Zeitschriftenartikel: „Effets fluides“

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Fruman, D. H., und F. Beuzelin. „Effets thermiques dans la cavitation des fluides cryogéniques“. La Houille Blanche, Nr. 7-8 (Dezember 1992): 557–61. http://dx.doi.org/10.1051/lhb/1992057.

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2

Laycock, Dallin P., Rick D. Schroeder und Reza Safari. „Breaking boulders: experimental examination of hydraulic fracturing in the Montney Formation“. Bulletin of Canadian Energy Geoscience 71, Nr. 1 (01.03.2024): 41–62. http://dx.doi.org/10.35767/gscpgbull.71.1.41.

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Abstract The low permeabilities of unconventional reservoirs such as the Montney Formation require hydraulic fracturing to enhance fluid flow and achieve economic production of hydrocarbons. Efficient hydraulic fracturing operations rely on properly characterizing the controlling factors responsible for fracture complexity, fracture conductivity, and fracture dimensions. Since direct observation of fractures in the subsurface are very challenging, technologies have been developed to help characterize fractures in laboratories. However, the scale of these tools is insufficient to capture the fine detail needed to observe how these hydraulic fractures are interacting with the rock fabric, stress state, or fluid viscosity. Presented here is a laboratory experiment designed to evaluate the effects of rock fabric, stress anisotropies, and fluid viscosities using large boulders of Sulfur Mountain Formation (Montney Formation equivalent). These experiments were designed to simulate subsurface conditions and provide an opportunity to directly examine a scaled fracture face. Four large boulders were collected from outcrop and trimmed to fit inside a large stress frame. A borehole was drilled to facilitate the injection of fluids and generate scaled hydraulic fractures. Experiments tested the effects of different stress states, fluid viscosities, and rock fabric on the growth and geometry of hydraulic fractures. Of these factors, the fabric of the rock was the dominant factor controlling hydraulic fracture growth. In all stress regimes, hydraulic fractures were arrested, deflected, or bridged by pre-existing cemented and open natural fractures. Fluid viscosity had a minor effect on fracture complexity, but no discernable difference could be observed between any of the tested stress regimes. Subsurface core data provided additional data to support the laboratory experiments. Hardness measurements showed that finely laminated facies have variable hardness at the lamination scale. Darker laminations with more clay are softer than the more silt-rich light-coloured laminations. The result of this can be observed in both core and outcrop as natural fractures in these facies often display highly irregular geometries. In addition, fracture filling cement was significantly softer than the surrounding rock. The collective result of both core and laboratory data provides valuable insight into the role of rock fabric in the development of hydraulic fractures in the Montney Formation and that is not obtainable from traditional data collection methods. Résumé La faible perméabilité des réservoirs non conventionnels, tels que la Formation de Montney, nécessite la fracturation hydraulique pour améliorer l’écoulement des fluides et réaliser une production d’hydrocarbures rentables. Pour réaliser des opérations de fracturation efficientes, on doit caractériser proprement les facteurs qui régissent la complexité, la conductivité et la dimension des fractures. Puisque l’observation directe des fractures dans la subsurface reste un défi, des technologies ont été mises au point pour mieux caractériser les fractures en laboratoire. Toutefois, l’étendue de ces outils se révèle insuffisante pour saisir les fins détails nécessaires à l’observation de ces fractures hydrauliques qui interagissent avec la fabrique des roches, l’état de contrainte ou la viscosité des fluides. Le présent document expose une expérience en laboratoire conçue pour évaluer les effets de la fabrique des roches, des anisotropies de contrainte et des viscosités de fluides au moyen de gros blocs rocheux extraits de la Formation de mont Sulphur (équivalente à la Formation de Montney). Ces expériences permettent de simuler les conditions en subsurface et d’examiner directement un plan à l’échelle des fractures. Quatre gros blocs rocheux ont été extraits d’un affleurement puis taillés afin de les disposer dans un grand cadre de contrainte. Puis, un trou de sondage a été foré pour faciliter l’injection de fluides et générer des fractures hydrauliques à l’échelle. L’expérience visait à constater les effets de différents états de contrainte, de différentes viscosités des fluides et fabrique des roches sur la croissance et la géométrie des fractures hydrauliques. Entre tous ces facteurs, la fabrique de la roche était le facteur prédominant régissant la croissance des fractures hydrauliques. Dans tous les régimes de contrainte, les fractures hydrauliques ont été arrêtées, déviées ou pontées par des fractures cimentées préexistantes naturelles et ouvertes. La viscosité des fluides avaient eu un effet mineur sur la complexité des fractures, mais aucune différence discernable n’a pu être observée entre tous les régimes de contrainte testés. Les carottes de sondage de la subsurface ont apporté des données additionnelles pour appuyer les expériences en laboratoire. Le duromètre montrait que les faciès finement laminés présentaient une dureté variable à l’échelle de lamination. Les laminations plus foncées avec plus d’argile se révélaient plus molles que celles plus claires, riches en silt. Nous pouvons observer les résultats de ce qui précède dans les carottes de sondage et les affleurements puisque les fractures naturelles de ces faciès affichent souvent des géométrie fortement irrégulières. De plus, le ciment de remplissage des fractures était notablement plus mou que la roche adjacente. Les résultats collectifs des carottes de sondage et du laboratoire nous fournissent un aperçu précieux dans le rôle de la fabrique des roches dans l’évolution des fractures hydrauliques de la Formation de Montney, que l’on ne pourrait obtenir autrement par des méthodes de collecte de données traditionnelles. Michel Ory

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Al-Sharai, Abdo Ali, Chin Fhong Soon, Chan Hwang See, See Khee Yee, Kian Sek Tee und Mohammed Abdul Wahab. „MODELLING OF CO-AXIAL AND TRI-AXIAL MILLI-FLUIDIC DEVICES FOR CO-EXTRUSION OF SEMI-SOLID SOLIDS“. ASEAN Engineering Journal 13, Nr. 2 (31.05.2023): 93–100. http://dx.doi.org/10.11113/aej.v13.18953.

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With the use of a milli-fluidics device, it is possible to manipulate small amounts of fluid in the millimeter range with pinpoint accuracy. The milli-fluidics are currently lacking in studies of the relationship between fluid viscosity, output velocity and output pressure. Thus, this study examines the effects of viscosity on fluid dynamics in the co-axial and tri-axial milli-fluidics. This geometry of the co-axial and tri-axial milli-fluidics consist of single outlet, two inlets and three inlets, respectively. The tri-axial milli-fluidics is 46 mm long and 11.31 mm wide, while, the coaxial milli-fluidic is 64.73 mm long and 9.2 mm wide. The co-axial milli-fluidics constituted of 775 domain elements and 147 boundary elements, while, the tri-axial milli-fluidics mesh constituted of 1518 domain elements and 178 boundary elements. Laminar flow was observed for the flow of the materials through the channels. When the dynamic viscosity approaches 5 mPa.s, the simulation reveals that the flow rate is inversely proportional to the dynamic viscosity for co-axial milli-fluidics. It was difficult to combine fluids with different viscosities with small volume of water in a narrow boundary, thus the parallel flow of material was observed. When using the one outlet channel for the tri-axial milli-fluidics, the assemble pressure at the three inlets was decreased compared with co-axial milli-fluidic. Even when the dynamic velocity of the fluid at outlet 1 increased, its velocity remained consistent. An extruder using tri-axial milli-fluidics can be used if the interfacial tension for intake 1 is higher than for inlet 2 and the dynamic viscosity of fluid 1 is above 2 mPas, according to the volumetric fraction model. The tri-axial milli-fluidic was found to be suitable for producing cladding of material with the balanced pressure from the two side channels.

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Althobaiti, Nesreen. „Importance of Activation Energy on Magnetized Dissipative Casson-Maxwell Fluid through Porous Medium Incorporating Chemical Reaction, Joule Heating, and Soret Effects: Numerical Study“. Journal of Applied Mathematics 2024 (05.01.2024): 1–14. http://dx.doi.org/10.1155/2024/5730530.

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In recent decades, the study of non-Newtonian fluids has attracted the interest of numerous researchers. Their study is encouraged by the significance of these fluids in fields including industrial implementations. Furthermore, the importance of heat and mass transfer is greatly increased by a variety of scientific and engineering processes, including air conditioning, crop damage, refrigeration, equipment power collectors, and heat exchangers. The key objective of this work is to use the mathematical representation of a chemically reactive Casson-Maxwell fluid over a stretched sheet circumstance. Arrhenius activation energy and aspects of the magnetic field also have a role. In addition, the consequences of both viscous dissipation, Joule heating, and nonlinear thermal radiation are considered. The method transforms partial differential equations originating in fluidic systems into nonlinear differential equation systems with the proper degree of similarity which is subsequently resolved utilizing the Lobatto IIIA technique’s powerful computing capabilities. It is important to recall that the velocity profile drops as the Maxwell fluid parameter increases. Additionally, the increase in the temperature ratio parameter raises both the fluid’s temperature and the corresponding thickness of the boundary layer.

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Fetecau, Constantin, Dumitru Vieru, Lucian Eva und Norina Consuela Forna. „Memory Effects in the Magnetohydrodynamic Axial Symmetric Flows of Oldroyd-B Fluids in a Porous Annular Channel“. Symmetry 16, Nr. 9 (26.08.2024): 1108. http://dx.doi.org/10.3390/sym16091108.

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In this article, we analytically investigate the isothermal magnetohydrodynamic axial symmetric flows of ordinary and fractional incompressible Oldroyd-B fluids through a porous medium in an annular channel. The fluid’s motion is generated by an outer cylinder, which moves along its symmetry axis with an arbitrary time-dependent velocity Vh(t). Closed-form expressions are established for the dimensionless velocity fields of both kinds of fluids, generating exact solutions for any motion of this type. To illustrate the concept, two particular cases are considered, and the velocity fields corresponding to the flow induced by the outer cylinder are presented in simple forms, with the results validated graphically. The motion of fractional and ordinary fluids becomes steady over time, and their corresponding velocities are presented as the sum of their steady and transient components. Moreover, the steady components of these velocities are identical. The influence of magnetic fields and porous media on the flow of fractional fluids is graphically depicted and discussed. It was found that a steady state is reached earlier in the presence of a magnetic field and later in the presence of a porous medium. Moreover, this state is obtained earlier in fractional fluids compared with ordinary fluids.

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Lomba, Rosana F. T., Carlos H. M. de Sa´ und Edimir M. Branda˜o. „A New Approach to Evaluate Temperature Effects on Rheological Behavior of Formate-Based Fluids“. Journal of Energy Resources Technology 124, Nr. 3 (06.08.2002): 141–45. http://dx.doi.org/10.1115/1.1485293.

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Organic salt brines represent a good alternative to drill through deep productive zones. The literature presents these salts as thermal stabilizers of polymers used in the formulation of drill-in fluids. An extensive study was carried out to evaluate the rheological behavior of formate-based fluids as a function of temperature and density. An analytical expression was developed to correlate shear stresses with temperature for general drilling fluids and a special case of this expression results in a greatly simplified expression that is valid for a number of drilling and completion fluids produced using different alkali-metal salts of formic acid. The advantage of this new approach is the lack of dependence between the proposed correlation and the choice of a rheological model. Unlike many expressions presented in the literature, the expression proposed and methodology that follows allows the choice of a best-fit model to predict the fluid’s rheological behavior as a function of temperature. Experimental results show that formates do improve the thermal stability of polymers. The proposed correlations will soon be incorporated in a wellbore cleaning numerical simulator to compensate for thermal effects.

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Fetecau, Constantin, Shehraz Akhtar und Costică Moroşanu. „Porous and Magnetic Effects on Modified Stokes’ Problems for Generalized Burgers’ Fluids“. Dynamics 3, Nr. 4 (01.12.2023): 803–19. http://dx.doi.org/10.3390/dynamics3040044.

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In this paper, exact analytical expressions are derived for dimensionless steady-state solutions corresponding to the modified Stokes’ problems for incompressible generalized Burgers’ fluids, considering the influence of porous and magnetic effects. Actually, these are the first exact solutions for such motions of these fluids. They can easily be particularized to give similar solutions for Newtonian, second-grade, Maxwell, Oldroyd-B and Burgers’ fluids. It is also proven that MHD motion problems of such fluids between infinite parallel plates can be investigated when shear stress is applied at the boundary. To validate the obtained results, the velocity fields are presented in two distinct forms, and their equivalence is proven through graphical representations. The obtained outcomes are utilized to determine the time required to reach a steady state and to elucidate the impacts of porous and magnetic parameters on the fluid motion. This investigation reveals that the attainment of a steady state occurs later when a porous medium or magnetic field is present. Additionally, the fluid’s flow resistance is augmented in the presence of a magnetic field or through a porous medium. Thus, as was expected, the fluid moves slower through porous media or in the presence of a magnetic field.

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Yerin, C. V. „SPECTRAL DEPENDENCIES OF MAGNETOOPTICAL EFFECTS IN MAGNETIC FLUIDS“. Eurasian Physical Technical Journal 19, Nr. 2 (40) (15.06.2022): 86–92. http://dx.doi.org/10.31489/2022no2/86-92.

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The spectral dependences of the transmittance and optical anisotropy effects in magnetic fluid have been investigated. It is shown that the refractive index spectra of bulk magnetite known are of little use for the quantitativeand qualitative interpretation of optical effects in magnetic fluids. The transmission, birefringence, and dichroism spectra are calculated using the known refractive index spectra of magnetite. The best agreement with the experiment was obtained using the experimental spectra of the complex refractive index of the powder of magnetite nanoparticles. It is concluded that there is a significant difference in the spectra of the complex refractive index for bulk and nanosized magnetite.

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Song, Sanggeun, Seong Jun Park, Minjung Kim, Jun Soo Kim, Bong June Sung, Sangyoub Lee, Ji-Hyun Kim und Jaeyoung Sung. „Transport dynamics of complex fluids“. Proceedings of the National Academy of Sciences 116, Nr. 26 (07.06.2019): 12733–42. http://dx.doi.org/10.1073/pnas.1900239116.

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Thermal motion in complex fluids is a complicated stochastic process but ubiquitously exhibits initial ballistic, intermediate subdiffusive, and long-time diffusive motion, unless interrupted. Despite its relevance to numerous dynamical processes of interest in modern science, a unified, quantitative understanding of thermal motion in complex fluids remains a challenging problem. Here, we present a transport equation and its solutions, which yield a unified quantitative explanation of the mean-square displacement (MSD), the non-Gaussian parameter (NGP), and the displacement distribution of complex fluids. In our approach, the environment-coupled diffusion kernel and its time correlation function (TCF) are the essential quantities that determine transport dynamics and characterize mobility fluctuation of complex fluids; their time profiles are directly extractable from a model-free analysis of the MSD and NGP or, with greater computational expense, from the two-point and four-point velocity autocorrelation functions. We construct a general, explicit model of the diffusion kernel, comprising one unbound-mode and multiple bound-mode components, which provides an excellent approximate description of transport dynamics of various complex fluidic systems such as supercooled water, colloidal beads diffusing on lipid tubes, and dense hard disk fluid. We also introduce the concepts of intrinsic disorder and extrinsic disorder that have distinct effects on transport dynamics and different dependencies on temperature and density. This work presents an unexplored direction for quantitative understanding of transport and transport-coupled processes in complex disordered media.

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Alasaly, Hasanaliabbood, und Ibtehal Kareem Shakir. „Enhance the Properties of Lignosulfonate Mud by Adding Nanoparticles of Aluminum Oxide and Iron Oxide“. Iraqi Journal of Chemical and Petroleum Engineering 23, Nr. 4 (30.12.2022): 25–32. http://dx.doi.org/10.31699/ijcpe.2022.4.4.

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Oil well drilling fluid rheology, lubricity, swelling, and fluid loss control are all critical factors to take into account before beginning the hole's construction. Drilling fluids can be made smoother, more cost-effective, and more efficient by investigating and evaluating the effects of various nanoparticles including aluminum oxide (Al2O3) and iron oxide (Fe2O3) on their performance. A drilling fluid's performance can be assessed by comparing its baseline characteristics to those of nanoparticle (NPs) enhanced fluids. It was found that the drilling mud contained NPs in concentrations of 0,0.25, 0. 5, 0.75 and 1 g. According to the results, when drilling fluid was used without NPs, the coefficient of fraction (CoF) was 44%, when added Al2O3 NP and Fe2O3 NP at 0.75g reduced CoF by 31% and 33% respectively. When Al2O3 and Fe2O3 NPs were used, particularly at a concentration of 1g, the amount of mud filtration decreased from 13.5ml to 9.3 ml and 8.5 ml respectively. Additional improvements rheological properties as well as swelling when Fe2O3NPs and Al2O3 NPs were added at 1g. Overall, it was found that adding NPs to the Lignosulfonate-WBM at a concentration of 1g can improve rheological, swelling, and filtration properties as well as lubrication at 0.75g.

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Gorodkin, S., R. James und W. Kordonski. „Irreversible Effects in Magnetorheological Fluids“. Journal of Intelligent Material Systems and Structures 22, Nr. 15 (Oktober 2011): 1749–54. http://dx.doi.org/10.1177/1045389x11426180.

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Giannitsis, A. T., P. C. Fannin und S. W. Charles. „Nonlinear effects in magnetic fluids“. Journal of Magnetism and Magnetic Materials 289 (März 2005): 165–67. http://dx.doi.org/10.1016/j.jmmm.2004.11.048.

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13

Joshi, Amey. „Elastic effects in superposed fluids“. Physics of Fluids 26, Nr. 2 (Februar 2014): 024113. http://dx.doi.org/10.1063/1.4866608.

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14

Li, Tao, Bin Liu, Jinzhi Zhou, Wenxuan Xi, Xiulan Huai und Hang Zhang. „A Comparative Study of Cavitation Characteristics of Nano-Fluid and Deionized Water in Micro-Channels“. Micromachines 11, Nr. 3 (16.03.2020): 310. http://dx.doi.org/10.3390/mi11030310.

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Hydrodynamic cavitation has been widely applied in micro-fluidic systems. Cavitating flow characteristics are closely related to the fluid properties. In this paper, the cavitation characteristics of Cu nano-fluid in micro-channels were numerically investigated and compared with those of the deionized (DI) water. The mathematical model was verified by comparing the numerical results with the experiment observation. The curved orifice (R = 0.3 mm) was found to have the highest efficiencies of cavitation for both fluids. With the increase of inlet pressure, cavitating jet lengths of the two fluids significantly increased. While, the cavitating jet length of the nano-fluid was shorter than that of the DI water at the same inlet pressure. The cavitation inception number of the DI water and nano-fluid were approximately 0.061 and 0.039, respectively. The results indicate that the nano-particles played negative effects on the cavitation inception. In addition, with the decrease of outlet pressure, the cavitation strength gradually increased and the mass flow rate remained nearly unchanged at the same time.

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King, Danielle, Hakan Başağaoğlu, Hoa Nguyen, Frank Healy, Melissa Whitman und Sauro Succi. „Effects of Advective-Diffusive Transport of Multiple Chemoattractants on Motility of Engineered Chemosensory Particles in Fluidic Environments“. Entropy 21, Nr. 5 (04.05.2019): 465. http://dx.doi.org/10.3390/e21050465.

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Motility behavior of an engineered chemosensory particle (ECP) in fluidic environments is driven by its responses to chemical stimuli. One of the challenges to understanding such behaviors lies in tracking changes in chemical signal gradients of chemoattractants and ECP-fluid dynamics as the fluid is continuously disturbed by ECP motion. To address this challenge, we introduce a new multiscale numerical model to simulate chemotactic swimming of an ECP in confined fluidic environments by accounting for motility-induced disturbances in spatiotemporal chemoattractant distributions. The model accommodates advective-diffusive transport of unmixed chemoattractants, ECP-fluid hydrodynamics at the ECP-fluid interface, and spatiotemporal disturbances in the chemoattractant concentrations due to particle motion. Demonstrative simulations are presented with an ECP, mimicking Escherichia coli (E. coli) chemotaxis, released into initially quiescent fluids with different source configurations of the chemoattractants N-methyl-L-aspartate and L-serine. Simulations demonstrate that initial distributions and temporal evolution of chemoattractants and their release modes (instantaneous vs. continuous, point source vs. distributed) dictate time histories of chemotactic motility of an ECP. Chemotactic motility is shown to be largely determined by spatiotemporal variation in chemoattractant concentration gradients due to transient disturbances imposed by ECP-fluid hydrodynamics, an observation not captured in previous numerical studies that relied on static chemoattractant concentration fields.

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Berkovsky, B. M., und N. N. Smirnov. „Capillary hydrodynamic effects in high magnetic fields“. Journal of Fluid Mechanics 187 (Februar 1988): 319–27. http://dx.doi.org/10.1017/s0022112088000448.

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A set of hydrodynamic equations has been applied to processes occurring in non-conductive fluids placed into magnetic fields. The equations are valid for equilibrium magnetization within the framework of a continuous medium. The ranges of physical parameters have been evaluated for which magnetization of a fluid should be taken into account in problems concerning the determination of equilibrium forms, and flows and their stability. The conclusion has been drawn that magnetization of natural fluids in these problems must be taken into consideration for fluids in high (exceeding 1 T) magnetic fields. As examples, the solutions of several typical problems concerning the equilibrium surface of capillary fluids and their stability in external magnetic fields have been considered. Hydrodynamic effects related to magnetization of natural capillary fluids in high magnetic fields are studied with due regard for the above solutions. Hydrodynamic effects in para- and diamagnetic fluids have been studied and the common and distinctive features of these effects discussed.

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Shah, Nehad Ali, Bander Almutairi, Dumitru Vieru und Ahmed A. El-Deeb. „The Effects of Thermal Memory on a Transient MHD Buoyancy-Driven Flow in a Rectangular Channel with Permeable Walls: A Free Convection Flow with a Fractional Thermal Flux“. Fractal and Fractional 7, Nr. 9 (01.09.2023): 664. http://dx.doi.org/10.3390/fractalfract7090664.

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This study investigates the effects of magnetic induction, ion slip and Hall current on the flow of linear viscous fluids in a rectangular buoyant channel. In a hydro-magnetic flow scenario with permeable and conducting walls, one wall has a temperature variation that changes over time, while the other wall keeps a constant temperature; the research focuses on this situation. Asymmetric wall heating and suction/injection effects are also examined in the study. Using the Laplace transform, analytical solutions in the Laplace domain for temperature, velocity and induced magnetic field have been determined. The Stehfest approach has been used to find numerical solutions in the real domain by reversing Laplace transforms. The generalized thermal process makes use of an original fractional constitutive equation, in which the thermal flux is influenced by the history of temperature gradients, which has an impact on both the thermal process and the fluid’s hydro-magnetic behavior. The influence of thermal memory on heat transfer, fluid movement and magnetic induction was highlighted by comparing the solutions of the fractional model with the classic one based on Fourier’s law.

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Ravazzoli, P. D., A. G. González und J. A. Diez. „GRAVITY EFFECTS IN THE RETRACTION OF LIQUID FILAMENTS RESTING ON AN INCLINED PLANE“. Anales AFA 33, Special Fluids (16.08.2022): 52–56. http://dx.doi.org/10.31527/analesafa.2022.fluidos.52.

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We study the retraction of liquid filaments resting on inclined solid substrates under partially wetting condition. This one causes each extreme of the filament to retract and form a region of mass accumulation (head) that subsequently develops a neck at its rear part. This neck then breaks up into a separate drop, while the rest of the filament restarts the sequence. In the horizontal case, this process is symmetric and leads to a regular arrangement of evenly spaced drops. When the substrate is inclined, gravity acts differently at each end, thus modifying the distance retracted by each end, the retraction speed and the final distance between drops, which also ceases to be uniform. We find that in the case of the inclined plane, the maximum distance retracted by the end that recedes against (in favor of) gravity decreases(increases) with respect to the horizontal case. This effect turns out to be a useful mechanism for the self–positioning of the resulting drops at the end of the process. Our experimental results, such as end positions, thickness profiles in the longitudinal section, etc., are contrasted with numerical simulations of the Navier–Stokes equations, obtaining a good agreement. This is achieved by using in the contact line the boundary condition known as Cox–Voinov–Blake (CVB)relationship, which includes both the effects of macroscopic hydrodynamics as well as molecular dynamics.

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Jamil, Muhammad, und Najeeb Alam Khan. „Slip Effects on Fractional Viscoelastic Fluids“. International Journal of Differential Equations 2011 (2011): 1–19. http://dx.doi.org/10.1155/2011/193813.

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Unsteady flow of an incompressible Maxwell fluid with fractional derivative induced by a sudden moved plate has been studied, where the no-slip assumption between the wall and the fluid is no longer valid. The solutions obtained for the velocity field and shear stress, written in terms of Wright generalized hypergeometric functions , by using discrete Laplace transform of the sequential fractional derivatives, satisfy all imposed initial and boundary conditions. The no-slip contributions, that appeared in the general solutions, as expected, tend to zero when slip parameter is . Furthermore, the solutions for ordinary Maxwell and Newtonian fluids, performing the same motion, are obtained as special cases of general solutions. The solutions for fractional and ordinary Maxwell fluid for no-slip condition also obtained as limiting cases, and they are equivalent to the previously known results. Finally, the influence of the material, slip, and the fractional parameters on the fluid motion as well as a comparison among fractional Maxwell, ordinary Maxwell, and Newtonian fluids is also discussed by graphical illustrations.

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Zhao, T., und H. R. Ma. „Column size effects of DER fluids“. European Physical Journal E 5, Nr. 4 (Juli 2001): 481–83. http://dx.doi.org/10.1007/s101890170055.

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21

Hunter, L. W., F. F. Mark, D. A. Kitchin, M. R. Feinstein, N. A. Blum, B. R. Platte, F. G. Arcella, D. R. Kuespert und M. D. Donohue. „Optical Effects of Electro-Rheological Fluids“. Journal of Intelligent Material Systems and Structures 4, Nr. 3 (Juli 1993): 415–18. http://dx.doi.org/10.1177/1045389x9300400316.

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22

Long, Z. Q., P. Zhang und B. Shen. „Thermomechanical effects in supercritical binary fluids“. International Journal of Heat and Mass Transfer 99 (August 2016): 470–84. http://dx.doi.org/10.1016/j.ijheatmasstransfer.2016.03.104.

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23

McLean, D. J., und A. D. Shaw. „Intravenous fluids: effects on renal outcomes“. British Journal of Anaesthesia 120, Nr. 2 (Februar 2018): 397–402. http://dx.doi.org/10.1016/j.bja.2017.11.090.

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Bruyn, John R. de, und David A. Balzarini. „Quantum effects near the liquid–vapour critical point“. Canadian Journal of Physics 68, Nr. 4-5 (01.04.1990): 449–53. http://dx.doi.org/10.1139/p90-069.

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We gather together a number of recent measurements of the coexistence curve and compressibility of fluids close to the critical point, and investigate the variation of the critical exponents and amplitudes as quantum effects become more important. We find that the universal critical exponents and amplitude ratios are the same for quantum fluids as for room-temperature fluids, as expected. Some of the nonuniversal critical amplitudes, however, show systematic variations as quantum effects become significant, in at least qualitative agreement with theoretical predictions.

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Kim, Bongsu, Soyoung Kwon, Manhee Lee, QHwan Kim, Sangmin An und Wonho Jhe. „Probing nonlinear rheology layer-by-layer in interfacial hydration water“. Proceedings of the National Academy of Sciences 112, Nr. 51 (07.12.2015): 15619–23. http://dx.doi.org/10.1073/pnas.1515033112.

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Viscoelastic fluids exhibit rheological nonlinearity at a high shear rate. Although typical nonlinear effects, shear thinning and shear thickening, have been usually understood by variation of intrinsic quantities such as viscosity, one still requires a better understanding of the microscopic origins, currently under debate, especially on the shear-thickening mechanism. We present accurate measurements of shear stress in the bound hydration water layer using noncontact dynamic force microscopy. We find shear thickening occurs above ∼ 106s−1shear rate beyond 0.3-nm layer thickness, which is attributed to the nonviscous, elasticity-associated fluidic instability via fluctuation correlation. Such a nonlinear fluidic transition is observed due to the long relaxation time (∼ 10−6s) of water available in the nanoconfined hydration layer, which indicates the onset of elastic turbulence at nanoscale, elucidating the interplay between relaxation and shear motion, which also indicates the onset of elastic turbulence at nanoscale above a universal shear velocity of ∼ 1 mm/s. This extensive layer-by-layer control paves the way for fundamental studies of nonlinear nanorheology and nanoscale hydrodynamics, as well as provides novel insights on viscoelastic dynamics of interfacial water.

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Desgranges, Caroline, und Jerome Delhommelle. „Many-Body Effects on the Thermodynamics of Fluids, Mixtures, and Nanoconfined Fluids“. Journal of Chemical Theory and Computation 11, Nr. 11 (07.10.2015): 5401–14. http://dx.doi.org/10.1021/acs.jctc.5b00693.

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XU, M. X., W. G. WANG und Y. Y. ZHANG. „EFFECTS OF NONMAGNETIC SPHERES ON THE MAGNETO-OPTICS OF Fe3O4 COMPOSITE MAGNETIC FLUIDS“. International Journal of Modern Physics B 24, Nr. 28 (10.11.2010): 5553–60. http://dx.doi.org/10.1142/s0217979210056207.

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Both pure Fe 3 O 4 magnetic fluids and containing polystyrene sphere composite magnetic fluids have been prepared. The magneto-optical characteristics such as magnetic birefringence and linear dichroism of both magnetic fluids and composite magnetic fluids have been investigated by the magneto-optically modulated double-frequency method. The results reveal that the order structure of nonmagnetic spheres and the interactions between the spheres and the neighbor magnetic chains of Fe 3 O 4 particles in the composite magnetic fluids strongly affect the magneto-optical properties. The magneto-optical properties from the study can be used for further development of related new optical devices.

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Odenbach, S. „Magnetoviscous Effects In Ferrofluids“. Applied Rheology 10, Nr. 4 (01.08.2000): 178–84. http://dx.doi.org/10.1515/arh-2000-0011.

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Abstract Suspensions of magnetic particles with diameters in the nanometer range exhibit longterm sedimentation stability as well as the possibility of magnetic field induced control of their properties and flow. One of the most famous field induced effects is the change of viscosity of the fluids due to the action of magnetic influences. An explanation of these effects on basis of microscopic models is a challenging field of actual experimental and theoretical research. Within this article the state of knowledge on magnetoviscous effects in magnetic fluids will be summarized and in particular the experimental methods used to obtain related results will be discussed.

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Hamilton, Ben, und J. G. Brisson. „Modified 3ω conductivity technique for measurements of thermal conductivity in cryogenic fluids“. IOP Conference Series: Materials Science and Engineering 1301, Nr. 1 (01.05.2024): 012164. http://dx.doi.org/10.1088/1757-899x/1301/1/012164.

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Abstract An instrument based on a modification to the 3-omega thermal conductivity technique that allows precise measurement of thermal properties in fluids is presented. Existing hot-wire techniques have difficulty measuring thermal conductivity because of the effects of natural convection distorting the measurement, however the standard 3-omega technique has been used extensively in the measurement of the properties of solids with great success. To address the challenge posed by natural convection in fluids, we modify the boundary condition of the 3-omega device configuration to be finite in extent, thereby restricting fluid motion and enabling a direct high-precision measurement of a fluid’s thermal conductivity. This modified scenario also presents an opportunity for a simultaneous measurement of the thermal diffusivity of the fluid. The behavior of the device is described with the reformed boundary conditions to show how a simultaneous measurement is made. By applying a constant temperature finite boundary condition, the solution characteristic in the frequency domain gains features that allow for simultaneous measurements of the fluid thermal conductivity and diffusivity. Given the density of the fluid, measured separately, the specific heat of the fluid can be calculated. The effects of the thermal properties of the measurement wire influence the measurement characteristic, and only when the wire thermal properties are sufficiently small compared to those of the fluid can a simultaneous measurement be made. Due to limitations in the dynamic reserve of the measurement devices, a setup is described that allows the signal of interest to be extracted and a precise measurement to be made with minimal distortion. Initial data on the thermal conductivity of helium is presented in the 4-300K temperature range. Preliminary specific heat data is also presented. Limitations on the device’s thermal properties prevent a specific heat measurement above 70K. This data is compared with reference fluid properties databases to validate the device performance.

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Chetti, Boualem. „Analysis of a circular journal bearing lubricated with micropolar fluids including EHD effects“. Industrial Lubrication and Tribology 66, Nr. 2 (04.03.2014): 168–73. http://dx.doi.org/10.1108/ilt-12-2011-0114.

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Purpose – The performance of finite circular journal bearing lubricated with micropolar fluids taking into account the elastic deformation of the bearing liner is presented. The paper aims to discuss these issues. Design/methodology/approach – The modified Reynolds equation is obtained using the micropolar lubrication theory. The solution of the modified Reynolds equation is determined using finite difference technique. The static characteristics in terms of load-carrying capacity, attitude angle, side leakage and friction coefficient for micropolar and Newtonian fluids are determined for various values of eccentricity ratio and different values of elastic coefficient. Findings – Compared with Newtonian fluids, the micropolar fluids produce an increase in the load-carrying capacity and a reduction in the attitude angle, the friction factor and side leakage for both the rigid and deformable bearings. Originality/value – It is concluded that the influence of elastic deformation on the bearing characteristics lubricated with micropolar fluids is significantly apparent compared with bearing lubricated with Newtonian fluids.

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Ahmad, Samaila Kenga-Kwai, Sani Abdullahi Aliero, Muhammad Ibtrahim und Halima Usman. „Impacts of Exponentially Growing/Decaying Pressure Gradient on Mixed Convection Flow of Viscous Reactive Fluid in a Vertical Tube: A Numerical Approach“. Saudi Journal of Engineering and Technology 8, Nr. 07 (25.07.2023): 181–88. http://dx.doi.org/10.36348/sjet.2023.v08i07.004.

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This study examined the effects of a pressure gradient that was exponentially increasing or decreasing on the mixed convection flow of viscous reactive fluids in a vertical tube between two concentric tubes with r = 0 and r = b. The nonlinear partial differential equation governing the flow formation are solved using the implicit finite difference form where all time differentials were calculated using the forward difference formula, and second order central differences were utilized to approximate the first and second derivatives. The impacts of several physical parameters, including shear stress, the rate of heat transfer, mixed convection, viscous reactive fluid parameter, activation energy, Prandtl number, and exponential decaying/growing pressure gradient on skin friction and Nusselt number were investigated. It's intriguing to see that raising the values of Frank–Kamenetskii (λ), mixed convection (Gre) as well as exponential growing pressure term increases the velocity fluid, However, in the case of exponential decay, the parameter drop also causes the fluid's velocity to diminish. The results also showed that a small bump in the viscous reactive fluid parameter considerably improves the energy profile.

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Fernandes, Célio, Luís L. Ferrás und Alexandre Afonso. „A Primer on CFD-DEM for Polymer-Filled Suspensions“. Applied Sciences 13, Nr. 4 (14.02.2023): 2466. http://dx.doi.org/10.3390/app13042466.

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This work reports on an evaluation of the computational fluid dynamics–discrete element method (CFD-DEM) numerical approach to study the behavior of polymer-filled suspensions in a parallel-plate rheometer. For this purpose, an open-source CFD-DEM solver is used to model the behavior of such suspensions considering different particle volume fractions and different types of fluid rheology. We first validate the numerical approach for the single-phase flow of the continuum phase (fluid phase) by comparing the fluid’s azimuthal velocity and shear stress components obtained from the open-source solver against the analytical expressions given in cylindrical coordinates. In addition, we compare the numerical torque given by the numerical procedure with analytical expressions obtained for Newtonian and power law fluids. For both cases, there is a remarkable agreement between the numerical and analytical results. Subsequently, we investigated the effects of the particle volume fraction on the rheology of the suspension. The numerical results agree well with the experimentally measured ones and show a yield stress phenomenon with the increase of the particle volume fraction.

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Claes, Leander, Lars Moritz Hülskämper, Elmar Baumhögger, Nadine Feldmann, René Spencer Chatwell, Jadran Vrabec und Bernd Henning. „Acoustic absorption measurement for the determination of the volume viscosity of pure fluids / Messverfahren für die akustischen Absorption zur Bestimmung der Volumenviskosität reiner Fluide“. tm - Technisches Messen 86, s1 (01.09.2019): 2–6. http://dx.doi.org/10.1515/teme-2019-0038.

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AbstractA realistic description of fluid mechanical and acoustic processes requires the volume viscosity of the medium to be known. This work describes how the volume viscosity of pure fluids can be determined by measuring acoustic absorption with the pulse-echo method. The challenge in realizing such a measurement method lies in the separation of the different dissipative effects that superimpose on absorption. Diffraction effects ultimately cause a dissipation of acoustic energy and acoustic reflector surfaces have a small, but finite transmission coefficient. Further, influences of the transducer (in particular its frequency response), as well as the system’s electrical components have to be taken into account. In contrast to the classical approach relying on the amplitude ratio, the absorption is determined by the moments of the amplitude spectrum. The measurement system applied is originally designed for precision measurements of the sound velocity by means of the propagation time difference of two acoustic signals.

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Chang, Kuo T., und Rong F. Huang. „Development and Characterization of Jet-Injected Vee-Gutter“. Journal of Mechanics 20, Nr. 1 (März 2004): 77–83. http://dx.doi.org/10.1017/s1727719100004068.

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ABSTRACTThe vee-gutter, which was conventionally used in a combustor for flame holding, was re-designed by employing the unsteady Coanda effect to inject fluids periodically into near wake of the vee-gutter. Fluidic targets were developed to induce self-sustained transverse oscillation of slit-jet. The self-sustained oscillating jet was conducted through passages and injected into the near wake of the vee-gutter. The behaviors and frequency characteristics of the slit-jet in the oscillation cavity and the turbulence properties in the wake were studied experimentally in a wind-tunnel by using the smoke-wire flow visualization technique and the hot-wire anemometer. The oscillation frequencies of the presently developed jet-injection vee-gutter were about 25 to 40 times higher than that of the conventionally used fluidic flowmeter. By estimating the Lagrangian integral time scale and employing the Taylor's frozen flow hypothesis, the integral length scales of turbulence fluctuations were calculated. The results showed that the integral length scales of turbulences of the jet-injected vee-gutter were significantly smaller than their counter parts of the conventional vee-gutter, which indicated the effects of vortex stretching induced by the periodic jet injection. The modifications of turbulence properties were presented and discussed.

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Lhermitte, P. „MOUVEMENTS DES MATERIAUX DE FOND SOUS L'ACTION DE LA HOULE“. Coastal Engineering Proceedings 1, Nr. 7 (29.01.2011): 13. http://dx.doi.org/10.9753/icce.v7.13.

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Hous exposerons dans cet article, les resultats d'experiences que nous avons obtenues, relativement aux mouvemen des materiaux de fond sous 1'action des houles progressives, et nous tenterons de fournir des schemas d'explication des differenph^ nomenes observes. Certains aspects des mouvements. de materiaux sous 1*action des houles, n© peuvent s'expliquer que par 1*extension de certains phenomenes hydrauliques lies a. la propagation des houles progressives : repartition des courants d'entrainement, effet de viscosite des fluides, developpement de la eouche-limit* pres du fond, etc .... Hous nous bornerons d'ailleurs dans cette etude, a la description des mouvements de materiaux, qui dependent directemer des caracteristiques hydrauliques du mouvement du fluide, et plus .particulierement des caracteristiques de la couche limite, mais nous ne nous attacherons pas a, 1* etude de 1'influence des caracteres geologiques ou sedimentologiqu.es du materiau sur le comportement de ce dernier, l'etude detaill^e de ces phenomenes sortani du cadre de cette etude. Sans exposer de facon complete et rigoureuse les phenc menes hydrauliques, il nous a semble" utile, pour la comprdhensior du texte, d'indiquersommairement certains aspects shhematiques d€ ces phenomenes. £es lecteurs desirant approfondir ces questions pourront se reporter aux ouvrages citds en bibliographie -(6) (7) pour les courants d'entrainement, (5) et (4) pour les phenomenes de couche limite.

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Fang, Daoyuan, Ting Zhang und Ruizhao Zi. „Dispersive effects of the incompressible viscoelastic fluids“. Discrete & Continuous Dynamical Systems - A 38, Nr. 10 (2018): 5261–95. http://dx.doi.org/10.3934/dcds.2018233.

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Kume, Eni, Patrick Baroni und Laurence Noirez. „Highlighting Thermo-Elastic Effects in Confined Fluids“. Polymers 13, Nr. 14 (20.07.2021): 2378. http://dx.doi.org/10.3390/polym13142378.

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The recent identification of a finite shear elasticity in mesoscopic fluids has motivated the search of other solid-like properties of liquids. We present an innovative thermal approach of liquids. We identify a dynamic thermo-elastic mesoscopic behavior by building the thermal image produced by different liquids upon applying a low frequency mechanical shear field. We selected three fluids: a low molecular weight polybutylacrylate (PBuA), polypropyleneglycol (PPG), and glycerol. We demonstrate that a part of the energy of the shear strain is converted in cold and hot shear bands varying synchronously with the applied shear field. This thermodynamic change suggests a coupling to shear elastic modes in agreement with the low frequency shear elasticity theoretically foreseen and experimentally demonstrated.

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Elliott, J. Richard, Uday S. Kanetkar und Venkatesh J. Vasudevan. „Attractive-force effects in chain molecular fluids“. Molecular Physics 71, Nr. 4 (November 1990): 883–95. http://dx.doi.org/10.1080/00268979000102181.

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Van Damme, H., C. Laroche, L. Gatineau und P. Levitz. „Viscoelastic effects in fingering between miscible fluids“. Journal de Physique 48, Nr. 7 (1987): 1121–33. http://dx.doi.org/10.1051/jphys:019870048070112100.

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Biben, Thierry, Peter Bladon und Daan Frenkel. „Depletion effects in binary hard-sphere fluids“. Journal of Physics: Condensed Matter 8, Nr. 50 (09.12.1996): 10799–821. http://dx.doi.org/10.1088/0953-8984/8/50/008.

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Lacava, Z. G. M., R. B. Azevedo, E. V. Martins, L. M. Lacava, M. L. L. Freitas, V. A. P. Garcia, C. A. Rébula et al. „Biological effects of magnetic fluids: toxicity studies“. Journal of Magnetism and Magnetic Materials 201, Nr. 1-3 (Juli 1999): 431–34. http://dx.doi.org/10.1016/s0304-8853(99)00002-5.

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42

Wu, Benjamin C., Michael T. Klein und Stanley I. Sandler. „Solvent effects on reactions in supercritical fluids“. Industrial & Engineering Chemistry Research 30, Nr. 5 (Mai 1991): 822–28. http://dx.doi.org/10.1021/ie00053a003.

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Onuki, Akira. „On New Nonequilibrium Effects in Stirred Fluids“. Progress of Theoretical Physics Supplement 99 (1989): 382–98. http://dx.doi.org/10.1143/ptps.99.382.

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Zhang, Liucheng, Kai Su und Xiucuo Li. „Electrorheological effects of polyaniline-type electrorheological fluids“. Journal of Applied Polymer Science 87, Nr. 5 (03.12.2002): 733–40. http://dx.doi.org/10.1002/app.11356.

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Bobroff, Linda B. „Healthy Eating: Fluids“. EDIS 2016, Nr. 4 (03.06.2016): 2. http://dx.doi.org/10.32473/edis-fy070-2016.

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More than one-half of an adult’s body weight is water. Water brings nutrients to the cells in our bodies and removes waste. Our bodies cannot function if they do not receive enough water. This 2-page fact sheet is a major revision that addresses the importance of water to physical functions, effects of dehydration, risk factors for dehydration in older adults, and fluid intake suggestions. Written by Linda B. Bobroff, and published by the UF Department of Family, Youth and Community Sciences, June 2016.

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Korobeinikov, A. „Numerical simulation of the oscillations of non-newtonian viscous fluids with a free surface“. Journal of Applied Mathematics and Decision Sciences 4, Nr. 2 (01.01.2000): 111–23. http://dx.doi.org/10.1155/s1173912600000080.

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Non-Newtonian fluids are increasingly being transported by a variety of vehicles. It has been observed that vehicles containing such fluids demonstrate behaviour which could be explained only by non-linearity characteristics of such fluids. In this paper small oscillations of non-Newtonian fluids in tanks are considered. A numerical method suitable for both Newtonian and non-Newtonian fluids is suggested. Examples of numerical simulations with emphasis on Bingham fluids are given to demonstrate effects of non-linear properties.

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Wieslander, Anders P., Anders H. G. Andrén, Carin Nilsson-Thorell, Natalia Muscalu, Per T. T. Kjellstrand und Bengt Rippe. „Are Aldehydes in Heat-Sterllized Peritoneal Dialysis Fluids Toxic in Vitro?“ Peritoneal Dialysis International: Journal of the International Society for Peritoneal Dialysis 15, Nr. 4 (Oktober 1995): 348–52. http://dx.doi.org/10.1177/089686089501500411.

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Objective Chemical analysis of several brands of peritoneal dialysis fluids (PD fluids) has revealed the presence of 2-furaldehyde, 5-HMF (5-hydroxymethylfuraldehyde), acetaldehyde, formaldehyde, glyoxal, and methylglyoxal. The aim of this study was to investigate if the in vitro side effects caused by glucose degradation products, mainly formed during heat sterilization, are due to any of these recently identified aldehydes. Design Cell growth media or sterile filtered PD fluids were spiked with different concentrations ofthealdehydes. Measurements In vitro side effects were determined as the inhibition of cell growth of cultured mouse fibro blasts or stimulated superoxide radical release from human peritoneal cells. Results Our results demonstrate that the occurrences of 2-furaldehyde, 5-HMF, acetaldehyde, formaldehyde, glyoxal, or methylglyoxal in heat-sterilized PD fluids are probably not the direct cause of in vitro side effects. In order to induce the same magnitude of cell growth inhibition as the heat-sterilized PD fluids, the concentrations of 2-furaldehyde, glyoxal, and 5-HMF had to be 50 to 350 times higher than those quantified in the PD fluids. The concentrations of acetaldehyde, formaldehyde, and methylglyoxal observed in the heat-sterilized PD fluids were closer to the cytotoxic concentrations although still 3 to 7 times lower. Conclusion Since none of these aldehydes caused in vitro toxicity at the tested concentrations, the toxicity found in PD fluids is likely to be due to another glucose degradation product, not yet identified. However, it is possible that these aldehydes may still have adverse effects for patients on peritoneal dialysis.

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Sacnun, Juan Manuel, Robin Hoogenboom, Fabian Eibensteiner, Isabel J. Sobieszek, Markus Unterwurzacher, Anja Wagner, Rebecca Herzog und Klaus Kratochwill. „Proteome-Wide Differential Effects of Peritoneal Dialysis Fluid Properties in an In Vitro Human Endothelial Cell Model“. International Journal of Molecular Sciences 23, Nr. 14 (20.07.2022): 8010. http://dx.doi.org/10.3390/ijms23148010.

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To replace kidney function, peritoneal dialysis (PD) utilizes hyperosmotic PD fluids with specific physico-chemical properties. Their composition induces progressive damage of the peritoneum, leading to vasculopathies, decline of membrane function, and PD technique failure. Clinically used PD fluids differ in their composition but still remain bioincompatible. We mapped the molecular pathomechanisms in human endothelial cells induced by the different characteristics of widely used PD fluids by proteomics. Of 7894 identified proteins, 3871 were regulated at least by 1 and 49 by all tested PD fluids. The latter subset was enriched for cell junction-associated proteins. The different PD fluids individually perturbed proteins commonly related to cell stress, survival, and immune function pathways. Modeling two major bioincompatibility factors of PD fluids, acidosis, and glucose degradation products (GDPs) revealed distinct effects on endothelial cell function and regulation of cellular stress responses. Proteins and pathways most strongly affected were members of the oxidative stress response. Addition of the antioxidant and cytoprotective additive, alanyl-glutamine (AlaGln), to PD fluids led to upregulation of thioredoxin reductase-1, an antioxidant protein, potentially explaining the cytoprotective effect of AlaGln. In conclusion, we mapped out the molecular response of endothelial cells to PD fluids, and provided new evidence for their specific pathomechanisms, crucial for improvement of PD therapies.

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Jerković-Babović, Bojana. „Fluid state of architecture“. SAJ - Serbian Architectural Journal 11, Nr. 3 (2019): 501–10. http://dx.doi.org/10.5937/saj1903501j.

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This paper focuses on the changes in architectural aesthetic criteria, from static to dynamic values of both figurative and non-figurative aspects in contemporary architecture and its cultural context. Fluid state of architecture refers to the notions of constant variability occurring in relations between architecture and contemporary cultural context of globalisation. Contemporary context dynamises everyday perceptual experiences, living conditions and terms of spatial appropriations. Accordingly, new networking phenomena appearing on informational, communicational and spatial levels transform the city and architecture into constant process of flows, dematerialising its elements into the new fluid, variable character. Architectural aesthetic qualities simultaneously shift trough events and effects affirmation over static formal whole in transformation from objective to (inter)subjective aesthetic spatial experience. This paper is based on hypothesis that contemporary architecture is characterised by the loss of object singularity in terms of contextual conditions and assimilation of particular characters into the dynamic character of the whole. Therefore, architectural design principles shift through dispersion of disciplinary boundaries and boundaries of inner and outer architectural space, hybridity and typological definition loss. This paper presents how dematerialisation of architectural values transforms contemporary architectural space into the complex dynamic system of infrastructure, flows, events and effects.

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STOKES, JASON R., LACHLAN J. W. GRAHAM, NICK J. LAWSON und DAVID V. BOGER. „Swirling flow of viscoelastic fluids. Part 2. Elastic effects“. Journal of Fluid Mechanics 429 (25.02.2001): 117–53. http://dx.doi.org/10.1017/s0022112000002901.

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A torsionally driven cavity has been used to examine the influence of elasticity on the swirling flow of constant-viscosity elastic liquids (Boger fluids). A wealth of phenomena is observed as the degree of inertia, elasticity and viscous forces are varied by using a range of low- to high-viscosity flexible polyacrylamide Boger fluids and a semi-rigid xanthan gum Boger fluid. As the inertia is decreased and elasticity increased by using polyacrylamide Boger fluids, the circulation rates for a ‘Newtonian-like’ secondary flow decreases until flow reversal occurs owing to the increasing magnitude of the primary normal stress difference. For each polyacrylamide fluid, the flow becomes highly unstable at a critical combination of Reynolds number and Weissenberg number resulting in a new time-dependent elastic instability. Each fluid is characterized by a dimensionless elasticity number and a correlation with Reynolds number is found for the occurrence of the instability. In the elasticity dominated flow of the polyacrylamide Boger fluids, the instability disrupts the flow dramatically and causes an increase in the peak axial velocity along the central axis by as much as 400%. In this case, the core vortex spirals with the primary motion of fluid and is observed in some cases at Reynolds numbers much less than unity. Elastic ‘reverse’ flow is observed for the xanthan gum Boger fluid at high Weissenberg number. As the Weissenberg number decreases, and Reynolds number increases, counter-rotating vortices flowing in the inertial direction form on the rotating lid. The peak axial velocity decreases for the xanthan gum Boger fluid with decreasing Weissenberg number. In addition, several constitutive models are used to describe accurately the rheological properties of the fluids used in this work in shear and extensional flow. This experimental investigation of a complex three-dimensional flow using well-characterized fluids provides the information necessary for the validation of non-Newtonian constitutive models through numerical analysis of the torsionally driven cavity flow.

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