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1
Nouri, J. M., and J. H. Whitelaw. "Flow of Newtonian and Non-Newtonian Fluids in a Concentric Annulus With Rotation of the Inner Cylinder." Journal of Fluids Engineering 116, no. 4 (1994): 821–27. http://dx.doi.org/10.1115/1.2911856.
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Mean velocity and the corresponding Reynolds shear stresses of Newtonian and non-Newtonian fluids have been measured in a fully developed concentric flow with a diameter ratio of 0.5 and at a inner cylinder rotational speed of 300 rpm. With the Newtonian fluid in laminar flow the effects of the inner shaft rotation were a uniform increase in the drag coefficient by about 28 percent, a flatter and less skewed axial mean velocity and a swirl profile with a narrow boundary close to the inner wall with a thickness of about 22 percent of the gap between the pipes. These effects reduced gradually with bulk flow Reynolds number so that, in the turbulent flow region with a Rossby number of 10, the drag coefficient and profiles of axial mean velocity with and without rotation were similar. The intensity of the turbulence quantities was enhanced by rotation particularly close to the inner wall at a Reynolds number of 9,000 and was similar to that of the nonrotating flow at the higher Reynolds number. The effects of the rotation with the 0.2 percent CMC solution were similar to those of the Newtonian fluids but smaller in magnitude since the Rossby number with the CMC solution is considerably higher for a similar Reynolds number. Comparison between the results of the Newtonian and non-Newtonian fluids with rotation at a Reynolds number of 9000 showed similar features to those of nonrotating flows with an extension of non-turbulent flow, a drag reduction of up to 67 percent, and suppression of all fluctuation velocities compared with Newtonian values particularly the cross-flow components. The results also showed that the swirl velocity profiles of both fluids were the same at a similar Rossby number.
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Sui, Dan, and Juan Carlos Martinez Vidaur. "Automated Characterization of Non-Newtonian Fluids Using Laboratory Setup." Applied Rheology 30, no. 1 (2020): 39–53. http://dx.doi.org/10.1515/arh-2020-0101.
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AbstractThe automation towards drilling fluid properties’ measurement has been pursued in the recent years in order to increase drilling efficiency with less human intervention. Adequately monitoring and adjusting density and rheology of drilling fluids are fundamental responsibilities of mud engineers. In this study, experimental tests that automatically characterize fluids were conducted. The basic objective is to measure the differential pressures along two sections of the pipes: one horizontal section and one vertical section. Using such measuring data, mathematical algorithms are then proposed to estimate fluids’ density and subsequently viscosity with respect to flow regimes, laminar and turbulence. The results were compared and validated with the values measured on rotational rheometers. With the help of models and numerical schemes, the work presented in the paper reveals a good opportunity to improve the accuracy and precision of continuous-measuring and monitoring fluids’ properties.
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FORBES, LAWRENCE K. "ON TURBULENCE MODELLING AND THE TRANSITION FROM LAMINAR TO TURBULENT FLOW." ANZIAM Journal 56, no. 1 (2014): 28–47. http://dx.doi.org/10.1017/s1446181114000224.
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AbstractFluid turbulence is often modelled using equations derived from the Navier–Stokes equations, perhaps with some semi-heuristic closure model for the turbulent viscosity. This paper considers a possible alternative hypothesis. It is argued that regarding turbulence as a manifestation of non-Newtonian behaviour may be a viewpoint of at least comparable validity. For a general description of nonlinear viscosity in a Stokes fluid, it is shown that the flow patterns are indistinguishable from those predicted by the Navier–Stokes equation in one- or two-dimensional geometry, but that fully three-dimensional flows differ markedly. The stability of linearized plane Poiseuille flow to three-dimensional disturbances is then considered, in a Tollmien–Schlichting formulation. It is demonstrated that the flow may become unstable at significantly lower Reynolds numbers than those expected from Navier–Stokes theory. Although similar results are known in sections of the rheological literature, the present work attempts to advance the philosophical viewpoint that turbulence might always be regarded as a non-Newtonian effect, to a degree that is dependent only on the particular fluid in question. Such an approach could give a more satisfactory account of the underlying physics.
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DRAAD, A. A., G. D. C. KUIKEN, and F. T. M. NIEUWSTADT. "Laminar–turbulent transition in pipe flow for Newtonian and non-Newtonian fluids." Journal of Fluid Mechanics 377 (December 25, 1998): 267–312. http://dx.doi.org/10.1017/s0022112098003139.
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A cylindrical pipe facility with a length of 32 m and a diameter of 40 mm has been designed. The natural transition Reynolds number, i.e. the Reynolds number at which transition occurs as a result of non-forced, natural disturbances, is approximately 60 000. In this facility we have studied the stability of cylindrical pipe flow to imposed disturbances. The disturbance consists of periodic suction and injection of fluid from a slit over the whole circumference in the pipe wall. The injection and suction are equal in magnitude and each distributed over half the circumference so that the disturbance is divergence free. The amplitude and frequency can be varied over a wide range.First, we consider a Newtonian fluid, water in our case. From the observations we compute the critical disturbance velocity, which is the smallest disturbance at a given Reynolds number for which transition occurs. For large wavenumbers, i.e. large frequencies, the dimensionless critical disturbance velocity scales according to Re−1, while for small wavenumbers, i.e. small frequencies, it scales as Re−2/3. The latter is in agreement with weak nonlinear stability theory. For Reynolds numbers above 30 000 multiple transition points are found which means that increasing the disturbance velocity at constant dimensionless wavenumber leads to the following course of events. First, the flow changes from laminar to turbulent at the critical disturbance velocity; subsequently at a higher value of the disturbance it returns back to laminar and at still larger disturbance velocities the flow again becomes turbulent.Secondly, we have carried out stability measurements for (non-Newtonian) dilute polymer solutions. The results show that the polymers reduce in general the natural transition Reynolds number. The cause of this reduction remains unclear, but a possible explanation may be related to a destabilizing effect of the elasticity on the developing boundary layers in the entry region of the flow. At the same time the polymers have a stabilizing effect with respect to the forced disturbances, namely the critical disturbance velocity for the polymer solutions is larger than for water. The stabilization is stronger for fresh polymer solutions and it is also larger when the polymers adopt a more extended conformation. A delay in transition has been only found for extended fresh polymers where delay means an increase of the critical Reynolds number, i.e. the number below which the flow remains laminar at any imposed disturbance.
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GÜZEL, B., T. BURGHELEA, I. A. FRIGAARD, and D. M. MARTINEZ. "Observation of laminar–turbulent transition of a yield stress fluid in Hagen–Poiseuille flow." Journal of Fluid Mechanics 627 (May 25, 2009): 97–128. http://dx.doi.org/10.1017/s0022112009005813.
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We investigate experimentally the transition to turbulence of a yield stress shear-thinning fluid in Hagen–Poiseuille flow. By combining direct high-speed imaging of the flow structures with Laser Doppler Velocimetry (LDV), we provide a systematic description of the different flow regimes from laminar to fully turbulent. Each flow regime is characterized by measurements of the radial velocity, velocity fluctuations and turbulence intensity profiles. In addition we estimate the autocorrelation, the probability distribution and the structure functions in an attempt to further characterize transition. For all cases tested, our results indicate that transition occurs only when the Reynolds stresses of the flow equal or exceed the yield stress of the fluid, i.e. the plug is broken before transition commences. Once in transition and when turbulent, the behaviour of the yield stress fluid is somewhat similar to a (simpler) shear-thinning fluid. Finally, we have observed the shape of slugs during transition and found their leading edges to be highly elongated and located off the central axis of the pipe, for the non-Newtonian fluids examined.
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Debnath, Suman, Tarun Kanti Bandyopadhyay, and Apu Kumar Saha. "CFD Analysis of Non-Newtonian Pseudo Plastic Liquid Flow through Bends." Periodica Polytechnica Mechanical Engineering 61, no. 3 (2017): 184. http://dx.doi.org/10.3311/ppme.9494.
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Non-Newtonian pseudo plastic liquid flow through different types of 0.0127 m diameter pipe bends as well as straight pipe have been investigated experimentally to evaluate frictional pressure drop across the bends in laminar and water flow in turbulent condition. We have studied here the effect of flow rate, bend angle, fluid behavior on static pressure and pressure drop. A Computational Fluid Dynamics (CFD) based software is used to predict the static pressure, pressure drop, shear stress, shear strain, flow structure, friction factor, loss co- efficient inside the bends for Sodium Carboxy Methyl Cellulose (SCMC) solution as a non-Newtonian pseudo plastic fluids and water as a Newtonian fluid. Laminar Non-Newtonian pseudo plastic Power law model is used for SCMC solution to numerically solve the continuity and the momentum equations. The experimental data are compared with the CFD generated data and is well matched. The software predicted data may be used to solve any industrial problem and also to design various equipment.
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Plaut, Emmanuel, Nicolas Roland, and Chérif Nouar. "Nonlinear waves with a threefold rotational symmetry in pipe flow: influence of a strongly shear-thinning rheology." Journal of Fluid Mechanics 818 (April 5, 2017): 595–622. http://dx.doi.org/10.1017/jfm.2017.149.
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In order to model the transition to turbulence in pipe flow of non-Newtonian fluids, the influence of a strongly shear-thinning rheology on the travelling waves with a threefold rotational symmetry of Faisst & Eckhardt (Phys. Rev. Lett., vol. 91, 2003, 224502) and Wedin & Kerswell (J. Fluid Mech., vol. 508, 2004, pp. 333–371) is analysed. The rheological model is Carreau’s law. Besides the shear-thinning index $n_{C}$, the dimensionless characteristic time $\unicode[STIX]{x1D706}$ of the fluid is considered as the main non-Newtonian control parameter. If $\unicode[STIX]{x1D706}=0$, the fluid is Newtonian. In the relevant limit $\unicode[STIX]{x1D706}\rightarrow +\infty$, the fluid approaches a power-law behaviour. The laminar base flows are first characterized. To compute the nonlinear waves, a Petrov–Galerkin code is used, with continuation methods, starting from the Newtonian case. The axial wavenumber is optimized and the critical waves appearing at minimal values of the Reynolds number $\mathit{Re}_{w}$ based on the mean velocity and wall viscosity are characterized. As $\unicode[STIX]{x1D706}$ increases, these correspond to a constant value of the Reynolds number based on the mean velocity and viscosity. This viscosity, close to the one of the laminar flow, can be estimated analytically. Therefore the experimentally relevant critical Reynolds number $\mathit{Re}_{wc}$ can also be estimated analytically. This Reynolds number may be viewed as a lower estimate of the Reynolds number for the transition to developed turbulence. This demonstrates a quantified stabilizing effect of the shear-thinning rheology. Finally, the increase of the pressure gradient in waves, as compared to the one in the laminar flow with the same mass flux, is calculated, and a kind of ‘drag reduction effect’ is found.
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LIU, R., and Q. S. LIU. "Non-modal instability in plane Couette flow of a power-law fluid." Journal of Fluid Mechanics 676 (April 26, 2011): 145–71. http://dx.doi.org/10.1017/jfm.2011.36.
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In this paper, we study the linear stability of a plane Couette flow of a power-law fluid. The influence of shear-thinning effect on the stability is investigated using the classical eigenvalue analysis, the energy method and the non-modal stability theory. For the plane Couette flow, there is no stratification of viscosity. Thus, for the stability problem the stress tensor is anisotropic aligned with the strain rate perturbation. The results of the eigenvalue analysis and the energy method show that the shear-thinning effect is destabilizing. We focus on the effect of non-Newtonian viscosity on the transition from laminar flow towards turbulence in the framework of non-modal stability theory. Response to external excitations and initial conditions has been studied by examining the ε-pseudospectrum and the transient energy growth. For both Newtonian and non-Newtonian fluids, it is found that there can be a rather large transient growth even though the linear operator of the Couette flow has no unstable eigenvalue. The results show that shear-thinning significantly increases the amplitude of response to external excitations and initial conditions.
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Jovanović, J., M. Pashtrapanska, B. Frohnapfel, F. Durst, J. Koskinen, and K. Koskinen. "On the Mechanism Responsible for Turbulent Drag Reduction by Dilute Addition of High Polymers: Theory, Experiments, Simulations, and Predictions." Journal of Fluids Engineering 128, no. 1 (2005): 118–30. http://dx.doi.org/10.1115/1.2073227.
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Turbulent drag reduction by dilute addition of high polymers is studied by considering local stretching of the molecular structure of a polymer by small-scale turbulent motions in the region very close to the wall. The stretching process is assumed to restructure turbulence at small scales by forcing these to satisfy local axisymmetry with invariance under rotation about the axis aligned with the main flow. It can be shown analytically that kinematic constraints imposed by local axisymmetry force turbulence near the wall to tend towards the one-component state and when turbulence reaches this limiting state it must be entirely suppressed across the viscous sublayer. For the limiting state of wall turbulence, the statistical dynamics of the turbulent stresses, constructed by combining the two-point correlation technique and invariant theory, suggest that turbulent drag reduction by homogeneously distributed high polymers, cast into the functional space which emphasizes the anisotropy of turbulence, resembles the process of reverse transition from the turbulent state towards the laminar flow state. These findings are supported by results of direct numerical simulations of wall-bounded turbulent flows of Newtonian and non-Newtonian fluids and by experiments carried out, under well-controlled laboratory conditions, in a refractive index-matched pipe flow facility using state-of-the art laser-Doppler anemometry. Theoretical considerations based on the elastic behavior of a polymer and spatial intermittency of turbulence at small scales enabled quantitative estimates to be made for the relaxation time of a polymer and its concentration that ensure maximum drag reduction in turbulent pipe flows, and it is shown that predictions based on these are in very good agreement with available experimental data.
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Zhou, Yunxu, and Subhash Nandlal Shah. "Theoretical Analysis of Turbulent Flow of Power-Law Fluids in Coiled Tubing." SPE Journal 12, no. 04 (2007): 447–57. http://dx.doi.org/10.2118/84123-pa.
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Summary A comprehensive theoretical analysis of turbulent flow of a power-law fluid in coiled tubing was conducted with the approach of boundary layer approximation. Equations of momentum integrals for the boundary layer flow were derived and solved numerically. Based on the results of the numerical analysis, a new friction-factor correlation was developed which is applicable to a wide range of flow behavior index of power-law fluid model. The new correlation was verified by comparing it with the published Ito correlation for the special case of Newtonian fluid. For non-Newtonian fluids, there is also a close agreement between the new correlation and the experimental data from recent full-scale coiled tubing flow experiments. Introduction Many fluids that are pumped through coiled tubing are typically non-Newtonian fluids, such as polymer gels or drilling muds. Understanding their flow behavior and being able to accurately predict frictional pressure through coiled tubing are essential for better operations design. A recent literature review (Zhou and Shah 2004) indicates that though there are numerous studies on the flow of Newtonian fluids in coiled pipes, there is, however, very little information with regard to the corresponding flow of non-Newtonian fluids. Among the various approaches of investigating fluid flow in coiled pipes, there is one important method called boundary layer approximation analysis. It is especially useful for high-Dean (1927, 1928) number flows where the effect of secondary flow is largely confined in a thin boundary layer adjacent to the pipe wall (Dean number is commonly defined as: (equation). According to this approach, the tubing cross-section can be divided into two regions: the central in viscid core, and the thin viscous boundary layer. This leads to much simplified flow equations for high-Dean number flows in curved geometry. This approach has been used by a number of researchers, for example, by Adler (1934), Barua (1963), Mori and Nakayama (1965), and Ito (1959, 1969) for Newtonian fluids, and by Mashelkar and Devarajan (1976, 1977) for non-Newtonian fluids. In a previous attempt, Zhou and Shah (2007) applied the method of boundary layer approximation to solve the laminar flow problem of a power-law fluid in coiled tubing and obtained an empirical friction-factor correlation based on the theoretical analysis and numerical solutions. In the present study, we take the same analysis approach but consider the turbulent flow of a power-law fluid in coiled tubing. A friction-factor correlation for turbulent flow in coiled tubing is developed, and its validity is evaluated with a published correlation (Ito 1959) and recent full-scale experimental data.
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Güzel, B., I. Frigaard, and D. M. Martinez. "Predicting laminar–turbulent transition in Poiseuille pipe flow for non-Newtonian fluids." Chemical Engineering Science 64, no. 2 (2009): 254–64. http://dx.doi.org/10.1016/j.ces.2008.10.011.
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Mu¨ller, A. J., A. E. Saez, J. P. Tatham, and J. A. Odell. "Effect of Polymeric Additives on Turbulent Flow in Opposed Jets." Applied Mechanics Reviews 48, no. 11S (1995): S216—S221. http://dx.doi.org/10.1115/1.3005075.
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In this work we study the effect of polymeric additives on the transition to turbulence in opposed-jets flow. In this type of flow, the transition to turbulence for Newtonian fluids is characterized by a decrease in the rate of change of pressure drop with flow rate. We have used various polymers whose equilibrium molecular conformation in aqueous solution is different: poly (ethylene oxide), which exists in a conformation close to a random coil, hydroxypropyl guar, which adopts an expanded coil conformation, and hydrolyzed polyacrylamide, whose conformation is close to a random coil in the presence of an electrolyte (sodium chloride) but it changes to an expanded coil in distilled water. The results show that small amounts of either flexible or semi-rigid polymers induce a delay in the critical Reynolds number at which turbulence sets in. This delay seems to be a result of the suppression of flow instabilities in a region close to the stagnation point, which is linked to macromolecular orientation. Since, for Newtonian fluids, this flow has an increase of drag with flow rate that is slower in the turbulent flow regime than in the laminar regime, the addition of polymer causes a substantially higher pressure drop in turbulent flow with respect to that of the pure solvent. Therefore, polymer addition causes, in this particular case, a drag increase in turbulent flow, as opposed to the commonly observed drag reduction in turbulent flow through pipes.
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Brkić, Dejan, and Pavel Praks. "Unified Friction Formulation from Laminar to Fully Rough Turbulent Flow." Applied Sciences 8, no. 11 (2018): 2036. http://dx.doi.org/10.3390/app8112036.
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This paper provides a new unified formula for Newtonian fluids valid for all pipe flow regimes from laminar to fully rough turbulent flow. This includes laminar flow; the unstable sharp jump from laminar to turbulent flow; and all types of turbulent regimes, including the smooth turbulent regime, the partial non-fully developed turbulent regime, and the fully developed rough turbulent regime. The new unified formula follows the inflectional form of curves suggested in Nikuradse’s experiment rather than the monotonic shape proposed by Colebrook and White. The composition of the proposed unified formula uses switching functions and interchangeable formulas for the laminar, smooth turbulent, and fully rough turbulent flow regimes. Thus, the formulation presented below represents a coherent hydraulic model suitable for engineering use. This new flow friction model is more flexible than existing literature models and provides smooth and computationally cheap transitions between hydraulic regimes.
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Jovanovic, Jovan, Bettina Frohnapfel, Mira Pashtrapanska, and Franz Durst. "The effect of polymers on the dynamics of turbulence in a drag reduced flow." Thermal Science 9, no. 1 (2005): 13–41. http://dx.doi.org/10.2298/tsci0501013j.
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An experimental investigation of a polymer drag reduced flow using state-of-the-art laser-Doppler anemometry in a refractive index-matched pipe flow facility is reported. The measured turbulent stresses deep in the viscous sublayer are analyzed using the tools of invariant theory. It is shown that with higher polymer concentration the anisotropy of the Reynolds stresses increases. This trend is consistent with the trends extracted from DNS data of non-Newtonian fluids yielding different amounts of drag reduction. The interaction between polymer and turbulence is studied by considering local stretching of the molecular structure of a polymer by small-scale turbulent motions in the region very close to the wall. The stretching process is assumed to re-structure turbulence at small scales by forcing these to satisfy local axisymmetry with invariance under rotation about the axis aligned with the main flow. It is shown analytically that kinematic constraints imposed by local axisymmetry farce turbulence near the wall to tend towards the one-component state and when turbulence reaches this limiting state it must be entirely suppressed across the viscous sublayer. Based on this consideration it is suggested that turbulent drag reduction by high polymers resembles the reverse transition process from turbulent to laminar. Theoretical considerations based on the elastic behavior of a polymer and spatial intermittency of turbulence at small scales enabled quantitative estimates to be made for the relaxation time of a polymer and its concentration that ensure maximum drag reduction in turbulent pipe flows, and it is shown that predictions based on these are in very good agreement with available experimental data.
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Proff, Erwin A., and Jürgen H. Lohmann. "Calculation of pressure drop in the tube flow of sewage sludges with the aid of flow curves." Water Science and Technology 36, no. 11 (1997): 27–32. http://dx.doi.org/10.2166/wst.1997.0390.
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The layout of pumps for the transport of sewage sludges in sewage plants is of great importance. The understanding of pressure drop plays a decisive role. In this paper, a method, existing in the literature, which was developed within the framework of treating the frictional behaviour of viscoelastic fluids, will be presented for the calculation of the pressure drop in pipes. Sewage sludges belong to the class of non-Newtonian fluids. They exhibit intrinsically viscous behaviour and elastic properties. Due to the variation of the viscosity across the cross-section of flow, a representative Reynolds number at the operating point of the flow is defined with the aid of a representative viscosity, in order to determine the type of flow. Exact statements about the pipe friction coefficient in laminar flow are facilitated knowing the correlations for Newtonian fluids. For the case of the turbulent region, a modified formula for Newtonian fluids is taken as a basis. The validity of the method of calculation for sewage sludge flow is compared and discussed with and with respect to numerous experiments in research plants and actual sewage plants.
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Foolad, Yasaman, Majid Bizhani, and Ian A. Frigaard. "A Comparative Study of Laminar-Turbulent Displacement in an Eccentric Annulus under Imposed Flow Rate and Imposed Pressure Drop Conditions." Energies 14, no. 6 (2021): 1654. http://dx.doi.org/10.3390/en14061654.
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This paper presents a series of experiments focused on the displacement of viscoplastic fluids by various Newtonian and non-Newtonian fluids from a long horizontal, eccentric annulus. The flow regimes range from high Reynolds number laminar regimes through to fully turbulent. These experiments represent the primary cementing operation in a horizontal well. The main objective of our experiments is to gain insight into the role of the flow regime in the fluid-fluid displacement flows of relevance to primary cementing. We study strongly eccentric annuli and displaced fluids with a significant yield stress, i.e., those scenarios where a mud channel is most likely to persist. For fully eccentric annuli, the displacements are uniformly poor, regardless of regime. This improves for an eccentricity of 0.7. However, at these large eccentricities that are typical of horizontal well cementing, the displacement is generally poor and involves a rapid “breakthrough” advance along the wide upper side of the annulus followed only by a much slower removal of the residual fluids. This dynamic renders contact time estimates meaningless. We conclude that some of the simple statements/preferences widely employed in industry do not necessarily apply for all design scenarios. Instead, a detailed study of the fluids involved and the specification of the operational constraints is needed to yield improved displacement quality.
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Duda, Daniel, Marek Klimko, Radek Škach, Jan Uher, and Václav Uruba. "Hydrodynamic education with rheoscopic fluid." EPJ Web of Conferences 213 (2019): 02014. http://dx.doi.org/10.1051/epjconf/201921302014.
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We present a educational poster supporting the subject „Mechanics of fluids I“, which the students evaluate to be difficult mainly due to abstractness. Our goal is to show in vivo the behavior, especially the non-linearity, of various flows transiting into turbulence. The fluid motion is visualized by using the rheoscopic fluid, which consist of water and the dust of mica, whose particles are longitudinal and shiny resulting into easily observable reflections, when the particles coherently orient along the maximum stress. This happens mainly in shear layers, e.g. at the boundary between vortex core and envelope. An example of flow transiting into turbulence is the Taylor-Couette flow between two concentric cylinders, which with increasing Taylor number passes through various regimes from fully laminar bearing flow through the Taylor vortex flow (TVF) and later Wavy vortex flow (WVF) up to Turbulent Taylor vortices regime (TTV) and, finally, the regime of featureless turbulence.
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Pawar, S. S., and Vivek K. Sunnapwar. "Experimental studies on heat transfer to Newtonian and non-Newtonian fluids in helical coils with laminar and turbulent flow." Experimental Thermal and Fluid Science 44 (January 2013): 792–804. http://dx.doi.org/10.1016/j.expthermflusci.2012.09.024.
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Khan, Aamir, Rehan Ali Shah, M. Kamran Alam, et al. "Flow dynamics of a time-dependent non-Newtonian and non-isothermal fluid between coaxial squeezing disks." Advances in Mechanical Engineering 13, no. 7 (2021): 168781402110333. http://dx.doi.org/10.1177/16878140211033370.
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The goal of this research is to investigate the behaviours of porosity and squeezing phenomena in the presence of time-dependent heat flow that affect the flow rate and improve the system’s heating/cooling mechanism, reduce non-Newtonian fluid turbulence and scale-up flow tracers. Squeezing discs in the presence of no-slip velocity and convective surface boundary conditions induces a laminar, unstable and incompressible non-Newtonian fluid. The convective form of the momentum, concentration and energy equations are modelled for smooth discs to evaluate and offer an analytical and numerical examination of the flow for heat and mass transfer, which are further transformed to a highly non-linear system of ordinary differential equation using similarity transformations. In the case of smooth disks, the self-similar equations are solved using Homotopy Analysis Method (HAM) with appropriate initial guesses and auxiliary parameters to produce an algorithm with an accelerated and assured convergence. The comparison of HAM solutions with numerical solver programme BVP4 c proves the validity and correctness of HAM results. It is found that increasing or bypassing the Hartman number reduces the capillary region, making the Lorentz force effect more visible for small values of non-Newtonian parameter. The concentration rate at the bottom disc rises rapidly as the thermal diffusivity rises. In addition, because the rate of outflow from the flow domain increases, the suction/injection parameter lowers the radial velocity. Additionally, as the non-Newtonian parameter is increased, skin friction and heat/mass flux rise. In the suction/injection situation, all physical characteristics have the opposite effect on flow field profiles.
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Burger, J. H., R. Haldenwang, and N. J. Alderman. "Laminar and Turbulent Flow of Non-Newtonian Fluids in Open Channels for Different Cross-Sectional Shapes." Journal of Hydraulic Engineering 141, no. 4 (2015): 04014084. http://dx.doi.org/10.1061/(asce)hy.1943-7900.0000968.
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Jha, Narsing K., and Victor Steinberg. "Elastically driven Kelvin–Helmholtz-like instability in straight channel flow." Proceedings of the National Academy of Sciences 118, no. 34 (2021): e2105211118. http://dx.doi.org/10.1073/pnas.2105211118.
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Originally, Kelvin–Helmholtz instability (KHI) describes the growth of perturbations at the interface separating counterpropagating streams of Newtonian fluids of different densities with heavier fluid at the bottom. Generalized KHI is also used to describe instability of free shear layers with continuous variations of velocity and density. KHI is one of the most studied shear flow instabilities. It is widespread in nature in laminar as well as turbulent flows and acts on different spatial scales from galactic down to Saturn’s bands, oceanographic and meteorological flows, and down to laboratory and industrial scales. Here, we report the observation of elastically driven KH-like instability in straight viscoelastic channel flow, observed in elastic turbulence (ET). The present findings contradict the established opinion that interface perturbations are stable at negligible inertia. The flow reveals weakly unstable coherent structures (CSs) of velocity fluctuations, namely, streaks self-organized into a self-sustained cycling process of CSs, which is synchronized by accompanied elastic waves. During each cycle in ET, counter propagating streaks are destroyed by the elastic KH-like instability. Its dynamics remarkably recall Newtonian KHI, but despite the similarity, the instability mechanism is distinctly different. Velocity difference across the perturbed streak interface destabilizes the flow, and curvature at interface perturbation generates stabilizing hoop stress. The latter is the main stabilizing factor overcoming the destabilization by velocity difference. The suggested destabilizing mechanism is the interaction of elastic waves with wall-normal vorticity leading to interface perturbation amplification. Elastic wave energy is drawn from the main flow and pumped into wall-normal vorticity growth, which destroys the streaks.
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Kelly, Nathaniel S., Harinderjit S. Gill, Andrew N. Cookson, and Katharine H. Fraser. "Influence of Shear-Thinning Blood Rheology on the Laminar-Turbulent Transition over a Backward Facing Step." Fluids 5, no. 2 (2020): 57. http://dx.doi.org/10.3390/fluids5020057.
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Cardiovascular diseases are the leading cause of death globally and there is an unmet need for effective, safer blood-contacting devices, including valves, stents and artificial hearts. In these, recirculation regions promote thrombosis, triggering mechanical failure, neurological dysfunction and infarctions. Transitional flow over a backward facing step is an idealised model of these flow conditions; the aim was to understand the impact of non-Newtonian blood rheology on modelling this flow. Flow simulations of shear-thinning and Newtonian fluids were compared for Reynolds numbers ( R e ) covering the comprehensive range of laminar, transitional and turbulent flow for the first time. Both unsteady Reynolds Averaged Navier–Stokes ( k − ω SST) and Smagorinsky Large Eddy Simulations (LES) were assessed; only LES correctly predicted trends in the recirculation zone length for all R e . Turbulent-transition was assessed by several criteria, revealing a complex picture. Instantaneous turbulent parameters, such as velocity, indicated delayed transition: R e = 1600 versus R e = 2000, for Newtonian and shear-thinning transitions, respectively. Conversely, when using a Re defined on spatially averaged viscosity, the shear-thinning model transitioned below the Newtonian. However, recirculation zone length, a mean flow parameter, did not indicate any difference in the transitional Re between the two. This work shows a shear-thinning rheology can explain the delayed transition for whole blood seen in published experimental data, but this delay is not the full story. The results show that, to accurately model transitional blood flow, and so enable the design of advanced cardiovascular devices, it is essential to incorporate the shear-thinning rheology, and to explicitly model the turbulent eddies.
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Boussaha, Bilal, Mustapha Lahmar, Benyebka Bou-Said, and Hamid Boucherit. "Non-Newtonian couple-stress squeeze film behaviour between oscillating anisotropic porous circular discs with sealed boundary." Mechanics & Industry 21, no. 3 (2020): 311. http://dx.doi.org/10.1051/meca/2020004.
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The thrust of this paper is to investigate theoretically the non-Newtonian couple stress squeeze film behaviour between oscillating circular discs based on V. K. Stokes micro-continuum theory. The lubricant squeezed out between parallel porous and rigid facings is supposed to be a concentrated suspension which consists of small particles dispersed in a Newtonian base fluid (solvent). The effective viscosity of the suspension is determined by using the Krieger-Dougherty viscosity model for a given volume fraction of particles in the base fluid. For low frequency and amplitude of sinusoidal squeezing where cavitation as well as turbulence are unlikely, the governing equations including the modified Reynolds equation coupled with the modified Darcy's equation are derived and solved numerically using the finite difference method and a sub-relaxed iterative procedure. The slip velocity at the porous-fluid interface is directly evaluated by means of the modified Darcy's law considering laminar and isothermal squeezing flow. For a given volume fraction, the couple stress effects on the squeeze film characteristics are analyzed through the dimensionless couple stress parameter ℓ˜ considering sealed and unsealed boundary of the porous disc. The obtained relevant results reveal that the use of couple stress suspending fluids as lubricants and the effect of sealing the boundary of the porous matrix improves substantially the squeeze film behaviour by increasing the squeeze film force. On the other hand, side leakage flow calculated in the sealed case remains constant in comparison to that of open end (unsealed) porous disc for all values of couple stress parameter and volume fraction of particle.
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Ameur, Houari. "Investigation of the Performance of V-cut Turbines for Stirring Shear-thinning Fluids in a Cylindrical Vessel." Periodica Polytechnica Mechanical Engineering 64, no. 3 (2020): 207–11. http://dx.doi.org/10.3311/ppme.13359.
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The impeller design is the most crucial parameter to enhance the performance of stirred tanks. The cut in the impeller blade is a new technique to save the energy of impellers in mixing vessels without increasing the mixing time or reducing the product quality. In this paper, the new technique of cut is applied for a disc turbine rotating in an unbaffled cylindrical tank. Effects of the V-cut shape are highlighted. Non-Newtonian shear-thinning fluids are considered for the three flow regimes (laminar, transient, and turbulent). Effects of the number of blades on the flow patterns, pumping rate (Nq) and power consumption (Np) are explored. From the obtained results, a recirculation loop of flow is observed at the tip of each blade for impellers with less than three blades. These recirculation loops disappear with the increased number of blades. Under laminar flow conditions, the obtained results also revealed a decrease in power consumption and an increase in the discharge flow rate with the rise of Reynolds number. However, almost any changes were observed for these parameters (Np and Nq) under turbulent flow conditions.
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Mehta, Dhruv, Adithya Thota Radhakrishnan, Jules van Lier, and Francois Clemens. "Sensitivity Analysis of a Wall Boundary Condition for the Turbulent Pipe Flow of Herschel–Bulkley Fluids." Water 11, no. 1 (2018): 19. http://dx.doi.org/10.3390/w11010019.
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This article follows from a previous study by the authors on the computational fluid dynamics-based analysis of Herschel–Bulkley fluids in a pipe-bounded turbulent flow. The study aims to propose a numerical method that could support engineering processes involving the design and implementation of a waste water transport system, for concentrated domestic slurry. Concentrated domestic slurry results from the reduction in the amount of water used in domestic activities (and also the separation of black and grey water). This primarily saves water and also increases the concentration of nutrients and biomass in the slurry, facilitating efficient recovery. Experiments revealed that upon concentration, domestic slurry flows as a non-Newtonian fluid of the Herschel–Bulkley type. An analytical solution for the laminar transport of such a fluid is available in literature. However, a similar solution for the turbulent transport of a Herschel–Bulkley fluid is unavailable, which prompted the development of an appropriate wall function to aid the analysis of such flows. The wall function (called ψ 1 hereafter) was developed using Launder and Spalding’s standard wall function as a guide and was validated against a range of experimental test-cases, with positive results. ψ 1 is assessed for its sensitivity to rheological parameters, namely the yield stress, the fluid consistency index and the behaviour index and their impact on the accuracy with which ψ 1 can correctly quantify the pressure loss through a pipe. This is done while simulating the flow of concentrated domestic slurry using the Reynolds-Averaged Navier–Stokes (RANS) approach for turbulent flows. This serves to establish an operational envelope in terms of the rheological parameters and the average flow velocity within which ψ 1 is a must for accuracy. One observes that, regardless of the fluid behaviour index, ψ 1 is necessary to ensure accuracy with RANS models only in flow regimes where the wall shear stress is comparable to the yield stress within an order of magnitude. This is also the regime within which the concentrated slurry analysed as part of this research flows, making ψ 1 a requirement. In addition, when the wall shear stress exceeds the yield stress by more than one order (either due to an inherent lower yield stress or a high flow velocity), the regular Newtonian wall function proposed by Launder and Spalding is sufficient for an accurate estimate of the pressure loss, owing to the relative reduction in non-Newtonian viscosity as compared to the turbulent viscosity.
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Csizmadia, Péter, and Sára Till. "The Effect of Rheology Model of an Activated Sludge on to the Predicted Losses by an Elbow." Periodica Polytechnica Mechanical Engineering 62, no. 4 (2018): 305–11. http://dx.doi.org/10.3311/ppme.12348.
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This study presents a numerical investigation of flow and rheological behaviour of activated sludge. These materials are usually driven by pumps in wastewater treatment plants. Because of the correct sizing of the pipeline systems, which is of great importance from the point of view of efficiency, the friction losses and loss coefficients of the components have to be known. These are well-known in the case of Newtonian fluids but few data are available if the rheological properties are non-Newtonian. Three non-Newtonian models (Ostwald, Bingham, Herschel-Bulkley) are investigated related to the friction factor of a straight pipe, the loss coefficients of an elbow and to the pressure drop on this element. For our study the rheological data were used from the literature, where the same sample origin was diluted or concentrated to achieve three different TSS (total suspended solids) contents for the same sludge (7.4 g/l; 6.2 g/l; 3.6 g/l). Moreover, modified Reynolds-number definitions are tested related to the non-Newtonian models in the case of the laminar, transition and turbulent regions.
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Parekh, Siddharth, Ali Pilehvari, and Robert Serth. "Prediction of Fluid Behavior Using Generalized Hydraulic Calculation Method in Hydraulic Fractures." Journal of Advanced Research in Fluid Mechanics and Thermal Sciences 81, no. 1 (2021): 120–30. http://dx.doi.org/10.37934/arfmts.81.1.120130.
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Hydraulic fracturing has been used as one of the stimulation techniques to economically increase oil and gas production by creating small cracks in subsurface geologic formations to allow oil or gas to move toward a producing well. Hydraulics plays a vital role in many oil field operations including drilling, completion, fracturing and production. In the case of fracturing, however, the role of hydraulics becomes important since optimized hydraulics can minimize the cost and conversely, any miscalculations may cause problems such as the fluid loss or may potentially even lead to loss of the well. The current methods of the hydraulic calculation for non-Newtonian fluids necessitate determination of the robust model. This paper presented a new method for calculating pressure losses in the hydraulic fractures. The objective of this study was to develop the generalized model for hydraulic calculation for non-Newtonian fluid and run the case studies for the model validation. In the present work, detailed algorithm for the hydraulic calculation has been developed and then programmed in C++. The only input to the program is the raw rheological data, shear stress versus shear rate and the geometrical characteristics of the slit. Model validation with the new method has established a very small percentage difference between the values predicted by the model and experimental data. The results demonstrate that the new method is accurately predicting the pressure drop in both laminar and turbulent flow regimes. It is shown that the fluid behavior is more accurately represented using the new method than that with the standard fluid models available in the petroleum industry. Further validation and development to be carried out using experimental data for variety of fluid types.
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Kostic, M. "On turbulent drag and heat transfer reduction phenomena and laminar heat transfer enhancement in non-circular duct flow of certain non-Newtonian fluids." International Journal of Heat and Mass Transfer 37 (March 1994): 133–47. http://dx.doi.org/10.1016/0017-9310(94)90017-5.
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Speziale, Charles G. "A Review of Material Frame-Indifference in Mechanics." Applied Mechanics Reviews 51, no. 8 (1998): 489–504. http://dx.doi.org/10.1115/1.3099017.
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The Principle of Material Frame-Indifference in various areas of mechanics is critically reviewed from a basic theoretical standpoint. Modern continuum mechanics is considered along with statistical mechanics and turbulence in an effort to better understand this commonly used axiom. It is argued that Material Frame-Indifference is a restricted invariance that can be highly useful in the formulation of constitutive equations but must be applied with caution. Material Frame-Indifference applies, in a strong approximate sense, to most areas of continuum mechanics where there is a clear cut separation of scales so that the ratio of fluctuating to mean time scales is extremely small. While it breaks down for the three-dimensional case, it rigorously applies to Reynolds stress models in the limit of two-dimensional turbulence where an analogy is made between the Reynolds stress tensor and the non-Newtonian part of the stress tensor in the laminar flow of a non-Newtonian fluid. On the other hand, the general invariance group of constitutive equations that is universally valid is the extended Galilean group of transformations which includes arbitrary time-dependent translations of the spatial frame of reference; rotational frame-dependence then enters exclusively through the intrinsic spin tensor. In order to definitively address this issue it is necessary to establish what the invariance group is of solutions to the fluctuation dynamics from which constitutive equations are formally constructed. The implications of these results for future research in a variety of different fields in mechanics are thoroughly discussed. This article includes 52 references.
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AGARWAL, SATISH, ANKUSH AGGARWAL, SUNANDO DASGUPTA, and SIRSHENDU DE. "PERFORMANCE PREDICTION OF MEMBRANE MODULES INCORPORATING THE EFFECTS OF SUCTION IN THE MASS TRANSFER COEFFICIENT UNDER LAMINAR AND TURBULENT FLOW CONDITIONS FOR NON-NEWTONIAN FLUIDS." Journal of Food Process Engineering 32, no. 5 (2009): 752–74. http://dx.doi.org/10.1111/j.1745-4530.2008.00243.x.
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Oruganti, Surya Kaundinya, Guillaume Millet, and Mikhael Gorokhovski. "Assessment of LES-STRIP approach for modeling of droplet dispersion in diesel-like sprays." Oil & Gas Science and Technology – Revue d’IFP Energies nouvelles 74 (2019): 60. http://dx.doi.org/10.2516/ogst/2019025.
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In this paper, the stochastic equations of droplet motion in turbulent flow, proposed recently by Gorokhovski and Zamansky (2018, Phys. Rev. Fluids 3, 3, 034602), are assessed for turbulent spray dispersion in diesel like conditions along with Large Eddy Simulation (LES) for the gaseous flow. For droplets above the Kolmogorov length scale, this model introduces the concept of the stochastic drag, independently of laminar viscosity. For droplets below the Kolmogorov length scale, the model equation does depend on the laminar viscosity through the Stokes drag but the particle motion is stochastically forced. Both the stochastic drag and the stochastic forcing of the Stokes drag equation are based on the simple log-normal stochastic process for the viscous dissipation (ϵ) “seen” along the droplet trajectory. In this paper, this model is applied in the framework of two-way coupling, wherein the turbulence generated by the spray inturn controls the spray dispersion. The criterion for the choice of one of the approaches, i.e., the stochastic drag or the stochastic forcing, follows the classical condition for drag coefficient based on the droplet Reynolds number (Re p). The non-vaporizing spray experiments from Engine Combustion Network (ECN) are used as test cases. In addition to the comparison of the spray penetration length, spreading angle and spray structure with the experimental data, a qualitative analysis of the statistics of the droplet acceleration and gas phase velocities is presented. It was shown that the new approach is much more effective in modeling the spray dynamics on relatively coarser mesh. Consequently, the new approach in the framework of two-way coupling may predict the preferential concentration effects better, which is important for spray combustion.
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Ó Náraigh, Lennon, Prashant Valluri, David M. Scott, Iain Bethune, and Peter D. M. Spelt. "Linear instability, nonlinear instability and ligament dynamics in three-dimensional laminar two-layer liquid–liquid flows." Journal of Fluid Mechanics 750 (June 10, 2014): 464–506. http://dx.doi.org/10.1017/jfm.2014.274.
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AbstractWe consider the linear and nonlinear stability of two-phase density-matched but viscosity-contrasted fluids subject to laminar Poiseuille flow in a channel, paying particular attention to the formation of three-dimensional waves. A combination of Orr–Sommerfeld–Squire analysis (both modal and non-modal) with direct numerical simulation of the three-dimensional two-phase Navier–Stokes equations is used. For the parameter regimes under consideration, under linear theory, the most unstable waves are two-dimensional. Nevertheless, we demonstrate several mechanisms whereby three-dimensional waves enter the system, and dominate at late time. There exists a direct route, whereby three-dimensional waves are amplified by the standard linear mechanism; for certain parameter classes, such waves grow at a rate less than but comparable to that of the most dangerous two-dimensional mode. Additionally, there is a weakly nonlinear route, whereby a purely spanwise wave grows according to transient linear theory and subsequently couples to a streamwise mode in weakly nonlinear fashion. Consideration is also given to the ultimate state of these waves: persistent three-dimensional nonlinear waves are stretched and distorted by the base flow, thereby producing regimes of ligaments, ‘sheets’ or ‘interfacial turbulence’. Depending on the parameter regime, these regimes are observed either in isolation, or acting together.
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Pereira, Anselmo S., Roney L. Thompson, and Gilmar Mompean. "Common features between the Newtonian laminar–turbulent transition and the viscoelastic drag-reducing turbulence." Journal of Fluid Mechanics 877 (August 27, 2019): 405–28. http://dx.doi.org/10.1017/jfm.2019.567.
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The transition from laminar to turbulent flows has challenged the scientific community since the seminal work of Reynolds (Phil. Trans. R. Soc. Lond. A, vol. 174, 1883, pp. 935–982). Recently, experimental and numerical investigations on this matter have demonstrated that the spatio-temporal dynamics that are associated with transitional flows belong to the directed percolation class. In the present work, we explore the analysis of laminar–turbulent transition from the perspective of the recent theoretical development that concerns viscoelastic turbulence, i.e. the drag-reducing turbulent flow obtained from adding polymers to a Newtonian fluid. We found remarkable fingerprints of the variety of states that are present in both types of flows, as captured by a series of features that are known to be present in drag-reducing viscoelastic turbulence. In particular, when compared to a Newtonian fully turbulent flow, the universal nature of these flows includes: (i) the statistical dynamics of the alternation between active and hibernating turbulence; (ii) the weakening of elliptical and hyperbolic structures; (iii) the existence of high and low drag reduction regimes with the same boundary; (iv) the relative enhancement of the streamwise-normal stress; and (v) the slope of the energy spectrum decay with respect to the wavenumber. The maximum drag reduction profile was attained in a Newtonian flow with a Reynolds number near the boundary of the laminar regime and in a hibernating state. It is generally conjectured that, as the Reynolds number increases, the dynamics of the intermittency that characterises transitional flows migrate from a situation where heteroclinic connections between the upper and the lower branches of solutions are more frequent to another where homoclinic orbits around the upper solution become the general rule.
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Park, J. T., R. J. Mannheimer, T. A. Grimley, and T. B. Morrow. "Pipe Flow Measurements of a Transparent Non-Newtonian Slurry." Journal of Fluids Engineering 111, no. 3 (1989): 331–36. http://dx.doi.org/10.1115/1.3243648.
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An experimental description of the flow structure of non-Newtonian slurries in the laminar, transitional, and full turbulent pipe flow regimes is the primary objective of this research. Experiments were conducted in a large-scale pipe slurry flow facility with an inside pipe diameter of 51 mm. The transparent slurry formulated for these experiments from silica, mineral oil, and Stoddard solvent exhibited a yield-power-law behavior from concentric-cylinder viscometer measurements. The velocity profile for laminar flow from laser Doppler velocimeter (LDV) measurements had a central plug flow region, and it was in agreement with theory. The range of the transition region was narrower than that for a Newtonian fluid. The mean velocity profile for turbulent flow was close to a 1/7 power-law velocity profile. The rms longitudinal velocity profile was also similar to a classical turbulent pipe flow experiment for a Newtonian fluid; however, the rms tangential velocity profile was significantly different.
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YANG, SHU-QING, and G. DOU. "Turbulent drag reduction with polymer additive in rough pipes." Journal of Fluid Mechanics 642 (December 11, 2009): 279–94. http://dx.doi.org/10.1017/s002211200999187x.
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Friction factor of drag-reducing flow with presence of polymers in a rough pipe has been investigated based on the eddy diffusivity model, which shows that the ratio of effective viscosity caused by polymers to kinematic viscosity of fluid should be proportional to the Reynolds number, i.e. u∗R/ν and the proportionality factor depends on polymer's type and concentration. A formula of flow resistance covering all regions from laminar, transitional and fully turbulent flows has been derived, and it is valid in hydraulically smooth, transitional and fully rough regimes. This new formula has been tested against Nikuradse and Virk's experimental data in both Newtonian and non-Newtonian fluid flows. The agreement between the measured and predicted friction factors is satisfactory, indicating that the addition of polymer into Newtonian fluid flow leads to the non-zero effective viscosity and it also thickens the viscous sublayer, subsequently the drag is reduced. The investigation shows that the effect of polymer also changes the velocity at the top of roughness elements. Both experimental data and theoretical predictions indicate that, if same polymer solution is used, the drag reduction (DR) in roughened pipes becomes smaller relative to smooth pipe flows at the same Reynolds number.
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Brunetie`re, Noe¨l, Bernard Tournerie, and Jean Fre^ne. "Influence of Fluid Flow Regime on Performances of Non-Contacting Liquid Face Seals." Journal of Tribology 124, no. 3 (2002): 515–23. http://dx.doi.org/10.1115/1.1456453.
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Some non contacting mechanical face seals are running near the laminar boundary flow limit. A modification of operating conditions leads to a non laminar fluid flow in the seal interface while inertia forces remain negligible. A numerical model has been developed to determine pressure and velocity fields in the sealing dam for laminar to turbulent regime. The turbulent viscosity determination is based on the Elrod and Ng model. Evolutions of seal characteristics (opening force, friction torque, leakage rate…) and fluid film dynamic coefficients versus running conditions are presented. Numerical results show that great variations appear in the transition to turbulence.
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Rosti, Marco E., Daulet Izbassarov, Outi Tammisola, Sarah Hormozi, and Luca Brandt. "Turbulent channel flow of an elastoviscoplastic fluid." Journal of Fluid Mechanics 853 (August 23, 2018): 488–514. http://dx.doi.org/10.1017/jfm.2018.591.
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We present numerical simulations of laminar and turbulent channel flow of an elastoviscoplastic fluid. The non-Newtonian flow is simulated by solving the full incompressible Navier–Stokes equations coupled with the evolution equation for the elastoviscoplastic stress tensor. The laminar simulations are carried out for a wide range of Reynolds numbers, Bingham numbers and ratios of the fluid and total viscosity, while the turbulent flow simulations are performed at a fixed bulk Reynolds number equal to 2800 and weak elasticity. We show that in the laminar flow regime the friction factor increases monotonically with the Bingham number (yield stress) and decreases with the viscosity ratio, while in the turbulent regime the friction factor is almost independent of the viscosity ratio and decreases with the Bingham number, until the flow eventually returns to a fully laminar condition for large enough yield stresses. Three main regimes are found in the turbulent case, depending on the Bingham number: for low values, the friction Reynolds number and the turbulent flow statistics only slightly differ from those of a Newtonian fluid; for intermediate values of the Bingham number, the fluctuations increase and the inertial equilibrium range is lost. Finally, for higher values the flow completely laminarizes. These different behaviours are associated with a progressive increases of the volume where the fluid is not yielded, growing from the centreline towards the walls as the Bingham number increases. The unyielded region interacts with the near-wall structures, forming preferentially above the high-speed streaks. In particular, the near-wall streaks and the associated quasi-streamwise vortices are strongly enhanced in an highly elastoviscoplastic fluid and the flow becomes more correlated in the streamwise direction.
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Fayed, Hassan E., Nadeem A. Sheikh, and Oleg Iliev. "On Laminar Flow of Non-Newtonian Fluids in Porous Media." Transport in Porous Media 111, no. 1 (2015): 253–64. http://dx.doi.org/10.1007/s11242-015-0592-8.
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Eshtiaghi, Nicky, Flora Markis, and Paul Slatter. "The laminar/turbulent transition in a sludge pipeline." Water Science and Technology 65, no. 4 (2012): 697–702. http://dx.doi.org/10.2166/wst.2012.893.
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Globally, wastewater treatment plants are under pressure to handle high concentration sludge in a sludge treatment line. Unawareness of the non-Newtonian behaviour of the thickened sludge has the potential to cause unexpected problems when the fluid behaviour changes from turbulent to laminar flow. In this study, sludge apparent viscosity was plotted as a function of total suspended solids concentration (TSS) and shear rate. Then, the transition velocity based on several predictive models in the literature was determined. This analysis provides a practical basis for the prediction of the pipe flow behaviour of thickened sludge in troubleshooting and engineering design.
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Haciislamoglu, M., and J. Langlinais. "Non-Newtonian Flow in Eccentric Annuli." Journal of Energy Resources Technology 112, no. 3 (1990): 163–69. http://dx.doi.org/10.1115/1.2905753.
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A common assumption for annular flow used in the petroleum industry is that the inner pipe is concentrically located inside the flow geometry; however, this is rarely the case, even in slightly deviated wells. Considering the increasing number of directional and horizontal wells, the flow behavior of drilling fluids and cement slurries in eccentric annuli is becoming particularly important. In this paper, the governing equation of laminar flow is numerically solved using a finite differences technique to obtain velocity and viscosity profiles of yield-power law fluids (including Bingham plastic and power law fluids). Later, the velocity profile is integrated to obtain flow rate. Results show that the velocity profile is substantially altered in the annulus when the inner pipe is no longer concentric. Stagnant regions of flow were calculated in the low side of the hole. Viscosity profiles predicted for an eccentric annulus show how misleading the widely used single-value apparent viscosity term can be for non-Newtonian fluids. Profiles of velocity and viscosity in concentric and varying eccentric annuli are presented in 3-D and 2-D contour plots for a better visualization of annular flow. Frictional pressure loss gradient versus flow rate relationship data for power law fluids is generated using the computer program. Later, this data is fitted to obtain a simple equation utilizing regressional analysis, allowing for a quick calculation of friction pressure losses in eccentric annuli. For a given flow rate, frictional pressure loss is reduced as the inner pipe becomes eccentric. In most cases, about a 50-percent reduction in frictional pressure loss is predicted when the inner pipe lies on the low side.
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McNeil, D. A., A. J. Addlesee, and A. Stuart. "Newtonian and non-Newtonian viscous flows in nozzles." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 214, no. 11 (2000): 1425–36. http://dx.doi.org/10.1243/0954406001523399.
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A study of laminar, Newtonian and non-Newtonian fluids in nozzles has been undertaken. A theoretical model, previously deduced for Newtonian flows in expansions, was developed for Newtonian and non-Newtonian flows in nozzles. The model is based on a two-stream approach where the momentum and kinetic energy stored in the velocity profile of the fluid is altered by an area change of one stream relative to the other. The non-Newtonian liquids investigated were shear thinning. The model was used to investigate these non-Newtonian fluids and to justify the use of simpler, more approximate equations developed for the loss and flow coefficients. The model is compared favourably with data available in the open literature.
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Helal, Mohamed M., Tamer M. Ahmed, Adel A. Banawan, and Mohamed A. Kotb. "Numerical prediction of the performance of marine propellers using computational fluid dynamics simulation with transition-sensitive turbulence model." Proceedings of the Institution of Mechanical Engineers, Part M: Journal of Engineering for the Maritime Environment 233, no. 2 (2018): 515–27. http://dx.doi.org/10.1177/1475090218763199.
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Determining and understanding the performance characteristics of marine propellers by experiments is quite a complex and costly task. Numerical predictions using computational fluid dynamics simulations could be a valuable alternative provided that the laminar-to-turbulent transition flow effects are fundamentally understood with the suitable numerical models developed. Experience suggests that the use of classical turbulent flow models may lead to high discrepancies especially at low rotational speeds where the effects of fluid flow transition from the laminar to the turbulent state may influence the predicted propeller’s performance. This article proposes a complete and detailed procedure for the computational fluid dynamics simulation of non-cavitating flow over marine propellers using the “ k–kl–ω” transition-sensitive turbulence model. Results are evaluated by “ANSYS FLUENT 16” for the “INSEAN E779A” propeller. Comparisons against the fully turbulent standard “ k–ε” model and against experiments show improved agreement in way of flow transition zones at lower rotational speeds, that is, at low Reynolds numbers.
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Arafin, Sayyadul, and S. M. Mujibur Rahman. "Dynamical Properties of Omani Crude Oils for Flow Through a Vertical Annulus and a Cylindrical Pipe." Sultan Qaboos University Journal for Science [SQUJS] 16 (December 1, 2011): 102. http://dx.doi.org/10.24200/squjs.vol16iss0pp102-117.
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We have initially investigated the temperature dependence of density and viscosity of a number of crude oils, collected from various hydrocarbon reservoirs in Oman. The measured data are then utilized to investigate the flow dynamics of these hydrocarbon fluids under gravity and applied pressures at various temperatures. We have modeled the flow of the various crude oil samples through a vertical (a) annulus and (b) cylindrical pipe - all treated within the Newtonian fluid flow approximation of a laminar flow - to investigate the flow properties of these samples. A computer program is developed so that the temperature dependence of the fluid flow distinctly separates the laminar mode from a turbulent mode with respect to Reynolds numbers within the ranges Re<2000 and Re>2000. The adopted models of the velocity profiles, mass rate of flow and viscous force on the solid surface are not novel, but the present calculations aim to specifically use the various Omani crude oil samples with various AIP values; the calculated results shed some light on the dynamics of these specific samples within Newtonian approximation. The measured physical properties and the subsequent calculations of the relevant dynamical properties might be useful for various purposes e.g. extraction and transportation of crude oils through pipes.
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TAKAMI, Toshihiro, Kouzou SUDOU, and Yukio TOMITA. "Flow of Non-Newtonian Fluids in Curved Pipes : Laminar Flow in Entrance Region." JSME international journal. Ser. 2, Fluids engineering, heat transfer, power, combustion, thermophysical properties 33, no. 1 (1990): 26–32. http://dx.doi.org/10.1299/jsmeb1988.33.1_26.
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Aadnøy, Bernt S., and Jarle M. Ravnøy. "Improved pressure drop/flow rate equation for non-Newtonian fluids in laminar flow." Journal of Petroleum Science and Engineering 11, no. 3 (1994): 261–66. http://dx.doi.org/10.1016/0920-4105(94)90045-0.
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Nag, Debabrata, and Amitava Datta. "Variation of the Recirculation Length of Newtonian and Non-Newtonian Power-Law Fluids in Laminar Flow Through a Suddenly Expanded Axisymmetric Geometry." Journal of Fluids Engineering 129, no. 2 (2006): 245–50. http://dx.doi.org/10.1115/1.2409361.
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A numerical study has been carried out for the laminar flow of Newtonian and non-Newtonian power-law fluids through a suddenly expanded axisymmetric geometry. Mathematical correlations are proposed for the prediction of the length of the recirculating eddy in terms of Reynolds number, expansion ratio and rheological parameters. A wide range of expansion ratios (1.25⩽ER⩽8.0) has been covered for the Newtonian fluid and both the shear-thinning and shear-thickening flow characteristic fluids have been considered for the non-Newtonian fluids.
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Litvinov, W. G. "Model for laminar and turbulent flows of viscous and nonlinear viscous non-Newtonian fluids." Journal of Mathematical Physics 52, no. 5 (2011): 053102. http://dx.doi.org/10.1063/1.3578752.
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Watanabe, Keizo, and Takashi Akino. "Drag Reduction in Laminar Flow Between Two Vertical Coaxial Cylinders." Journal of Fluids Engineering 121, no. 3 (1999): 541–47. http://dx.doi.org/10.1115/1.2823502.
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Laminar drag reduction has been shown for the flow of a Newtonian fluid in the space between two vertical coaxial cylinders. Experiments were carried out to measure the torque of a bob with a highly water-repellent wall to clarify the effect of the contact surface of the bob on the flow behavior. The basic material of the highly water-repellent wall is fluorine alkane modified acrylic resin with added hydrophobic silica, and the contact angle of the wall is about 150 degree. The radius rations of the bob were 0.932 and 0.676. Test fluids were Newtonian aqueous solutions of 60, 70, and 80 wt% glycerin and polymer solutions. The maximum drag reduction ratio was about 12% for 80 wt% glycerin solution at a radius ratio of 0.932. The moment coefficient of the coaxial cylinder in Newtonian fluids was analyzed for fluid slip, and it was shown that the analytical results agreed well with the experimental data. For the case of non-Newtonian fluids, the fluid slip velocity of polymer solutions is not proportional to the shear stress and the relationship is approximated by power-law equations.
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Chaves, C. L., Joao N. N. Quaresma, E. N. Macedo, L. M. Pereira, and J. A. Lima. "HYDRODYNAMICALLY DEVELOPED LAMINAR FLOW OF NON-NEWTONIAN FLUIDS INSIDE DOUBLE-SINE DUCTS." Hybrid Methods in Engineering 3, no. 2-3 (2001): 16. http://dx.doi.org/10.1615/hybmetheng.v3.i2-3.60.
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Naccache, Mônica F., and Paulo R. Souza Mendes. "Heat transfer to non-Newtonian fluids in laminar flow through rectangular ducts." International Journal of Heat and Fluid Flow 17, no. 6 (1996): 613–20. http://dx.doi.org/10.1016/s0142-727x(96)00062-8.
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