Academic literature on the topic 'Laminar flow. Non-Newtonian fluids. Turbulence'
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Journal articles on the topic "Laminar flow. Non-Newtonian fluids. Turbulence"
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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.
Dissertations / Theses on the topic "Laminar flow. Non-Newtonian fluids. Turbulence"
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Guzel, Bulent. "Observation of laminar-turbulent transition of a yield stress fluid in Hagen-Poiseuille flow." Thesis, University of British Columbia, 2009. http://hdl.handle.net/2429/5040.
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The main focus of this work is to 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 equals or exceeds the yield stress of the fluid, i.e. the plug is broken before transition commences. Once in transition and when turbulent, the behavior of the yield stress fluid is somewhat similar to a (simpler) shear thinning fluid. We have also observed the shape of slugs during transition and find that their leading edges to be highly elongated and located off the central axis of the pipe, for the non-Newtonian fluids examined. Finally we present a new phenomenological approach for quantifying laminar-turbulent transition in pipe flow. This criterion is based on averaging a local Reynolds number to give ReG. Our localised parameter shows strong radial variations that are maximal at approximately the radial positions where puffs first appear during the first stages of turbulent transition.
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Burger, Johannes Hendrik. "Non-Newtonian open channel flow: the effect of shape." Thesis, Cape Peninsula University of Technology, 2014. http://hdl.handle.net/20.500.11838/1296.
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Thesis submitted in fulfilment of the requirements for the degree
Doctor of Technology: Mechanical Engineering
in the
Faculty of Engineering
at the
Cape Peninsula University of Technology
2014<br>Open channels, flumes or launders are used in the mining industry to transport slurries during processing and to disposal sites. Water plays a major part in the makeup of these slurries, its usage and availability is critical in countries where there are strict water usage management programs. The optimisation of flume design involves the maximisation of solids transport efficiency whilst, at the same time reduces water usage. The design of open channels is complex as it is dependent on both the slurry rheology and the channel shape. Very little has been reported in the literature for predicting non-Newtonian laminar flow in open channels of arbitrary cross-section. The only method available was that proposed by Kozicki and Tiu (1967, 1986). The shape factors they used were those evaluated from analytical solutions for flow of Newtonian fluids in open channels of the same cross-section. However, they carried out no experimental work to validate their model. Few experimental studies have been made on the effect of shape on non-Newtonian flow in open channels. Naik (1983) tested kaolin in water suspensions in a rectangular channel. Coussot (1994) provided some data for the flow of a Herschel-Bulkley fluid in rectangular and trapezoidal channels. Fitton (2007; 2008) obtained data for flow of three different non-Newtonian fluids (carboxymethylcellulose, carbopol and thickened tailings) in a semi-circular channel. A large experimental database for non-Newtonian flow in rectangular open channels was published by Haldenwang (2003) at the Flow Process Research Centre, Cape Peninsula University of Technology. Guang et al. (2011) performed Direct Numerical Simulations of turbulent flow of a yield- pseudoplastic fluid in a semi-circular channel. They compared their simulations with actual field measurements and found them to over-predict the flow velocity by approximately 40%. The source for this discrepancy was difficult to ascertain.
A comprehensive database was compiled during this research of the flow of three non–Newtonian fluids in rectangular, trapezoidal, semi-circular and triangular channels. The flow of carboxymethylcellulose solutions and aqueous kaolin and bentonite suspensions was investigated in a 10 meter long flume at angles ranging from 1° to 5° from the horizontal plane. The effect of channel shape on the friction factor-Reynolds number relationship for laminar and turbulent open channel flow of these three fluids was investigated. New models for the prediction of laminar and turbulent flow of non-Newtonian fluids in open channels of different cross-sectional shapes are proposed. The new laminar and turbulent velocity models are compared with three previously-published velocity models for laminar flow and five previously-published velocity models for turbulent flow using average velocity as comparison criteria.
For each channel shape, the laminar flow data can be described by a general relationship, f = K/Re where f is the Fanning friction factor and Re is the appropriate Haldenwang et al. (2002) Reynolds number. The K values were found to be 14.6 for triangular channels with a vertex angle of 90°, 16.2 for semi-circular channels, 16.4 for rectangular channels and 17.6 for trapezoidal channels with 60 degree sides. These K values were found to be in line with those reported by Straub et al. (1958) and Chow (1969) for open channel laminar flow of Newtonian fluids as opposed to the assumption made by Haldenwang et al. (2002; 2004) of using a constant value of 16 based on the pipe flow paradigm for all channel shapes.
This new laminar model gave a closer fit to the laminar flow data than those from the three previously-published models. However, the presence of the yield stress still presents a problem, which makes the flow prediction in laminar flow for such fluids not very accurate. The investigation on non-Newtonian turbulent flow of the three fluids in the four different shaped open channels revealed that the data was described by the modified Blasius equation f = a Re b where a and b are constant values determined for each channel shape and Re is the Haldenwang et al. (2002) Reynolds number. Values of a and b for a rectangular channel were found to be 0.12 and -0.330, for a semi- circular channel 0.048 and -0.205, for a trapezoidal channel with 60° sides, 0.085 and -0.266 and for a triangular channel with vertex angle of 90°, 0.042 and -0.202. New laminar and turbulent velocity models were derived from using the new laminar f = K/Re and turbulent f = a Re b, friction factor-Reynolds number relationship. The laminar velocity model did not always give the best result, but the majority of the time it did, compared to the three previously published models. The new turbulent velocity model yielded the best results when compared to the five previously published models using average velocity as comparison criteria. The composite power law modelling procedure of Garcia et al. (2003) used for pipe flow predictions was extended to the present work on non-Newtonian flow in open channels of various cross-sections. The results show that the modelling technique used by Garcia et al. (2003) for pipe flow can be used to adequately predict flow in an open channel of a given cross-sectional shape provided that an appropriate Reynolds number is used to take into account the non-Newtonian behaviour of the test fluid. It was found that the results using the Haldenwang et al. (2002) Reynolds number yielded better results than those based on the adapted Metzner-Reed Reynolds number.
The correlations and models developed and experimentally validated during this research can be used to further improve the design of rectangular, semi-circular, trapezoidal and triangular open channels to transport non-Newtonian fluids.
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Vanyaza, Sydwell Luvo. "Non-newtonian open-channel flow : effect of shape on laminar and transitional flow." Thesis, Cape Technikon, 2004. http://hdl.handle.net/20.500.11838/874.
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Thesis (MTech (Chemical Engineering))--Cape Technikon, 2004<br>When designing the open channels to transport the homogenous non-Newtonian slurries, the
effect of channel shape is one of the parameters that should be checked and very little research
has been conducted to address this matter. Open channels are commonly applied in the mining
industry where mine tailings have to be transported to the disposal dams at high concentrations
to save water consumption. This thesis addresses the effect of the cross-sectional shape of the
channel with emphasis on laminar and transitional flow of non-Newtonian fluids.
The literature review on the flow of Newtonian and non-Newtonian fluids has been presented.
The most relevant one to this topic is the work done by Straub et al (1958) for Newtonian
fluids and the analytical work presented by Kozicki and Tiu (1967) for non-Newtonian fluids.
Authors like Coussot (1994) and Haldenwang (2003) referred to their work but did not
comprehensively verified it experimentally.
Three flume shapes were designed to investigate this problem namely, rectangular, semi
circular, and trapezoidal flume shape. The test rig consisted of a 10 m long by 300mm wide
tilting flume that can be partitioned into two sections to form a 150 mm wide channel. All
three flume shapes were tested in both the 150 mm and 300 mm wide flumes. This flume is
linked to the in-line tube viscometer with three tube diameters namely, 13 mm; 28 mm; and 80
mm. The experimental investigation covered a wide range of flow rates (0.1-45l/s), and flume
slopes (1-5 degrees). The fluids tested were kaolin suspension (5.4 - 9% v/v), CMC solution (1
- 4% m/m), and bentonite suspension (4.6 and 6.2% mlm).
The models found in the literature were evaluated with the large database compiled from the
test results to predict the laminar and transitional flow of these fluids with the aim of checking
the effect of the cross-sectional shape of these channels selected in these flow regimes.
For all the flume shapes and non-Newtonian fluids selected in this thesis it was found that in
predicting the laminar flow, the effect of shape is adequately accounted for by the use of
hydraulic radius. In predicting the transitional flow, it was found that the effect of shape does
not have to be included.
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Samanta, Devranjan [Verfasser], and Christian [Akademischer Betreuer] Wagner. "Transition to turbulence in pipe flow of Newtonian and Non Newtonian fluids / Devranjan Samanta. Betreuer: Christian Wagner." Saarbrücken : Saarländische Universitäts- und Landesbibliothek, 2013. http://d-nb.info/1052953999/34.
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Rundora, Lazarus. "Laminar flow in a channel filled with saturated porous media." Thesis, Cape Peninsula University of Technology, 2013. http://hdl.handle.net/20.500.11838/1306.
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Thesis (DTech (Mechanical Engineering))--Cape Peninsula University of Technology, 2013<br>The flow of reactive viscous fluids in porous media presents a theoretically challenging problem
and has a broad range of scientific, technological and engineering applications. Real life areas
where such flow systems are encountered include drying of food, geothermal energy extraction,
nuclear waste disposal, the flow of heat and fluid inside human organs, insulation of buildings,
groundwater movement, oil and gas production, astrophysical plasmas, magnetohydrodynamic
(MHD) pumps and generators, metal extraction and granulation of metals, aerospace and ship
propulsion and automobile exhaust systems. The reactions within such flow systems are
inherently exothermic. It is in this view that we carry out studies of thermal effects and thermal
stability criteria for unsteady flows of reactive variable viscosity non-Newtonian fluids through
saturated porous media. The study focuses on non-Newtonian fluids mainly because the
majority of industrial fluids exhibit non-Newtonian character. Particular focus will be on fluids of
the differential type exemplified by third grade fluid.
Both analytical and numerical techniques were employed to solve the nonlinear partial
differential equations that were derived from the conservation principles, namely the principles
of conservation of mass, momentum and energy balance. Graphical representations were
adopted in trying to explain the response of solutions to various flow parameter variations.
In chapter 1 we defined important terms and expressions, laid down a summary of important
applications, carried out literature survey, stated the statement of the problem, the aims and
objectives of the study as well as an outline of the envisaged research methodology. Chapter 2
focuses on the derivations of the fundamental equations that derive the flow system. These are
the continuity equation, the momentum equation and the energy equation.
In chapter 3 we computationally investigated the unsteady flow of a reactive temperature
dependent viscosity third grade fluid through a porous saturated medium with asymmetric
convective boundary conditions. The response of velocity and temperature fields to each of the
various flow parameters was analysed and interpreted. A transient increase in both the velocity
and temperature profiles with an increase in the reaction strength, viscous heating and fluid
viscosity parameter was observed. On the other hand, a transient decrease in the field
properties was observed with increase in non-Newtonian character and the porous medium
shape parameter. The reaction was noticed to blow-up if, depending on other flow parameters,
the reaction strength is not carefully controlled.
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López, Carranza Santiago Nicolás. "Transition laminaire-turbulent en conduite cylindrique pour un fluide non Newtonien." Thesis, Université de Lorraine, 2012. http://www.theses.fr/2012LORR0118/document.
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L'objectif de cette thèse est de fournir une analyse de la transition vers la turbulence d'un fluide rhéofluidifiant (fluide de Carreau) dans une conduite cylindrique. Pour cela, un code pseudo-spectral de type Petrov-Galerkin a été développé. Une analyse linéaire de stabilité de l'écoulement laminaire est effectuée, montrant que cet écoulement est linéairement stable. Ensuite, des perturbations sous la forme des rouleaux longitudinaux contra-rotatifs sont utilisées comme condition initiale. Les termes non linéaires d'inertie et visqueux créent un écoulement secondaire avec des points d'inflexion, linéairement instable vis-à-vis de perturbations 3D. Une analyse linéaire de stabilité de ce nouvel écoulement de base bidimensionnelle est réalisée. La forme des vecteurs propres critiques est analysé. Enfin, une analyse non linéaire de stabilité de rouleaux vis-à-vis des perturbations tridimensionnelles de faible amplitude est effectuée, obtenant un retard pour la transition vers la turbulence des fluides rhéofluidifiants par rapport au cas Newtonien et une tendance à l'asymétrie du profil de vitesse axiale<br>The main objective of this thesis is to provide a description of the transition to turbulence of a shear thinning fluid in pipe flow. A linear stability analysis of the base flow is done. Results show that the flow is linearly stable and the optimal perturbation is given by a pair of counter rotating vortex. This kind of perturbation is used as an initial condition of a computational code which integrates the governing equations. Inertial and viscous non linear terms generate a secondary base flow with inflection points, which is linearly unstable to 3D perturbations. A secondary instability analysis is done, regarding the shape of unstable eigenvectors. Depending the rheological parameters and the size of the primary perturbation, the unstable mode might be near the wall or the center of the pipe. Finally, a non linear stability analysis of the streaks to 3D perturbations of weak amplitude, obtaining a delay in the transition to turbulence due to shear thinning
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Niazi, Ardekani Mehdi. "Numerical study of non-spherical/spherical particles in laminar and turbulent flows." Licentiate thesis, KTH, Mekanik, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-204421.
Full textAbstract:
The presence of solid rigid particles alters the global transport and rheological properties of the mixture in complex (and often unpredictable) ways. In recent years a few studies have been devoted to investigating the behavior of dense suspensions in the turbulent/inertial regime with the majority of theses analyses limited to mono-disperse rigid neutrally-buoyant spheres. However, one interesting parameter that is rarely studied for particles with high inertia is the particle shape. Spheroidal particles introduce an anisotropy, e.g. a tendency to orient in a certain direction, which can affect the bulk behavior of a suspension in an unexpected ways. The main focus of this study is therefore to investigate the behavior of spheroidal particles and their effect on turbulent/inertial flows. We perform fully resolved simulations of particulate flows with spherical/spheroidal particles, using an efficient/accurate numerical approach that enables us to simulate thousands of particles with high resolutions in order to capture all the fluid-solid interactions. Several conclusions are drawn from this study that reveal the importance of particle's shape effect on the behaviour of a suspension e.g. spheroidal particles tend to cluster while sedimenting. This phenomenon is observed in this work for both particles with high inertia, sedimenting in a quiescent fluid and inertialess particles (point-like tracer prolates) settling in homogenous isotropic turbulence. The mechanisms for clustering is indeed different between these two situations, however, it is the shape of particles that governs these mechanisms, as clustering is not observed for spherical particles. Another striking finding of this work is drag reduction in particulate turbulent channel flow with rigid oblate particles. Again this drag reduction is absent for spherical particles, which instead increase the drag with respect to single-phase turbulence.<br><p>QC 20170328</p>
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Pinheiro, Jorge Vagaroso de Barros. "Escoamento laminar de fluidos não-Newtonianos em permutadores de calor." Master's thesis, Instituto Politecnico de Bragança, 2008. http://hdl.handle.net/10198/1682.
Full textAbstract:
Este trabalho teve como objectivo estudar numericamente o escoamento laminar de fluidos Newtonianos
e não-Newtonianos em canais de permutadores de calor de placas do tipo chevron com ângulo de
corrugação igual a zero (canais do tipo sinusoidal).
Em particular, foram estudados os factores de fricção de Fanning para o fluxo laminar completamente
desenvolvido de fluidos Newtonianos e de fluidos não-Newtonianos (descritos pela lei de potência) em
canais do tipo sinusoidal, sendo os factores de fricção de Fannning, f, descritos pela relação 1 Reg f K −
= ,
em que Reg representa o número de Reynolds generalizado.
Para fluidos Newtonianos o coeficiente K da relação acima referida foi relacionado com o rácio de
aspecto dos diferentes canais sinusoidais. Uma vez que o coeficiente K depende do factor de forma, K0, e
do coeficiente de tortuosidade, t, através de 2
0
K = K t , K0 e t foram também relacionados com o rácio de
aspecto dos diferentes canais.
Foram ainda estabelecidas curvas de fricção únicas para fluidos Newtonianos e não-Newtonianos, através
da implementação de um número de Reynolds generalizado adequado, nos canais referidos.
As relações propostas são simples e úteis para cálculos de engenharia. In this work it were numerically studied the fully developed laminar flows of Newtonian and non-
Newtonian fluids in the channels from chevron type plate heat exchangers with corrugation angle equal to
zero (sinusoidal channels).
In particular, were studied the Fanning friction factors for the fully developed laminar flow of Newtonian
fluids and non-Newtonian fluids (from the power-law type) in sinusoidal channels, being the Fanning
friction factors, f, described by 1 Reg f K −
= , where Reg represents the generalized Reynolds number.
For Newtonian fluids, the coefficient K was related with the channel aspect ratio of the different
sinusoidal channels. The coefficient K is dependent from the shape factor, K0, and tortuosity coefficient, t
, by 2
0
K = K t . The shape factor and t were also related with the channel aspect ratio from the different
channels.
In addition, it were proposed single friction curve equations for the flow of Newtonian and non-
Newtonian fluids, through the implementation of an appropriate generalized Reynolds number, in the
referred channels.
The proposed relations are simple and useful for engineering calculations
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Gratão, Ana Carolina Amaral. "Termofluidodinamica de sucos de frutas pseudoplasticos em dutos cilindricos e anulos concentricos." [s.n.], 2006. http://repositorio.unicamp.br/jspui/handle/REPOSIP/255776.
Full textAbstract:
Orientadores: Vivaldo Silveira Junior, Javier Telis Romero<br>Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos<br>Made available in DSpace on 2018-08-06T15:00:42Z (GMT). No. of bitstreams: 1
Gratao_AnaCarolinaAmaral_D.pdf: 2034155 bytes, checksum: 7a7cc4a961cab6b38ae3dc5ee5f3f9d8 (MD5)
Previous issue date: 2006<br>Doutorado<br>Engenharia de Alimentos<br>Doutor em Engenharia de Alimentos
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Goufo, Emile Franc Doungmo. "A mathematical explanation of the transition between laminar and turbulent flow in Newtonian fluids, using the Lie groups and finite element methods." Diss., 2007. http://hdl.handle.net/10500/1596.
Full textAbstract:
In this scientific work, we use two effective methods : Lie groups theory and the finite
element method, to explain why the transition from laminar flow to turbulence flow
depends on the variation of the Reynolds number. We restrict ourselves to the case
of incompressible viscous Newtonian fluid flows. Their governing equations, i.e. the
continuity and Navier-Stokes equations are established and investigated. Their solutions
are expressed explicitly thanks to Lie's theory. The stability theory, which leads to an
eigenvalue problem is used together with the finite element method, showing a way to
compute the critical Reynolds number, for which the transition to turbulence occurs.
The stationary flow is also studied and a finite element method, the Newton method, is
used to prove the stability of its convergence, which is guaranteed for small variations of
the Reynolds number.<br>Mathematical Sciences<br>M.Sc. (Applied Mathematics)
Books on the topic "Laminar flow. Non-Newtonian fluids. Turbulence"
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Yudaev, Vasiliy. Hydraulics. INFRA-M Academic Publishing LLC., 2021. http://dx.doi.org/10.12737/996354.
Full textAbstract:
The textbook corresponds to the general education programs of the general courses "Hydraulics" and "Fluid Mechanics". The basic physical properties of liquids, gases, and their mixtures, including the quantum nature of viscosity in a liquid, are described; the laws of hydrostatics, their observation in natural phenomena, and their application in engineering are described. The fundamentals of the kinematics and dynamics of an incompressible fluid are given; original examples of the application of the Bernoulli equation are given. The modes of fluid motion are supplemented by the features of the transient flow mode at high local resistances. The basics of flow similarity are shown. Laminar and turbulent modes of motion in pipes are described, and the classification of flows from a creeping current to four types of hypersonic flow around the body is given. The coefficients of nonuniformity of momentum and kinetic energy for several flows of Newtonian and non-Newtonian fluids are calculated. Examples of solving problems of transient flows by hydraulic methods are given. Local hydraulic resistances, their use in measuring equipment and industry, hydraulic shock, polytropic flow of gas in the pipe and its outflow from the tank are considered. The characteristics of different types of pumps, their advantages and disadvantages, and ways of adjustment are described. A brief biography of the scientists mentioned in the textbook is given, and their contribution to the development of the theory of hydroaeromechanics is shown. The four appendices can be used as a reference to the main text, as well as a subject index. Meets the requirements of the federal state educational standards of higher education of the latest generation. For students of higher educational institutions who study full-time, part-time, evening, distance learning forms of technological and mechanical specialties belonging to the group "Food Technology".
Book chapters on the topic "Laminar flow. Non-Newtonian fluids. Turbulence"
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Draad, Aswin A., and Martien A. Hulsen. "Transition From Laminar to Turbulent Flow for Non-Newtonian Fluids." In Fluid Mechanics and Its Applications. Springer Netherlands, 1995. http://dx.doi.org/10.1007/978-94-011-0457-9_21.
Full text
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Jou, David, José Casas-Vázquez, and Manuel Criado-Sancho. "Non-equilibrium Thermodynamics of Laminar and Turbulent Superfluids." In Thermodynamics of Fluids Under Flow. Springer Netherlands, 2010. http://dx.doi.org/10.1007/978-94-007-0199-1_11.
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Stacharska-Targosz, J., and P. Gryglaszewski. "Heat transfer in laminar flow of non-Newtonian fluids." In Progress and Trends in Rheology II. Steinkopff, 1988. http://dx.doi.org/10.1007/978-3-642-49337-9_43.
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Furbish, David Jon. "Turbulent Flows." In Fluid Physics in Geology. Oxford University Press, 1997. http://dx.doi.org/10.1093/oso/9780195077018.003.0018.
Full textAbstract:
Many geological flows involve turbulence, wherein the velocity field involves complex, fluctuating motions superimposed on a mean motion. Flows in natural river channels are virtually always turbulent. Magma flow in dikes and sills, and lava flows, can be turbulent. Atmospheric flows involving eolian transport are turbulent. The complex, convective overturning of fluid in a magma chamber or geyser is a form of turbulence. Thus, a description of the basic qualities of these complex flows is essential for understanding many geological flow phenomena. Turbulent flows generally are associated with large Reynolds numbers. Recall from Chapter 5 that the Reynolds number Re is a measure of the ratio of inertial to viscous forces acting on a fluid element, . . . Re = ρUL/μ . . . . . . (14.1) . . . where the characteristic velocity U and length L are defined in terms of the particular flow system. Thus, turbulence is typically associated, for given fluid density ρ and viscosity μ, with high-speed flows (although we must be careful in applying this generality to thermally driven convective motions; see Chapter 16). A simple, visual illustration of this occurs when smoke rises from a cigar within otherwise calm, surrounding air. The smoke acts as a flow tracer. Smoke molecules at the cigar tip start from rest, since they are initially attached to the cigar. Upward fluid motion, as traced by the smoke, initially is of low speed, and viscous forces have a relatively important influence on its behavior. The flow is laminar; smoke streaklines are smooth and locally parallel. But as the flow accelerates upward, it typically reaches a point where viscous forces are no longer sufficient to damp out destabilizing effects of growing inertial forces, and the flow becomes turbulent, manifest as whirling, swirling fluid motions (see Tolkien [1937]). Throughout this chapter we will consider only incompressible Newtonian fluids. Unfortunately, the complexity of turbulent fluid motions precludes directly using the Navier–Stokes equations to describe them. Instead, we will adopt a procedure whereby the Navier–Stokes equations are recast in terms of temporally averaged or spatially averaged values of velocity and pressure, and fluctuations about these averages.
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"Laminar Flow of Non-Newtonian Fluids." In Mechanics of Fluid Flow. John Wiley & Sons, Inc., 2012. http://dx.doi.org/10.1002/9781118533628.ch16.
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"Non-Newtonian Fluids Flow in a Circular Pipe." In Laminar Drag Reduction, edited by Keizo Watanabe. BENTHAM SCIENCE PUBLISHERS, 2015. http://dx.doi.org/10.2174/9781681080840115010005.
Full textConference papers on the topic "Laminar flow. Non-Newtonian fluids. Turbulence"
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Poole, R. J., M. P. Escudier, F. Presti, et al. "Asymmetrical Flow Behaviour in Transitional Pipe Flow of Non-Newtonian Liquids." In ASME 2005 International Mechanical Engineering Congress and Exposition. ASMEDC, 2005. http://dx.doi.org/10.1115/imece2005-79386.
Full textAbstract:
The purpose of this presentation is to report mean velocity-profile data for fully-developed pipe flow of a wide range of shear-thinning liquids together with two Newtonian control liquids. Although most of the data reported are for the laminar-turbulent transition regime, data are also included for laminar and turbulent flow. The experimental data were obtained in unrelated research programmes in UK, France and Australia, all using laser Doppler anemometry (LDA) as the measurement technique. In the majority of cases, axisymmetric flow is observed for the laminar and turbulent flow conditions, although asymmetry due to the Earth’s rotation is evident for the laminar flow of a Newtonian fluid of low viscosity (i.e. low Ekman number). The key point, however, is that for certain fluids, both yield-stress and viscoelastic (all fluids in this study are shear thinning), asymmetry to varying degrees is apparent at all stages of transition from laminar to turbulent flow, i.e. from the first indications to almost fully-developed turbulence. The fact that symmetrical velocity profiles are obtained for both laminar and turbulent flow of all the non-Newtonian fluids in all three laboratories leads to the conclusion that the asymmetry must be a consequence of a fluid-dynamic mechanism, as yet not identified, rather than imperfections in the flow facilities.
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Simpson, Melissa M., and William S. Janna. "Newtonian and Non-Newtonian Fluids: Velocity Profiles, Viscosity Data, and Laminar Flow Friction Factor Equations for Flow in a Circular Duct." In ASME 2008 International Mechanical Engineering Congress and Exposition. ASMEDC, 2008. http://dx.doi.org/10.1115/imece2008-67611.
Full textAbstract:
Newtonian fluid flow in a duct has been studied extensively, and velocity profiles for both laminar and turbulent flows can be found in countless references. Non-Newtonian fluids have also been studied extensively, however, but are not given the same attention in the Mechanical Engineering curriculum. Because of a perceived need for the study of such fluids, data were collected and analyzed for various common non-Newtonian fluids in order to make the topic more compelling for study. The viscosity and apparent viscosity of non-Newtonian fluids are both defined in this paper. A comparison is made between these fluids and Newtonian fluids. Velocity profiles for Newtonian and non-Newtonian fluid flow in a circular duct are described and sketched. Included are profiles for dilatant, pseudoplastic and Bingham fluids. Only laminar flow is considered, because the differences for turbulent flow are less distinct. Also included is a procedure for determining the laminar flow friction factor which allows for calculating pressure drop. The laminar flow friction factor in classical non-Newtonian fluid studies is the Fanning friction factor. The equations developed in this study involve the Darcy-Weisbach friction factor which is preferred for Newtonian fluids. Also presented in this paper are viscosity data of Heinz Ketchup, Kroger Honey, Jif Creamy Peanut Butter, and Kraft Mayonnaise. These data were obtained with a TA viscometer. The results of this study will thus provide the student with the following for non-Newtonian fluids: • Viscosity data and how it is measured for several common non-Newtonian fluids; • A knowledge of velocity profiles for laminar flow in a circular duct for both Newtonian and non-Newtonian fluids; • A procedure for determining friction factor and calculating pressure drop for non-Newtonian flow in a duct.
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Owen, I., I. Fyrippi, and M. P. Escudier. "Flowmetering of Shear-Thinning Non-Newtonian Liquids (Keynote)." In ASME/JSME 2003 4th Joint Fluids Summer Engineering Conference. ASMEDC, 2003. http://dx.doi.org/10.1115/fedsm2003-45588.
Full textAbstract:
This paper describes the results of an investigation into the performance of Coriolis, Electromagnetic, and clamp-on single-beam Ultrasonic flowmeters operating with non-Newtonian liquids. The flowmeters have been tested on Newtonian liquids (water and a glycerine/water solution) and non-Newtonian liquids (various polymer solutions and a synthetic clay) with flow rates that span the laminar and turbulent regions. It has been shown that the Coriolis flowmeter operates within the manufacturer’s specification with non-Newtonian liquids. The Electromagnetic flowmeter showed a slight deviation during transition, typically 1%. The Ultrasonic flowmeter showed very significant deviations during transition, typically 15%. It has been clearly demonstrated that flowmeters which are sensitive to flow velocity profile are particularly unsuitable for use with non-Newtonian liquids. Not only do non-Newtonian liquids have different flow velocity profiles to Newtonian liquids, they also have different criteria for laminar/turbulent transition.
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Adane, Kofi Freeman K., and Martin Agelin-Chaab. "Laminar-Turbulent Transition Flows of Non-Newtonian Slurries: Models Assessment." In ASME 2016 Fluids Engineering Division Summer Meeting collocated with the ASME 2016 Heat Transfer Summer Conference and the ASME 2016 14th International Conference on Nanochannels, Microchannels, and Minichannels. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/fedsm2016-7597.
Full textAbstract:
In this study a qualitative assessment of transitional velocity engineering models for predicting non-Newtonian slurry flows in a horizontal pipe was performed using data from wide pipe diameters (25–268 mm). In addition, Gamma Theta transition model was used to compute selected flow conditions. In general, it was observed that most of the current engineering models predict conservative transitional velocities. However, caution should be exercised in design situations where both pipe diameter and viscoplastic viscosity influence the value of Hedström number. It was found that the Gamma Theta transition model predicted a laminar flow condition in the fully developed region which is contrary to what has been observed in experiment.
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Kim, Young-Ju, Nam-Sub Woo, and Young-Kyu Hwang. "Flow of Newtonian and Non-Newtonian Fluids in a Concentric Annulus With Rotation of the Inner Cylinder." In ASME/JSME 2003 4th Joint Fluids Summer Engineering Conference. ASMEDC, 2003. http://dx.doi.org/10.1115/fedsm2003-45791.
Full textAbstract:
This experimental study concerns the characteristics of vortex flow in a concentric annulus with a diameter ratio of 0.52, whose outer cylinder is stationary and inner one is rotating. Pressure losses and skin friction coefficients have been measured for fully developed flows of water and of 0.4% aqueous solution of sodium carboxymethyl cellulose (CMC), respectively, when the inner cylinder rotates at the speed of 0∼600 rpm. The results of present study reveal the relation of the bulk flow Reynolds number Re and Rossby number Ro with respect to the skin friction coefficients. In somehow, they show the existence of flow instability mechanism. The effect of rotation on the skin friction coefficient is significantly dependent on the flow regime. In all flow regime, the skin friction coefficient is increased by the inner cylinder rotation. The change of skin friction coefficient corresponding to the variation of rotating speed is large for the laminar flow regime, whereas it becomes smaller as Re increases for the transitional flow regime and, then, it gradually approach to zero for the turbulent flow regime. Consequently, the critical (bulk flow) Reynolds number Rec decreases as the rotational speed increases. Thus, the rotation of the inner cylinder promotes the onset of transition due to the excitation of Taylor vortices.
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Kalayci, Goktug, Evren M. Ozbayoglu, Stefan Z. Miska, et al. "Transition Criteria for Laminar to Turbulent Flow for Yield Power Law (YPL) Fluids Based on Stability Analysis." In ASME 2013 Fluids Engineering Division Summer Meeting. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/fedsm2013-16188.
Full textAbstract:
It is well known that a Newtonian fluid with the presence of solid particles in suspension behaves non-Newtonian. Higher the solid content, more significant the yield stress of the fluid. Determination of the hydraulic behavior of fluids having a significant yield stress is a challenging task. For engineering purposes, pressure drop within the system, during pipeline transportation, has to be estimated carefully and accurately. Flow regime plays a vital role during hydraulic calculations. The inaccurate determination of flow regime can lead us to large errors in frictional pressure drop calculations and ultimately leads to error in designing and flow assurance point of view, since hydraulic calculations are including a friction factor term, which is a direct function of flow regime. In general, Reynolds number is the main parameter used by the industry for determining the flow regime, and the friction factor. This approach works reasonably accurate for Newtonian fluids. However, as the yield stress of the fluid increases, this conventional technique for determining the flow regime is not as accurate. Although many approaches have been introduced for estimating the flow regime for non-Newtonian fluids, there exists a lack of information and confidence of such predictions for fluids having high yield stress, such as Yield Power Law (YPL) fluids (i.e., Herchel-Bulkley). (1)τ=τy+Kγm This study presents an analytical solution for predicting the transition from laminar to non-laminar flow regime based on Ryan & Johnson’s approach using the stability analysis and equation of motion for YPL fluids. Comparing with the experimental results for YPL fluids under different flow conditions, including laminar and non-laminar flow regimes, show that presented approach gives a better estimation of the transition from laminar to non-laminar flow regime than conventional Reynolds number approach. In some cases, it is observed that although the Reynolds number is high, flow is still laminar, which is predicted accurately using the presented model. This study provides a higher accuracy in estimating the flow regime, which leads to a higher confidence in hydraulic designs and determining limitations of the system in concern.
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Pawar, Sandipan S., Vivek K. Sunnapwar, and Vivek K. Yakkundi. "Experimental and CFD Investigations of Heat Transfer in Helical Coils for the Development of Correlations for Newtonian and Non-Newtonian Fluids in Transient State-Space Conditions." In ASME 2013 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/imece2013-63481.
Full textAbstract:
Experimental studies and CFD investigations were carried out under laminar and turbulent flow regimes in isothermal steady state and non-isothermal unsteady state conditions in helical coils for Newtonian and non-Newtonian fluids. Water and glycerol-water mixture (10 and 20 % glycerol) as Newtonian fluids and dilute aqueous polymer solutions of sodium carboxymethyl cellulose (SCMC), sodium alginate (SA) as non-Newtonian fluids were used in this study. The experiments were performed for three helical coils of coil curvature ratios as 0.0757, 0.064 and 0.055 in laminar and turbulent flow regimes. For the first time, two innovative correlations to calculate Nusselt number (Nu) in terms of new dimensionless ‘M’ number, Prandtl number and coil curvature ratio under different conditions for Newtonian fluids are proposed in this paper. Third correlation of Nu vs. Graetz number (Gz) including the effects of coil curvature on heat transfer coefficient which was not considered by earlier investigators is developed based on tests conducted in laminar flow for Newtonian fluids. All these three innovative correlations developed based on experimental data which were not found in the literature. These correlations were compared with the work of earlier investigators and were found to be in good agreement. The CFD analysis for laminar and turbulent flow was carried out using the CFD package FLUENT 12.0.16. The CFD calculation results (Nui, U) for laminar and turbulent flows were compared with the experimental results, and also the work of earlier investigators was found to be in excellent agreement. Further, the effect of helix diameter on heat transfer for Newtonian and Non-Newtonian fluids are also presented in this paper and it was observed that as helix diameter increases, overall heat transfer coefficient decreases.
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Bamberger, Judith Ann, Carl W. Enderlin, and S. Tzemos. "Air Sparging for Mixing Non-Newtonian Slurries." In ASME 2010 International Mechanical Engineering Congress and Exposition. ASMEDC, 2010. http://dx.doi.org/10.1115/imece2010-40833.
Full textAbstract:
The mechanics of air sparger systems have been primarily investigated for aqueous-based Newtonian fluids. Tilton et al. (1982) [1] describes the fluid mechanics of air sparging systems in non-Newtonian fluids as having two primary flow regions. A center region surrounding the sparger, referred to as the region of bubbles (ROB), contains upward flow due to the buoyant driving force of the rising bubbles. In an annular region, outside the ROB, referred to as the zone of influence (ZOI), the fluid flow is reversed and is opposed to the direction of bubble rise. Outside the ZOI the fluid is unaffected by the air sparger system. The flow regime in the ROB is often turbulent, and the flow regime in the ZOI is laminar; the flow regime outside the ZOI is quiescent. Tests conducted with shear thinning non-Newtonian fluid in a 34-in. diameter tank showed that the ROB forms an approximately inverted cone that is the envelop of the bubble trajectories. The depth to which the air bubbles reach below the sparger nozzle is a linear function of the air-flow rate. The recirculation time through the ZOI was found to vary proportionally with the inverse square of the sparging air-flow rate. Visual observations of the ROB were made in both water and Carbopol®. The bubbles released from the sparge tube in Carbopol® were larger than those in water.
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Podryabinkin, Evgeny, Valery Rudyak, Andrey Gavrilov, and Roland May. "Detailed Modeling of Drilling Fluid Flow in a Wellbore Annulus While Drilling." In ASME 2013 32nd International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/omae2013-11031.
Full textAbstract:
To produce a well safely, the wellbore pressure during drilling must be in a range that prevents collapse yet avoids fracturing. This range is often called “the operating window”. Exceeding the limits of this range can trigger wellbore instability or initiate well control incidents. Pressure prediction requires an understanding of the hydrodynamics processes that occur in a borehole while drilling. Describing these processes is complicated by many factors: the mud rheology is usually non-Newtonian, the flow mode can be laminar or turbulent, and the drillstring can rotate and be positioned eccentrically. Known semi-analytical approaches cannot account for the full range of fluid flows that can arise during drilling. These techniques don’t take into account all factors. Accurate numerical simulation of the flow of drilling fluids is a means to describe the fluid behavior in detail. For numerical solutions of hydrodynamics equations a unique algorithm based on a finite-volume method and a new model of turbulence for non-Newtonian fluids was developed. The model considers string rotation and eccentricity of the drillstring. Newtonian and non-Newtonian fluids as described by the Herschel–Bulkley rheological model have been implemented. Data obtained via systematic parameter studies of the flow in a borehole are available for fast determination of parameters like pressure drop, velocity field, and stresses corresponding to any drilling condition. Applying the new model for the annulus flow and comparing the results to the parallel plate flow approximation enabled us to quantify the error made due to the approximated solution for non-Newtonian fluid rheology. The difference between the solutions grows as the annular gap increases. This situation is a function of the rheological parameters. Secondary flow effects can only be seen when applying the new solution method.
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Li, F. C., H. Kinoshita, M. Oishi, T. Fujii, and M. Oshima. "Visualizations of Viscoelastic Fluid Flow in Microchannels." In ASME 2008 6th International Conference on Nanochannels, Microchannels, and Minichannels. ASMEDC, 2008. http://dx.doi.org/10.1115/icnmm2008-62238.
Full textAbstract:
Solutions of flexible high-molecular-weight polymers or some kinds of surfactant can be viscoelastic fluids. The elastic stress is induced in such viscoelastic fluids and grow nonlinearly with the flow rate and results in many special flow phenomena, including purely elastic instability in the viscoelastic fluid flow. The elastic flow instability can even result in a special kind of turbulent motion, the so-called elastic turbulence, which is a newly discovered flow phenomenon and arises at arbitrary small Reynolds number. In this study, we experimentally investigated the peculiar flow phenomena of viscoelastic fluids in several different microchannels with curvilinear geometry by visualization technique. The viscoelastic working fluids were aqueous solutions of surfactant, CTAC/NaSal (cetyltrimethyl ammonium chloride/Sodium Salysilate). CTAC solutions with weight concentration of 200 ppm (part per million) and 1000 ppm, respectively, at room temperature were tested. For comparison, water flow in the same microchannels was also visualized. The Reynolds numbers for all the microchannel flows were quite small (for solution flows, the Reynolds numbers were smaller than 1) and the flow should be definitely laminar for Newtonian fluid. It was found that the regular laminar flow patterns for low-Reynolds number Newtonian fluid flow in different microchannels were strongly deformed in solution flows: either asymmetrical flow structures or time-dependent vortical flow motions appeared. These phenomena were considered to be induced by the viscoelasticity of the CTAC solutions.