aparecimento de um pequeno furo no filme. O segundo, movido por forças capilares, provoca o crescimento desse furo levando à desintegração do filme de líquido. A estabilidade de uma cortina de líquido depende das características da perturbação, da espessura do filme e das propriedades do fluido. Análises experimentais mostraram que uma cortina super fina pode ser obtida pela utilização de fluidos viscoelásticos. Os mecanismos físicos associados à esta estabilidade, contudo, não são totalmente compreendidos. Este trabalho apresenta um estudo numérico e teórico dos efeitos das propriedades viscoelásticas na estabilidade de uma cortina de fluido, englobando ambos os estágio do processo. As análises numéricas foram desenvolvidas através da expansão assintótica das variáveis do escoamento com aplicação de um esquema de integração no tempo totalmente implícito. A partir da análise teórica da dinâmica de ruptura foi possível obter um critério de estabilidade linear para perturbações planares e axissimétricas em fluidos Newtonianos e não-Newtonianos. O tempo de ruptura e a velocidade de retração do filme foram calculados numericamente como função das propriedades viscoelásticas do líquido. Resultados mostraram que as forças elásticas atuam de forma a dificultar o processo de quebra e retração. Análises da evolução da espessura mostraram que as propriedades reológicas do fluído também interferem no formato que o filme de fluido assume durante o processo de retração. Para regimes de baixa viscosidade, as forças elásticas atuaram evitando a formação de ondas capilares observadas em fluidos Newtonianos.
Thin free liquid sheets are ubiquitous in many industrial processes, such as atomization and curtain coating. Liquid sheets are susceptible to instabilities at the interface, which can grow, triggering a breakup process. This process can be divided into two different stages: the rupture stage and retraction. The first, driven by van der Waals force, occurs when a small instability grows until it pinches-off the sheet. The second, driven by capillary forces, induces the growth of the hole caused by the pinch-off, leading to the full disintegration of the liquid sheet. The stability of a liquid sheet depends on disturbance characteristics, sheet thickness, and fluid properties. Experimental analyses have shown that thinner stable liquid curtain can be obtained with viscoelastic liquids. The underlyning physical mechanisms associated with increased stability are, however, not fully understood. This work presents a theoretical and numerical analysis of the effect of viscoelasticity on the stability of a thin liquid sheet during both stages of the breakup process. We first analyze the rupture dynamics, deriving linear stability criteria for both planar and axisymmetric perturbations of Newtonian and Oldroyd-B liquids. The time evolution of planar and axisymmetric perturbations in an Oldroyd-B liquid sheet is evaluated using the asymptotic expansion of the flow variables and a fully-implicit time integration scheme. The rupture time and retraction velocity are calculated as a function of the viscoelastic properties. The results show that the liquid rheological behavior does not influence the linear stability criterion. Nevertheless, it has a strong effect on the growth rate of the disturbance and retraction velocity, increasing, thus, the breakup time. The results show that elastic forces act to hinder the rupture and retraction stages. Analysis of the temporal evolution of the thickness profile reveals that liquid rheological behavior also affects the shape of the liquid sheet. For low viscosity regime, the elastic forces damp the capillary waves that arise during the retraction of Newtonian sheets.
Chakraborty, Symphony. "Dynamics and stability of a non-Newtonian falling film." Phd thesis, Université Pierre et Marie Curie - Paris VI, 2012. http://tel.archives-ouvertes.fr/tel-00828305.
Pachmann, Sydney. "Swimming in slime." Thesis, University of British Columbia, 2008. http://hdl.handle.net/2429/1503.
RIBEIRO, GERALDO AFONSO SPINELLI MARTINS. "DYNAMICS OF RELATIVE MOTION BETWEEN SOLID PARTICLES AND NON-NEWTONIAN FLUIDS." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 1987. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=19130@1.
Este trabalho descreve experimentos relacionamentos com o movimento relativo entre partículas sólidas e fluido não-newtoniano, confinados no interior de um duto circular. Medições da pressão dinâmica adicional, devida unicamente à presença da partícula (fonte de perturbação no escoamento) e do arrasto viscoso foram conduzidas de forma a se verificar a validade da Teoria de Brenner (1962). Esta teoria, já confirmada para fluidos newtonianos, permite que parâmetros característicos do escoamento perturbado sejam determinados, convenientemente, através de parâmetros do escoamento não-perturbado (ausência de partícula). Para o caso de fluido não-newtoniano, denominados puramente viscosos, do tipo Power-law, a teoria se mostrou perfeitamente aplicável. O valor da razão Delta P mais A/D descrito por Brenner foi confirmado com uma precisão de 3 por cento, num total de 70 experimentos realizados. Para fluidos não-newtonianos, viscoelásticos, com função viscosidade tipo Power-law, a validade da teoria parece, entretanto, depender de um parâmetro capaz de descrever na natureza constitutiva do fluido utilizado. Experimentos realizados com três diferentes fluidos viscoelásticos (expoentes power-law n igual 0,303; 0,343; 0,483) conduziram à identificação deste parâmetro, o Segundo Número Elástico, El2. Para valores de El2, inferiores a 14, caracterizando um escoamento predominantemente viscoso, o valor da razão Delta P mais A/D novamente é confirmado com precisão inferior a 4 por cento. Para valores de El2 superiores a 40 a razão Delta P mais A/D não mais pode ser avaliada com base em parâmetros do escoamento perturbado, analogamente ao que havia sido proposto por Brenner para o caso de fluidos newtonianos. Neste trabalho incluem-se também registros contínuos dos experimentos enfatizando os efeitos viscoelásticos envolvidos, bem como uma análise dos efeitos de parede associados ao movimento relativo entre fluidos não-newtonianos e partículas sólidas. Todos os experimentos foram realizados num regime de Reynolds variando de 0,1 a 90 e num regime de Weissenberg (calculando com base no modelo de Powell-Eyring) variando de 850 a 3800.
This work describes experiments related to relative motion between solid particles and mon-newtonian fluid, inside a circular duct. Measurements of the aditional dynamic pressure, due to the presence of the particle (a source of disturbance in the flow) ando f the viscous drag, were conducted to verify the validity of Brenner’s Theory (1962). This theory, already confirmed for newtonian fluids, allows the determination of the characteristic parameters of the disturbed flow using parameters of non-disturbed flow (without particle). In the case of purely viscous non-newtonian fluids, of the power-law type, the theory was confirmed. The value of the ratio Delta P plus A/D, described by Brenner, was confirmed. The value an accuracy of 3 per cent, in a total of 70 experiments. For viscoelastic fluids, with Power-law viscosity function, it appears that the validity of the theory depends on the Second Elastic Number, El2. Experiments conducted with three different viscoelastic fluids (power-law exponents, n equal 0,303; 0,343 and 0,483) shows that for values of El2 bellow 14, which characterizes a predominantly viscous flow, the value of of the ratio Delta P plus A/D is agair confirmed, with na accuracy of 4 per cent. For values of the El2, parameter above 40, the ratio Delta P plus A/D cannot be determined using parameters of the non-disturbed flow, as proposed by Brenner for newtonian fluids. In this work are also included graphic registers of the experiment, showing the complex viscoelastic effects, as well as na analysis of the wall effects associated with the relative motion between non- newtonian fluid and solid particles. All the experiments were conducted with Reynolds number between 0,1 and 90 and a Weissenberg number (based in Powell-Eyring model) between 850 and 38.00.
Vera, Vidal Camila Constanza. "Analysis of cooling effects and non-Newtonian rheology on lava flow dynamics." Tesis, Universidad de Chile, 2018. http://repositorio.uchile.cl/handle/2250/169867.
Memoria para optar al título de Geóloga
La actividad volcanica representa una gran amenaza para la propiedad privada, comunidades y habitantes ubicados en las cercanias de centros volcanicos. La volcanologia y mecanica de fluidos se utilizan en conjunto con el fin de estudiar la evolucion de los flujos de lava. Nos enfocamos en el estudio de flujos de lava simples y viscosos, de composiciones andesitica hasta riolitica, para determinar la relevancia de la evolucion reologica del flujo en tiempos de emplazamiento, distancias, y proporciones finales. Los experimentos analogos han sido una herramienta util en previos estudios de flujos de lava. Para este trabajo se caracterizo el manjar, un derivado de la leche, para utilizarlo como material analogo de lava viscosa con una reologia dependiente de la temperatura. Los experimentos simularon un flujo no confinado simple sobre una superficie inclinada, en el Laboratorio de Volcanologia Experimental del Laboratoire de Magmas et Volcans, Clermont-Ferrand, Francia. Un total de 33 experimentos de extrusiones puntuales sobre una superficie inclinada, con caudales desde 1 $ (cc/s) $ a 25 $ (cc/s) $, con inclinaciones entre 10$^\circ$ - 15$^\circ$, y diferentes temperaturas iniciales desde ambiente hasta 71\textcelsius{}. Cada experimento fue grabado con camara visual y camara termica, con los cuales se pudo obtener la evolucion termica y las distancias en el tiempo a las que avanzaba cada flujo. Se utilizo python para obtener la base de datos de temperatura, y bibliotecas especificas para manejar, procesar y visualizar datos, tales com matplotlib, scipy y pandas. Los resultados indican que la formacion de una pseudo corteza en los flujos de manjar que estan sujetos a enfriamiento, controlan las distintas dimensiones y tiempos de emplazamiento obtenidos para los flujos estudiados, mientras que los cambios de pendiente tambien juegan un rol importante en estos resultados. La existencia de esta pseudo corteza esta basada en la perdida de agua presente en el manjar, asi como tambien en la buena correlacion existente que muestra el numero de Graetz con las diferentes dimensiones obtenidas, que dependen de la tasa efusiva, la escala de tiempo de extrusion, y por ende el desarrollo de esta corteza obtenida segun estimaciones basadas en la difusividad termica del material. Mayores caudales presentan flujos mas anchos con menores espesores, mientras que menores caudales se desarrollan de manera vertical, teniendo menor expansion areal y mayores espesores. Mayores pendientes resultan en flujos que se desarrollan principalmente pendiente abajo, con distancias de $ X_{min} $ e $ Y_{max} $ menores. Por otro lado, la comparacion entre flujos sujetos a enfriamiento versus flujos en condiciones isotermales, tambien apoyan la teoria de existencia de una pseudo corteza que controla la dinamica de flujo. Los modelos DEM realizados presentan caracteristicas similares a las presentes en flujos de lava, con zonas de menor espesor cerca del punto extrusivo, seguido por un posible canal central entre estructuras tipo levee que culminan en un frente de flujo de gran espesor, presentando la mayor potencia del flujo. Este frente de flujo inflado, consideramos que es evidencia de que existe una pseudo corteza que contiene material con mayor movilidad en su interior. Los perfiles de temperatura de termocuplas y FLIR, tambien muestran como existe un perfil termal vertical en los flujos, con altas temperaturas en porciones internas luego de que todo el material ya ha sido extruido, mientras la superficie del flujo presenta menores temperaturas.
Aggarwal, Nishith. "Computational viscoelastic drop dynamics and rheology." Access to citation, abstract and download form provided by ProQuest Information and Learning Company; downloadable PDF file, 122 p, 2008. http://proquest.umi.com/pqdweb?did=1456285651&sid=2&Fmt=2&clientId=8331&RQT=309&VName=PQD.
Cordonnier, Benoît. "Non-Newtonian effects in silicate liquids and crystal bearing melts : implication for magma dynamics." kostenfrei, 2009. http://edoc.ub.uni-muenchen.de/10647/.
Tshilumbu, Nsenda Ngenda. "The effect of type and concentration of surfactant on stability and rheological properties of explosive emulsions." Thesis, [S.l. : s.n.], 2009. http://dk.cput.ac.za/cgi/viewcontent.cgi?article=1063&context=td_cput.
Hodson, Alistair. "A non-Newtonian perspective of gravity : testing modified gravity theories in galaxies and galaxy clusters." Thesis, University of St Andrews, 2017. http://hdl.handle.net/10023/12016.
Shu, Yupeng. "Numerical Solutions of Generalized Burgers' Equations for Some Incompressible Non-Newtonian Fluids." ScholarWorks@UNO, 2015. http://scholarworks.uno.edu/td/2051.
Nyekwe, Ichegbo Maxwell. "Investigation of factors effecting yield stress determinations using the slump test." Thesis, Cape Peninsula University of Technology, 2008. http://hdl.handle.net/20.500.11838/2160.
Certain non-Newtonian fluids exhibit a yield stress which can be measured with a variety of instruments varying from very sophisticated rotary and tube viscometers to hand-held slump cones and cylinders of various sizes. Accurate yield stress measurement is significant for process design and disposal operations for thickenend tailings. The slump value was first related to the yield stress by Murata (1984). Later, that work was corrected by Christensen (1991) for an error in the mathematical analysis. Slump, based on a circular cylindrical geometry was first investigated by Chandler (1986). These concepts led to the study by Pashias et al., (1996) that formed the basis for the current research. The Flow Process Research Centre (FPRC) at the Cape Peninsula University of Technology developed a slump meter designed to lift the cone or cylinder vertically at controlled lifting speeds. In addition the simple hand-held cylinder which is an adaptation of slump cones which were originally developed by the concrete industry to determine the flowability of fresh concrete was also used. The vane technique was used as a control. Cones and cylinders made of stainless steel and PVC were fitted to the slump meter. The yield stresses of four non-Newtonian fluids at different concentrations were tested in four different configurations at different lift speeds to ascertain whether the measuring position, lift speed, slip, geometry, wall surface material, and stability has an effect on the value of yield stress measured. The effect of different predictive models was also ascertained.The cylinder, lump and cone models relating slump to yield stress was used in the dimensional analysis of the results. The objective of this work was to determine if the slump tests (cone, cylinder and the hand-held cylinder) would generate yield stress values comparable to those found using the vane technique. It was establised that there was no significant effect of lift speed, stability, geometry and wall surface material on the value of yield stress. The effect of measuring position on the value of yield stress calculated gave a difference of 25%. Using dimensional analysis, the lump model (Hallbom, 2005) more accurately predicts the material yield stress when using the hand-held cylinder as well as all the cone results (due to its specific geometry), and cylinder configurations, thus affirming the work of Clayton et al., 2003. It is concluded that, although the materials and concentrations tested induced errors within 40%, the hand-held cylinder shows promise as a reliable, quick and simple way of measuring the yield stress.
Chadwick, Kenneth Michael. "An experimental investigation of the breakup of a viscoelastic non-newtonian fluid in a supersonic stream." Thesis, Virginia Tech, 1990. http://hdl.handle.net/10919/42082.
Sridharan, Harini. "COUPLED DYNAMICS OF HEAT TRANSFER AND FLUID FLOW IN SHEAR RHEOMETRY." University of Akron / OhioLINK, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=akron1597346164780318.
Koronias, George. "Elastomultibody dynamics of RWD axle whine phenomena." Thesis, Loughborough University, 2012. https://dspace.lboro.ac.uk/2134/9721.
Lashgari, Iman. "Stability analysis and inertial regimes in complex flows." Doctoral thesis, KTH, Fysiokemisk strömningsmekanik, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-177850.
QC 20151127
Tran-Canh, Dung. "Simulating the flow of some non-Newtonian fluids with neural-like networks and stochastic processes." University of Southern Queensland, Faculty of Engineering and Surveying, 2004. http://eprints.usq.edu.au/archive/00001518/.
Cloete, Maret. "Modelling of non-Newtonian fluid flow through and over porous media with the inclusion of boundary effects." Thesis, Stellenbosch : Stellenbosch University, 2013. http://hdl.handle.net/10019.1/80240.
ENGLISH ABSTRACT: Different generalized Newtonian fluids (where the normal stresses were neglected) were considered in this study. Analytical expressions were derived for time independent, fully developed velocity profiles of Herschel-Bulkley fluids (including the simplifications thereof: Newtonian, power law and Bingham plastic fluids) and Casson fluids through open channel sections. Both flow through cylindrical pipes (Hagen-Poiseuille flow) and parallel plates (plane Poiseuille flow) were brought under consideration. Equations were derived for the wall shear stresses in terms of the average channel velocities. These expressions for plane Poiseuille flow were then utilized in the modelling of flow through homogeneous, isotropic porous media. Flow through parallel plates was extended and a possibility of a moving lower wall (plane Couette-Poiseuille flow) was included for Herschel-Bulkley fluids (and the simplifications thereof). The velocity of the wall was assumed to be opposite to the pressure gradient (thus in the streamwise direction) yielding three different possible flow scenarios. These equations were again revisited in the study on flow over porous structures. Averaging of the microscopic momentum transport equation was carried out by means of volume averaging over an REV (Representative Elementary Volume). Flow through parallel plates enclosing a homogeneous porous medium (assumed homogeneous up to the external boundary) was studied at the hand of Brinkman’s equation. It was as- sumed (also for non-Newtonian fluids) that the term dominating outside the external boundary layer area is directly proportional to the superficial velocity that is, since only the viscous flow regime was considered, referred to as the ‘Darcy’ velocity if the diffusive Brinkman term is completely neglected. For a shear thinning or shear thickening fluid, the excess superficial velocity term was included in the proportionality coefficient that is constant for a particular fluid traversing a particular porous medium subjected to a specific pressure gradient. For such fluids only the inverse functions could be solved. If the ‘Darcy’ velocity is not reached within the considered domain, Gauss’s hypergeo- metric function had to be utilized. For Newtonian and Bingham plastic fluids, direct solutions were obtained. The effect of the constant yield stress was embedded in the proportionality coefficient. For linear flow, the proportionality coefficient consists of both a Darcy and a Forch- heimer term applicable to the viscous and inertial flow regimes respectively. Secondary averaging for different types of porous media was accomplished by using an RUC (Representative Unit Cell) to estimate average interstitial properties. Only homoge- neous, isotropic media were considered. Expressions for the apparent permeability as well as the passability in the Forchheimer regime (also sometimes referred to as the non-Darcian permeability) were derived for the various fluid types. Finally fluid flow in a domain consisting of an open channel adjacent to an infinite porous domain is considered. The analytically derived velocity profiles for both plane Couette- Poiseuille flow and the Brinkman equation were matched by assuming continuity in the shear stress at the porosity jump between the two domains. An in-house code was developed to simulate such a composite domain numerically. The difference between the analytically assumed constant apparent permeability in a macro- scopic boundary layer region as opposed to a dependency of the varying superficial velocity was discussed. This code included the possibility to alter the construction of the domain and to simulate axisymmetrical flow in a cylinder.
AFRIKAANSE OPSOMMING: Verskeie veralgemeende Newtoniese vloeistowwe (waarvan die normaalspannings ignoreer- baar is) word in hierdie studie beskou. Analitiese uitdrukkings vir tyd-onafhanklike, ten volle ontwikkelde snelheidsprofiele vir Herschel-Bulkley vloeistowwe (wat die vereen- voudigde weergawes daarvan insluit: Newtoniese, magswet- en Bingham-plastiek vloei- stowwe), sowel as Casson vloeistowwe, is afgelei vir vloei deur ‘n oop kanaal. Beide vloei deur silindriese pype (Hagen-Poiseuille vloei) en parallelle plate (vlak-Poiseuille vloei) is oorweeg. Vergelykings vir die skuifspannings op ‘n wand in terme van die gemiddelde snelhede is afgelei. Hierdie uitdrukking wat vir vlak-Poiseuille vloei verkry is, is in die modellering van vloei deur homogene, isotropiese poreuse media ook gebruik. Vloei deur parallelle plate is uitgebrei en die moontlikheid van ‘n bewegende onderste wand (vlak-Couette-Poiseuille vloei) is ondersoek vir Herschel-Bulkley vloeistowwe (en die vereenvoudigings daarvan). Dit word aangeneem dat die snelheid van die wand in die teenoorgestelde rigting as die drukgradiënt georiënteer is (dus in die stroomgewyse rigting) wat dan tot drie verskillende moontlike vloeigevalle lei. Hierdie vergelykings is weer in die studie van vloei oor poreuse strukture gebruik. Die gemiddelde van die mikroskopiese momentum transportvergelyking is bereken oor die volume van ‘n REV (“Representative Elementary Volume”). Vloei deur parallelle plate wat ‘n homogene poreuse medium omsluit (waar die medium homogeen aanvaar word tot by die eksterne grens) is bestudeer aan die hand van Brinkman se vergelyking. Daar is aanvaar (ook vir nie-Newtoniese vloeistowwe) dat die dominante term buite die eksterne grenslaaggebied direk eweredig is aan die oppervlaksnelheid en, aangesien slegs vloei in die viskeuse gebied oorweeg word, daarna verwys word as die “Darcy”- snelheid, indien die diffusiewe Brinkman-term heeltemal weglaatbaar is. Vir ‘n span-ningsverdunnende of -verdikkende vloeistof, word die oortollige oppervlaksnelheidsterm ingesluit by die proporsionaliteitskoëffisiënt wat konstant is vir ‘n spesifieke vloeistof wat deur ‘n sekere poreuse medium, onderhewig aan ‘n spesifieke drukgradiënt, vloei. Vir sulke vloeistowwe kon slegs die inverse funksies opgelos word. As die “Darcy”- snelheid nie binne die betrokke gebied bereik word nie, is daar van Gauss se hipergeometriese funksie gebruik gemaak. Vir Newtoniese en Bingham-plastiek vloeistowwe is egter direkte oplossings verkry. Die effek van die konstante toegeespanning is ingebed in die proporsionaliteitskoëffisiënt. Vir lineêre vloei bestaan die proporsionaliteitskoëffisiënt uit beide ‘n Darcy- en ‘n Forch- heimer-term wat van toepassing is in die viskeuse- en traagheidsvloeigebiede onder- skeidelik. Sekondˆere gemiddeldes vir verskillende tipes poreuse media is verkry; deur gebruik te maak van ‘n RUC (“Representative Unit Cell”) kan interstisiële gemiddelde eienskappe geskat word. Slegs homogene, isotrope media is in oorweging gebring. Uit- drukkings vir die o¨enskynlike deurlaatbaarheid sowel as die deurdringbaarheid in die Forchheimer-gebied (ook soms na verwys as die nie-Darcy deurlaatbaarheid) is afgelei vir die verskillende vloeistoftipes. Ten slotte is vloeistofvloei in ‘n gebied wat bestaan uit ‘n oop kanaal aangrensend aan ‘n oneindige poreuse domein ondersoek. Die analities-afgeleide snelheidsprofiele vir beide vlak-Couette-Poiseuille vloei en die Brinkman-vergelyking is gekoppel deur ‘n kontinu¨ıteit in die skuifspanning by die poreuse-sprong tussen die twee gebiede te aanvaar. ‘n Interne numeriese kode is ontwikkel om so ‘n saamgestelde domein numeries te simuleer. Die verskil tussen die analities konstant-aanvaarde deurlaatbaarheid in ‘n makroskopiese grenslaagstreek, eerder as ‘n afhanklikheid met die veranderende opper- vlaksnelheid, is bespreek. Hierdie kode sluit ook die moontlikheid in om die domein te herkonstrueer, asook om die simulasie van aksiaal-simmetriese vloei in ‘n silinder te ondersoek.
Ravi, Vishaul. "Effects of Interfacial and Viscous Properties of Pure Liquids and Polymeric Solutions on Drop Spread Dynamics." University of Cincinnati / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1331300235.
Hopkins, Alan John. "Computer simulation studies of dense suspension rheology : computational studies of model sheared fluids : elucidation, interpretation and description of the observed rheological behaviour of simple colloidal suspensions in the granulo-viscous domain by non-equilibrium particulate dynamics." Thesis, University of Bradford, 1989. http://hdl.handle.net/10454/4408.
Ahlkrona, Josefin. "Computational Ice Sheet Dynamics : Error control and efficiency." Doctoral thesis, Uppsala universitet, Avdelningen för beräkningsvetenskap, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-283442.
eSSENCE
Casey, David Michael. "Characterization of Transition to Turbulence for Blood in an Eccentric Stenosis Under Steady Flow Conditions." University of Akron / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=akron1418066674.
Rundora, Lazarus. "Laminar flow in a channel filled with saturated porous media." Thesis, Cape Peninsula University of Technology, 2013. http://hdl.handle.net/20.500.11838/1306.
The flow of reactive viscous fluids in porous media presents a theoretically challenging problem and has a broad range of scientific, technological and engineering applications. Real life areas where such flow systems are encountered include drying of food, geothermal energy extraction, nuclear waste disposal, the flow of heat and fluid inside human organs, insulation of buildings, groundwater movement, oil and gas production, astrophysical plasmas, magnetohydrodynamic (MHD) pumps and generators, metal extraction and granulation of metals, aerospace and ship propulsion and automobile exhaust systems. The reactions within such flow systems are inherently exothermic. It is in this view that we carry out studies of thermal effects and thermal stability criteria for unsteady flows of reactive variable viscosity non-Newtonian fluids through saturated porous media. The study focuses on non-Newtonian fluids mainly because the majority of industrial fluids exhibit non-Newtonian character. Particular focus will be on fluids of the differential type exemplified by third grade fluid. Both analytical and numerical techniques were employed to solve the nonlinear partial differential equations that were derived from the conservation principles, namely the principles of conservation of mass, momentum and energy balance. Graphical representations were adopted in trying to explain the response of solutions to various flow parameter variations. In chapter 1 we defined important terms and expressions, laid down a summary of important applications, carried out literature survey, stated the statement of the problem, the aims and objectives of the study as well as an outline of the envisaged research methodology. Chapter 2 focuses on the derivations of the fundamental equations that derive the flow system. These are the continuity equation, the momentum equation and the energy equation. In chapter 3 we computationally investigated the unsteady flow of a reactive temperature dependent viscosity third grade fluid through a porous saturated medium with asymmetric convective boundary conditions. The response of velocity and temperature fields to each of the various flow parameters was analysed and interpreted. A transient increase in both the velocity and temperature profiles with an increase in the reaction strength, viscous heating and fluid viscosity parameter was observed. On the other hand, a transient decrease in the field properties was observed with increase in non-Newtonian character and the porous medium shape parameter. The reaction was noticed to blow-up if, depending on other flow parameters, the reaction strength is not carefully controlled.
Schneider, Jean. "Dynamique non-newtonienne de courants de gravité chargés en particules : Étude en régime turbulent." Electronic Thesis or Diss., Université de Lorraine, 2023. http://www.theses.fr/2023LORR0308.
Gravity currents are geophysical phenomena that occur mainly in oceanic environments. These currents have been the subject of numerous studies in the absence of particles. However, their dynamics become significantly more complex when particles are in suspension. In this thesis, we aim to characterize the dynamics of these currents in the presence of particles in multiple configurations corresponding to those found in nature. The use of new measurement techniques with high spatial and temporal resolution enables us to probe the internal structure of these currents in the case of isodense flows, and to isolate the effects of high-concentration viscosity. This technique can then be used to probe the internal structure of particle-laden gravity currents according to their buoyancy properties (sedimentation, isodensity, creaming). Finally, configurations representative of those found in nature reveal dynamics far more complex than expected. The appearance of convection effects is revealed by the study of particle-laden hypopycnal currents
Shcherbakov, Victor. "Localised Radial Basis Function Methods for Partial Differential Equations." Doctoral thesis, Uppsala universitet, Avdelningen för beräkningsvetenskap, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-332715.
Siqueira, Eduardo Schnurr. "Aproximação numérica de escoamento de fluidos power-law utilizando o código livre MFIX." Universidade do Vale do Rio dos Sinos, 2013. http://www.repositorio.jesuita.org.br/handle/UNISINOS/4430.
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Fluidos não-Newtonianos apresentam relação não linear entre a tensão de cisalhamento e a taxa de cisalhamento, ou seja, sua viscosidade não é constante. Eles estão presentes na natureza (sangue, lamas, areia movediça), assim como em muitos produtos industriais classificam-se nesta categoria, tais como produtos alimentícios (iogurtes, queijos cremosos, doces de frutas, chocolate ), tintas, borrachas, polímeros fundidos, soluções poliméricas, adesivos e gomas. Nos casos em que a viscosidade diminui com aumento da taxa de cisalhamento, os fluidos são classificados como pseudoplásticos; os que apresentam comportamento inverso são classificados como dilatantes. O modelo Power-Law é utilizado em engenharia para modelar ambos os comportamentos. Computational Fluid Dynamics - CFD (Dinâmica dos Fluidos Computacional) é uma ferramenta utilizada na simulação numérica de escoamentos de fluidos Newtonianos e não-Newtonianos. Inúmeros códigos comerciais e livres são utilizados atualmente, dentre eles o código livre e aberto Multiphase Flow with Interphase Exchanges (MFIX), o qual foi desenvolvido visando a simulação numérica de escoamentos multifásicos reativos do tipo sólido-gás em leitos fluidizados. O objetivo do presente trabalho é implementar no MFIX o modelo Power-Law, validar a modificação e realizar um estudo de caso utilizando o modelo. Com a implementação de um modelo não-Newtoniano ao código, pretende-se abrir caminho para a simulação de escoamentos multifásicos do tipo sólido-líquido não-Newtoniano, bem como aumentar a potencialidade do código, a fim de se estudar casos monofásicos de escoamentos de fluidos não-Newtonianos sujeitos à transferência de calor. O modelo implementado foi validado através da comparação com resultados da literatura para o escoamento em uma cavidade. Posteriormente, foram realizadas simulações do escoamento não isotérmico e isotérmico em torno de um prisma de seção quadrada imerso em um canal. Foram variados os parâmetros número de Prandtl, índice do modelo Power-Law e razão de bloqueio. Verificou-se que o número de Nusselt tem influência direta e é fortemente influenciado pela razão de bloqueio e inversamente, com pouca intensidade, pelo índice Power-Law. O número de Prandtl também influenciou diretamente no número de Nusselt e demonstrou que, quanto maior o seu valor, mais acentuada fica a variação do número de Nusselt em função da razão de bloqueio.
Non-Newtonian fluids exhibit nonlinear relationship between the shear stress and the shear rate, that is, its viscosity is not constant. They are present in nature (blood, sludge) as well as many industrial products are classified in this category, such as food products (yoghurt, soft cheeses, jams, chocolate), paints, rubber, polymer melts, polymer solutions, adhesives and gums. In cases where viscosity decreases with increasing shear rate, the fluids are classified as shear-thinning, while the opposite behavior is classified as shear-thickening. The Power-Law model is used in engineering to model both behaviors. Computational Fluid Dynamics - CFD is a tool used in the numerical simulation of Newtonian and non-Newtonian fluid flow. Numerous free and commercial codes are used today, including the free and open source Multiphase Flow with Interphase Exchanges (MFIX), which was developed to the numerical simulation of multiphase (fluid-solid) and reactive flows. The goal of this work is to implement the Power-Law model in MFIX, validate the implementation and conduct a case study using the model implemented. With the implementation of a non-Newtonian model to the code, a new possibility for the simulation of multiphase flows of solid-non-Newtonian liquids is opened, as well as there is an increase in the capability of the code regarding the study of single-phase fluid flows of Non-Newtonian fluids subject to heat transfer. The model was implemented and validated by comparison with literature results for the flow in a lid driven cavity. Subsequently, simulations were carried out concerning isothermal and non-isothermal flows around a square cylinder immersed in a channel. Parameters of analyses consisted of Prandtl number, Power-Law index and blockage ratio, for a fixed Reynolds number. It was found that the Nusselt number is strongly influenced by the blockage ratio and decreases with the increase of the Power-Law index. The Prandtl number also directly influences the process. With its increase, the dependence of the Nusselt number with the blockage ratio is more pronounced.
Ilunga, Luc Mwamba. "Performance of a symmetrical converging-diverging tube differential pressure flow meter." Thesis, Cape Peninsula University of Technology, 2014. http://hdl.handle.net/20.500.11838/1029.
The current problems of orifice, nozzle and Venturi flow meters are that they are limited to turbulent flow and the permanent pressure drop produced in the pipeline. To improve these inadequacies, converging-diverging (C-D) tubes were manufactured, consisting of symmetrical converging and diverging cones, where the throat is the annular section between the two cones, with various angles and diameter ratios to improve the permanent pressure loss and flow measurement range. The objective of this study was firstly to evaluate the permanent pressure loss, secondly to determine the discharge coefficient values for various C-D tubes and compare them with the existing differential pressure flow meter using Newtonian and non-Newtonian fluids, and finally to assess the performance of these differential pressure flow meters. The tests were conducted on the multipurpose test rig in the slurry laboratory at the Cape Peninsula University of Technology. Newtonian and non-Newtonian fluids were used to conduct experiments in five different C-D tube flow meters with diameter ratios (β) of 0.5, 0.6 and 0.7, and with angles of the wall to the axis of the tube (θ) of 15°, 30° and 45°. The results for each test are presented firstly in the form of static pressure at different flow rates. It was observed that the permanent pressure loss decreases with the flow rate and the length of the C-D tube. Secondly, the results are presented in terms of discharge coefficient versus Reynolds number. It was found that the Cd values at 15° drop earlier than at 30° and 45°; when viscous forces become predominant, the Cd increases with increasing beta ratio. The Cd was found to be independent of the Reynolds number for Re>2000 and also a function of angle and beta ratio. Preamble Performance of a symmetrical converging-diverging tube differential pressure flow meter Finally, the error analyses of discharge coefficients were assessed to determine the performance criteria. The standard variation was found to increase when the Reynolds number decreases. The average discharge coefficient values and their uncertainties were determined to select the most promising C-D tube geometry. An average Cd of 0.96, with an uncertainty of ±0.5 % for a range of Reynolds numbers greater than 2,000 was found. The comparison between C-D tubes 0.6(15-15) and classical Venturi flow meters reveals that C-D 0.6(15-15) performs well in turbulent range and shows only a slight inaccuracy in laminar. This thesis provides a simple geometrical differential pressure flow meter with a constant Cd value over a Reynolds number range of 2000 to 150 000.
Neto, Apiano Ferreira de Morais. "Escoamento de fluidos complexos e transporte de partÃculas em geometrias irregulares." Universidade Federal do CearÃ, 2011. http://www.teses.ufc.br/tde_busca/arquivo.php?codArquivo=5889.
Neste trabalho, foram estudados vÃrios tipos de escoamentos laminares de fluidos incompressÃveis Newtonianos e nÃo-Newtonianos. Isto foi feito atravÃs do estudo da interaÃÃo destes escoamentos com geometrias complexas atravÃs de modelagem computacional e da soluÃÃo numÃrica das equaÃÃes de conservaÃÃo do momento e continuidade de massa. Numa primeira etapa, a modelagem computacional de uma rede de poros foi usada para a gerar padrÃes de agregados granulares resultando de mecanismos de erosÃo-deposiÃÃo de grÃos leves. A geometria da rede de poros foi alterada dinamicamente de acordo com a transferÃncia de momento do escoamento para as partÃculas localizadas em cada vÃrtice da rede de poros. Os resultados mostraram que, para esse processo irreversÃvel, o modelo foi capaz de reproduzir padrÃes tÃpicos de processos de erosÃo bem-conhecidos. Numa segunda etapa, um separador de partÃculas semelhante à estrutura pulmonar foi proposto com base nas propriedades de escoamento em uma estrutura ramificada e nas propriedades de transporte inercial das partÃculas, quantificadas atravÃs do nÃmero de Stokes. Os resultados indicaram que a variaÃÃo dos parÃmetros de construÃÃo da estrutura ramificada leva a um regime eficiente do processo de separaÃÃo em um amplo espectro de valores do nÃmero de Stokes. Por Ãltimo, o escoamento de vÃrios fluidos nÃo-Newtonianos atravÃs de meios porosos desordenados em trÃs-dimensÃes foi estudado. Os resultados mostraram, para fluidos do tipo lei-de-potÃncia, que o escoamento pode ser descrito como uma curva universal se o nÃmero de Reynolds e a permeabilidade hidrÃulica forem redefinidos de maneira apropriada. Fluidos de Bingham tambÃm foram estudados atravÃs do modelo de Herschel-Bulkley. Neste caso, as simulaÃÃes revelaram que as interaÃÃes entre a geometria complexa do espaÃo poroso, as propriedades reolÃgicas do fluido e os efeitos inerciais do escoamento sÃo responsÃveis por uma melhora substancial da permeabilidade hidrÃulica do sistema em valores intermediÃrios do nÃmero de Reynolds.
In this work many types of incompressible laminar Newtonian and Non-Newtonian flows are studied. The interplay of these flows with complex geometries was investigated using computational modeling and numerical solution of the conservation of momentum and mass continuity equations. As a first step, the computational modeling of a network of pores was adopted to reveal the formation patterns caused by the mechanism of erosion-deposition of light grains. The geometry of the pore network was changed dynamically according to the flow momentum transfer for particles located on each vertex of the pore network. The results showed that, for this irreversible processes, the model is capable of reproducing patterns of formation of well-known erosion processes. In a second step, a particle separator inspired on the lung structure was proposed based on the flow properties in a branched structure and transport of inertial particles, quantified in terms of the Stokes number. The results indicated that the variation of construction parameters of the branched structure leads to an efficient design of the separation process in a wide range of values of the Stokes number. Finally, the flow of non-Newtonian fluids through three-dimensional disordered porous media has been studied. The results showed, for power-law fluids that the flow can de described as a universal curve if the Reynolds number and the hydraulic permeability are redefined properly. The flow of Bingham fluids was also studied using the model of Herschel-Bulkley. In this case, the simulations showed that the interaction between the complex geometry of the pore space, the rheological properties of the fluid and the inertial effects of the flow is responsible for a substantial improvement of the hydraulic permeability of the system at intermediate values of the Reynolds number.
Mokhtarpour, Vanaki Shayan. "Numerical investigation of muco-ciliary transport." Thesis, Queensland University of Technology, 2020. https://eprints.qut.edu.au/203744/1/Shayan_Mokhtarpour%20Vanaki_Thesis.pdf.
Wang, Yuli. "Capillarity and wetting of non-Newtonian droplets." Doctoral thesis, KTH, Mekanik, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-184146.
QC 20160329
Schaer, Nicolas. "Modélisation des écoulements à surface libre de fluides non-newtoniens." Thesis, Strasbourg, 2018. http://www.theses.fr/2018STRAD033/document.
The objective of this thesis is to develop a 3D numerical model to assess debris flow. These viscous flows, heavily loaded with solid matter, form when heavy rain occurs in mountains. Today, forecasts of potentially impacted areas are based on 0D, 1D and 2D numerical tools. However, these tools cannot fully represent the free surface behaviour of debris flows due to the approximations and assumptions on which they are based. Thus, this work utilises a 3D numerical code to study this phenomenon. A specific model is built with real field data. Several flow scenarios are studied and compared with a 2D numerical model. The results highlight the significant benefits of a 3D approach by providing information on the fine representation of flow dynamics over the catchment area. The model also predicts the impact of debris flow (overflowing on a road bridge) and the zones of deposition and spreading. It highlights possible congestion phenomena and reproduces flows in the channels by fully accounting for parietal friction, capabilities not provided by 2D models. Prior to this application, the 3D model was evaluated with five sets of experimental data to validate its ability to represent viscoplastic flows. Different types of flows are studied and are representative of those observed on real sites when debris flow occur
Lavarda, Jairo Vinícius. "Convecção natural de fluidos de lei de potência e de Bingham em cavidade fechada preenchida com meio heterogêneo." Universidade Tecnológica Federal do Paraná, 2015. http://repositorio.utfpr.edu.br/jspui/handle/1/1306.
Vários estudos numéricos investigaram cavidades fechadas sob o efeito da convecção natural preenchidas com fluidos newtonianos generalizados (FNG) nos últimos anos pelas aplicações diretas em trocadores de calor compactos, no resfriamento de sistemas eletrônicos e na engenharia de polímeros. Neste trabalho é realizada a investigação numérica do processo de convecção natural de fluidos de lei de Potência e de Bingham em cavidades fechadas, aquecidas lateralmente e preenchidas com meios heterogêneos e bloco centrado. O meio heterogêneo é constituído de blocos sólidos, quadrados, desconectados e condutores de calor. Como parâmetros são utilizados a faixa de Rayleigh de 104 à 107, índice de potência n de 0, 6 à 1, 6, número de Bingham de 0, 5 até Bimax , sendo investigado da influência do número de Prandtl para cada modelo de fluido. Nas cavidades com meio heterogêneo são utilizadas as quantidades de blocos de 9, 16, 36 e 64, mantendo-se a razão entre a condutividade térmica do sólido e do fluido κ = 1. Para as cavidades com bloco centrado, são utilizados os tamanhos adimensionais de 0, 1 à 0, 9 com κ = 0, 1; 1 e 10. A modelagem matemática é realizada pelas equações de balanço de massa, de quantidade de movimento e de energia. As simulações são conduzidas no programa comercial ANSYS FLUENT R . Inicialmente são resolvidos problemas com fluidos newtonianos em cavidade limpa, seguida de cavidade preenchida com meio heterogêneo e posteriormente bloco centrado para validação da metodologia de solução. Na segunda etapa é realizada o estudo com os modelos de fluidos de lei de Potência e de Bingham seguindo a mesma sequência. Os resultados são apresentados na forma de linhas de corrente, isotermas e pelo número de Nusselt médio na parede quente. De maneira geral, a transferência de calor na cavidade é regida pelo número de Rayleigh, tamanho e condutividade térmica dos blocos, pelo índice de potência para o modelo de lei de Potência e do número de Bingham para o modelo de Bingham. O número de Prandtl tem grande influência nos dois modelos de fluidos. O meio heterogêneo reduz a transferência de calor na cavidade quando interfere na camada limite térmica para ambos os fluidos, sendo feita uma previsão analítica para o fluido de lei de Potência. Para bloco centrado, a interferência na camada limite com fluido de lei de Potência também foi prevista analiticamente. A transferência de calor aumentou com bloco de baixa condutividade térmica e pouca interferência e com bloco de alta condutividade térmica e grande interferência, para ambos os fluidos.
Many studies have been carried out in square enclosures with generalized Newtonian fluids with natural convection in past few years for directly applications in compact heat exchangers, cooling of electronics systems and polymeric engineering. The natural convection in square enclosures with differently heated sidewalls, filled with power-law and Bingham fluids in addition with heterogeneous medium and centered block are analyzed in this study. The heterogeneous medium are solid, square, disconnected and conducting blocks. The parameters used are the Rayleigh number in the range 104 - 107 , power index n range of 0, 6 - 1, 6, Bingham number range of 0, 5 - Bimax , being the influence of Prandtl number investigated for each fluid model. The number of blocks for heterogeneous medium are 9, 16, 36 and 64, keeping constant solid to fluid conductive ratio, κ = 1. For enclosures with centered block are used the nondimensional block size from 0, 1 to 0, 9, with solid to fluid conductive ratio in range κ = 0, 1; 1 and 10. Mathematical modeling is done by mass, momentum and energy balance equations. The solution of equations have been numerically solved in ANSYS FLUENT R software. Firstly, numerical solutions for validation with Newtonian fluids in clean enclosures are conducted, followed by enclosures with heterogeneous medium and centered block. Subsequently, numerical solutions of power-law and Bingham fluids with same enclosures configurations are conducted. The results are reported in the form of streamlines, isotherms and average Nusselt number at hot wall. In general, the heat transfer process in enclosure is governed by Rayleigh number, size and thermal conductivity of the blocks, power index n for power-law fluid and Bingham number for Bingham fluid. Both fluid models are very sensitive with Prandtl number changes. Heterogeneous medium decrease heat transfer in enclosure when affects thermal boundary layer for both fluid models. One analytical prediction was made for power-law fluid. An increase in heat transfer occurs with low thermal conductivity block and few interference and with high thermal conductivity block and great interference, for both fluids.
Khahledi, Morakane Charlotte. "Non-Newtonian fluid flow measurement using sharp crested notches." Thesis, Cape Peninsula University of Technology, 2014. http://hdl.handle.net/20.500.11838/1038.
Notches, particularly rectangular and V shaped are the cheapest and most common devices used to measure the flow rate of water in open channels. However, they have not been used to measure the flow rate of non-Newtonian fluids. These viscous fluids behave differently from water. It is difficult to predict the flow rate of such fluids during transportation in open channels due to their complex viscous properties. The aim of this work was to explore the possibility of extending the application of especially rectangular and V-shaped notches to non-Newtonian fluids. The tests reported in this document were carried out in the Flow Process and Rheology Centre laboratory. Notches fitted to the entrance of a 10 m flume and an in-line tube viscometer were calibrated using water. The in-line tube viscometer with 13 and 28 mm diameter tubes was used to determine the fluid rheology. Flow depth was determined using digital depth gauges and flow rate measurements using magnetic flow meters. Three different non-Newtonian fluids, namely, aqueous solutions of Carboxymethyl Cellulose (CMC) and water-based suspensions of kaolin and bentonite were used as model non-Newtonian test fluids. From these the coefficient of discharge (Cd) values and appropriate non-Newtonian Reynolds numbers for each fluid and concentration were calculated. The experimental values of the coefficient of discharge (Cd) were plotted against three different definitions of the Reynolds number. Under laminar flow conditions, the discharge coefficient exhibited a typical dependence on the Reynolds number with slopes of ~0.43-0.44 for rectangular and V notches respectively. The discharge coefficient was nearly constant in the turbulent flow regime. Single composite power-law functions were used to correlate the Cd-Re relationship for each of the two notch shapes used. Using these correlations, the Cd values could be predicted to within ±5% for the rectangular and V notches. This is the first time that such a prediction has been done for a range of non-Newtonian fluids through sharp crested notches. The research will benefit the mining and food processing industries where high concentrations of non-Newtonian fluids are transported to either disposal sites or during processing.
Dawson, Matthew A. (Matthew Aaron) 1983. "Modeling the dynamic response of low-density, reticulated, elastomeric foam impregnated with Newtonian and non-Newtonian fluids." Thesis, Massachusetts Institute of Technology, 2008. http://hdl.handle.net/1721.1/44750.
Includes bibliographical references.
Engineering cellular solids, such as honeycombs and foams, are widely used in applications ranging from thermal insulation to energy absorption. Natural cellular materials, such as wood, have been used in structures for millennia. However, despite their extensive use, a comprehensive understanding of the dynamic interaction between the interstitial fluid in the cells of the foam and the foam itself has yet to be developed. In this thesis, we explore the dynamic, compressive response of low-density, reticulated, elastomeric foam impregnated with Newtonian and non-Newtonian fluids. To develop tractable analytical models for this complex, non-linear phenomenon, a study is first undertaken on the permeability of foam under deformation. Using these results, a model is developed for the dynamic, uniaxial compressive response of low-density, reticulated, elastomeric foam filled with a viscous Newtonian fluid. This comprehensive model is found to be well approximated by a simpler model, based on the lubrication approximation. Furthermore, in the lubrication limit, a model for the dynamic, uniaxial compressive response of foam filled with a non-Newtonian fluid is also developed. All of the models presented in this thesis are supported by extensive experimental studies. The experiments also suggest that these models are applicable over a wide-range of parameters, such as strain, strain rate, and pore size. Finally, these models are used in two case studies to assess the feasibility of composite structures containing a layer of liquid-filled foam in dynamic loading applications. The first case study focuses on applications in energy absorption with the experimental design of a motorcycle helmet. The second case study focuses on applications in mitigating the effects of blast waves with a parametric study of the design of a blast wall.
(cont.) These studies provide insight into the usefulness of the models and demonstrate that composite structures with a layer of liquid-filled foam have enormous potential in a wide range of dynamic loading applications.
by Matthew A. Dawson.
Ph.D.
Nikfarjam, Farhad. "Extension de la méthode LS-STAG de type frontière immergée/cut-cell aux géométries 3D extrudées : applications aux écoulements newtoniens et non newtoniens." Thesis, Université de Lorraine, 2018. http://www.theses.fr/2018LORR0023/document.
The LS-STAG method is an immersed boundary/cut-cell method for viscous incompressible flows based on the staggered MAC arrangement for Cartesian grids where the irregular boundary is sharply represented by its level-set function. This approach results in a significant gain in computer resources compared to commercial body-fitted CFD codes. The 2D version of LS-STAG method is now well-established and this manuscript presents its extension to 3D geometries with translational symmetry in the z direction (3D extruded configurations). This intermediate step will be regarded as the milestone for the full 3D solver, since both discretization and implementation issues on distributed memory machines are tackled at this stage of development. The LS-STAG method is then applied to Newtonian and non-Newtonian flows in 3D extruded geometries (axisymmetric pipe, circular cylinder, duct with an abrupt expansion, etc.) for which benchmark results and experimental data are available. The purpose of these investigations is to evaluate the accuracy of LS-STAG method, to assess the versatility of method for flow applications at various regimes (Newtonian and shear-thinning fluids, steady and unsteady laminar to turbulent flows, granular flows) and to compare its performance with well-established numerical methods (body-fitted and immersed boundary methods)
Zhang, Qindan. "Écoulements polyphasiques et phénomènes interfaciaux à multi échelles." Electronic Thesis or Diss., Université de Lorraine, 2020. http://www.theses.fr/2020LORR0110.
Multiphase flows and interfacial phenomena are widely involved in the natural world, our daily life, and numerous industrial processes. By employing three different techniques including a high-speed camera, an ultra-high-speed Direct Current (DC) electrical device, and a high-speed micro-Particle Image Velocimetry (micro-PIV), the multiphase flows and interfacial phenomena at multiscale were investigated experimentally by both passive and active methods. The flow behaviors of the elastic non-Newtonian two-phase flow in both T-junction and flow-focusing devices were investigated. The fluid elasticity affected the dynamics of droplet formation, stretching and breakup. During the droplet formation, the peculiar beads-on-string flow was observed. The influences of the fluid elasticity on the minimum neck width, the maximum length of the dispersed thread and the droplet size were studied. The predicting models for the droplet size were optimized by introducing the dimensionless parameters to characterize the fluid elasticity. For the stretching and breakup of elastic droplets, the influences of elasticity on the transition from droplet stretching to breakup, the dynamics of droplet stretching and breakup as well as the size ratio of the daughter droplets were also investigated. The power-law models were proposed to predict the maximum stretching length. Subsequently, the initial coalescence of a pendant drop at a liquid surface and the initial spreading on a solid surface were investigated. The ultra-high-speed DC electrical device with the sampling speed of 1.25×106 Hz allows to monitoring the dynamics of coalescence and spreading within 10 µs. The coalescing width expands linearly with time in the inertially limited viscous regime and follows a power law in the inertial regime. The evolutions of the velocity fields during the initial coalescence and spreading were measured and computed by the high-speed micro-PIV with a capturing rate up to 5000 velocity fields per second, revealing the transformation of surface energy to kinetic energy. Besides, the consecutive electrical peaks with a regular interval of 20 ms were observed during the filament thinning of the polymer liquid neck. In addition, the active manipulation of the ferrofluid drop was realized by introducing an external magnetic field. Evident deformations of both the pendant ferrofluid drop and the bulk surface were observed prior to the contact even in the absence of a magnetic field. The exponential laws were proposed to predict the increasing coalescing width with time and the decreasing maximum coalescing width with the magnetic field. A high-speed micro-PIV technique was employed with a transparent model fluid to reveal the flow fields during the ferrofluid drop coalescence. The self-sustained coalescence-breakup cycles of ferrofluid drops were observed for the first time. The exponential model was proposed to predict the increasing periodic frequency with the applied magnetic field
Siquieri, Ricardo da Silva. "Análise e implementação de modelos não newtonianos no sistema FreeFlow-2D." Universidade de São Paulo, 2002. http://www.teses.usp.br/teses/disponiveis/55/55134/tde-31072002-102814/.
This work presents an extention of the Freeflow-2D system to non-Newtonian free surface flows. The governing equations are solved by the finite difference method on a staggered grid. Marker particles are used to describe the fluid providing the location and the visualization of the free surface. The methodology employed is based on the GENSMAC method. The fluid is modelled by the Cross and power-law models. Numerical examples are presented. The code is validated by making a comparison between analytical and numerical solutions
Ashrafi, Khorasani Nariman. "A low-order dynamical systems approach to nonlinear stability of non-Newtonian fluids." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape4/PQDD_0033/NQ58114.pdf.
Das, Suma Rani. "Investigation of Design and Operating Parameters in Partially-Filled Rubber Mixing Simulations." University of Akron / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=akron1479151141596147.
Searle, Toby William. "Purely elastic shear flow instabilities : linear stability, coherent states and direct numerical simulations." Thesis, University of Edinburgh, 2017. http://hdl.handle.net/1842/28991.
Шудрик, Олександр Леонідович. "Підвищення ефективності використання відцентрових насосів за рахунок вдосконалення математичних моделей робочого процесу". Thesis, НТУ "ХПІ", 2018. http://repository.kpi.kharkov.ua/handle/KhPI-Press/35499.
Thesis for granting the Degree of Candidate of Technical sciences in speciality 05.05.16 – Hydraulic machines and hydropneumatic units. – National Technical University "Kharkiv Politechnic Institute", 2018. The dissertation is devoted to the solution of an important scientific and technical problem of increasing the efficiency of a submersible electric centrifugal pump when it operates on a real liquid, which is a mixture of viscous non-Newtonian fluid, water and gas by improving mathematical models. An analysis of the concepts of development of pumping plant in Ukraine is carried out. The methods of mathematical modeling of three-dimensional flows of a viscous real liquid and their advantages over physical experiments are described. Selected software package for numerical experiment in OpenFOAM submersible pump channels. A system of indeterminate and Navier-Stokes equations was used to simulate the flow of fluid in the flow section of the pump. For its closure a k-ε turbulence model was chosen. The influence of rheological properties of non-Newtonian fluids on the characteristics of a centrifugal pump is investigated. The mathematical model of the turbulent three-dimensional flow of the non-Newtonian fluid is given. For calculations, a model of the Herschel-Bulkley non-Newtonian fluid is chosen, which most accurately describes the behavior of liquids of this type. The dependencies for the recalculation of the characteristics of the pump during its operation on the real liquid have been improved. The approach and mathematical model for modeling the three-dimensional flow of a viscous gas-liquid mixture are determined and chosen, and features are shown in the calculations of this type of fluid in the OpenFOAM package. The ways of increasing the efficiency of submersible pumps by changing the flow part are considered. The rational angle of inclination of the initial edge is determined. The modified degree of the pump, protected by the Ukrainian patent, is offered for pumping a liquid with an increased gas content. The mathematical model of a compatible operation of a real well and a submersible centrifugal pump in the form of a package of applied programs is considered and improved. This made it possible to determine the basic physical characteristics of the liquid, depending on the thermodynamic conditions.
Шудрик, Олександр Леонідович. "Підвищення ефективності використання відцентрових насосів за рахунок вдосконалення математичних моделей робочого процесу". Thesis, НТУ "ХПІ", 2018. http://repository.kpi.kharkov.ua/handle/KhPI-Press/35496.
Thesis for granting the Degree of Candidate of Technical sciences in speciality 05.05.16 – Hydraulic machines and hydropneumatic units. – National Technical University "Kharkiv Politechnic Institute", 2018. The dissertation is devoted to the solution of an important scientific and technical problem of increasing the efficiency of a submersible electric centrifugal pump when it operates on a real liquid, which is a mixture of viscous non-Newtonian fluid, water and gas by improving mathematical models. An analysis of the concepts of development of pumping plant in Ukraine is carried out. The methods of mathematical modeling of three-dimensional flows of a viscous real liquid and their advantages over physical experiments are described. Selected software package for numerical experiment in OpenFOAM submersible pump channels. A system of indeterminate and Navier-Stokes equations was used to simulate the flow of fluid in the flow section of the pump. For its closure a k-ε turbulence model was chosen. The influence of rheological properties of non-Newtonian fluids on the characteristics of a centrifugal pump is investigated. The mathematical model of the turbulent three-dimensional flow of the non-Newtonian fluid is given. For calculations, a model of the Herschel-Bulkley non-Newtonian fluid is chosen, which most accurately describes the behavior of liquids of this type. The dependencies for the recalculation of the characteristics of the pump during its operation on the real liquid have been improved. The approach and mathematical model for modeling the three-dimensional flow of a viscous gas-liquid mixture are determined and chosen, and features are shown in the calculations of this type of fluid in the OpenFOAM package. The ways of increasing the efficiency of submersible pumps by changing the flow part are considered. The rational angle of inclination of the initial edge is determined. The modified degree of the pump, protected by the Ukrainian patent, is offered for pumping a liquid with an increased gas content. The mathematical model of a compatible operation of a real well and a submersible centrifugal pump in the form of a package of applied programs is considered and improved. This made it possible to determine the basic physical characteristics of the liquid, depending on the thermodynamic conditions.
Gnambode, Sourou. "Simulation des grandes échelles des transferts thermo-convectifs dans les écoulements turbulents d'un fluide non-Newtonien en conduite cylindrique." Thesis, Paris Est, 2015. http://www.theses.fr/2015PESC1143/document.
This thesis is a numerical contribution of momentum and heat transfer of turbulent pipe flows of non-Newtonian fluids. The apparent viscosity of the fluid is modelled by a power-law (Ostwald de Waele model). Two models subgrid of LES were considered: the dynamic model of Germano et al. (1991) and model Smagorinsky non-Newtonian. They are used to describe the physical mechanisms involved in the isothermal flow of these complex rheology fluids. Heat transfer are simulated with the model of non-Newtonian Smagorinsky. These are processed in two parts. The first concerns the heat exchange without affecting the velocity distribution. This is non-thermo dependent flow or isothermal flow. The second part concerns the resolution of thermo dependent flows that focus on changes induced by the temperature-velocity coupling. The turbulent fields are analyzed statistically by averaging over time and space (according to the periodic directions) the instantaneous field of velocity and temperature to establish the average profiles of velocity and temperature, the root mean square of turbulent fluctuations (rms), Reynolds stress, the heat flow, the moments of higher order (skewness and flatness), the pdf (probability density function), the jpdf (attached probability density function), the coefficient of friction, the number of Nusselt ... These differents variables are analyzed for various parameters governing the problem: the Reynolds and Prandtl flow index and the number of Pearson
Feng, Libo. "Numerical investigation and application of fractional dynamical systems." Thesis, Queensland University of Technology, 2019. https://eprints.qut.edu.au/126980/1/Libo_Feng_Thesis.pdf.
Chrobák, Jan. "Analýza vlastností provozních kapalin." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2012. http://www.nusl.cz/ntk/nusl-219800.
Plan, Emmanuel Lance Christopher VI Medillo. "Retournement, flexion, étirement : particules dans les écoulements laminaires et chaotiques." Thesis, Université Côte d'Azur (ComUE), 2017. http://www.theses.fr/2017AZUR4032/document.
Particles, when subjected into a flow, may display preferred orientations and a variety of deformations depending on their geometry and elasticity and the flow velocity field. Flows can conversely be modified when the particle stresses are sufficiently large. This thesis presents theoretical and numerical results on this two-way relationship between particles and flows in two parts. Part I starts with a stability analysis and numerical simulations that show a simple semiflexible Brownian particle in an extensional flow undergo tumbling, a phenomenon normally associated to shear flows. Chapter 2 extends analytical tools available only for elementary polymer models or for steady flows to general bead-rod-spring models in random flows. By building on the results from the previous chapters, Chap. 3 culminates with the study of an unexplored Lagrangian degree of freedom in a turbulent flow: bending. A semiflexible particle is shown to display different bending behaviours in two- and three-dimensional random flows. This prediction is confirmed via direct numerical simulations of the particle in a turbulent flow. Part II concerns “elastic turbulence", a chaotic regime created in a flow with low inertial forces by the addition of elastic polymers. Chapter 4 provides an estimate for the number of degrees of freedom of a solution of this chaotic system via the Lyapunov dimension of the attractor of the two-dimensional Oldroyd-B model, a model known to reproduce elastic turbulence in numerical simulations. Chapter 5 questions the necessity of elasticity in producing a chaotic regime and concludes that a rodlike polymer solution can create a regime similar to elastic turbulence
Khapre, Akhilesh Prabhakar. "Numerical Study of Mixing of Different Newtonian and Non-Newtonian Fluids in Stirred Tank." Thesis, 2015. http://ethesis.nitrkl.ac.in/6898/1/Akhilesh_Phd__510ch102.pdf.
Barth, William L. Carey Graham F. "Simulation of non-Newtonian fluids on workstation clusters." 2004. http://repositories.lib.utexas.edu/bitstream/handle/2152/1874/barthwl042.pdf.
Sekyi, Elorm. "Simulations of agitated dilute non-Newtonian suspensions." Master's thesis, 2009. http://hdl.handle.net/10048/638.
Title from pdf file main screen (viewed on Dec. 10, 2009). "A thesis submitted to the Faculty of Graduate Studies and Research in partial fulfillment of the requirements for the degree of Master of Science in Chemical Engineering, [Department of] Chemical and Materials Engineering, University of Alberta." Includes bibliographical references.
Langner, Jeremy M. "Investigation of non-Newtonian flow in anaerobic digesters." 2010. http://hdl.handle.net/1993/3852.
Barth, William L. "Simulation of non-Newtonian fluids on workstation clusters." Thesis, 2004. http://hdl.handle.net/2152/1874.