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Journal articles on the topic 'Viscoelastic fluid'
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1
Li, Chuanbin, Boyang Qin, Arvind Gopinath, Paulo E. Arratia, Becca Thomases, and Robert D. Guy. "Flagellar swimming in viscoelastic fluids: role of fluid elastic stress revealed by simulations based on experimental data." Journal of The Royal Society Interface 14, no. 135 (October 2017): 20170289. http://dx.doi.org/10.1098/rsif.2017.0289.
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Many important biological functions depend on microorganisms' ability to move in viscoelastic fluids such as mucus and wet soil. The effects of fluid elasticity on motility remain poorly understood, partly because the swimmer strokes depend on the properties of the fluid medium, which obfuscates the mechanisms responsible for observed behavioural changes. In this study, we use experimental data on the gaits of Chlamydomonas reinhardtii swimming in Newtonian and viscoelastic fluids as inputs to numerical simulations that decouple the swimmer gait and fluid type in order to isolate the effect of fluid elasticity on swimming. In viscoelastic fluids, cells employing the Newtonian gait swim faster but generate larger stresses and use more power, and as a result the viscoelastic gait is more efficient. Furthermore, we show that fundamental principles of swimming based on viscous fluid theory miss important flow dynamics: fluid elasticity provides an elastic memory effect that increases both the forward and backward speeds, and (unlike purely viscous fluids) larger fluid stress accumulates around flagella moving tangent to the swimming direction, compared with the normal direction.
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Song, Jinhyeuk, Jaekyeong Jang, Taehoon Kim, and Younghak Cho. "Particle Separation in a Microchannel with a T-Shaped Cross-Section Using Co-Flow of Newtonian and Viscoelastic Fluids." Micromachines 14, no. 10 (September 28, 2023): 1863. http://dx.doi.org/10.3390/mi14101863.
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In this study, we investigated the particle separation phenomenon in a microchannel with a T-shaped cross-section, a unique design detailed in our previous study. Utilizing a co-flow system within this T-shaped microchannel, we examined two types of flow configuration: one where a Newtonian fluid served as the inner fluid and a viscoelastic fluid as the outer fluid (Newtonian/viscoelastic), and another where both the inner and outer fluids were Newtonian fluids (Newtonian/Newtonian). We introduced a mixture of three differently sized particles into the microchannel through the outer fluid and observed that the co-flow of Newtonian/viscoelastic fluids effectively separated particles based on their size compared with Newtonian/Newtonian fluids. In this context, we evaluated and compared the particle separation efficiency, recovery rate, and enrichment factor across both co-flow configurations. The Newtonian/viscoelastic co-flow system demonstrated a superior efficiency and recovery ratio when compared with the Newtonian/Newtonian system. Additionally, we assessed the influence of the flow rate ratio between the inner and outer fluids on particle separation within each co-flow system. Our results indicated that increasing the flow rate ratio enhanced the separation efficiency, particularly in the Newtonian/viscoelastic co-flow configuration. Consequently, this study substantiates the potential of utilizing a Newtonian/viscoelastic co-flow system in a T-shaped straight microchannel for the simultaneous separation of three differently sized particles.
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FUKUMA, MASAFUMI, and YUHO SAKATANI. "RELATIVISTIC VISCOELASTIC FLUID MECHANICS." International Journal of Modern Physics: Conference Series 21 (January 2013): 189–90. http://dx.doi.org/10.1142/s2010194513009744.
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We explain the relativistic theory of viscoelasticity which we have recently constructed on the basis of Onsager's linear nonequilibrium thermodynamics. This theory universally reduces to the standard relativistic Navier-Stokes fluid mechanics in the long time limit. Since effects of elasticity are taken into account, the dynamics at short time scales is modified from that given by the Navier-Stokes equations, so that acausal problems intrinsic to relativistic Navier-Stokes fluids are significantly remedied. We then present conformal higher-order viscoelastic fluid mechanics with strain allowed to take arbitrarily large values. We particularly show that a conformal second-order fluid with all possible parameters in the constitutive equations can be obtained without breaking the hypothesis of local thermodynamic equilibrium, if the conformal fluid is defined as the long time limit of a conformal second-order viscoelastic system.
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Bizhani, M., and E. Kuru. "Particle Removal From Sandbed Deposits in Horizontal Annuli Using Viscoelastic Fluids." SPE Journal 23, no. 02 (December 19, 2017): 256–73. http://dx.doi.org/10.2118/189443-pa.
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Summary This paper presents results of an experimental study on how fluid viscoelastic properties would influence the particle removal from the sandbed deposited in horizontal annuli. Water and two different viscoelastic fluids were used for bed-erosion experiments. The particle-image-velocimetry (PIV) technique was used to measure the local fluid velocity at the fluid/sandbed interface, allowing for accurate estimation of the fluid-drag forces and the turbulence stresses. It was found that polymer fluids needed to exert higher level drag forces (than those of water) on the sandbed to start movement of the particles. Results have also shown that, at the critical flow rate of bed erosion, the polymer fluids yielded higher local fluid velocities and turbulent stresses than those of water. Moreover, the local velocity measurements by means of the PIV technique and the resultant bed-shear-stress calculations indicated that enhancing polymer concentration under the constant flow rate should also enhance the drag forces acting on the sandbed. However, these improved fluid hydrodynamic forces did not result in any improvement in the bed erosion. Therefore, the mechanism causing the delay in the bed erosion by polymer additives could not be explained by any decrease in the local fluid velocity and the turbulence. The primary reason for the delayed bed erosion by the polymer fluids was suggested to be linked to their viscoelastic properties. Two possible mechanisms arising from the elastic properties of the polymer fluids that hinder bed erosion were further discussed in the paper. The stress tensor of the viscoelastic-fluid flow was analyzed to determine the normal stress differences and the resultant normal fluid force acting on the particles at the fluid/sandbed interface. The normal force induced by the normal stress differences of the viscoelastic fluid was identified as one of the possible causes of the delayed bed erosion by these types of fluids.
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Khan, Nabeel, Farhad Ali, Ilyas Khan, and Nadeem Ahmad Sheikh. "A scientific report on the flow of Maxwell fluid with heat transfer in vertical oscillating cylinder." City University International Journal of Computational Analysis 1, no. 1 (July 8, 2019): 10–19. http://dx.doi.org/10.33959/cuijca.v1i1.18.
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The nonlinear nature of viscoelastic non-Newtonian fluids, introduce a unique challenge to physicists and mathematicians. By developing and utilizing viscoelastic models can play a special role in saving and treatments of every living species and to describe its particular characteristics. In the past three decades, viscoelastic fluid models are focused to improve its accuracy and reliability. Some rate type viscoelastic fluids include Maxwell fluid which effects in relaxation time. Such effect of relaxation time cannot be predicted by differential-type fluids. The polymers of low molecular weight are usefully described by Maxwell model. However, a keen interest of the researchers is seen in studying rate type fluids due to the fact that they incorporate both the elastic nature and memory behaviour together. In this article, viscoelastic Maxwell fluid is considered in cylindrical tube together with heat transfer due to convection caused by the buoyancy force. This problem is modelled using the classical approach and then solved for exact solution using joint the Laplace and Hankel transforms. Effects of pertinent parameters on Maxwell fluid velocity have been shown graphically. Behaviour of temperature is studied for various values of Prandtl number.
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Makarynska, Dina, Boris Gurevich, Jyoti Behura, and Mike Batzle. "Fluid substitution in rocks saturated with viscoelastic fluids." GEOPHYSICS 75, no. 2 (March 2010): E115—E122. http://dx.doi.org/10.1190/1.3360313.
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Heavy oils have high densities and extremely high viscosities, and they exhibit viscoelastic behavior. Traditional rock physics based on Gassmann theory does not apply to materials saturated with viscoelastic fluids. We use an effective-medium approach known as coherent potential approximation (CPA) as an alternative fluid-substitution scheme for rocks saturated with viscoelastic fluids. Such rocks are modeled as solids with elliptical fluid inclusions when fluid concentration is small and as suspensions of solid particles in the fluid when the solid concentration is small. This approach is consistent with concepts of percolation and critical porosity, and it allows one to model sandstones and unconsolidated sands.We model the viscoelastic properties of a heavy-oil-saturated rock sample using CPA and a measured frequency-dependent complex shear modulus of the heavy oil. Comparison of modeled results with measured properties of the heavy-oil rock reveals a large discrepancy over a range of frequencies and temperatures. We modify the CPA scheme to account for the effect of binary pore structure by introducing a compliant porosity term. This dramatically improves the predictions. The predicted values of the effective shear modulus of the rock are in good agreement with laboratory data for the range of frequencies and temperatures. This confirms that our scheme realistically estimates the frequency- and temperature-dependent properties of heavy-oil rocks and can be used as an approximate fluid-substitution approach for rocks saturated with viscoelastic fluids.
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Yuan, Chao, Hong-Na Zhang, Yu-Ke Li, Xiao-Bin Li, Jian Wu, and Feng-Chen Li. "Nonlinear effects of viscoelastic fluid flows and applications in microfluidics: A review." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 234, no. 22 (May 7, 2020): 4390–414. http://dx.doi.org/10.1177/0954406220922863.
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Viscoelastic fluid naturally has both viscous and elastic properties. Therefore, there are two sources of nonlinear effects, namely inertial and elastic nonlinearities. The existence of elastic nonlinearity brings about various interesting flow phenomena in viscoelastic fluid flow, especially in microfluidics where the inertial nonlinearity can be negligible while the elastic nonlinearity can dominate the flow. Specifically, purely elasticity-induced instability and turbulence can occur in microchannels when the elastic nonlinearity is strong enough. Recently, those intriguing properties of viscoelastic fluid flow have motivated lots of researches on taking viscoelastic fluid as working fluid in different types of microfluidic devices, such as micro-mixers, micro heat exchangers, logic microfluidic circuits and particle manipulation. This paper aims to provide a state-of-the-art review of the nonlinear effect of viscoelastic fluids and its applications in the aforementioned microfluidic fields, which may provide a useful guidance for the researchers who are interested in this area.
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Yasappan, Justine, Ángela Jiménez-Casas, and Mario Castro. "Asymptotic Behavior of a Viscoelastic Fluid in a Closed Loop Thermosyphon: Physical Derivation, Asymptotic Analysis, and Numerical Experiments." Abstract and Applied Analysis 2013 (2013): 1–20. http://dx.doi.org/10.1155/2013/748683.
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Fluids subject to thermal gradients produce complex behaviors that arise from the competition with gravitational effects. Although such sort of systems have been widely studied in the literature for simple (Newtonian) fluids, the behavior of viscoelastic fluids has not been explored thus far. We present a theoretical study of the dynamics of a Maxwell viscoelastic fluid in a closed-loop thermosyphon. This sort of fluid presents elastic-like behavior and memory effects. We study the asymptotic properties of the fluid inside the thermosyphon and the exact equations of motion in the inertial manifold that characterizes the asymptotic behavior. We derive, for the first time, the mathematical derivations of the motion of a viscoelastic fluid in the interior of a closed-loop thermosyphon under the effects of natural convection and a given external temperature gradient.
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Hsu, C. H., S. Y. Hu, K. Y. Kung, C. C. Kuo, and C. C. Chang. "A Study on the Flow Patterns of a Second Grade Viscoe-Lastic Fluid Past a Cavity in a Horizontal Channel." Journal of Mechanics 29, no. 2 (December 20, 2012): 207–15. http://dx.doi.org/10.1017/jmech.2012.143.
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AbstractThis paper studies the behavior of second grade viscoelastic fluid past a cavity in a horizontal channel. The effects of Reynolds number, fluid elasticity and the aspect ratio of the cavity on the flow field are simulated numerically. The equations are converted into the vorticity and stream function equations. The solution is obtained by the finite difference method.The behavior of viscoelastic fluids is quite different from the Newtonian fluid, due to the effects of fluid elasticity. Only one flow pattern appears when the Newtonian fluid past the cavity. However, three kinds of flow patterns appear while the viscoelastic fluids past the cavity by increasing Reynolds number from 20 to 300. The flow field is affected by the fluid elasticity as well as the aspect ratio of the cavity. The transitional flow pattern appears at lower Reynolds number as the higher elasticity fluid past the cavity with larger aspect ratio.
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Chen, Dilin, Jie Li, Haiwen Chen, Lai Zhang, Hongna Zhang, and Yu Ma. "Electroosmotic Flow Behavior of Viscoelastic LPTT Fluid in a Microchannel." Micromachines 10, no. 12 (December 15, 2019): 881. http://dx.doi.org/10.3390/mi10120881.
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In many research works, the fluid medium in electroosmosis is considered to be a Newtonian fluid, while the polymer solutions and biological fluids used in biomedical fields mostly belong to the non-Newtonian category. Based on the finite volume method (FVM), the electroosmotic flow (EOF) of viscoelastic fluids in near-neutral (pH = 7.5) solution considering four ions (K+, Cl−, H+, OH−) is numerically studied, as well as the viscoelastic fluids’ flow characteristics in a microchannel described by the Linear Phan-Thien–Tanner (LPTT) constitutive model under different conditions, including the electrical double layer (EDL) thickness, the Weissenberg number (Wi), the viscosity ratio and the polymer extensibility parameters. When the EDL does not overlap, the velocity profiles for both Newtonian and viscoelastic fluids are plug-like and increase sharply near the charged wall. Compared with Newtonian fluid at Wi = 3, the viscoelastic fluid velocity increases by 5 times and 9 times, respectively, under the EDL conditions of kH = 15 and kH = 250, indicating the shear thinning behavior of LPTT fluid. Shear stress obviously depends on the viscosity ratio and different Wi number conditions. The EOF is also enhanced by the increase (decrease) in polymer extensibility parameters (viscosity ratio). When the extensibility parameters are large, the contribution to velocity is gradually weakened.
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Wang, Fang, and Yu Wang. "A Finite Difference Method for Solving Unsteady Fractional Oldroyd-B Viscoelastic Flow Based on Caputo Derivative." Advances in Mathematical Physics 2023 (April 29, 2023): 1–22. http://dx.doi.org/10.1155/2023/8963904.
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In this paper, the effect of a fractional constitutive model on the rheological properties of fluids and its application in numerical simulation are investigated, which is important to characterize the rheological properties of fluids and physical characteristics of materials more accurately. Based on this consideration, numerical simulation and analytical study of unsteady fractional Oldroyd-B viscoelastic flow are carried out. In order to improve the degree of accuracy, the mixed partial derivative including the fractional derivative in the differential equation is converted effectively by integrating by parts instead of by direct discretization. Then, the stability, convergence, and unique solvability of the difference scheme are verified. The validity of the finite difference method is tested by making comparisons with analytical solutions for two kinds of fractional Oldroyd-B viscoelastic flow. Numerical results obtained using the finite difference method are in good agreement with analytical solutions obtained via the variable separation method. Viscoelastic characteristics of the unsteady Poiseuille flow are similar to the second-order fluid or integer-order Oldroyd-B fluid when the parameter is close to 0 or to 1. Oscillation characteristics of fractional viscoelastic oscillatory flow are similar to those of the classical viscoelastic fluid under the same condition. Compared with the previous research, the present work studies the rheological properties of fluids with the finite difference method, and the application of fractional constitutive models in describing the rheological properties of fluids is developed. Meanwhile, more cases reflecting the fractional-order characteristics are given. The present method can accurately capture the flow characteristics of unsteady fractional Oldroyd-B viscoelastic fluid and is applicable for the generalized fractional fluid.
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Alves, M. A., P. J. Oliveira, and F. T. Pinho. "Numerical Methods for Viscoelastic Fluid Flows." Annual Review of Fluid Mechanics 53, no. 1 (January 5, 2021): 509–41. http://dx.doi.org/10.1146/annurev-fluid-010719-060107.
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Complex fluids exist in nature and are continually engineered for specific applications involving the addition of macromolecules to a solvent, among other means. This imparts viscoelasticity to the fluid, a property responsible for various flow instabilities and major modifications to the fluid dynamics. Recent developments in the numerical methods for the simulation of viscoelastic fluid flows, described by continuum-level differential constitutive equations, are surveyed, with a particular emphasis on the finite-volume method. This method is briefly described, and the main benchmark flows currently used in computational rheology to assess the performance of numerical methods are presented. Outstanding issues in numerical methods and novel and challenging applications of viscoelastic fluids, some of which require further developments in numerical methods, are discussed.
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Guillopé, Colette, and Jean-Claude Saut. "Existence and stability of steady flows of weakly viscoelastic fluids." Proceedings of the Royal Society of Edinburgh: Section A Mathematics 119, no. 1-2 (1991): 137–58. http://dx.doi.org/10.1017/s0308210500028377.
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SynopsisWe consider steady flows of viscoelastic fluids for which the extrastress tensor is given by a differential constitutive equation and is such that the retardation time is large (weakly viscoelastic fluids).We show the existence of a unique viscoelastic steady flow close to a given Newtonian flow and investigate its linear stability.As an example, we consider the Bénard problem for viscoelastic fluids and we prove that there exists a nontrivial linearly stable flow of a weakly viscoelastic fluid in a container heated from below.
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Huang, Jingting, Liqiong Chen, Shuxuan Li, Jinghang Guo, and Yuanyuan Li. "Numerical Study for the Performance of Viscoelastic Fluids on Displacing Oil Based on the Fractional-Order Maxwell Model." Polymers 14, no. 24 (December 8, 2022): 5381. http://dx.doi.org/10.3390/polym14245381.
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In the study of polymer flooding, researchers usually ignore the genetic stress properties of viscoelastic fluids. In this paper, we investigate the process of viscoelastic fluid flooding the remaining oil in the dead end. This work uses the fractional-order Maxwell in the traditional momentum equation. Furthermore, a semi-analytic solution of the flow control equation for fractional-order viscoelastic fluids is derived, and the oil-repelling process of viscoelastic fluids is simulated by a secondary development of OpenFOAM. The results show that velocity fractional-order derivative α significantly affects polymer solution characteristics, and increasing the elasticity of the fluid can significantly improve the oil repelling efficiency. Compared to the Newtonian fluid flow model, the fractional order derivative a and relaxation time b in the two-parameter instanton equation can accurately characterize the degree of elasticity of the fluid. The smaller the a, the more elastic the fluid is and the higher the oil-repelling efficiency. The larger the b, the less elastic the fluid is and the lower the cancellation efficiency. Moreover, the disturbance of the polymer solution to the dead end is divided into two elastic perturbation areas. The stronger the elasticity of the polymer solution, the higher the peak value of the area in the dead end and the higher the final oil displacement efficiency.
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Procopio, Giuseppe, and Massimiliano Giona. "Modal Representation of Inertial Effects in Fluid–Particle Interactions and the Regularity of the Memory Kernels." Fluids 8, no. 3 (February 28, 2023): 84. http://dx.doi.org/10.3390/fluids8030084.
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This article develops a modal expansion (in terms of functions exponentially decaying with time) of the force acting on a micrometric particle and stemming from fluid inertial effects (usually referred to as the Basset force) deriving from the application of the time-dependent Stokes equation to model fluid–particle interactions. One of the main results is that viscoelastic effects induce the regularization of the inertial memory kernels at t=0, eliminating the 1/t-singularity characterizing Newtonian fluids. The physical origin of this regularization stems from the finite propagation velocity of the internal shear stresses characterizing viscoelastic constitutive equations. The analytical expression for the fluid inertial kernel is derived for a Maxwell fluid, and a general method is proposed to obtain accurate approximations of it for generic complex viscoelastic fluids, characterized by a spectrum of relaxation times.
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Rusak, Zvi, Nguyen Ly, John A. Tichy, and Shixiao Wang. "Near-critical swirling flow of a viscoelastic fluid in a circular pipe." Journal of Fluid Mechanics 814 (February 6, 2017): 325–60. http://dx.doi.org/10.1017/jfm.2017.16.
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The interaction between flow inertia and elasticity in high-Reynolds-number, axisymmetric and near-critical swirling flows of an incompressible and viscoelastic fluid in an open finite-length straight circular pipe is studied at the limit of low elasticity. The stresses of the viscoelastic fluid are described by the generalized Giesekus constitutive model. This model helps to focus the analysis on low fluid elastic effects with shear thinning of the viscosity. The application of the Giesekus model to columnar streamwise vortices is first investigated. Then, a nonlinear small-disturbance analysis is developed from the governing equations of motion. It reveals the complicated interactions between flow inertia, swirl and fluid rheology. An effective Reynolds number that links between steady states of swirling flows of a viscoelastic fluid and those of a Newtonian fluid is revealed. The effects of the fluid viscosity, relaxation time, retardation time and mobility parameter on the flow development in the pipe and on the critical swirl for the appearance of vortex breakdown are explored. It is found that in vortex flows with either an axial jet or an axial wake profile, increasing the shear thinning by decreasing the ratio of the viscoelastic characteristic times from one (with fixed values of the Weissenberg number and the mobility parameter) increases the critical swirl ratio for breakdown. Increasing the fluid elasticity by increasing the Weissenberg number from zero (with a fixed ratio of the viscoelastic characteristic times and a fixed value of the mobility parameter) or increasing the fluid mobility parameter from zero (with fixed values of the Weissenberg number and the ratio of viscoelastic times) causes a similar effect. The results may explain the trend of changes in the appearance of breakdown zones as a function of swirl level that were observed in the experiments by Stokes et al. (J. Fluid Mech., vol. 429, 2001, pp. 67–115), where Boger fluids were used. This work extends for the first time the theory of vortex breakdown to include effects of non-Newtonian fluids.
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Xu, Zhengming, Xianzhi Song, and Zhaopeng Zhu. "Development of Elastic Drag Coefficient Model and Explicit Terminal Settling Velocity Equation for Particles in Viscoelastic Fluids." SPE Journal 25, no. 06 (May 22, 2020): 2962–83. http://dx.doi.org/10.2118/201194-pa.
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Summary Viscoelastic fluids are frequently used as drilling or fracturing fluids to enhance cuttings or proppant transport efficiency. The solid transport performance of these fluids largely depends on the settling behaviors of suspended particles. Different from viscoinelastic fluids, the elastic and viscous characteristics of viscoelastic fluids both affect particle settling behaviors. In this study, to separately quantify the contribution degrees of the shear viscosity and fluid elasticity on the terminal settling velocity, we decompose the total drag force into a viscous drag force and an elastic drag force. Based on the experimental data from the available literature, it is concluded that the elastic drag force is a function of the fluid elasticity, particle diameter, particle terminal settling velocity, and density difference between the fluid and particle. The formula for the elastic drag force is determined on the basis of the force analysis, and a relationship between the elastic drag coefficient and particle Reynolds number (Re) is developed. An explicit equation that directly predicts the terminal settling velocity in viscoelastic fluids is determined by correlating the dimensionless particle diameter and Re. To validate the proposed model, a total of 108 settling experiments in viscoelastic fluids are conducted. The absolute percentage error (APE) between the predicted and measured terminal settling velocities is 15.26%, which indicates that the proposed explicit terminal settling velocity equation can provide satisfactory prediction accuracy of the terminal settling velocity for particles in viscoelastic fluids. Furthermore, an illustrative example is provided to show that the proposed model can be used to calculate the required fluid elasticity to obtain the desired terminal settling velocity when the fluid shear viscosity is fixed. The proposed models are valid with a consistency index range of approximately 0.16 to 1.2 Pa⋅sn, flow behavior index range of approximately 0.282 to 0.579, an Re range of approximately 0.005 to 30, and a fluid relaxation time range of approximately 0.183 to 110 seconds. This study can help operators choose proper drilling/fracturing fluids to enhance the cuttings/proppant transport and maximize drilling/fracturing performance.
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Zhurba Eremeeva, I. A., D. Scerrato, C. Cardillo, and A. Tran. "A MATHEMATICAL MODEL OF NONSTATIONARY MOTION OF A VISCOELASTIC FLUID IN ROLLER BEARINGS." Problems of strenght and plasticity 81, no. 4 (2019): 500–511. http://dx.doi.org/10.32326/1814-9146-2019-81-4-500-511.
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Nowadays, the emergence of new lubricants requires an enhancement of the rheological models and methods used for solution of corresponding initial boundary-value problems. In particular, models that take into account viscoelastic properties are of great interest. In the present paper we consider the mathematical model of nonstationary motion of a viscoelastic fluid in roller bearings. We used the Maxwell fluid model for the modeling of fluid properties. The viscoelastic properties are exhibited by many lubricants that use polymer additives. In addition, viscoelastic properties can be essential at high fluid speeds. Also, viscoelastic properties can be significant in the case of thin gaps. Maxwell's model is one of the most common models of viscoelastic materials. It combines the relative simplicity of constitutive equations with the ability to describe a stress relaxation. In addition, viscoelastic fluids also allow us to describe some effects that are missing in the case of viscous fluid. An example it is worth to mention the Weissenberg effect and a number of others. In particular, such effects can be used to increase the efficiency of the film carrier in the sliding bearings. Here we introduced characteristic assumptions on the form of the flow, allowing to significantly simplify the solution of the problem. We consider so-called self-similar solutions, which allows us to get a solution in an analytical form. As a result these assumptions, the formulae for pressure and friction forces are derived. Their dependency on time and Deborah number is analyzed. The limiting values of the flow characteristics were obtained. The latter can be used for steady state of the flow regime. Differences from the case of Newtonian fluid are discussed. It is shown that viscoelastic properties are most evident at the initial stage of flow, when the effects of non-stationarity are most important.
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Zhurba Eremeeva, I. A., D. Scerrato, C. Cardillo, and A. Tran. "A MATHEMATICAL MODEL OF NONSTATIONARY MOTION OF A VISCOELASTIC FLUID IN ROLLER BEARINGS." Problems of strenght and plasticity 81, no. 4 (2019): 501–12. http://dx.doi.org/10.32326/1814-9146-2019-81-4-501-512.
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Nowadays, the emergence of new lubricants requires an enhancement of the rheological models and methods used for solution of corresponding initial boundary-value problems. In particular, models that take into account viscoelastic properties are of great interest. In the present paper we consider the mathematical model of nonstationary motion of a viscoelastic fluid in roller bearings. We used the Maxwell fluid model for the modeling of fluid properties. The viscoelastic properties are exhibited by many lubricants that use polymer additives. In addition, viscoelastic properties can be essential at high fluid speeds. Also, viscoelastic properties can be significant in the case of thin gaps. Maxwell's model is one of the most common models of viscoelastic materials. It combines the relative simplicity of constitutive equations with the ability to describe a stress relaxation. In addition, viscoelastic fluids also allow us to describe some effects that are missing in the case of viscous fluid. An example it is worth to mention the Weissenberg effect and a number of others. In particular, such effects can be used to increase the efficiency of the film carrier in the sliding bearings. Here we introduced characteristic assumptions on the form of the flow, allowing to significantly simplify the solution of the problem. We consider so-called self-similar solutions, which allows us to get a solution in an analytical form. As a result these assumptions, the formulae for pressure and friction forces are derived. Their dependency on time and Deborah number is analyzed. The limiting values of the flow characteristics were obtained. The latter can be used for steady state of the flow regime. Differences from the case of Newtonian fluid are discussed. It is shown that viscoelastic properties are most evident at the initial stage of flow, when the effects of non-stationarity are most important.
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Loginova, Marianna E., and Farit A. Agzamov. "Viscoelastic systems for well construction." Kazakhstan journal for oil & gas industry 4, no. 1 (May 16, 2022): 58–68. http://dx.doi.org/10.54859/kjogi104413.
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One of the most important factors ensuring the required quality of well cementing is the use of effective flushing fluids (spacers). Among these fluids are viscoelastic systems (VES), which provide the best displacement of the drilling fluid during the cementing process.
The article discusses the mechanism of polymerization of viscoelastic systems when using polyacrylamide cross-linked with polyvalent metal cations and the prospects for using these systems for oil and gas wells cementing. Models of the viscoelastic systems flow and their differences due to the presence of normal stresses in viscoelastic systems are shown in this article. The substantiation of the component composition of viscoelastic systems and their main properties, ensuring their efficiency as flushing fluids are given. The article also provides a description of the scientific instruments that were used during the research.
It has been experimentally confirmed that it is necessary to use additives with the highest oxidation state when choosing a polyvalent cation as a "cross-linker" for viscoelastic systems. This will help to increase the rate of strength characteristics development. The most adequate ratios of components have been experimentally substantiated and the best solids-carrying capacity of a viscoelastic flushing fluid in comparison with other types has been proven. This eliminates the possibility of cement slurry flowing down in the annular space after the completion of the cementing process.
The special installations proved the best degree of wellbore cleaning in vugular formation zones with a laminar flow regime. In order to minimize the negative effect of polymer films from viscoelastic systems on the adhesion of the cement stone to the casing strings it is recommended to inject a portion of the liquid containing the polymer destructor after a portion of the viscoelastic fluid.
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Chaffin, Stephen, Nicholas Monk, Julia Rees, and William Zimmerman. "Re-Entrant Corner for a White-Metzner Fluid." Fluids 6, no. 7 (July 2, 2021): 241. http://dx.doi.org/10.3390/fluids6070241.
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Viscoelastic fluids can be difficult to model due to the wide range of different physical behaviors that polymer melts can exhibit. One such feature is the viscous elastic boundary layer. We address the particular problem of a viscoelastic shear-dependent fluid flowing past a corner and investigate how the properties of the boundary layer change for a White-Metzner fluid. The boundary layer equations are derived and the upstream layer is matched with the far-field flow. It was found that if the fluid is sufficiently shear thinning then the viscoelastic boundary layer formulation fails due to the inertial forces becoming dominant. The depth of the boundary layer is controlled by the shear-thinning parameters. These effects are not a feature of other shear-thinning models, such as the Phan-Thien-Tanner model. This study provides insight in the different effects of some commonly used viscoelastic models in corner flows in the upstream boundary layer, the downstream boundary layer is not addressed.
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Joseph, D. D., and T. Y. Liao. "Potential flows of viscous and viscoelastic fluids." Journal of Fluid Mechanics 265 (April 25, 1994): 1–23. http://dx.doi.org/10.1017/s0022112094000741.
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Potential flows of incompressible fluids admit a pressure (Bernoulli) equation when the divergence of the stress is a gradient as in inviscid fluids, viscous fluids, linear viscoelastic fluids and second-order fluids. We show that in potential flow without boundary layers the equation balancing drag and acceleration is the same for all these fluids, independent of the viscosity or any viscoelastic parameter, and that the drag is zero when the flow is steady. But, if the potential flow is viewed as an approximation to the actual flow field, the unsteady drag on bubbles in a viscous (and possibly in a viscoelastic) fluid may be approximated by evaluating the dissipation integral of the approximating potential flow because the neglected dissipation in the vorticity layer at the traction-free boundary of the bubble gets smaller as the Reynolds number is increased. Using the potential flow approximation, the actual drag D on a spherical gas bubble of radius a rising with velocity U(t) in a linear viscoelastic liquid of density ρ and shear modules G(s) is estimated to be \[D = \frac{2}{3}\pi a^3 \rho {\dot U} + 12\pi a \int_{-\infty}^t G(t - \tau)U(\tau){\rm d}\tau\] and, in a second-order fluid, \[D = \pi a\left(\frac{2}{3}a^2 \rho + 12\alpha _1\right ) {\dot U} + 12\pi a\mu U,\] where α1, < 0 is the coefficient of the first normal stress and μ is the viscosity of the fluid. Because α1 is negative, we see from this formula that the unsteady normal stresses oppose inertia; that is, oppose the acceleration reaction. When U(t) is slowly varying, the two formulae coincide. For steady flow, we obtain the approximate drag D = 12πaμU for both viscous and viscoelastic fluids. In the case where the dynamic contribution of the interior flow of the bubble cannot be ignored as in the case of liquid bubbles, the dissipation method gives an estimation of the rate of total kinetic energy of the flows instead of the drag. When the dynamic effect of the interior flow is negligible but the density is important, this formula for the rate of total kinetic energy leads to D = (ρa – ρ) VBg · ex – ρaVB U where ρa is the density of the fluid (or air) inside the bubble and VB is the volume of the bubble.Classical theorems of vorticity for potential flow of ideal fluids hold equally for second-order fluid. The drag and lift on two-dimensional bodies of arbitrary cross-section in a potential flow of second-order and linear viscoelastic fluids are the same as in potential flow of an inviscid fluid but the moment M in a linear viscoelastic fluid is given by \[M = M_I + 2 \int_{-\infty}^t [G(t - \tau)\Gamma (\tau)]{\rm d}\tau,\] where MI is the inviscid moment and Γ(t) is the circulation, and \[M = M_I + 2 \mu \Gamma + 2\alpha _1 \partial \Gamma /\partial t\] in a second-order fluid. When Γ(t) is slowly varying, the two formulae for M coincide. For steady flow, they reduce to \[M = M_I + 2 \mu \Gamma ,\] which is also the expression for M in both steady and unsteady potential flow of a viscous fluid. Moreover, when there is no stream, this moment reduces to the actual moment M = 2μΓ on a rotating rod.Potential flows of models of a viscoelastic fluid like Maxwell's are studied. These models do not admit potential flows unless the curl of the divergence of the extra stress vanishes. This leads to an over-determined system of equations for the components of the stress. Special potential flow solutions like uniform flow and simple extension satisfy these extra conditions automatically but other special solutions like the potential vortex can satisfy the equations for some models and not for others.
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Jamil, Muhammad, and 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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Yuan, Chao, Hong-Na Zhang, Li-Xia Chen, Jun-Long Zhao, Xiao-Bin Li, and Feng-Chen Li. "Numerical Study on the Characteristics of Boger Type Viscoelastic Fluid Flow in a Micro Cross-Slot under Sinusoidal Stimulation." Entropy 22, no. 1 (January 3, 2020): 64. http://dx.doi.org/10.3390/e22010064.
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The cross-slot geometry plays an important role in the study of nonlinear effects of viscoelastic fluids. The flow of viscoelastic fluid in a micro cross-slot with a high channel aspect ratio (AR, the ratio of channel depth to width) can be divided into three types, which are symmetric flow, steady-state asymmetric flow and time-dependent flow under the inlet condition with a constant velocity. However, the flow pattern of a viscoelastic fluid in the cross-slot when a stimulation is applied at inlets has been rarely reported. In this paper, the response of cross-slot flow under an external sinusoidal stimulation is studied by numerical simulations of a two-dimensional model representing the geometry with a maximum limit of AR. For the cases under constant inlet velocity conditions, three different flow patterns occur successively with the increase of Weissenberg number (Wi). For the cases under sinusoidal varying inlet velocity conditions, when the stimulation frequency is far away from the natural frequency of a viscoelastic fluid, the frequency spectrum of velocity fluctuation field shows the characteristics of a fundamental frequency and several harmonics. However, the harmonic frequency disappears when the stimulation frequency is close to the natural frequency of the viscoelastic fluid. Besides, the flow pattern shows spatial symmetry and changes with time. In conclusion, the external stimulation has an effect on the flow pattern of viscoelastic fluid in the 2D micro cross-slot channel, and a resonance occurs when the stimulation frequency is close to the natural frequency of the fluid.
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Li, Juan, Hong Zhi Yang, Mei Han, Jin Chao Xu, Xiao Dong Li, and Xiu Ting Han. "Application and Design of Plunger Pump Lifting Viscoelastic Fluid." Advanced Materials Research 291-294 (July 2011): 2507–11. http://dx.doi.org/10.4028/www.scientific.net/amr.291-294.2507.
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Daqing Oilfield has more than 10,000 million kilograms of oil through tertiary recovery every year. However, eccentric wear of sucker rod and tubing severely impede the implementation effectiveness and large-scale utilization of tertiary oil production when injecting viscoelastic fluids containing polymer. Therefore, a plunger pump lifting viscoelastic fluid is designed based on the analysis of the mechanism of eccentric wear. The principle to reduce eccentric wear is increasing hydraulic and viscoelastic friction, and expanding clearance. Due to make use of the plunger pump lifting viscoelastic, laboratory experiment and field application have demonstrated effective reduction of eccentric wear, extend the life of the sucker rod and tubing, and improve pump efficiency.
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Tsukahara, Takahiro, Masaaki Tanabe, and Yasuo Kawaguchi. "Effect of Fluid Viscoelasticity on Turbulence and Large-Scale Vortices behind Wall-Mounted Plates." Advances in Mechanical Engineering 6 (January 1, 2014): 823138. http://dx.doi.org/10.1155/2014/823138.
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Direct numerical simulations of turbulent viscoelastic fluid flows in a channel with wall-mounted plates were performed to investigate the influence of viscoelasticity on turbulent structures and the mean flow around the plate. The constitutive equation follows the Giesekus model, valid for polymer or surfactant solutions, which are generally capable of reducing the turbulent frictional drag in a smooth channel. We found that turbulent eddies just behind the plates in viscoelastic fluid decreased in number and in magnitude, but their size increased. Three pairs of organized longitudinal vortices were observed downstream of the plates in both Newtonian and viscoelastic fluids: two vortex pairs were behind the plates and the other one with the longest length was in a plate-free area. In the viscoelastic fluid, the latter vortex pair in the plate-free area was maintained and reached the downstream rib, but its swirling strength was weakened and the local skin-friction drag near the vortex was much weaker than those in the Newtonian flow. The mean flow and small spanwise eddies were influenced by the additional fluid force due to the viscoelasticity and, moreover, the spanwise component of the fluid elastic force may also play a role in the suppression of fluid vortical motions behind the plates.
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Mavko, Gary. "Relaxation shift in rocks containing viscoelastic pore fluids." GEOPHYSICS 78, no. 3 (May 1, 2013): M19—M28. http://dx.doi.org/10.1190/geo2012-0272.1.
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The interaction of pore stiffness with pore fluid moduli leads to shifts in viscoelastic relaxation times of the overall rock relative to those of the fluids alone. Crack-based and fluid substitution models indicate that stiff pores cause little shift, whereas thin, soft cracks can shift relaxation times by several orders of magnitude toward lower frequencies (longer relaxation times). Pore stiffness also causes a shift in apparent temperature dependence of rock viscoelasticity toward higher temperatures when cracks are present. As with more conventional fluid substitution problems, quantifying the effects of pore fluids on rock properties requires information about the crack and pore stiffness distributions in addition to the complex moduli and viscosity of the pure fluid.
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Cho, Mira, Sun Ok Hong, Seung Hak Lee, Kyu Hyun, and Ju Min Kim. "Effects of Ionic Strength on Lateral Particle Migration in Shear-Thinning Xanthan Gum Solutions." Micromachines 10, no. 8 (August 15, 2019): 535. http://dx.doi.org/10.3390/mi10080535.
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Viscoelastic fluids, including particulate systems, are found in various biological and industrial systems including blood flow, food, cosmetics, and electronic materials. Particles suspended in viscoelastic fluids such as polymer solutions migrate laterally, forming spatially segregated streams in pressure-driven flow. Viscoelastic particle migration was recently applied to microfluidic technologies including particle counting and sorting and the micromechanical measurement of living cells. Understanding the effects on equilibrium particle positions of rheological properties of suspending viscoelastic fluid is essential for designing microfluidic applications. It has been considered that the shear-thinning behavior of viscoelastic fluid is a critical factor in determining the equilibrium particle positions. This work presents the lateral particle migration in two different xanthan gum-based viscoelastic fluids with similar shear-thinning viscosities and the linear viscoelastic properties. The flexibility and contour length of the xanthan gum molecules were tuned by varying the ionic strength of the solvent. Particles suspended in flexible and short xanthan gum solution, dissolved at high ionic strength, migrated toward the corners in a square channel, whereas particles in the rigid and long xanthan gum solutions in deionized water migrated toward the centerline. This work suggests that the structural properties of polymer molecules play significant roles in determining the equilibrium positions in shear-thinning fluids, despite similar bulk rheological properties. The current results are expected to be used in a wide range of applications such as cell counting and sorting.
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Poole, R. J. "Three-dimensional viscoelastic instabilities in microchannels." Journal of Fluid Mechanics 870 (May 7, 2019): 1–4. http://dx.doi.org/10.1017/jfm.2019.260.
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Whereas the flow of simple single-phase Newtonian fluids tends to become more complex as the characteristic length scale in the problem (and hence the Reynolds number) increases, for complex elastic fluids such as dilute polymer solutions the opposite holds true. Thus small-scale, so-called ‘microfluidic’ flows of complex fluids can exhibit rich dynamics in situations where the ‘equivalent’ flow of Newtonian fluids remains linear and predictable. In the recent study of Qin et al. (J. Fluid Mech., vol. 864, 2019, R2) of the flow of a dilute polymeric fluid past a $50~\unicode[STIX]{x03BC}\text{m}$ cylinder (in a $100\times 60~\unicode[STIX]{x03BC}\text{m}$ channel), a novel 3-D holographic particle velocimetry technique reveals the underlying complexity of the flow, including inherent three-dimensionality and symmetry breaking as well as strong upstream propagation effects via elastic waves.
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Sheremet, Mikhail A., and Ioan Pop. "Natural convection combined with thermal radiation in a square cavity filled with a viscoelastic fluid." International Journal of Numerical Methods for Heat & Fluid Flow 28, no. 3 (March 5, 2018): 624–40. http://dx.doi.org/10.1108/hff-02-2017-0059.
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Purpose The purpose of this paper is to study natural convective heat transfer and viscoelastic fluid flow in a differentially heated square cavity under the effect of thermal radiation. Design/methodology/approach The cavity filled with a viscoelastic fluid is heated uniformly from the left wall and cooled from the right side while insulated from horizontal walls. Governing partial differential equations formulated in non-dimensional stream function, vorticity and temperature with corresponding boundary conditions have been solved by finite difference method of second order accuracy. The effects of Rayleigh number (Ra = 1e+3−1e+5), radiation parameter (Rd = 0 − 10), Prandtl number (Pr = 1 − 30) and elastic number (E = 0.0001 − 0.001) on flow patterns, temperature fields, average Nusselt number at hot vertical wall and rate of fluid flow have been studied. Findings It has been found that a growth of elastic number leads to the heat transfer reduction and convective flow attenuation. The heat conduction is a dominating heat transfer mechanism for high values of radiation parameter. Originality/value The originality of this work is to analyze heat transfer and fluid flow of a viscoelastic fluid inside a differentially heated cavity. The results would benefit scientists and engineers to become familiar with the flow and heat behavior of non-Newtonian fluids, and the way to predict the properties of this flow for possibility of using viscoelastic fluids in compact heat exchangers, electronic cooling systems, polymer engineering, etc.
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Yanbarisov, Ruslan, Yuri Efremov, Nastasia Kosheleva, Peter Timashev, and Yuri Vassilevski. "Numerical Modelling of Multicellular Spheroid Compression: Viscoelastic Fluid vs. Viscoelastic Solid." Mathematics 9, no. 18 (September 20, 2021): 2333. http://dx.doi.org/10.3390/math9182333.
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Parallel-plate compression of multicellular spheroids (MCSs) is a promising and popular technique to quantify the viscoelastic properties of living tissues. This work presents two different approaches to the simulation of the MCS compression based on viscoelastic solid and viscoelastic fluid models. The first one is the standard linear solid model implemented in ABAQUS/CAE. The second one is the new model for 3D viscoelastic free surface fluid flow, which combines the Oldroyd-B incompressible fluid model and the incompressible neo-Hookean solid model via incorporation of an additional elastic tensor and a dynamic equation for it. The simulation results indicate that either approach can be applied to model the MCS compression with reasonable accuracy. Future application of the viscoelastic free surface fluid model is the MCSs fusion highly-demanded in bioprinting.
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Jegatheeswaran, Sinthuran, Farhad Ein-Mozaffari, and Jiangning Wu. "Laminar mixing of non-Newtonian fluids in static mixers: process intensification perspective." Reviews in Chemical Engineering 36, no. 3 (April 28, 2020): 423–36. http://dx.doi.org/10.1515/revce-2017-0104.
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AbstractStatic mixers are widely used in various industrial applications to intensify the laminar mixing of non-Newtonian fluids. Non-Newtonian fluids can be categorized into (1) time-independent, (2) time-dependent, and (3) viscoelastic fluids. Computational fluid dynamics studies on the laminar mixing of viscoelastic fluids are very limited due to the complexity in incorporating the multiple relaxation times and the associated stress tensor into the constitutive equations. This review paper provides recommendations for future research studies while summarizing the key research contributions in the field of non-Newtonian fluid mixing using static mixers. This review discusses the different experimental techniques employed such as electrical resistance tomography, magnetic resonance imaging, planar laser-induced fluorescence, and positron emission particle tracking. A comprehensive overview of the mixing fundamentals, fluid chaos, numerical characterization of fluid stretching, development of pressure drop correlations, and derivations of generalized Reynolds number is also provided in this review paper.
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Patel, Mahesh Chandra, Mohammed Abdalla Ayoub, Mazlin Bt Idress, and Anirbid Sircar. "Development of a Novel Surfactant-Based Viscoelastic Fluid System as an Alternative Nonpolymeric Fracturing Fluid and Comparative Analysis with Traditional Guar Gum Gel Fluid." Polymers 15, no. 11 (May 25, 2023): 2444. http://dx.doi.org/10.3390/polym15112444.
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Surfactant-based viscoelastic (SBVE) fluids have recently gained interest from many oil industry researchers due to their polymer-like viscoelastic behaviour and ability to mitigate problems of polymeric fluids by replacing them during various operations. This study investigates an alternative SBVE fluid system for hydraulic fracturing with comparable rheological characteristics to conventional polymeric guar gum fluid. In this study, low and high surfactant concentration SBVE fluid and nanofluid systems were synthesized, optimized, and compared. Cetyltrimethylammonium bromide and counterion inorganic sodium nitrate salt, with and without 1 wt% ZnO nano-dispersion additives, were used; these are entangled wormlike micellar solutions of cationic surfactant. The fluids were divided into the categories of type 1, type 2, type 3, and type 4, and were optimized by comparing the rheological characteristics of different concentration fluids in each category at 25 °C. The authors have reported recently that ZnO NPs can improve the rheological characteristics of fluids with a low surfactant concentration of 0.1 M cetyltrimethylammonium bromide by proposing fluids and nanofluids of type 1 and type 2. In addition, conventional polymeric guar gum gel fluid is prepared in this study and analyzed for its rheological characteristics. The rheology of all SBVE fluids and the guar gum fluid was analyzed using a rotational rheometer at varying shear rate conditions from 0.1 to 500 s−1 under 25 °C, 35 °C, 45 °C, 55 °C, 65 °C, and 75 °C temperature conditions. The comparative analysis section compares the rheology of the optimal SBVE fluids and nanofluids in each category to the rheology of polymeric guar gum fluid for the entire range of shear rates and temperature conditions. The type 3 optimum fluid with high surfactant concentration of 0.2 M cetyltrimethylammonium bromide and 1.2 M sodium nitrate was the best of all the optimum fluids and nanofluids. This fluid shows comparative rheology to guar gum fluid even at elevated shear rate and temperature conditions. The comparison of average viscosity values under a different group of shear rate conditions suggests that the overall optimum SBVE fluid prepared in this study is a potential nonpolymeric viscoelastic fluid candidate for hydraulic fracturing operation that could replace polymeric guar gum fluids.
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BOFFETTA, GUIDO, ANDREA MAZZINO, STEFANO MUSACCHIO, and LARA VOZELLA. "Rayleigh–Taylor instability in a viscoelastic binary fluid." Journal of Fluid Mechanics 643 (January 15, 2010): 127–36. http://dx.doi.org/10.1017/s0022112009992497.
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The effects of polymer additives on Rayleigh–Taylor (RT) instability of immiscible fluids is investigated using the Oldroyd-B viscoelastic model. Analytic results obtained exploiting the phase-field approach show that in polymer solution the growth rate of the instability speeds up with elasticity (but remains slower than in the pure solvent case). Numerical simulations of the viscoelastic binary fluid model confirm this picture.
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Bulíček, Miroslav, Tomáš Los, and Josef Málek. "On three-dimensional flows of viscoelastic fluids of Giesekus type*." Nonlinearity 38, no. 1 (November 22, 2024): 015004. http://dx.doi.org/10.1088/1361-6544/ad7cb5.
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Abstract Viscoelastic rate-type fluids are popular models of choice in many applications involving flows of fluid-like materials with complex micro-structure. A well-developed mathematical theory for the most of these classical fluid models is however missing. The main purpose of this study is to provide a complete proof of long-time and large-data existence of weak solutions to unsteady internal three-dimensional flows of Giesekus fluids subject to a no-slip boundary condition. As a new auxiliary tool, we provide the identification of certain biting limits in the parabolic setting, presented here within the framework of evolutionary Stokes problems. We also generalize the long-time and large-data existence result to higher dimensions, to viscoelastic models with multiple relaxation mechanisms and to viscoelastic models with different type of dissipation.
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Zhang, Zhang, Wu, Shen, Chen, Lan, Li, and Cai. "Comparison of Micro-Mixing in Time Pulsed Newtonian Fluid and Viscoelastic Fluid." Micromachines 10, no. 4 (April 18, 2019): 262. http://dx.doi.org/10.3390/mi10040262.
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Fluid mixing plays an essential role in many microfluidic applications. Here, we compare the mixing in time pulsing flows for both a Newtonian fluid and a viscoelastic fluid at different pulsing frequencies. In general, the mixing degree in the viscoelastic fluid is higher than that in the Newtonian fluid. Particularly, the mixing in Newtonian fluid with time pulsing is decreased when the Reynolds number Re is between 0.002 and 0.01, while it is enhanced when Re is between 0.1 and 0.2 compared with that at a constant flow rate. In the viscoelastic fluid, on the other hand, the time pulsing does not change the mixing degree when the Weissenberg number Wi ≤ 20, while a larger mixing degree is realized at a higher pulsing frequency when Wi = 50.
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ELFRING, GWYNN J., ON SHUN PAK, and ERIC LAUGA. "Two-dimensional flagellar synchronization in viscoelastic fluids." Journal of Fluid Mechanics 646 (March 8, 2010): 505–15. http://dx.doi.org/10.1017/s0022112009994010.
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Experimental studies have demonstrated that spermatozoa synchronize their flagella when swimming in close proximity. In a Newtonian fluid, it was shown theoretically that such synchronization arises passively due to hydrodynamic forces between the two swimmers if their waveforms exhibit a front–back geometrical asymmetry. Motivated by the fact that most biological fluids possess a polymeric microstructure, here we address synchronization in a viscoelastic fluid analytically. Using a two-dimensional infinite sheet model, we show that the presence of polymeric stresses removes the geometrical asymmetry constraint and therefore even symmetric swimmers synchronize. Such synchronization occurs on asymptotically faster time scales than in a Newtonian fluid, and the swimmers are seen to be driven into a stable in-phase conformation minimizing the energy dissipated in the surrounding fluid.
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Mavi, Anele, and Tiri Chinyoka. "Finite Volume Computational Analysis of the Heat Transfer Characteristic in a Double-Cylinder Counter-Flow Heat Exchanger with Viscoelastic Fluids." Defect and Diffusion Forum 424 (May 8, 2023): 19–43. http://dx.doi.org/10.4028/p-j482zy.
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This work presents a computational analysis of the heat-exchange characteristics in a double-cylinder (also known as a double-pipe) geometrical arrangement. The heat-exchange is from a hotter viscoelastic fluid flowing in the core (inner) cylinder to a cooler Newtonian fluid flowing in the shell (outer) annulus. For optimal heat-exchange characteristics, the core and shell fluid flow in opposite directions, the so-called counter-flow arrangement.The mathematical modelling of the given problem reduces to a system of nonlinear coupled Partial Differential Equations (PDEs). Specifically, the rheological behaviour of the core fluid is governed by the Giesekus viscoelastic constitutive model. The governing system of coupled nonlinear PDEs is intractable to analytic treatment and hence is solved numerically using Finite Volume Methods (FVM). The FVM numerical methodology is implemented via the open-source software package OpenFOAM. The numerical methods are stabilized, specifically to address numerical instabilities arising from the High Weissenberg Number Problem (HWNP), via a combination of the Discrete Elastic Viscous Stress Splitting (DEVSS) technique and the Log-Conformation Reformulation (LCR) methodology. The DEVSS and LCR stabilization techniques are integrated into the relevant viscoelastic fluid solvers. The novelties of the study center around the simulation and analysis of the optimal heat-exchange characteristics between the heated Giesekus fluid and the coolant Newtonian fluid within a double-pipe counter-flow arrangement. Existing studies in the literature have either focused exclusively on Newtonian fluids and/or on rectangular geometries. The existing OpenFOAM solvers have also largely focused on non-isothermal viscoelastic flows. The relevant OpenFOAM solvers are modified for the present purposes by incorporating the energy equation for viscoelastic fluid flow. The flow characteristics are presented qualitatively (graphically) via the fluid pressure, temperature, velocity, and the polymer-stress components as well as the related normal stress differences. The results illustrate the required decrease in the core fluid temperature in the longitudinal direction due to the cooling effects of the shell fluid, whose temperature predictably increases in the counter-flow direction.
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Rozhkov, Aleksey. "Elasticity and relaxation properties of oral fluid." Russian Journal of Biomechanics 25, no. 4 (December 30, 2021): 338–49. http://dx.doi.org/10.15593/rjbiomech/2021.4.05.
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The research is aimed at crating a method for rheological testing of viscoelastic fluids, the droplets of which, when stretched, form thinning filaments, i.e. exhibit the property of spinning. The typical example of such fluid is oral fluid (or mixed saliva). Among other things, the rheological features of the oral fluid actively affect the mechanisms of transmission of infection by airborne droplets. In this work, the oral fluid was studied both from the point of view of a participant in the transmission of infection and as a model for studying the rheology of viscoelastic fluids. The method is based on video recording of the stretching of a drop of the test liquid between the legs of the tweezers and the subsequent spontaneous thinning of the formed capillary filament of the liquid. The process is controlled by the competition of forces of inertia, elasticity, capillarity. By analyzing the video recording, it is possible to trace the contribution of each factor and, within the framework of the Oldroyd/Maxwell rheological constitutive equation (rheological model), determine the numerical values of all model constants. The obtained rheological characteristics of the oral fluid make it possible to theoretically model the processes of the formation of drops of oral fluid during sneezing, coughing, talking, as well as the processes of collision of drops with protective masks, filters and other obstacles. In general, the proposed method of rheological testing is applicable for studying a wide class of viscoelastic fluids, including biological ones. Among the latter are bronchial sputum, synovial fluid, reproductive fluids, and others. The method is distinguished by the simplicity of the experiment and the use of elementary equipment.
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Eslami, Fatemeh, Hossein Hamzehpour, Sanaz Derikvandi, and S. Amir Bahrani. "Acoustic interaction force between two particles immersed in a viscoelastic fluid." Physics of Fluids 35, no. 3 (March 2023): 031707. http://dx.doi.org/10.1063/5.0143005.
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The interaction acoustic radiation force in a standing plane wave applied to each small solid sphere in a two-particle system immersed in a viscoelastic fluid is studied in a framework based on perturbation theory. In this work, the first- and second-order perturbation theories are used in the governing equations with considering the upper-convected Maxwell model to obtain mathematical modeling. We use the finite element method to carry out simulations and describe the behavior of the viscoelastic fluid. The mathematical development is validated from three literature case studies: a one-particle system in a viscous fluid, a two-particle system in a viscous fluid, and a one-particle system in a viscoelastic fluid. The novelty of this study is to establish the acoustic interaction force between two spherical particles immersed in a viscoelastic fluid. The results show that the acoustic interaction force between two spheres is greater in a viscous fluid in comparison with the viscoelastic fluid with the same shear viscosity. This behavior is due to the relaxation time effect. It is also indicated that the acoustic interaction force between the particles decreases by the relaxation time and increases by the fluid's viscosity. A mathematical formula is proposed for the acoustic interaction force between particles located close to each other in a viscoelastic fluid.
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Jose T., Sherin, Kiran Kumar Patra, and Satyananda Panda. "Modeling and simulation of capillary ridges on the free surface dynamics of third-grade fluid." Zeitschrift für Naturforschung A 76, no. 3 (January 8, 2021): 217–29. http://dx.doi.org/10.1515/zna-2020-0225.
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Abstract Most of the viscoelastic fluids have deformation while flowing over a heated plate. A typical feature of a thin viscous or viscoelastic fluid is the formation of the capillary ridges over locally heated plates. The creation of such ridges in the thin-film surface can affect the smoothness of the coating. This work particularly concerned the flow of non-Newtonian third-grade fluid over an inclined heated plate and the formation of ridges. The conservation laws associated with free surface and wall boundary conditions model the two-dimensional fluid flow. The long wave approximation of the model results in an equation of evolution to explain the structure of free surfaces. The resulting equation is discretized implicitly using the finite volume method. The obtained results are discussed for different flow parameters that affect capillary ridge emergence on the free surface. Variation in the height of capillary ridges of third-grade fluid is compared with the second-grade fluid and Newtonian fluid flow. We observe, the ridge size gets smaller for the third-grade fluid compared to the Newtonian and the second-grade fluid. Our analysis investigates how the third-grade viscoelastic parameters affect the dynamics of the free surface and the size of the capillary ridge concerning temperature changes and other phenomena of interest.
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Navruzov, K., A. Sh Begjanov, N. I. Abdikarimov, and Sh Yusupov. "Examining laminar, non-stationary viscoelastic fluid flow between two parallel planes." BIO Web of Conferences 105 (2024): 05005. http://dx.doi.org/10.1051/bioconf/202410505005.
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The generalized Maxwell model is used to handle problems involving the unsteady flow of a viscoelastic fluid in a flat channel under the effect of a constant pressure gradient. Formulas for fluid flow, velocity distribution, and other hydrodynamic characteristics were found. Transient processes during unsteady flow of a viscoelastic fluid in a flat channel are investigated based on the discovered formulas. The analysis’s conclusions demonstrated that, at small Debord number values, the procedures of changing a viscoelastic fluid’s properties from an unstable to a stationary state essentially don’t differ from those of a Newtonian fluid. Exceeding the Debord number relatively unity, it has been established that the process of transition of a viscoelastic fluid from an unsteady state to a stationary state is of a wave nature, in contrast to the transition process of a Newtonian fluid, and the transition time is several times longer than that of a Newtonian fluid. It was also discovered that perturbed processes can arise during the transition. These disturbances occurring in unsteady flows of a viscoelastic fluid can be stabilized by mixing the Newtonian fluid within it. The implementation of this property is important in preventing technical failures or malfunctions.
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Halder, B., A. Mukherjee, and R. Karmakar. "Theoretical and Experimental Studies on Squeeze Film Stabilizers for Flexible Rotor-Bearing Systems Using Newtonian and Viscoelastic Lubricants." Journal of Vibration and Acoustics 112, no. 4 (October 1, 1990): 473–82. http://dx.doi.org/10.1115/1.2930131.
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A combination of a squeeze film damper and a plane journal bearing is studied as a stabilizing scheme. The damper is made to play the role of a stabilizer to postpone the instability threshold speeds of flexible rotors. Both Newtonian and viscoelastic fluids are used in the rotor-bearing system. Dynamics of the system is theoretically analyzed using bond graphs. Analysis reveals that the use of a Newtonian fluid in the stabilizer largely improves the high speed stability range. However, viscoelastic stabilizing fluid has a detrimental effect on highly flexible rotors. Experimental investigations, conducted on a flexible rotor (natural frequency, 30 Hz), confirm the theoretical findings. In addition, experiments indicate that though the use of viscoelastic stabilizing fluids leads to instability in flexible rotors, the growth of large amplitude whirl is postponed to very high speeds.
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Nassar, M. "Viscoelastic plate resting on fluid." International Shipbuilding Progress 34, no. 397 (September 1, 1987): 166–69. http://dx.doi.org/10.3233/isp-1987-3439701.
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Jones, H. W., H. W. Kwan, and E. Yeatman. "Surface waves in viscoelastic fluid." Journal of the Acoustical Society of America 82, S1 (November 1987): S101. http://dx.doi.org/10.1121/1.2024527.
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KAJITANI, Fumito, Mie ICHIHARA, and Masaharu KAMEDA. "Bubble oscillation in viscoelastic fluid." Proceedings of the Fluids engineering conference 2000 (2000): 161. http://dx.doi.org/10.1299/jsmefed.2000.161.
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Lauga, Eric. "Propulsion in a viscoelastic fluid." Physics of Fluids 19, no. 8 (August 2007): 083104. http://dx.doi.org/10.1063/1.2751388.
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Denn, M. M. "Issues in Viscoelastic Fluid Mechanics." Annual Review of Fluid Mechanics 22, no. 1 (January 1990): 13–32. http://dx.doi.org/10.1146/annurev.fl.22.010190.000305.
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Makarov, I. A. "Bifurcation of viscoelastic fluid counterflows." Journal of Engineering Physics and Thermophysics 85, no. 6 (November 2012): 1397–405. http://dx.doi.org/10.1007/s10891-012-0788-5.
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Shen, Yu, and Bo Wang. "Stability of viscoelastic fluid conveying pipe." Journal of Physics: Conference Series 2808, no. 1 (July 1, 2024): 012036. http://dx.doi.org/10.1088/1742-6596/2808/1/012036.
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Abstract In this paper, the dynamic stability of a pulsating fluid transport viscoelastic pipe under transverse vibration in the supported case is investigated, and a new variable-length beam element taking into account the beam rotation effect is proposed, which incorporates Kelvin-type viscoelastic intrinsic relations to describe the material properties of the beam-type pipe. Stability conditions are given for the subharmonic and combined resonance cases. Numerical models were used to analyze the stability of viscoelastic fluid pipes under the influence of different factors.