Applying Tiab’s direct synthesis technique to dilatant non-Newtonian/Newtonian fluids

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Javier Andrés Martínez

2011-09-01

Full Text Available Non-Newtonian fluids, such as polymer solutions, have been used by the oil industry for many years as fracturing agents and drilling mud. These solutions, which normally include thickened water and jelled fluids, are injected into the formation to enhanced oil recovery by improving sweep efficiency. It is worth noting that some heavy oils behave non-Newtonianly. Non-Newtonian fluids do not have direct proportionality between applied shear stress and shear rate and viscosity varies with shear rate depending on whether the fluid is either pseudoplastic or dilatant. Viscosity decreases as shear rate increases for the former whilst the reverse takes place for dilatants. Mathematical models of conventional fluids thus fail when applied to non-Newtonian fluids. The pressure derivative curve is introduced in this descriptive work for a dilatant fluid and its pattern was observed. Tiab’s direct synthesis (TDS methodology was used as a tool for interpreting pressure transient data to estimate effective permeability, skin factors and non-Newtonian bank radius. The methodology was successfully verified by its application to synthetic examples. Also, comparing it to pseudoplastic behavior, it was found that the radial flow regime in the Newtonian zone of dilatant fluids took longer to form regarding both the flow behavior index and consistency factor.

Characterization of the transition of regimes in a non-newtonian fluids in ducts

International Nuclear Information System (INIS)

Santana, C.C.; Ataide, C.H.; Massarani, G.

1983-01-01

By using own experimental data and also those obtained from the literature, the velocities at which transition from laminar to turbulent flows occurs are analysed in time-independent non-newtonian fluids, through the relationship between generalized Reynolds numbers and the rheological fluid parameters. (Author) [pt

Impinging jet spray formation using non-Newtonian liquids

Science.gov (United States)

Rodrigues, Neil S.

Over the past two decades there has been a heightened interest in implementing gelled propellants for rocket propulsion, especially for hypergolic bi-propellants such as monomethylhydrazine (MMH) and nitrogen tetroxide oxidizer (NTO). Due to the very high level of toxicity of hypergolic liquid rocket propellants, increasing safety is an important area of need for continued space exploration and defense operations. Gelled propellants provide an attractive solution to meeting the requirements for safety, while also potentially improving performance. A gelling agent can be added to liquid propellants exhibiting Newtonian behavior to transform the liquid into a non-Newtonian fluid with some solid-like behavior, i.e. a gel. Non-Newtonian jet impingement is very different from its Newtonian counterpart in terms of fluid flow, atomization, and combustion. This is due to the added agents changing physical properties such as the bulk rheology (viscosity) and interfacial rheology (surface tension). Spray characterization of jet impingement with Newtonian liquids has been studied extensively in existing literature. However, there is a scarcity in literature of studies that consider the spray characterization of jet impingement with gelled propellants. This is a rather critical void since a major tradeoff of utilizing gelled propellants is the difficulty with atomization due to the increased effective viscosity. However, this difficulty can be overcome by using gels that exhibit shear-thinning behavior---viscosity decreases with increasing strain rate. Shear-thinning fluids are ideal because they have the distinct advantage of only flowing easily upon pressure. Thereby, greatly reducing the amount of propellant that could be accidentally leaked during both critical functions such as liftoff or engagement in the battlefield and regular tasks like refilling propellant tanks. This experimental work seeks to help resolve the scarcity in existing literature by providing drop size

Change in the flow curves of non-Newtonian oils due to a magnetic field

International Nuclear Information System (INIS)

Veliev, F.G.

1979-01-01

The effect of a variable magnetic field on the rheological properties of non-Newtonian fluids is evaluated. Bituminous pitch oils were analyzed by recording the flow curves Q.Q(Δp) - the dependence of the volumetric flow rate on the pressure gradient - with and without a field. The results obtained indicate that variable magnetic fields can produce obvious changes in the rheological properties of bituminous pitch oils, although they are nonmagnetoactive and practically electrically nonconducting

Rheology in Pharmaceutical Sciences

DEFF Research Database (Denmark)

Aho, Johanna; Hvidt, Søren; Baldursdottir, Stefania

2016-01-01

Rheology is the science of flow and deformation of matter. Particularly gels and non-Newtonian fluids, which exhibit complex flow behavior, are frequently encountered in pharmaceutical engineering and manufacturing, or when dealing with various in vivo fluids. Therefore understanding rheology......, together with the common measurement techniques and their practical applications. Examples of the use of rheological techniques in the pharmaceutical field, as well as other closely related fields such as food and polymer science, are also given....... is important, and the ability to use rheological characterization tools is of great importance for any pharmaceutical scientist involved in the field. Flow can be generated by shear or extensional deformations, or a combination of both. This chapter introduces the basics of both shear and extensional rheology...

Secondary flow in a curved artery model with Newtonian and non-Newtonian blood-analog fluids

Science.gov (United States)

Najjari, Mohammad Reza; Plesniak, Michael W.

2016-11-01

Steady and pulsatile flows of Newtonian and non-Newtonian fluids through a 180°-curved pipe were investigated using particle image velocimetry (PIV). The experiment was inspired by physiological pulsatile flow through large curved arteries, with a carotid artery flow rate imposed. Sodium iodide (NaI) and sodium thiocyanate (NaSCN) were added to the working fluids to match the refractive index (RI) of the test section to eliminate optical distortion. Rheological measurements revealed that adding NaI or NaSCN changes the viscoelastic properties of non-Newtonian solutions and reduces their shear-thinning property. Measured centerline velocity profiles in the upstream straight pipe agreed well with an analytical solution. In the pulsatile case, secondary flow structures, i.e. deformed-Dean, Dean, Wall and Lyne vortices, were observed in various cross sections along the curved pipe. Vortical structures at each cross section were detected using the d2 vortex identification method. Circulation analysis was performed on each vortex separately during the systolic deceleration phase, and showed that vortices split and rejoin. Secondary flow structures in steady flows were found to be morphologically similar to those in pulsatile flows for sufficiently high Dean number. supported by the George Washington University Center for Biomimetics and Bioinspired Engineering.

Analysis of HD Journal Bearings Considering Elastic Deformation and Non-Newtonian Rabinowitsch Fluid Model

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J. Javorova

2016-06-01

Full Text Available The purpose of this paper is to study the performance of a finite length journal bearing, taking into account effects of non-Newtonian Rabinowitsch flow rheology and elastic deformations of the bearing liner. According to the Rabinowitsch fluid model, the cubic-stress constitutive equation is used to account for the non-Newtonian effects of pseudoplastic and dilatant lubricants. Integrating the continuity equation across the film, the nonlinear non-Newtonian Reynolds-type equation is derived. The elasticity part of the problem is solved on the base of Vlassov model of an elastic foundation. The numerical solution of the modified Reynolds equation is carried out by using FDM with over-relaxation technique. The results for steady state bearing performance characteristics have been calculated for various values of nonlinear factor and elasticity parameters. It was concluded that in comparison with the Newtonian lubricants, higher values of film pressure and load carrying capacity have been obtained for dilatant lubricants, while the case was reversed for pseudoplastic lubricants.

Rheology of dense suspensions of non colloidal particles

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Guazzelli Élisabeth

2017-01-01

Full Text Available Dense suspensions are materials with broad applications both in industrial processes (e.g. waste disposal, concrete, drilling muds, metalworking chip transport, and food processing and in natural phenomena (e.g. flows of slurries, debris, and lava. Despite its long research history and its practical relevance, the mechanics of dense suspensions remain poorly understood. The major difficulty is that the grains interact both by hydrodynamic interactions through the liquid and by mechanical contact. These systems thus belong to an intermediate regime between pure suspensions and granular flows. We show that we can unify suspension and granular rheology under a common framework by transferring the frictional approach of dry granular media to wet suspensions of spherical particles. We also discuss non-Newtonian behavior such as normal-stress differences and shear-induced migration. Beyond the classical problem of dense suspension of hard spheres which is far from being completely resolved, there are also entirely novel avenues of study concerning more complex mixtures of particles and fluids such as those involving other types of particles (e.g. fibers or non-Newtonian fluids that we will also address.

A Numerical Study of Mesh Adaptivity in Multiphase Flows with Non-Newtonian Fluids

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Percival, James; Pavlidis, Dimitrios; Xie, Zhihua; Alberini, Federico; Simmons, Mark; Pain, Christopher; Matar, Omar

2014-11-01

We present an investigation into the computational efficiency benefits of dynamic mesh adaptivity in the numerical simulation of transient multiphase fluid flow problems involving Non-Newtonian fluids. Such fluids appear in a range of industrial applications, from printing inks to toothpastes and introduce new challenges for mesh adaptivity due to the additional ``memory'' of viscoelastic fluids. Nevertheless, the multiscale nature of these flows implies huge potential benefits for a successful implementation. The study is performed using the open source package Fluidity, which couples an unstructured mesh control volume finite element solver for the multiphase Navier-Stokes equations to a dynamic anisotropic mesh adaptivity algorithm, based on estimated solution interpolation error criteria, and conservative mesh-to-mesh interpolation routine. The code is applied to problems involving rheologies ranging from simple Newtonian to shear-thinning to viscoelastic materials and verified against experimental data for various industrial and microfluidic flows. This work was undertaken as part of the EPSRC MEMPHIS programme grant EP/K003976/1.

Development of a new continuous process for mixing of complex non-Newtonian fluids

Science.gov (United States)

Migliozzi, Simona; Mazzei, Luca; Sochon, Bob; Angeli, Panagiota; Thames Multiphase Team; Coral Project Collaboration

2017-11-01

Design of new continuous mixing operations poses many challenges, especially when dealing with highly viscous non-Newtonian fluids. Knowledge of complex rheological behaviour of the working mixture is crucial for development of an efficient process. In this work, we investigate the mixing performance of two different static mixers and the effects of the mixture rheology on the manufacturing of novel non-aqueous-based oral care products using experimental and computational fluid dynamic methods. The two liquid phases employed, i.e. a carbomer suspension in polyethylene glycol and glycerol, start to form a gel when they mix. We studied the structure evolution of the liquid mixture using time-resolved rheometry and we obtained viscosity rheograms at different phase ratios from pressure drop measurements in a customized mini-channel. The numerical results and rheological model were validated with experimental measurements carried out in a specifically designed setup. EPSRS-CORAL.

The role of the rheological properties of non-newtonian fluids in controlling dispersive mixing in a batch electrophoretic cell with Joule heating

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M.A. Bosse

2001-03-01

Full Text Available The problem of the effect of Joule heating generation on the hydrodynamic profile and the solute transport found in electrophoretic devices is addressed in this article. The research is focused on the following two problems: The first one is centered around the effect of Joule heating on the hydrodynamic velocity profile and it is referred to as "the carrier fluid problem." The other one is related to the effect of Joule heating on the solute transport inside electrophoretic cells and it is referred to as "the solute problem". The hydrodynamic aspects were studied first to yield the velocity profiles required for analysis of the solute transport problem. The velocity profile obtained in this study is analytical and the results are valid for non-Newtonian fluids carriers. To this end, the power-law model was used to study the effect of the rheology of the material in conjunction with the effect of Joule heating generation inside batch electrophoretic devices. This aspect of the research was then effectively used to study the effect of Joule heating generation on the motion of solutes (such as macromolecules under the influence of non-Newtonian carriers. This aspect of the study was performed using an area-averaging approach that yielded analytical results for the effective diffusivity of the device.

A Wall Boundary Condition for the Simulation of a Turbulent Non-Newtonian Domestic Slurry in Pipes

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Dhruv Mehta

2018-01-01

Full Text Available The concentration (using a lesser amount of water of domestic slurry promotes resource recovery (nutrients and biomass while saving water. This article is aimed at developing numerical methods to support engineering processes such as the design and implementation of sewerage for concentrated domestic slurry. The current industrial standard for computational fluid dynamics-based analyses of turbulent flows is Reynolds-averaged Navier–Stokes (RANS modelling. This is assisted by the wall function approach proposed by Launder and Spalding, which permits the use of under-refined grids near wall boundaries while simulating a wall-bounded flow. Most RANS models combined with wall functions have been successfully validated for turbulent flows of Newtonian fluids. However, our experiments suggest that concentrated domestic slurry shows a Herschel–Bulkley-type non-Newtonian behaviour. Attempts have been made to derive wall functions and turbulence closures for non-Newtonian fluids; however, the resulting laws or equations are either inconsistent across experiments or lack relevant experimental support. Pertinent to this study, laws or equations reported in literature are restricted to a class of non-Newtonian fluids called power law fluids, which, as compared to Herschel–Bulkley fluids, yield at any amount of applied stress. An equivalent law for Herschel–Bulkley fluids that require a minimum-yield stress to flow is yet to be reported in literature. This article presents a theoretically derived (with necessary approximations law of the wall for Herschel–Bulkley fluids and implements it in a RANS solver using a specified shear approach. This results in a more accurate prediction of the wall shear stress experienced by a circular pipe with a turbulent Herschel–Bulkley fluid flowing through it. The numerical results are compared against data from our experiments and those reported in literature for a range of Reynolds numbers and rheological

Non-Newtonian behavior and molecular structure of Cooee bitumen under shear flow

DEFF Research Database (Denmark)

Lemarchand, Claire; Bailey, Nicholas; Daivis, Peter

2015-01-01

The rheology and molecular structure of a model bitumen (Cooee bitumen) under shear are investigated in the non-Newtonian regime using non-equilibrium molecular dynamics simulations. The shear viscosity, normal stress differences, and pressure of the bitumen mixture are computed at different shear...... rates and different temperatures. The model bitumen is shown to be a shear-thinning fluid at all temperatures. In addition, the Cooee model is able to reproduce experimental results showing the formation of nanoaggregates composed of stacks of flat aromatic molecules in bitumen. These nanoaggregates...

Unsteady non-Newtonian hydrodynamics in granular gases.

Science.gov (United States)

Astillero, Antonio; Santos, Andrés

2012-02-01

The temporal evolution of a dilute granular gas, both in a compressible flow (uniform longitudinal flow) and in an incompressible flow (uniform shear flow), is investigated by means of the direct simulation Monte Carlo method to solve the Boltzmann equation. Emphasis is laid on the identification of a first "kinetic" stage (where the physical properties are strongly dependent on the initial state) subsequently followed by an unsteady "hydrodynamic" stage (where the momentum fluxes are well-defined non-Newtonian functions of the rate of strain). The simulation data are seen to support this two-stage scenario. Furthermore, the rheological functions obtained from simulation are well described by an approximate analytical solution of a model kinetic equation. © 2012 American Physical Society

Non-Newtonian plastic flow of a Ni-Si-B metallic glass at low stresses

International Nuclear Information System (INIS)

Csach, K.; Fursova, Y.V.; Khonik, V.A.; Ocelik, V.

1998-01-01

The problem of the rheological behavior of metallic glasses (MGs) is quite important both from theoretical and practical viewpoints. Early experiments carried out on MGs at temperatures T > 300 K using low shear stress levels revealed plastic flow to be Newtonian while measurements at relative high shear stresses (more than 200 to 400 MPa, depending on temperature, thermal prehistory of samples and chemical composition) indicated a non-linear behavior with 1 < m < 12. Numerous investigations performed later both on as-cast and relaxed MGs of various chemical compositions using a number of testing methods (tensile creep, tensile and bend stress relaxation) showed that a transition from Newtonian behavior at low stresses to a non-linear flow at high stresses was observed. At present, such a situation is considered to be generally accepted. The authors performed precise creep measurements of a Ni-Si-B metallic glass. The results obtained indicate that plastic flow in this case at low tensile stress (12 le σ le 307 MPa) is clearly non-Newtonian and, consequently, the viscosity is stress dependent

Acoustic waveform of continuous bubbling in a non-Newtonian fluid.

Science.gov (United States)

Vidal, Valérie; Ichihara, Mie; Ripepe, Maurizio; Kurita, Kei

2009-12-01

We study experimentally the acoustic signal associated with a continuous bubble bursting at the free surface of a non-Newtonian fluid. Due to the fluid rheological properties, the bubble shape is elongated, and, when bursting at the free surface, acts as a resonator. For a given fluid concentration, at constant flow rate, repetitive bubble bursting occurs at the surface. We report a modulation pattern of the acoustic waveform through time. Moreover, we point out the existence of a precursor acoustic signal, recorded on the microphone array, previous to each bursting. The time delay between this precursor and the bursting signal is well correlated with the bursting signal frequency content. Their joint modulation through time is driven by the fluid rheology, which strongly depends on the presence of small satellite bubbles trapped in the fluid due to the yield stress.

Influence of bed material entrainment and non-Newtonian rheology on turbulent geophysical flows dynamics. Numerical study

Science.gov (United States)

Eglit, M. E.; Yakubenko, A. E.; Yakubenko, T. A.

2017-10-01

This paper deals with the mathematical and numerical modeling of the propagation stage of geophysical gravity-driven flows, such as snow avalanches, mudflows, and rapid landslides. New mathematical models are presented which are based on full, not-depth-averaged equations of mechanics of continuous media. The models account for three important issues: non-Newtonian rheology of the moving material, entrainment of the bed material by the flow, and turbulence. The main objective is to investigate the effect of these three factors on the flow dynamics and on the value of the entrainment rate. To exclude the influence of many other factors, e.g., the complicated slope topography, only the motion down a long uniform slope with a constant inclination angle is studied numerically. Moreover, the entire flow from the front to the rear area was not modeled, but only its middle part where the flow is approximately uniform in length. One of the qualitative results is that in motion along homogeneous slope the mass entrainment increases the flow velocity and depth while the entrainment rate at large time tends to become constant which depends on the physical properties of the flow and the underlying material but not on the current values of the flow velocity and depth.

Rheology of waxy oils

Energy Technology Data Exchange (ETDEWEB)

Alicke, Alexandra A.; Marchesini, Flavio H.; Mendes, Paulo R. de Souza [Pontificia Universidade Catolica do Rio de Janeiro (PUC-Rio), RJ (Brazil)], e-mails: fhmo@puc-rio.br, pmendes@puc-rio.br; Ziglio, Claudio [Petrobras Research Center, Rio de Janeiro, RJ (Brazil)], e-mail: ziglio@petrobras.com.br

2010-07-01

It is well known that below the crystallization temperature the rheology of waxy oils changes from Newtonian to an extremely complex non-Newtonian behavior, which is shear-rate and temperature-history dependent. Along the last decades a lot of effort has been put into obtaining reliable rheological measurements from different oils so as to understand the yielding of waxy oils as well as the effects of shear and temperature histories on rheological properties, such as viscosity, yield stress, storage and loss moduli. In this paper we examine in detail the related literature, discussing the main reasons for some disagreements concerning the history effects on the flow properties of waxy oils. In addition, we performed temperature ramps and stress-amplitude-sweep tests and compared the results obtained with the main trends observed, highlighting the effects of cooling and shear on the microstructure and consequently on the rheological properties of these oils. (author)

A new 3D immersed boundary method for non-Newtonian fluid-structure-interaction with application

Science.gov (United States)

Zhu, Luoding

2017-11-01

Motivated by fluid-structure-interaction (FSI) phenomena in life sciences (e.g., motions of sperm and cytoskeleton in complex fluids), we introduce a new immersed boundary method for FSI problems involving non-Newtonian fluids in three dimensions. The non-Newtonian fluids are modelled by the FENE-P model (including the Oldroyd-B model as an especial case) and numerically solved by a lattice Boltzmann scheme (the D3Q7 model). The fluid flow is modelled by the lattice Boltzmann equations and numerically solved by the D3Q19 model. The deformable structure and the fluid-structure-interaction are handled by the immersed boundary method. As an application, we study a FSI toy problem - interaction of an elastic plate (flapped at its leading edge and restricted nowhere else) with a non-Newtonian fluid in a 3D flow. Thanks to the support of NSF-DMS support under research Grant 1522554.

Are Non-Newtonian Effects Important in Hemodynamic Simulations of Patients With Autogenous Fistula?

Science.gov (United States)

Javid Mahmoudzadeh Akherat, S. M.; Cassel, Kevin; Boghosian, Michael; Dhar, Promila; Hammes, Mary

2017-01-01

Given the current emphasis on accurate computational fluid dynamics (CFD) modeling of cardiovascular flows, which incorporates realistic blood vessel geometries and cardiac waveforms, it is necessary to revisit the conventional wisdom regarding the influences of non-Newtonian effects. In this study, patient-specific reconstructed 3D geometries, whole blood viscosity data, and venous pulses postdialysis access surgery are used as the basis for the hemodynamic simulations of renal failure patients with native fistula access. Rheological analysis of the viscometry data initially suggested that the correct choice of constitutive relations to capture the non-Newtonian behavior of blood is important because the end-stage renal disease (ESRD) patient cohort under observation experience drastic variations in hematocrit (Hct) levels and whole blood viscosity throughout the hemodialysis treatment. For this purpose, various constitutive relations have been tested and implemented in CFD practice, namely Quemada and Casson. Because of the specific interest in neointimal hyperplasia and the onset of stenosis in this study, particular attention is placed on differences in nonhomeostatic wall shear stress (WSS) as that drives the venous adaptation process that leads to venous geometric evolution over time in ESRD patients. Surprisingly, the CFD results exhibit no major differences in the flow field and general flow characteristics of a non-Newtonian simulation and a corresponding identical Newtonian counterpart. It is found that the vein's geometric features and the dialysis-induced flow rate have far greater influence on the WSS distribution within the numerical domain. PMID:28249082

Are Non-Newtonian Effects Important in Hemodynamic Simulations of Patients With Autogenous Fistula?

Science.gov (United States)

Javid Mahmoudzadeh Akherat, S M; Cassel, Kevin; Boghosian, Michael; Dhar, Promila; Hammes, Mary

2017-04-01

Given the current emphasis on accurate computational fluid dynamics (CFD) modeling of cardiovascular flows, which incorporates realistic blood vessel geometries and cardiac waveforms, it is necessary to revisit the conventional wisdom regarding the influences of non-Newtonian effects. In this study, patient-specific reconstructed 3D geometries, whole blood viscosity data, and venous pulses postdialysis access surgery are used as the basis for the hemodynamic simulations of renal failure patients with native fistula access. Rheological analysis of the viscometry data initially suggested that the correct choice of constitutive relations to capture the non-Newtonian behavior of blood is important because the end-stage renal disease (ESRD) patient cohort under observation experience drastic variations in hematocrit (Hct) levels and whole blood viscosity throughout the hemodialysis treatment. For this purpose, various constitutive relations have been tested and implemented in CFD practice, namely Quemada and Casson. Because of the specific interest in neointimal hyperplasia and the onset of stenosis in this study, particular attention is placed on differences in nonhomeostatic wall shear stress (WSS) as that drives the venous adaptation process that leads to venous geometric evolution over time in ESRD patients. Surprisingly, the CFD results exhibit no major differences in the flow field and general flow characteristics of a non-Newtonian simulation and a corresponding identical Newtonian counterpart. It is found that the vein's geometric features and the dialysis-induced flow rate have far greater influence on the WSS distribution within the numerical domain.

Aerosol entrainment from a sparged non-Newtonian slurry.

Science.gov (United States)

Fritz, Brad G

2006-08-01

Previous bench-scale experiments have provided data necessary for the development of empirical models that describe aerosol entrainment from bubble bursting. However, previous work has not been extended to non-Newtonian liquid slurries. Design of a waste treatment plant on the Hanford Site in Washington required an evaluation of the applicability of these models outside of their intended range. For this evaluation, aerosol measurements were conducted above an air-sparged mixing tank filled with simulated waste slurry possessing Bingham plastic rheological properties. Three aerosol-size fractions were measured at three sampling heights and for three different sparging rates. The measured entrainment was compared with entrainment models. One model developed based on bench-scale air-water experiments agreed well with measured entrainment. Another model did not agree well with the measured entrainment. It appeared that the source of discrepancy between measured and modeled entrainment stemmed from application beyond the range of data used to develop the model. A possible separation in entrainment coefficients between air-water and steam-water systems was identified. A third entrainment model was adapted to match experimental conditions and fit a posteri to the experimental data, resulting in a modified version that resulted in estimated entrainment rates similar to the first model.

On Numerical Methods in Non-Newtonian Flows

International Nuclear Information System (INIS)

Fileas, G.

1982-12-01

The constitutive equations for non-Newtonian flows are presented and the various flow models derived from continuum mechanics and molecular theories are considered and evaluated. Detailed account is given of numerical simulation employing differential and integral models of different kinds of non-Newtonian flows using finite-difference and finite-element techniques. Appreciating the fact that no book or concentrated material on Numerical Non-Newtonian Fluid Flow exists at the present, procedures for computer set-ups are described and references are given for finite-difference, finite-element and molecular-theory based programmes for several kinds of flow. Achievements and unreached goals in the field of numerical simulation of non-Newtonian flows are discussed and the lack of numerical work in the fields of suspension flows and heat transfer is pointed out. Finally, FFOCUS is presented as a newly built computer program which can simulate freezing flows on Newtonian fluids through various geometries and is aimed to be further developed to handle non-Newtonian freezing flows and certain types of suspension phenomena involved in corium flow after a hypothetical core melt-down accident in a PWR. (author)

Turbulent Flow of Saudi Non-Newtonian Crude Oils in a Pipeline Écoulement turbulent de bruts non-newtoniens séoudiens dans une canalisation

Directory of Open Access Journals (Sweden)

Hemeidia A. M.

2006-11-01

Full Text Available Rheological properties of Saudi Arab-Light, Arab-Berri and Arab-Heavy crude oils were measured with Brookfield Viscometer (LVT Model at temperatures 10, 15, 20, 25, 38, 55 and 70°C. Saudi Arab-Light and Arab-Heavy exhibit non-Newtonian behavior at temperature less than or equal to 20°C, while Saudi Arab-Berri behaves as a non-Newtonian fluid at all temperatures. The main reason for this rheological behavior can be attributed to the thermal and shear histories; the relative amounts of wax and asphaltene content in Saudi crude oils as well. Therefore, Statistical Analysis (t-test was used to check the variability of the change in rheological behavior of Saudi non-Newtonian crude oils at a confidence level of 95%. The evaluation ensured that, all non-Newtonian data were statistically not different and were correlated with power-law model. Under turbulent flow conditions the pipeline design calculations were carried out through a computer program. Les propriétés rhéologiques des bruts séoudiens Arab-Light, Arab-Berri et Arab-Heavy ont été mesurées à l'aide d'un viscomètre Brookfield (modèle LVT à des températures de 10, 15, 20, 25, 38, 55 et 70°C. Les Saudi Arab-Light et Arab-Heavy présentent un comportement non newtonien à des températures égales ou inférieures à 20°C, tandis que le Saudi Arab-Berri se comporte comme un fluide non newtonien à toutes les températures. Ce comportement rhéologique est principalement dû aux historiques thermiques et de cisaillement, de même qu'aux quantités relatives de paraffine et à la teneur en asphaltène des bruts séoudiens. Une analyse statistique (essai t a donc été menée pour vérifier la variabilité des changements de comportement rhéologique des bruts séoudiens non newtoniens à un degré de fiabilité de 95%. Il en est ressorti que toutes les données non newtoniennes étaient statistiquement non différentes et étaient en corrélation avec le modèle de la loi des

Revisiting Newtonian and Non-Newtonian Fluid Mechanics Using Computer Algebra

Science.gov (United States)

Knight, D. G.

2006-01-01

This article illustrates how a computer algebra system, such as Maple[R], can assist in the study of theoretical fluid mechanics, for both Newtonian and non-Newtonian fluids. The continuity equation, the stress equations of motion, the Navier-Stokes equations, and various constitutive equations are treated, using a full, but straightforward,…

The quantification of hemodynamic parameters downstream of a Gianturco Zenith stent wire using newtonian and non-newtonian analog fluids in a pulsatile flow environment.

Science.gov (United States)

Walker, Andrew M; Johnston, Clifton R; Rival, David E

2012-11-01

stent wire promoted the development of flow patterns that are susceptible to intimal hyperplasia using both Newtonian and non-Newtonian analogs, although the magnitude of sites affected downstream was appreciably related to the rheological behavior of the analog. While the assumption of linear viscous behavior is often appropriate in quantifying flow in the largest arteries of the vasculature, the results presented here suggest this assumption overestimates sites susceptible to hyperplasia and restenosis in flow characterized by low and oscillatory shear.

Attenuation of seismic waves and the universal rheological model of the Earth's mantle

Science.gov (United States)

Birger, B. I.

2007-08-01

Analysis of results of laboratory studies on creep of mantle rocks, data on seismic wave attenuation in the mantle, and rheological micromechanisms shows that the universal, i.e., relevant to all time scales, rheological model of the mantle can be represented as four rheological elements connected in series. These elements account for elasticity, diffusion rheology, high temperature dislocation rheology, and low temperature dislocation rheology. The diffusion rheology element is described in terms of a Newtonian viscous fluid. The high temperature dislocation rheology element is described by the rheological model previously proposed by the author. This model is a combination of a power-law non-Newtonian fluid model for stationary flows and the linear hereditary Andrade model for flows associated with small strains. The low temperature dislocation rheology element is described by the linear hereditary Lomnitz model.

Active learning of constitutive relation from mesoscopic dynamics for macroscopic modeling of non-Newtonian flows

Science.gov (United States)

Zhao, Lifei; Li, Zhen; Caswell, Bruce; Ouyang, Jie; Karniadakis, George Em

2018-06-01

We simulate complex fluids by means of an on-the-fly coupling of the bulk rheology to the underlying microstructure dynamics. In particular, a continuum model of polymeric fluids is constructed without a pre-specified constitutive relation, but instead it is actively learned from mesoscopic simulations where the dynamics of polymer chains is explicitly computed. To couple the bulk rheology of polymeric fluids and the microscale dynamics of polymer chains, the continuum approach (based on the finite volume method) provides the transient flow field as inputs for the (mesoscopic) dissipative particle dynamics (DPD), and in turn DPD returns an effective constitutive relation to close the continuum equations. In this multiscale modeling procedure, we employ an active learning strategy based on Gaussian process regression (GPR) to minimize the number of expensive DPD simulations, where adaptively selected DPD simulations are performed only as necessary. Numerical experiments are carried out for flow past a circular cylinder of a non-Newtonian fluid, modeled at the mesoscopic level by bead-spring chains. The results show that only five DPD simulations are required to achieve an effective closure of the continuum equations at Reynolds number Re = 10. Furthermore, when Re is increased to 100, only one additional DPD simulation is required for constructing an extended GPR-informed model closure. Compared to traditional message-passing multiscale approaches, applying an active learning scheme to multiscale modeling of non-Newtonian fluids can significantly increase the computational efficiency. Although the method demonstrated here obtains only a local viscosity from the polymer dynamics, it can be extended to other multiscale models of complex fluids whose macro-rheology is unknown.

Negative wake behind bubbles in non-newtonian liquids

DEFF Research Database (Denmark)

Hassager, Ole

1979-01-01

Gas bubbles rising by gravity in non-Newtonian elastic liquids are different to gas bubbles in viscous Newtonian fluids in at least two ways. First, the bubbles in the non-Newtonian liquids often have a peculiar tip at the rear pole, and second, the terminal rise velocity versus volume curve ofte...

Non-Newtonian Flow Characteristics of Heavy Oil in the Bohai Bay Oilfield: Experimental and Simulation Studies

Directory of Open Access Journals (Sweden)

Xiankang Xin

2017-10-01

Full Text Available In this paper, physical experiments and numerical simulations were applied to systematically investigate the non-Newtonian flow characteristics of heavy oil in porous media. Rheological experiments were carried out to determine the rheology of heavy oil. Threshold pressure gradient (TPG measurement experiments performed by a new micro-flow method and flow experiments were conducted to study the effect of viscosity, permeability and mobility on the flow characteristics of heavy oil. An in-house developed novel simulator considering the non-Newtonian flow was designed based on the experimental investigations. The results from the physical experiments indicated that heavy oil was a Bingham fluid with non-Newtonian flow characteristics, and its viscosity-temperature relationship conformed to the Arrhenius equation. Its viscosity decreased with an increase in temperature and a decrease in asphaltene content. The TPG measurement experiments was impacted by the flow rate, and its critical flow rate was 0.003 mL/min. The TPG decreased as the viscosity decreased or the permeability increased and had a power-law relationship with mobility. In addition, the critical viscosity had a range of 42–54 mPa∙s, above which the TPG existed for a given permeability. The validation of the designed simulator was positive and acceptable when compared to the simulation results run in ECLIPSE V2013.1 and Computer Modelling Group (CMG V2012 software as well as when compared to the results obtained during physical experiments. The difference between 0.0005 and 0.0750 MPa/m in the TPG showed a decrease of 11.55% in the oil recovery based on the simulation results, which demonstrated the largely adverse impact the TPG had on heavy oil production.

Non-Newtonian particulate flow simulation: A direct-forcing immersed boundary-lattice Boltzmann approach

Science.gov (United States)

Amiri Delouei, A.; Nazari, M.; Kayhani, M. H.; Kang, S. K.; Succi, S.

2016-04-01

In the current study, a direct-forcing immersed boundary-non-Newtonian lattice Boltzmann method (IB-NLBM) is developed to investigate the sedimentation and interaction of particles in shear-thinning and shear-thickening fluids. In the proposed IB-NLBM, the non-linear mechanics of non-Newtonian particulate flows is detected by combination of the most desirable features of immersed boundary and lattice Boltzmann methods. The noticeable roles of non-Newtonian behavior on particle motion, settling velocity and generalized Reynolds number are investigated by simulating benchmark problem of one-particle sedimentation under the same generalized Archimedes number. The effects of extra force due to added accelerated mass are analyzed on the particle motion which have a significant impact on shear-thinning fluids. For the first time, the phenomena of interaction among the particles, such as Drafting, Kissing, and Tumbling in non-Newtonian fluids are investigated by simulation of two-particle sedimentation and twelve-particle sedimentation. The results show that increasing the shear-thickening behavior of fluid leads to a significant increase in the kissing time. Moreover, the transverse position of particles for shear-thinning fluids during the tumbling interval is different from Newtonian and the shear-thickening fluids. The present non-Newtonian particulate study can be applied in several industrial and scientific applications, like the non-Newtonian sedimentation behavior of particles in food industrial and biological fluids.

Non-Newtonian fluid flow in 2D fracture networks

Science.gov (United States)

Zou, L.; Håkansson, U.; Cvetkovic, V.

2017-12-01

Modeling of non-Newtonian fluid (e.g., drilling fluids and cement grouts) flow in fractured rocks is of interest in many geophysical and industrial practices, such as drilling operations, enhanced oil recovery and rock grouting. In fractured rock masses, the flow paths are dominated by fractures, which are often represented as discrete fracture networks (DFN). In the literature, many studies have been devoted to Newtonian fluid (e.g., groundwater) flow in fractured rock using the DFN concept, but few works are dedicated to non-Newtonian fluids.In this study, a generalized flow equation for common non-Newtonian fluids (such as Bingham, power-law and Herschel-Bulkley) in a single fracture is obtained from the analytical solutions for non-Newtonian fluid discharge between smooth parallel plates. Using Monte Carlo sampling based on site characterization data for the distribution of geometrical features (e.g., density, length, aperture and orientations) in crystalline fractured rock, a two dimensional (2D) DFN model is constructed for generic flow simulations. Due to complex properties of non-Newtonian fluids, the relationship between fluid discharge and the pressure gradient is nonlinear. A Galerkin finite element method solver is developed to iteratively solve the obtained nonlinear governing equations for the 2D DFN model. Using DFN realizations, simulation results for different geometrical distributions of the fracture network and different non-Newtonian fluid properties are presented to illustrate the spatial discharge distributions. The impact of geometrical structures and the fluid properties on the non-Newtonian fluid flow in 2D DFN is examined statistically. The results generally show that modeling non-Newtonian fluid flow in fractured rock as a DFN is feasible, and that the discharge distribution may be significantly affected by the geometrical structures as well as by the fluid constitutive properties.

Nonisothermal flow of a non-Newtonian fluid with viscous heating between two parallel plates

International Nuclear Information System (INIS)

Imal, M.; Pinarbasi, A.

2004-01-01

In this study the pressure gradient-flow rate relationship for steady-state nonisothermal pressure-driven flow of a non-Newtonian fluid in a channel is investigated including the effect of viscous heating is taken into account. The viscosity of the fluid depends on both temperature and shear-rate. Exponential dependence of viscosity on temperature is modelled through Arrhenius law. Non-Newtonian behaviour of the fluid is modelled according to the Carreau rheological equation, which reflects the characteristics of most polymers adequately with an exponential temperature dependence of viscosity. Flow governing motion and energy balance equations are coupled and solution of this non-linear boundary value problem is found iteratively using a pseudo spectral method based on Chebyshev polynomials. The effect of activation energy parameter and Brinkman number, as well as the power-law index and material time constant on the flow is studied. It is found that while the pressure gradient-flow rate graph is monotonic for certain ranges of flow controlling parameters, there is a large jump in the graph under certain values of these parameters.(1 table and 5 figures are included.)

Point-of-care Devices: Non-Newtonian Whole Blood Behavior and Capillary Flow on Reagent-coated Walls

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Jean BERTHIER

2016-08-01

Full Text Available Most point-of-care (POC and patient self-testing (PST devices are based on the analysis of whole blood taken from a finger prick. Whole blood contains a bountiful of information about the donor’s health. We analyze here two particularities of microsystems for blood analysis: the blood non-Newtonian behavior, and the capillary flow in reagent-coated channels. Capillarity is the most commonly used method to move fluids in portable systems. It is shown first that the capillary flow of blood does not follow the Lucas-Washburn-Rideal law when the capillary flow velocity is small, due to its non-Newtonian rheology and to the formation of rouleaux of RBCs. In a second step, the capillary flow of blood on reagent-coated surfaces is investigated; first experimentally by observing the spreading of a droplet of blood on different reagent-coated substrates; second theoretically and numerically using the general law for spontaneous capillary flows and the Evolver numerical program.

A Lagrangian PFEM approach for non-Newtonian viscoplastic materials

OpenAIRE

Larese, A.

2017-01-01

This paper presents the application of a stabilized mixed Particle Finite Element Method (PFEM) to the solution of viscoplastic non-Newtonian flows. The application of the proposed model to the deformation of granular non-cohesive material is analysed. A variable yield threshold modified Bingham model is presented, using a Mohr Coulomb resistance criterion. Since the granular material is expected to undergo severe deformation, a Lagrangian approach is preferred to a fixed mesh one. PFEM i...

Rheological behavior and constitutive equations of heterogeneous titanium-bearing molten slag

Science.gov (United States)

Jiang, Tao; Liao, De-ming; Zhou, Mi; Zhang, Qiao-yi; Yue, Hong-rui; Yang, Song-tao; Duan, Pei-ning; Xue, Xiang-xin

2015-08-01

Experimental studies on the rheological properties of a CaO-SiO2-Al2O3-MgO-TiO2-(TiC) blast furnace (BF) slag system were conducted using a high-temperature rheometer to reveal the non-Newtonian behavior of heterogeneous titanium-bearing molten slag. By measuring the relationships among the viscosity, the shear stress and the shear rate of molten slags with different TiC contents at different temperatures, the rheological constitutive equations were established along with the rheological parameters; in addition, the non-Newtonian fluid types of the molten slags were determined. The results indicated that, with increasing TiC content, the viscosity of the molten slag tended to increase. If the TiC content was less than 2wt%, the molten slag exhibited the Newtonian fluid behavior when the temperature was higher than the critical viscosity temperature of the molten slag. In contrast, the molten slag exhibited the non-Newtonian pseudoplastic fluid characteristic and the shear thinning behavior when the temperature was less than the critical viscosity temperature. However, if the TiC content exceeded 4wt%, the molten slag produced the yield stress and exhibited the Bingham and plastic pseudoplastic fluid behaviors when the temperature was higher and lower than the critical viscosity temperature, respectively. When the TiC content increased further, the yield stress of the molten slag increased and the shear thinning phenomenon became more obvious.

The Effect of Heat Transfer and Polymer Concentration on Non-Newtonian Fluid from Pore-Scale Simulation of Rock X-ray Micro-CT

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Moussa Tembely

2017-10-01

Full Text Available Most of the pore-scale imaging and simulations of non-Newtonian fluid are based on the simplifying geometry of network modeling and overlook the fluid rheology and heat transfer. In the present paper, we developed a non-isothermal and non-Newtonian numerical model of the flow properties at pore-scale by simulation of the 3D micro-CT images using a Finite Volume Method (FVM. The numerical model is based on the resolution of the momentum and energy conservation equations. Owing to an adaptive mesh generation technique and appropriate boundary conditions, rock permeability and mobility are accurately computed. A temperature and concentration-dependent power-law viscosity model in line with the experimental measurement of the fluid rheology is adopted. The model is first applied at isothermal condition to 2 benchmark samples, namely Fontainebleau sandstone and Grosmont carbonate, and is found to be in good agreement with the Lattice Boltzmann method (LBM. Finally, at non-isothermal conditions, an effective mobility is introduced that enables to perform a numerical sensitivity study to fluid rheology, heat transfer, and operating conditions. While the mobility seems to evolve linearly with polymer concentration in agreement with a derived theoretical model, the effect of the temperature seems negligible by comparison. However, a sharp contrast is found between carbonate and sandstone under the effect of a constant temperature gradient. Besides concerning the flow index and consistency factor, a master curve is derived when normalizing the mobility for both the carbonate and the sandstone.

Comparison of Rheological Properties of Hopped Wort and Malt Wort

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Petr Trávníček

2015-01-01

Full Text Available The aim of this work is determination rheological properties of hopped wort and malt wort and their comparison. In the paper following rheological properties has been described: the dependence of viscosity on a temperature of a sample and hysteresis loop test. The time dependence test was performed for a confirmation thixotropic behaviour. Based on measured values Arrhenius mathematical model has been applied. The activation energy was determined by using of this model. Tests have been carried out in the temperature range from 5 °C to 40 °C. Rheological tests proved that malt wort behaves as Newtonian fluid in all temperatures and hopped wort behaves as non-Newtonian fluid at low temperatures. Thixotropic behaviour is caused by the content of the rests of hops heads or malt scraps.

Asymmetric bubble collapse and jetting in generalized Newtonian fluids

Science.gov (United States)

Shukla, Ratnesh K.; Freund, Jonathan B.

2017-11-01

The jetting dynamics of a gas bubble near a rigid wall in a non-Newtonian fluid are investigated using an axisymmetric simulation model. The bubble gas is assumed to be homogeneous, with density and pressure related through a polytropic equation of state. An Eulerian numerical description, based on a sharp interface capturing method for the shear-free bubble-liquid interface and an incompressible Navier-Stokes flow solver for generalized fluids, is developed specifically for this problem. Detailed simulations for a range of rheological parameters in the Carreau model show both the stabilizing and destabilizing non-Newtonian effects on the jet formation and impact. In general, for fixed driving pressure ratio, stand-off distance and reference zero-shear-rate viscosity, shear-thinning and shear-thickening promote and suppress jet formation and impact, respectively. For a sufficiently large high-shear-rate limit viscosity, the jet impact is completely suppressed. Thresholds are also determined for the Carreau power-index and material time constant. The dependence of these threshold rheological parameters on the non-dimensional driving pressure ratio and wall stand-off distance is similarly established. Implications for tissue injury in therapeutic ultrasound will be discussed.

Spreading of Non-Newtonian and Newtonian Fluids on a Solid Substrate under Pressure

Energy Technology Data Exchange (ETDEWEB)

Choudhury, Moutushi Dutta; Chandra, Subrata; Nag, Soma; Tarafdar, Sujata [Condensed Matter Physics Research Centre, Physics Department, Jadavpur University, Kolkata 700032 (India); Das, Shantanu, E-mail: mou15july@gmail.com [Reactor Control Division, Bhabha Atomic Research Center, Trombay, Mumbai 400085 (India)

2011-09-15

Strongly non-Newtonian fluids namely, aqueous gels of starch, are shown to exhibit visco-elastic behavior, when subjected to a load. We study arrowroot and potato starch gels. When a droplet of the fluid is sandwiched between two glass plates and compressed, the area of contact between the fluid and plates increases in an oscillatory manner. This is unlike Newtonian fluids, where the area increases monotonically in a similar situation. The periphery moreover, develops an instability, which looks similar to Saffman Taylor fingers. This is not normally seen under compression. The loading history is also found to affect the manner of spreading. We attempt to describe the non-Newtonian nature of the fluid through a visco-elastic model incorporating generalized calculus. This is shown to reproduce qualitatively the oscillatory variation in the surface strain.

Rheological evaluation of simulated neutralized current acid waste

International Nuclear Information System (INIS)

Fow, C.L.; McCarthy, D.; Thornton, G.T.

1986-06-01

A byproduct of the Purex process is an aqueous waste stream that contains fission products. This waste stream, called current acid waste, is chemically neutralized and stored in double shell tanks on the Hanford Site. This neutralized current acid waste (NCAW) will be transported by pipe to B-Plant, a processing plant on the Hanford Site. Rheological and transport properties of NCAW slurry were evaluated. First, researchers conducted lab rheological evaluations of simulated NCAW. The results of these evaluations were then correlated with classical rheological models and scaled up to predict the performance that is likely to occur in the full-scale system. The NCAW in the tank will either be retrieved as is, i.e., no change in the concentration presently in the tank, or will be slightly concentrated before retrieval. Sluicing may be required to retrieve the solids. Three concentrations of simulated NCAW were evaluated that would simulate the different retrieval options: NCAW in the concentration that is presently in the tank; a slightly concentrated NCAW, called NCAW5.5; and equal parts of NCAW settled solids and water (simulating the sluicing stage), called NCAW1:1. The physical and rheological properties of three samples of each concentration at 25 and 100 0 C were evaluated in the laboratory. The properties displayed by NCAW and NCAW5.5 at 25 and 100 0 C allowed it to be classified as a pseudoplastic non-Newtonian fluid. NCAW1:1 at 25 and 100 0 C displayed properties of a yield-pseudoplastic non-Newtonian fluid. The classical non-Newtonian models for pseudoplastic and yield-pseudoplastic fluids were used with the laboratory data to predict the full-scale pump-pipe network parameters

Transverse thermopherotic MHD Oldroyd-B fluid with Newtonian heating

Science.gov (United States)

Mehmood, R.; Rana, S.; Nadeem, S.

2018-03-01

Hydromagnetic transverse flow of an Oldroyd-B type fluid with suspension of nanoparticles and Newtonian heating effects is conferred in this article. Relaxation and Retardation time effects are taken into consideration. Using suitable transformations physical problem is converted into non-linear ordinary differential equations which are tackled numerically via Runge-Kutta Fehlberg integration scheme. Illustration of embedded constraints on flow characteristics are extracted through graphs. The physical response of velocity, temperature and concentration are investigated computationally. Momentum boundary layer thickness decreases but local heat and mass flux rises for Deborah number and Hartman number. The results provide interesting insights into certain applicable transport phenomena involving hydromagnetic rheological fluids.

Experimental and CFD flow studies in an intracranial aneurysm model with Newtonian and non-Newtonian fluids.

Science.gov (United States)

Frolov, S V; Sindeev, S V; Liepsch, D; Balasso, A

2016-05-18

According to the clinical data, flow conditions play a major role in the genesis of intracranial aneurysms. The disorder of the flow structure is the cause of damage of the inner layer of the vessel wall, which leads to the development of cerebral aneurysms. Knowledge of the alteration of the flow field in the aneurysm region is important for treatment. The aim is to study quantitatively the flow structure in an patient-specific aneurysm model of the internal carotid artery using both experimental and computational fluid dynamics (CFD) methods with Newtonian and non-Newtonian fluids. A patient-specific geometry of aneurysm of the internal carotid artery was used. Patient data was segmented and smoothed to obtain geometrical model. An elastic true-to-scale silicone model was created with stereolithography. For initial investigation of the blood flow, the flow was visualized by adding particles into the silicone model. The precise flow velocity measurements were done using 1D Laser Doppler Anemometer with a spatial resolution of 50 μ m and a temporal resolution of 1 ms. The local velocity measurements were done at a distance of 4 mm to each other. A fluid with non-Newtonian properties was used in the experiment. The CFD simulations for unsteady-state problem were done using constructed hexahedral mesh for Newtonian and non-Newtonian fluids. Using 1D laser Doppler Anemometer the minimum velocity magnitude at the end of systole -0.01 m/s was obtained in the aneurysm dome while the maximum velocity 1 m/s was at the center of the outlet segment. On central cross section of the aneurysm the maximum velocity value is only 20% of the average inlet velocity. The average velocity on the cross-section is only 11% of the inlet axial velocity. Using the CFD simulation the wall shear stresses for Newtonian and non-Newtonian fluid at the end of systolic phase (t= 0.25 s) were computed. The wall shear stress varies from 3.52 mPa (minimum value) to 10.21 Pa (maximum value) for the

Numerical Modeling of Mixing of Chemically Reacting, Non-Newtonian Slurry for Tank Waste Retrieval

International Nuclear Information System (INIS)

Yuen, D.A.; Onishi, Y.

2001-01-01

In the U.S. Department of Energy (DOE) complex, 100 million gallons of radioactive and chemical wastes from plutonium production are stored in 281 underground storage tanks. Retrieval of the wastes from the tanks is the first step in its ultimate treatment and disposal. Because billions of dollars are being spent on this effort, waste retrieval demands a strong scientific basis for its successful completion. As will be discussed in Section 4.2, complex interactions among waste chemical reactions, rheology, and mixing of solid and liquid tank waste (and possibly with a solvent) will occur in DSTs during the waste retrieval (mixer pump) operations. The ultimate goal of this study was to develop the ability to simulate the complex chemical and rheological changes that occur in the waste during processing for retrieval. This capability would serve as a scientific assessment tool allowing a priori evaluation of the consequences of proposed waste retrieval operations. Hanford tan k waste is a multiphase, multicomponent, high-ionic strength, and highly basic mixture of liquids and solids. Wastes stored in the 4,000-m3 DSTs will be mixed by 300-hp mixer pumps that inject high-speed (18.3 m/s) jets to stir up the sludge and supernatant liquid for retrieval. During waste retrieval operations, complex interactions occur among waste mixing, chemical reactions, and associated rheology. Thus, to determine safe and cost-effective operational parameters for waste retrieval, decisions must rely on new scientific knowledge to account for physical mixing of multiphase flows, chemical reactions, and waste rheology. To satisfy this need, we integrated a computational fluid dynamics code with state-of-the-art equilibrium and kinetic chemical models and non-Newtonian rheology (Onishi (and others) 1999). This development is unique and holds great promise for addressing the complex phenomena of tank waste retrieval. The current model is, however, applicable only to idealized tank waste

A two-phase theory for non-Newtonian suspensions

Science.gov (United States)

Varsakelis, Christos

In this talk, a continuum and thermodynamically consistent theory for macroscopic particles immersed in a non-Newtonian fluid is presented. According to the employed methodology, each phase of the mixture is treated as a thermodynamic system, endowed with its own set of thermodynamic and kinetic variables, and is required to separately satisfy the equations for the balance of mass, momentum and energy. As both constituents of the mixture are not simple fluids, additional degrees of freedom are introduced for the proper description of their thermodynamic state. A subsequent exploitation of the entropy inequality asserts that the accommodation of the complicated rheological characteristics of both phases requires a departure from a linear current-force relationship. For this reason, a subtle nonlinear representation of the stress tensors is employed. Importantly, the inclusion of additional degrees of freedom allows us to obtain a rate equation for the evolution of the volume fraction of the particulate phase. Following a delineation of the fundamentals of the proposed theory, the talk concludes with the presentation of some limiting cases that also serve as preliminary, sanity tests.

Study of microvascular non-Newtonian blood flow modulated by electroosmosis.

Science.gov (United States)

Tripathi, Dharmendra; Yadav, Ashu; Anwar Bég, O; Kumar, Rakesh

2018-05-01

An analytical study of microvascular non-Newtonian blood flow is conducted incorporating the electro-osmosis phenomenon. Blood is considered as a Bingham rheological aqueous ionic solution. An externally applied static axial electrical field is imposed on the system. The Poisson-Boltzmann equation for electrical potential distribution is implemented to accommodate the electrical double layer in the microvascular regime. With long wavelength, lubrication and Debye-Hückel approximations, the boundary value problem is rendered non-dimensional. Analytical solutions are derived for the axial velocity, volumetric flow rate, pressure gradient, volumetric flow rate, averaged volumetric flow rate along one time period, pressure rise along one wavelength and stream function. A plug swidth is featured in the solutions. Via symbolic software (Mathematica), graphical plots are generated for the influence of Bingham plug flow width parameter, electrical Debye length and Helmholtz-Smoluchowski velocity (maximum electro-osmotic velocity) on the key hydrodynamic variables. This study reveals that blood flow rate accelerates with decreasing the plug width (i.e. viscoplastic nature of fluids) and also with increasing the Debye length parameter. Copyright © 2018 Elsevier Inc. All rights reserved.

Studying mixing in Non-Newtonian blue maize flour suspensions using color analysis.

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Grissel Trujillo-de Santiago

Full Text Available BACKGROUND: Non-Newtonian fluids occur in many relevant flow and mixing scenarios at the lab and industrial scale. The addition of acid or basic solutions to a non-Newtonian fluid is not an infrequent operation, particularly in Biotechnology applications where the pH of Non-Newtonian culture broths is usually regulated using this strategy. METHODOLOGY AND FINDINGS: We conducted mixing experiments in agitated vessels using Non-Newtonian blue maize flour suspensions. Acid or basic pulses were injected to reveal mixing patterns and flow structures and to follow their time evolution. No foreign pH indicator was used as blue maize flours naturally contain anthocyanins that act as a native, wide spectrum, pH indicator. We describe a novel method to quantitate mixedness and mixing evolution through Dynamic Color Analysis (DCA in this system. Color readings corresponding to different times and locations within the mixing vessel were taken with a digital camera (or a colorimeter and translated to the CIELab scale of colors. We use distances in the Lab space, a 3D color space, between a particular mixing state and the final mixing point to characterize segregation/mixing in the system. CONCLUSION AND RELEVANCE: Blue maize suspensions represent an adequate and flexible model to study mixing (and fluid mechanics in general in Non-Newtonian suspensions using acid/base tracer injections. Simple strategies based on the evaluation of color distances in the CIELab space (or other scales such as HSB can be adapted to characterize mixedness and mixing evolution in experiments using blue maize suspensions.

Estimation of semolina dough rheological parameters by inversion of a finite elements model

Directory of Open Access Journals (Sweden)

Angelo Fabbri

2015-10-01

Full Text Available The description of the rheological properties of food material plays an important role in food engineering. Particularly for the optimisation of pasta manufacturing process (extrusion is needful to know the rheological properties of semolina dough. Unfortunately characterisation of non-Newtonian fluids, such as food doughs, requires a notable time effort, especially in terms of number of tests to be carried out. The present work proposes an alternative method, based on the combination of laboratory measurement, made with a simplified tool, with the inversion of a finite elements numerical model. To determine the rheological parameters, an objective function, defined as the distance between simulation and experimental data, was considered and the well-known Levenberg-Marqard optimisation algorithm was used. In order to verify the feasibility of the method, the rheological characterisation of the dough was carried also by a traditional procedure. Results shown that the difference between measurements of rheological parameters of the semolina dough made with traditional procedure and inverse methods are very small (maximum percentage error equal to 3.6%. This agreement supports the coherence of the inverse method that, in general, may be used to characterise many non-Newtonian materials.

Empirical Correlations and CFD Simulations of Vertical Two-Phase Gas-Liquid (Newtonian and Non-Newtonian) Slug Flow Compared Against Experimental Data of Void Fraction

DEFF Research Database (Denmark)

Ratkovich, Nicolas Rios; Majumder, S.K.; Bentzen, Thomas Ruby

2013-01-01

Gas-Newtonian liquid two-phase flows (TPFs) are presented in several industrial processes (e.g. oil-gas industry). In spite of the common occurrence of these TPFs, the understanding of them is limited compared to single-phase flows. Various studies on TPF focus on developing empirical correlations...... based on large sets of experimental data for void fraction, which have proven accurate for specific conditions for which they were developed limiting their applicability. On the other hand, few studies focus on gas-non-Newtonian liquids TPFs, which are very common in chemical processes. The main reason...... is due to the characterization of the viscosity, which determines the hydraulic regime and flow behaviours of the system. The focus of this study is the analysis of the TPF (slug flow) for Newtonian and non-Newtonian liquids in a vertical pipe in terms of void fraction using computational fluid dynamics...

Assessing the microstructural and rheological changes induced by food additives on potato puree.

Science.gov (United States)

Dankar, Iman; Haddarah, Amira; El Omar, Fawaz; Sepulcre, Francesc; Pujolà, Montserrat

2018-02-01

The effects of agar, alginate, lecithin and glycerol on the rheological properties of commercial potato puree were investigated and interpreted in terms of starch microstructural changes, and the applicability of the Cox-Merz rule was evaluated. Each additive was applied separately at two concentrations (0.5 and 1%). Microscopic observations revealed more swollen starch aggregations in lecithin and glycerol compared with those of potato puree and agar, consequently affecting the rheological properties of potato puree. All samples exhibited shear thinning non-Newtonian behaviour. Rheological measurements were strongly concentration dependent. At 0.5% concentration, additives exerted decreases in all the rheological properties of potato puree in the order of glycerol>alginate>lecithin>agar, while at 1% concentration, the order changed to glycerol>lecithin>alginate, whereas 1% agar behaved differently, increasing all rheological values. This study also showed that agar and alginate in addition to potato puree could be valuable and advantageous for further technological processes, such as 3D printing. Copyright © 2017 Elsevier Ltd. All rights reserved.

Structural Optimization of Non-Newtonian Rectifiers

DEFF Research Database (Denmark)

Jensen, Kristian Ejlebjærg; Okkels, Fridolin

When the size of fluidic devices is scaled down, inertial effects start to vanish such that the governing equation becomes linear. Some microfluidic devices rely on the non-linear term related to the inertia of the fluid, and one example is fluid rectifiers (diodes) e.g. related to some micropumps....... These rectifiers rely on the device geometry for their working mechanism, but on further downscaling the inertial effect vanishes and the governing equation starts to show symmetry properties. These symmetry properties reduce the geometry influence to the point where fluid rectifiers cease to function....... In this context it is natural to look for other sources of non-linearity and one possibility is to introduce a non-Newtonian working fluid. Non-Newtonian properties are due to stretching of large particles/molecules in the fluid and this is commonly seen for biological samples in “lab-on-a-chip” systems...

Comparative PIV and LDA studies of Newtonian and non-Newtonian flows in an agitated tank.

Science.gov (United States)

Story, Anna; Jaworski, Zdzisław; Simmons, Mark J; Nowak, Emilia

2018-01-01

The paper presents results of an experimental study of the fluid velocity field in a stirred tank equipped with a Prochem Maxflo T (PMT) type impeller which was rotating at a constant frequency of N  = 4.1 or 8.2 s -1 inducing transitional ( Re  = 499 or 1307) or turbulent ( Re  = 2.43 × 10 4 ) flow of the fluid. The experiments were performed for a Newtonian fluid (water) and a non-Newtonian fluid (0.2 wt% aqueous solution of carboxymethyl cellulose, CMC) exhibiting mild viscoelastic properties. Measurements were carried out using laser light scattering on tracer particles which follow the flow (2-D PIV). For both the water and the CMC solution one primary and two secondary circulation loops were observed within the fluid volume; however, the secondary loops were characterized by much lower intensity. The applied PMT-type impeller produced in the Newtonian fluid an axial primary flow, whilst in the non-Newtonian fluid the flow was more radial. The results obtained in the form of the local mean velocity components were in satisfactory agreement with the literature data from LDA. Distribution of the shear rate in the studied system was also analyzed. For the non-Newtonian fluid an area was computed where the elastic force dominates over the viscous one. The area was nearly matching the region occupied by the primary circulation loop.

Post-Newtonian parameter γ in generalized non-local gravity

Science.gov (United States)

Zhang, Xue; Wu, YaBo; Yang, WeiQiang; Zhang, ChengYuan; Chen, BoHai; Zhang, Nan

2017-10-01

We investigate the post-Newtonian parameter γ and derive its formalism in generalized non-local (GNL) gravity, which is the modified theory of general relativity (GR) obtained by adding a term m 2 n-2 R☐-n R to the Einstein-Hilbert action. Concretely, based on parametrizing the generalized non-local action in which gravity is described by a series of dynamical scalar fields ϕ i in addition to the metric tensor g μν, the post-Newtonian limit is computed, and the effective gravitational constant as well as the post-Newtonian parameters are directly obtained from the generalized non-local gravity. Moreover, by discussing the values of the parametrized post-Newtonian parameters γ, we can compare our expressions and results with those in Hohmann and Järv et al. (2016), as well as current observational constraints on the values of γ in Will (2006). Hence, we draw restrictions on the nonminimal coupling terms F̅ around their background values.

Effect of rheology on flow displacement during cementing process in oil wells

Energy Technology Data Exchange (ETDEWEB)

Braghini, Andre; Naccache, Monica F.; Fonseca, Marcos I. [Dept. Mechanical Engineering. Pontificia Universidade Catolica (PUR-Rio), Rio de Janeiro, RJ (Brazil)], e-mails: mnaccache@puc-rio.br; Miranda, Cristiane R. de; Martins, Andre L.; Aranha, Pedro E. [PETROBRAS S.A., Rio de Janeiro, RJ (Brazil)], e-mails: crisrichard@petrobras.com.br, aleibsohn@petrobras.com.br, pearanha@petrobras.com.br

2010-07-01

This paper describes a set of numerical simulations of the displacement flow of three non-Newtonian fluids through annular eccentric wells. The main application of this work is the studying of drilling and completion processes of oil wells where a cement slurry pushes the drilling mud, used in the drilling process to lubricate the drill and to remove the produced drilling cuts. To avoid contamination, a spacer fluid is usually inserted between them. Both drilling mud and cement slurry behave as non-Newtonian fluids, and the spacer fluid can be Newtonian or non-Newtonian. The analysis of flow and interface configuration between these fluids helps to determine contamination, and is an important tool for the process optimization. The numerical solution of the governing conservation equations of mass and momentum is obtained with the Fluent software, using the finite volume technique and the volume of fluid method. The effects of rheological parameters, density ratios and pumped volume of the spacer fluid are investigated. The results obtained show that the displacement is better when a more viscous spacer fluid is used. The results also show that using lower amounts of the spacer fluid can lead to contamination, which is worse in the smaller gap region of the annular space, in the case of non-rectilinear well. It was also observed that the density ratios play a major role in the cementing operation. (author)

Experimental investigation of non-Newtonian droplet collisions : the role of extensional viscosity

NARCIS (Netherlands)

Finotello, Giulia; De, Shauvik; Vrouwenvelder, Jeroen C.R.; Padding, J.T.; Buist, Kay A.; Jongsma, Alfred; Innings, Fredrik; Kuipers, J.

2018-01-01

We investigate the collision behaviour of a shear thinning non-Newtonian fluid xanthan, by binary droplet collision experiments. Droplet collisions of non-Newtonian fluids are more complex than their Newtonian counterpart as the viscosity no longer remains constant during the collision process.

Empirical Correlations and CFD Simulations of Vertical Two-Phase Gas-Liquid (Newtonian and Non-Newtonian) Flow Compared Against Experimental Data of Void Fraction and Pressure Drop

DEFF Research Database (Denmark)

Ratkovich, Nicolas Rios; Bentzen, Thomas Ruby; Majumder, S.K.

2012-01-01

Gas-Newtonian liquid two-phase flows (TPFs) are presented in several industrial processes (i.e. oil-gas industry). In spite of the common occurrence of these TPFs, their understanding is limited compared to single-phase flows. Different studies on TPF have focus on developing empirical correlations...... based in large sets of experiment data for void fraction and pressure drop which have proven to be accurate for specific condition that their where developed for, which limit their applicability. On the other hand, scarce studies focus on gas-non-Newtonian liquids TPFs, which are very common in chemical...... processes. The main reason for it is due to the characterization of the viscosity, which determines the hydraulic regime and flow behaviours on the system. The focus of this study is the analysis of the TPF for Newtonian and non-Newtonian liquids in a vertical pipe in terms of void fraction and total...

Rheological evaluation of pretreated cladding removal waste

International Nuclear Information System (INIS)

McCarthy, D.; Chan, M.K.C.; Lokken, R.O.

1986-01-01

Cladding removal waste (CRW) contains concentrations of transuranic (TRU) elements in the 80 to 350 nCi/g range. This waste will require pretreatment before it can be disposed of as glass or grout at Hanford. The CRW will be pretreated with a rare earth strike and solids removal by centrifugation to segregate the TRU fraction from the non-TRU fraction of the waste. The centrifuge centrate will be neutralized with sodium hydroxide. This neutralized cladding removal waste (NCRW) is expected to be suitable for grouting. The TRU solids removed by centrifugation will be vitrified. The goal of the Rheological Evaluation of Pretreated Cladding Removal Waste Program was to evaluate those rheological and transport properties critical to assuring successful handling of the NCRW and TRU solids streams and to demonstrate transfers in a semi-prototypic pumping environment. This goal was achieved by a combination of laboratory and pilot-scale evaluations. The results obtained during these evaluations were correlated with classical rheological models and scaled-up to predict the performance that is likely to occur in the full-scale system. The Program used simulated NCRW and TRU solid slurries. Rockwell Hanford Operations (Rockwell) provided 150 gallons of simulated CRW and 5 gallons of simulated TRU solid slurry. The simulated CRW was neutralized by Pacific Northwest Laboratory (PNL). The physical and rheological properties of the NCRW and TRU solid slurries were evaluated in the laboratory. The properties displayed by NCRW allowed it to be classified as a pseudoplastic or yield-pseudoplastic non-Newtonian fluid. The TRU solids slurry contained very few solids. This slurry exhibited the properties associated with a pseudoplastic non-Newtonian fluid

Rheological Behavior of Bentonite-Polyester Dispersions

Science.gov (United States)

Abu-Jdayil, Basim; Al-Omari, Salah Addin

2013-07-01

The rheological behavior of a bentonite clay dispersed in unsaturated polyester was investigated. The effects of the solid content and particle size on the steady and transient rheological properties of the dispersions were studied. In addition, two types of bentonite with different Na+/Ca+2 ratio were used in this study. The Herschel-Bulkley and the Weltman models were used to describe the apparent viscosity of the bentonite-polyester composite in relation to the shear rate and shearing time. The bentonite-polyester dispersions were found to exhibit both Newtonian and non-Newtonian behavior. The transition from a Newtonian to a Bingham plastic and then to a shear-thinning material with a yield stress was found to depend on the solid concentration, the particle size, and the type of bentonite. At a low solid content, the apparent viscosity of the bentonite dispersion increased linearly with solid concentration. But a dramatic increase in the apparent viscosity beyond a solid content of 20 wt.% was observed. On the other hand, a thixotropic behavior was detected in bentonite-polyester dispersions with a high solid content and a low particle size. However, this behavior was more pronounced in dispersions with a high Na+/Ca+2 ratio.

Shear-induced structural transitions in Newtonian non-Newtonian two-phase flow

Science.gov (United States)

Cristobal, G.; Rouch, J.; Colin, A.; Panizza, P.

2000-09-01

We show the existence under shear flow of steady states in a two-phase region of a brine-surfactant system in which lyotropic dilute lamellar (non-Newtonian) and sponge (Newtonian) phases are coexisting. At high shear rates and low sponge phase-volume fractions, we report on the existence of a dynamic transition corresponding to the formation of a colloidal crystal of multilamellar vesicles (or ``onions'') immersed in the sponge matrix. As the sponge phase-volume fraction increases, this transition exhibits a hysteresis loop leading to a structural bistability of the two-phase flow. Contrary to single phase lamellar systems where it is always 100%, the onion volume fraction can be monitored continuously from 0 to 100 %.

Rheological behavior of oil and biodiesel from Moringa oleifera

International Nuclear Information System (INIS)

Díaz Domínguez, Yosvany; Tabio García, Danger; Rondón Macías, Maylin; Fernández Santana, Elina; Rodríguez Muñoz, Susana; Piloto‐Rodríguez, Ramón

2017-01-01

The seeds of Moringa oleifera contain between 30 and 45% of oil, which has motivated the development of investigations with a view to their possible use. The present work aims to determine the rheological behavior of Moringa oleifera oil and biodiesel. The synthesis of biodiesel from crude Moringa oleifera oil was made using methanol with presence of sodium hydroxide. The average yield of this stage was 93%. The results of the rheological study shown that the viscosity at 40°C of Moringa oleifera oil is independent of the shear rate, which corresponds to the behavior of a Newtonian fluid. However, for biodiesel it was demonstrated that there is a dependence of the viscosity with the shear rate (non-Newtonian fluid). This result is corroborated by the fluidity curve, assuring that Moringa oleifera biodiesel behaves as a dilating fluid. (author)

PREDICTION OF GAS HOLD-UP IN A COMBINED LOOP AIR LIFT FLUIDIZED BED REACTOR USING NEWTONIAN AND NON-NEWTONIAN LIQUIDS

Directory of Open Access Journals (Sweden)

Sivakumar Venkatachalam

2011-09-01

Full Text Available Many experiments have been conducted to study the hydrodynamic characteristics of column reactors and loop reactors. In this present work, a novel combined loop airlift fluidized bed reactor was developed to study the effect of superficial gas and liquid velocities, particle diameter, fluid properties on gas holdup by using Newtonian and non-Newtonian liquids. Compressed air was used as gas phase. Water, 5% n-butanol, various concentrations of glycerol (60 and 80% were used as Newtonian liquids, and different concentrations of carboxy methyl cellulose aqueous solutions (0.25, 0.6 and 1.0% were used as non-Newtonian liquids. Different sizes of spheres, Bearl saddles and Raschig rings were used as solid phases. From the experimental results, it was found that the increase in superficial gas velocity increases the gas holdup, but it decreases with increase in superficial liquid velocity and viscosity of liquids. Based on the experimental results a correlation was developed to predict the gas hold-up for Newtonian and non-Newtonian liquids for a wide range of operating conditions at a homogeneous flow regime where the superficial gas velocity is approximately less than 5 cm/s

Structure and rheological characteristics of fucoidan from sea cucumber Apostichopus japonicus.

Science.gov (United States)

Yu, Long; Xue, Changhu; Chang, Yaoguang; Hu, Yanfang; Xu, Xiaoqi; Ge, Lei; Liu, Guanchen

2015-08-01

Sea cucumber is a traditional health food consumed in East Asia. In this study, fucoidan from sea cucumber Apostichopus japonicus (Aj-FUC) was isolated, and its structure and rheological characteristics were elucidated for the first time. Aj-FUC was a branched polysaccharide mainly composed of a novel repeating unit [α-L-Fucp2(OSO3(-))-1 → 3,(α-L-Fucp-1 → 4-α-L-Fucp-1 →)4-α-L-Fucp2(OSO3(-))-1 → 3-α-L-Fucp2(OSO3(-))], clarified by using a combination of infrared spectroscopy, methylation analysis, enzymatic degradation and nuclear magnetic resonance. In steady shear measurement, Aj-FUC manifested a non-Newtonian shear-thinning behaviour at low shear rate (1-100 S(-1)) while exhibiting a non-Newtonian shear-thickening behaviour at high shear rate (100-1000 S(-1)); salts had limited impact on its flow curve. Comparative study on viscosity and rheological behaviour of Aj-FUC and a linear fucoidan extracted from sea cucumber Acaudina molpadioides suggested that the presence of branch structure might significantly influence the rheological characteristics of fucoidan. Copyright © 2015 Elsevier Ltd. All rights reserved.

Deposition Velocities of Newtonian and Non-Newtonian Slurries in Pipelines

Energy Technology Data Exchange (ETDEWEB)

Poloski, Adam P. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Adkins, Harold E. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Abrefah, John [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Casella, Andrew M. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Hohimer, Ryan E. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Nigl, Franz [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Minette, Michael J. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Toth, James J. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Tingey, Joel M. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Yokuda, Satoru T. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

2009-03-01

correlation used in the WTP design guide has been shown to be inaccurate for Hanford waste feed materials. The use of the Thomas (1979) correlation in the design guide is not conservative—In cases where 100% of the particles are smaller than 74 μm or particles are considered to be homogeneous due to yield stress forces suspending the particles the homogeneous fraction of the slurry can be set to 100%. In such cases, the predicted critical velocity based on the conservative Oroskar and Turian (1980) correlation is reduced to zero and the design guide returns a value from the Thomas (1979) correlation. The measured data in this report show that the Thomas (1979) correlation predictions often fall below that measured experimental values. A non-Newtonian deposition velocity design guide should be developed for the WTP— Since the WTP design guide is limited to Newtonian fluids and the WTP expects to process large quantities of such materials, the existing design guide should be modified address such systems. A central experimental finding of this testing is that the flow velocity required to reach turbulent flow increases with slurry rheological properties due to viscous forces dampening the formation of turbulent eddies. The flow becomes dominated by viscous forces rather than turbulent eddies. Since the turbulent eddies necessary for particle transport are not present, the particles will settle when crossing this boundary called the transitional deposition boundary. This deposition mechanism should be expected and designed for in the WTP.

Non-Gaussian initial conditions in ΛCDM: Newtonian, relativistic, and primordial contributions

International Nuclear Information System (INIS)

Bruni, Marco; Hidalgo, Juan Carlos; Meures, Nikolai; Wands, David

2014-01-01

The goal of the present paper is to set initial conditions for structure formation at nonlinear order, consistent with general relativity, while also allowing for primordial non-Gaussianity. We use the nonlinear continuity and Raychaudhuri equations, which together with the nonlinear energy constraint, determine the evolution of the matter density fluctuation in general relativity. We solve this equations at first and second order in a perturbative expansion, recovering and extending previous results derived in the matter-dominated limit and in the Newtonian regime. We present a second-order solution for the comoving density contrast in a ΛCDM universe, identifying nonlinear contributions coming from the Newtonian growing mode, primordial non-Gaussianity and intrinsic non-Gaussianity, due to the essential nonlinearity of the relativistic constraint equations. We discuss the application of these results to initial conditions in N-body simulations, showing that relativistic corrections mimic a non-zero nonlinear parameter f NL

A boundary integral method for two-dimensional (non)-Newtonian drops in slow viscous flow

NARCIS (Netherlands)

Toose, E.M.; Geurts, B.J.; Kuerten, J.G.M.

1995-01-01

A boundary integral method for the simulation of the time-dependent deformation of Newtonian or non-Newtonian drops suspended in a Newtonian fluid is developed. The boundary integral formulation for Stokes flow is used and the non-Newtonian stress is treated as a source term which yields an extra

Characteristics of gas-liquid dynamics in operation of oil fields producing non-Newtonian crude oils

Energy Technology Data Exchange (ETDEWEB)

Mirzadzhanzade, A Kh; Khasaev, A M; Gurbanov, R S; Akhmedov, Z M

1968-08-01

Experimental studies have shown that crude oils from Azerbaidzhan, Uzbekistan, Tataria, Kazakhstan and other areas have anomalous properties under reservoir conditions. Such crude oils are non-Newtonian and (1) obey Darcys Law at low velocities; (2) obey an exponential law at higher velocities; and (3) obey a modified Darcys Law at most velocities. A discussion is given of (1) flow of non-Newtonian crude oils together with gas or water; (2) flow of non-Newtonian crude oils in well tubing; (3) behavior of wells producing non-Newtonian crude oils; and (4) pumping of non-Newtonian oils in wells. Experiments have shown that a visco-plastic liquid does not fill pump inlets completely; as the diameter of the pump inlet decreases so also does the degree of liquid filling. A statistical analysis of production data from 160 fields with Newtonian oil and 129 fields with non- Newtonian oil has shown that much higher production is obtained from fields with Newtonian crude oils.

Rheological and interfacial properties at the equilibrium of almond gum tree exudate (Prunus dulcis) in comparison with gum arabic.

Science.gov (United States)

Mahfoudhi, Nesrine; Sessa, Mariarenata; Ferrari, Giovanna; Hamdi, Salem; Donsi, Francesco

2016-06-01

Almond gum contains an arabinogalactan-type polysaccharide, which plays an important role in defining its interfacial and rheological properties. In this study, rheological and interfacial properties of almond gum and gum arabic aqueous dispersions were comparatively investigated. The interfacial tension of almond gum and gum arabic aqueous dispersions was measured using the pendant drop method in hexadecane. The asymptotic interfacial tension values for almond gum were significantly lower than the corresponding values measured for gum arabic, especially at high concentration. Rheological properties were characterized by steady and oscillatory tests using a coaxial geometry. Almond gum flow curves exhibited a shear thinning non-Newtonian behavior with a tendency to a Newtonian plateau at low shear rate, while gum arabic flow curves exhibited such behavior only at high shear rate. The influence of temperature (5-50  ℃) on the flow curves was studied at 4% (m/m) gum concentration and the Newtonian viscosities at infinite and at zero shear rate, for gum arabic and almond gum, respectively, were accurately fitted by an Arrhenius-type equation. The dynamic properties of the two gum dispersions were also studied. Both gum dispersions exhibited viscoelastic properties, with the viscous component being predominant in a wider range of concentrations for almond gum, while for gum arabic the elastic component being higher than the elastic one especially at higher concentrations.The rheological and interfacial tension properties of almond gum suggest that it may represent a possible substitute of gum arabic in different food applications. © The Author(s) 2015.

Non-Newtonian ink transfer in gravure-offset printing

International Nuclear Information System (INIS)

Ghadiri, Fatemeh; Ahmed, Dewan Hasan; Sung, Hyung Jin; Shirani, Ebrahim

2011-01-01

The inks used in gravure-offset printing are non-Newtonian fluids with higher viscosities and lower surface tensions than Newtonian fluids. This paper examines the transfer of a non-Newtonian ink between a flat plate and a groove when the plate is moved upward with a constant velocity while the groove is held fixed. Numerical simulations were carried out with the Carreau model to explore the behavior of this non-Newtonian ink in gravure-offset printing. The volume of fluid (VOF) method was implemented to capture the interface during the ink transfer process. The effects of varying the contact angle of the ink on the flat plate and groove walls and geometrical parameters such as the groove angle and the groove depth on the breakup time of the liquid filament that forms between the plate and the groove and the ink transfer ratio were determined. Our results indicate that increasing the groove contact angle and decreasing the flat plate contact angle enhance the ink transfer ratio and the breakup time. However, increasing the groove depth and the groove angle decreases the transfer ratio and the breakup time. By optimizing these parameters, it is possible to achieve an ink transfer from the groove to the flat plate of approximately 92%. Moreover, the initial width and the vertical velocity of the neck of the ink filament have significant influences on the ink transfer ratio and the breakup time.

Electro-osmosis of non-Newtonian fluids in porous media using lattice Poisson-Boltzmann method.

Science.gov (United States)

Chen, Simeng; He, Xinting; Bertola, Volfango; Wang, Moran

2014-12-15

Electro-osmosis in porous media has many important applications in various areas such as oil and gas exploitation and biomedical detection. Very often, fluids relevant to these applications are non-Newtonian because of the shear-rate dependent viscosity. The purpose of this study was to investigate the behaviors and physical mechanism of electro-osmosis of non-Newtonian fluids in porous media. Model porous microstructures (granular, fibrous, and network) were created by a random generation-growth method. The nonlinear governing equations of electro-kinetic transport for a power-law fluid were solved by the lattice Poisson-Boltzmann method (LPBM). The model results indicate that: (i) the electro-osmosis of non-Newtonian fluids exhibits distinct nonlinear behaviors compared to that of Newtonian fluids; (ii) when the bulk ion concentration or zeta potential is high enough, shear-thinning fluids exhibit higher electro-osmotic permeability, while shear-thickening fluids lead to the higher electro-osmotic permeability for very low bulk ion concentration or zeta potential; (iii) the effect of the porous medium structure depends significantly on the constitutive parameters: for fluids with large constitutive coefficients strongly dependent on the power-law index, the network structure shows the highest electro-osmotic permeability while the granular structure exhibits the lowest permeability on the entire range of power law indices considered; when the dependence of the constitutive coefficient on the power law index is weaker, different behaviors can be observed especially in case of strong shear thinning. Copyright © 2014 Elsevier Inc. All rights reserved.

Boundary layer for non-newtonian fluids on curved surfaces

International Nuclear Information System (INIS)

Stenger, N.

1981-04-01

By using the basic equation of fluid motion (conservation of mass and momentum) the boundary layer parameters for a Non-Newtonian, incompressible and laminar fluid flow, has been evaluated. As a test, the flat plate boundary layer is first analized and afterwards, a case with pressure gradient, allowing separation, is studied. In the case of curved surfaces, the problem is first developed in general and afterwards particularized to a circular cylinder. Finally suction and slip in the flow interface are examined. The power law model is used to represent the stress strain relationship in Non-Newtonian flow. By varying the fluid exponent one can then, have an idea of how the Non-Newtonian behavior of the flow influences the parameters of the boundary layer. Two equations, in an appropriate coordinate system have been obtained after an order of magnitude analysis of the terms in the equations of motion is performed. (Author) [pt

Non-Newtonian fluid structure interaction in flexible biomimetic microchannels

Science.gov (United States)

Kiran, M.; Dasgupta, Sunando; Chakraborty, Suman

2017-11-01

To investigate the complex fluid structure interactions in a physiologically relevant microchannel with deformable wall and non-Newtonian fluid that flows within it, we fabricated cylindrical microchannels of various softness out of PDMS. Experiments to measure the transient pressure drop across the channel were carried out with high sampling frequencies to capture the intricate flow physics. In particular, we showed that the waveforms varies greatly for each of the non-Newtonian and Newtonian cases for both non-deformable and deformable microchannels in terms of the peak amplitude, r.m.s amplitude and the crest factor. In addition, we carried out frequency sweep experiments to evaluate the frequency response of the system. We believe that these results will aid in the design of polymer based microfluidic phantoms for arterial FSI studies, and in particular for studying blood analog fluids in cylindrical microchannels as well as developing frequency specific Lab-on-chip systems for medical diagnostics.

Downhole Temperature Modeling for Non-Newtonian Fluids in ERD Wells

Directory of Open Access Journals (Sweden)

Dan Sui

2018-04-01

Full Text Available Having precise information of fluids' temperatures is a critical process during planning of drilling operations, especially for extended reach drilling (ERD. The objective of this paper is to develop an accurate temperature model that can precisely calculate wellbore temperature distributions. An established semi-transient temperature model for vertical wellbores is extended and improved to include deviated wellbores and more realistic scenarios using non-Newtonian fluids. The temperature model is derived based on an energy balance between the formation and the wellbore. Heat transfer is considered steady-state in the wellbore and transient in the formation through the utilization of a formation cooling effect. In this paper, the energy balance is enhanced by implementing heat generation from the drill bit friction and contact friction force caused by drillpipe rotation. A non-linear geothermal gradient as a function of wellbore inclination, is also introduced to extend the model to deviated wellbores. Additionally, the model is improved by considering temperature dependent drilling fluid transport and thermal properties. Transport properties such as viscosity and density are obtained by lab measurements, which allows for investigation of the effect of non-Newtonian fluid behavior on the heat transfer. Furthermore, applying a non-Newtonian pressure loss model enables an opportunity to evaluate the impact of viscous forces on fluid properties and thus the overall heat transfer. Results from sensitivity analysis of both drilling fluid properties and other relevant parameters will be presented. The main application area of this model is related to optimization of drilling fluid, hydraulics, and wellbore design parameters, ultimately leading to safe and cost efficient operations.

Comparison between a generalized Newtonian model and a network-type multiscale model for hemodynamic behavior in the aortic arch: Validation with 4D MRI data for a case study.

Science.gov (United States)

Menut, Marine; Boussel, Loïc; Escriva, Xavier; Bou-Saïd, Benyebka; Walter-Le Berre, Hélène; Marchesse, Yann; Millon, Antoine; Della Schiava, Nellie; Lermusiaux, Patrick; Tichy, John

2018-05-17

Blood is a complex fluid in which the presence of the various constituents leads to significant changes in its rheological properties. Thus, an appropriate non-Newtonian model is advisable; and we choose a Modified version of the rheological model of Phan-Thien and Tanner (MPTT). The different parameters of this model, derived from the rheology of polymers, allow characterization of the non-Newtonian nature of blood, taking into account the behavior of red blood cells in plasma. Using the MPTT model that we implemented in the open access software OpenFOAM, numerical simulations have been performed on blood flow in the thoracic aorta for a healthy patient. We started from a patient-specific model which was constructed from medical images. Exiting flow boundary conditions have been developped, based on a 3-element Windkessel model to approximate physiological conditions. The parameters of the Windkessel model were calibrated with in vivo measurements of flow rate and pressure. The influence of the selected viscosity of red blood cells on the flow and wall shear stress (WSS) was investigated. Results obtained from this model were compared to those of the Newtonian model, and to those of a generalized Newtonian model, as well as to in vivo dynamic data from 4D MRI during a cardiac cycle. Upon evaluating the results, the MPTT model shows better agreement with the MRI data during the systolic and diastolic phases than the Newtonian or generalized Newtonian model, which confirms our interest in using a complex viscoelastic model. Copyright © 2018 Elsevier Ltd. All rights reserved.

Microstructural Dynamics and Rheology of Suspensions of Rigid Fibers

Science.gov (United States)

Butler, Jason E.; Snook, Braden

2018-01-01

The dynamics and rheology of suspensions of rigid, non-Brownian fibers in Newtonian fluids are reviewed. Experiments, theories, and computer simulations are considered, with an emphasis on suspensions at semidilute and concentrated conditions. In these suspensions, interactions between the particles strongly influence the microstructure and rheological properties of the suspension. The interactions can arise from hydrodynamic disturbances, giving multibody interactions at long ranges and pairwise lubrication forces over short distances. For concentrated suspensions, additional interactions due to excluded volume (contacts) and adhesive forces are addressed. The relative importance of the various interactions as a function of fiber concentration is assessed.

Effect of the fructose and glucose concentration on the rheological ...

African Journals Online (AJOL)

Jose Luis Montañez Soto

2013-03-20

Mar 20, 2013 ... Key words: High fructose syrups, viscosity, rheological behavior, Newtonian fluids. ... shear rate; ºBrix, soluble solids %; K, consistency index; n, flow behavior index. ... the correlations between rheological measurements and.

The rheology applied to the fluids used in perforation of wells of petroleum

International Nuclear Information System (INIS)

Sierra Restrepo, Carlos Mario

1997-01-01

The properties of flow of the drilling fluids should be controlled, because they play a very important paper when we are drilling a well and a wrong behaviour could occasion serious problems. These properties are in great part consequence of their viscosity or more exactly of their rheology. The drilling fluids are too complex and the relationship between shear stress and shear rate is not considered as a linear relation that passes for the origin, like it is the case of the Newtonian fluids for the one which they are classified like n on Newtonian fluids . Also, they should conquer a certain grade of internal resistance in order to begin to flow. There is not a mathematical equation that describes the rheology of all the non-Newtonian fluids exactly. On the other hand, they have proposed several equations that approach the true relationship shear stress -shear rate. Those that have shown more satisfactory outputs are: The Bingham plastic model, the power-law model, and the power-law modified model

On preconditioning incompressible non-Newtonian flow problems

NARCIS (Netherlands)

He, X.; Neytcheva, M.; Vuik, C.

2013-01-01

This paper deals with fast and reliable numerical solution methods for the incompressible non-Newtonian Navier-Stokes equations. To handle the nonlinearity of the governing equations, the Picard and Newton methods are used to linearize these coupled partial differential equations. For space

Rheology v.3 theory and applications

CERN Document Server

Eirich, Frederick

1960-01-01

Rheology: Theory and Applications, Volume 3 is a collection of articles contributed by experts in the field of rheology - the science of deformation and flow. This volume is composed of specialized chapters on the application of normal coordinate analysis to the theory of high polymers; principles of rheometry; and the rheology of cross-linked plastics, poly electrolytes, latexes, inks, pastes, and clay. Also included are a series of technological articles on lubrication, spinning, molding, extrusion, and adhesion and a survey of the general features of industrial rheology. Materials scientist

Potential Hydraulic Modelling Errors Associated with Rheological Data Extrapolation in Laminar Flow

International Nuclear Information System (INIS)

Shadday, Martin A. Jr.

1997-01-01

The potential errors associated with the modelling of flows of non-Newtonian slurries through pipes, due to inadequate rheological models and extrapolation outside of the ranges of data bases, are demonstrated. The behaviors of both dilatant and pseudoplastic fluids with yield stresses, and the errors associated with treating them as Bingham plastics, are investigated

Calculation of the Pitot tube correction factor for Newtonian and non-Newtonian fluids.

Science.gov (United States)

Etemad, S Gh; Thibault, J; Hashemabadi, S H

2003-10-01

This paper presents the numerical investigation performed to calculate the correction factor for Pitot tubes. The purely viscous non-Newtonian fluids with the power-law model constitutive equation were considered. It was shown that the power-law index, the Reynolds number, and the distance between the impact and static tubes have a major influence on the Pitot tube correction factor. The problem was solved for a wide range of these parameters. It was shown that employing Bernoulli's equation could lead to large errors, which depend on the magnitude of the kinetic energy and energy friction loss terms. A neural network model was used to correlate the correction factor of a Pitot tube as a function of these three parameters. This correlation is valid for most Newtonian, pseudoplastic, and dilatant fluids at low Reynolds number.

Numerical Modeling of Fluid-Structure Interaction with Rheologically Complex Fluids

OpenAIRE

Chen, Xingyuan

2014-01-01

In the present work the interaction between rheologically complex fluids and elastic solids is studied by means of numerical modeling. The investigated complex fluids are non-Newtonian viscoelastic fluids. The fluid-structure interaction (FSI) of this kind is frequently encountered in injection molding, food processing, pharmaceutical engineering and biomedicine. The investigation via experiments is costly, difficult or in some cases, even impossible. Therefore, research is increasingly aided...

On approximation of non-Newtonian fluid flow by the finite element method

Science.gov (United States)

Svácek, Petr

2008-08-01

In this paper the problem of numerical approximation of non-Newtonian fluid flow with free surface is considered. Namely, the flow of fresh concrete is addressed. Industrial mixtures often behaves like non-Newtonian fluids exhibiting a yield stress that needs to be overcome for the flow to take place, cf. [R.B. Bird, R.C. Armstrong, O. Hassager, Dynamics of Polymeric Liquids, vol. 1, Fluid Mechanics, Wiley, New York, 1987; R.P. Chhabra, J.F. Richardson, Non-Newtonian Flow in the Process Industries, Butterworth-Heinemann, London, 1999]. The main interest is paid to the mathematical formulation of the problem and to discretization with the aid of finite element method. The described numerical procedure is applied onto the solution of several problems.

Borehole guided waves in a non-Newtonian (Maxwell) fluid-saturated porous medium

International Nuclear Information System (INIS)

Zhi-Wen, Cui; Jin-Xia, Liu; Ke-Xie, Wang; Gui-Jin, Yao

2010-01-01

The property of acoustic guided waves generated in a fluid-filled borehole surrounded by a non-Newtonian (Maxwell) fluid-saturated porous formation with a permeable wall is investigated. The influence of non-Newtonian effects on acoustic guided waves such as Stoneley waves, pseudo-Rayleigh waves, flexural waves, and screw waves propagations in a fluid-filled borehole is demonstrated based on the generalized Biot–Tsiklauri model by calculating their velocity dispersion and attenuation coefficients. The corresponding acoustic waveforms illustrate their properties in time domain. The results are also compared with those based on generalized Biot's theory. The results show that the influence of non-Newtonian effect on acoustic guided wave, especially on the attenuation coefficient of guided wave propagation in borehole is noticeable. (classical areas of phenomenology)

Structural Optimization of non-Newtonian Microfluidics

DEFF Research Database (Denmark)

Jensen, Kristian Ejlebjærg; Okkels, Fridolin

2011-01-01

We present results for topology optimization of a non-Newtonian rectifier described with a differential constitutive model. The results are novel in the sense that a differential constitutive model has not been combined with topology optimization previously. We find that it is necessary to apply...... optimization of fluids. We test the method on a microfluidic rectifier and find solutions topologically different from experimentally realized designs....

Conceptual coherence of non-Newtonian worldviews in Force Concept Inventory data

Directory of Open Access Journals (Sweden)

Terry F. Scott

2017-05-01

Full Text Available The Force Concept Inventory is one of the most popular and most analyzed multiple-choice concept tests used to investigate students’ understanding of Newtonian mechanics. The correct answers poll a set of underlying Newtonian concepts and the coherence of these underlying concepts has been found in the data. However, this inventory was constructed after several years of research into the common preconceptions held by students and using these preconceptions as distractors in the questions. Their sole purpose is to deflect non-Newtonian candidates away from the correct answer. Alternatively, one can argue that the responses could also be treated as polling these preconceptions. In this paper we shift the emphasis of the analysis away from the correlation structure of the correct answers and look at the latent traits underlying the incorrect responses. Our analysis models the data employing exploratory factor analysis, which uses regularities in the data to suggest the existence of underlying structures in the cognitive processing of the students. This analysis allows us to determine whether the data support the claim that there are alternate non-Newtonian worldviews on which students’ incorrect responses are based. The existence of such worldviews, and their coherence, could explain the resilience of non-Newtonian preconceptions and would have significant implications to the design of instruction methods. We find that there are indeed coherent alternate conceptions of the world which can be categorized using the results of the research that led to the construction of the Force Concept Inventory.

Possible evidence for non-Newtonian gravity in the Greenland ice gap

International Nuclear Information System (INIS)

Ander, M.E.

1988-01-01

An Airy-type geophysical experiment was conducted down a 2 km deep hole in the Greenland ice cap in order to test for possible violations of Newton's inverse square law by making gravity measurements over a range of 213 m to 1460 m. A significant departure from Newtonian gravity was observed. This result can be explained by the existence of an attractive non-Newtonian component of gravity with a strength of about 3.4% that of Newtonian gravity at a scale of 1460 m. Unfortunately, we cannot completely, unambiguously attribute it to a breakdown of Newtonian gravity because we have shown that lateral density variations in the bedrock beneath the ice can cause such apparent departures. If such variations existed, they would have to be rather unusual but certainly no impossible. 8 refs

The effect of the expansion ratio on a turbulent non-Newtonian recirculating flow

Energy Technology Data Exchange (ETDEWEB)

Pereira, A.S. [Departamento de Engenharia Quimica Instituto Superior de Engenharia do Porto (Portugal); Pinho, F.T. [Centro de Estudos de Fenomenos de Transporte, DEMEGI, Faculdade de Engenharia, Universidade do Porto (Portugal)

2002-04-01

Measurements of the mean and turbulent flow characteristics of shear-thinning moderately elastic 0.1% and 0.2% xanthan gum aqueous solutions were carried out in a sudden expansion having a diameter ratio of 2. The inlet flow was turbulent and fully developed, and the results were compared with data for water in the same geometry and with previous published Newtonian and non-Newtonian data in a smaller expansion of diameter ratio equal to 1.538. An increase in expansion ratio led to an increase in the recirculation length and in the axial normal Reynolds stress at identical normalised locations, but the difference between Newtonian and non-Newtonian characteristics was less intense than in the smaller expansion. An extensive comparison of mean and turbulent flow characteristics was carried out in order to understand the variation of flow features. (orig.)

Attractors of equations of non-Newtonian fluid dynamics

International Nuclear Information System (INIS)

Zvyagin, V G; Kondrat'ev, S K

2014-01-01

This survey describes a version of the trajectory-attractor method, which is applied to study the limit asymptotic behaviour of solutions of equations of non-Newtonian fluid dynamics. The trajectory-attractor method emerged in papers of the Russian mathematicians Vishik and Chepyzhov and the American mathematician Sell under the condition that the corresponding trajectory spaces be invariant under the translation semigroup. The need for such an approach was caused by the fact that for many equations of mathematical physics for which the Cauchy initial-value problem has a global (weak) solution with respect to the time, the uniqueness of such a solution has either not been established or does not hold. In particular, this is the case for equations of fluid dynamics. At the same time, trajectory spaces invariant under the translation semigroup could not be constructed for many equations of non-Newtonian fluid dynamics. In this connection, a different approach to the construction of trajectory attractors for dissipative systems was proposed in papers of Zvyagin and Vorotnikov without using invariance of trajectory spaces under the translation semigroup and is based on the topological lemma of Shura-Bura. This paper presents examples of equations of non-Newtonian fluid dynamics (the Jeffreys system describing movement of the Earth's crust, the model of motion of weak aqueous solutions of polymers, a system with memory) for which the aforementioned construction is used to prove the existence of attractors in both the autonomous and the non-autonomous cases. At the beginning of the paper there is also a brief exposition of the results of Ladyzhenskaya on the existence of attractors of the two-dimensional Navier-Stokes system and the result of Vishik and Chepyzhov for the case of attractors of the three-dimensional Navier-Stokes system. Bibliography: 34 titles

RHEOLOGY OF CHICKPEA PROTEIN CONCENTRATE DISPERSIONS

Directory of Open Access Journals (Sweden)

Aurelia Ionescu

2011-12-01

Full Text Available Chickpea proteins are used as ingredients in comminuted sausage products and many oriental textured foods. Rheological behaviour of chickpea protein concentrate was studied using a controlled stress rheometer. The protein dispersion prepared with phosphate buffer at pH 7.0 presented non-Newtonian shear thinning behaviour and rheological data well fitted to the Sisko, Carreau and Cross models. The viscoelastic properties of the chickpea protein suspensions were estimated by measuring the storage and loss moduli in oscillatory frequency conditions (0.1-10 Hz at 20°C. Moreover, thermally induced gelation of the chickpea proteins (16, 24 and 36% was studied at pH 7.0 and 4.5 in the temperature range 50 to 100oC and salt concentration ranging from 0 to 1 M. Gelling behaviour was quantified by means of dynamic rheological measurements. Gels formation was preceded by the decrease of storage modulus and loss moduli, coupled with the increase of the phase angle (delta. The beginning of thermal gelation was influenced by protein concentration, pH and salt level. In all studied cases, storage modulus increased rapidly in the temperature range 70-90°C. All rheological parameters measured at 90°C were significantly higher at pH 4.5 compared to pH 7.0.

Chitosan solutions as injectable systems for dermal filler applications: Rheological characterization and biological evidence.

Science.gov (United States)

Halimi, C; Montembault, A; Guerry, A; Delair, T; Viguier, E; Fulchiron, R; David, L

2015-01-01

A new generation of dermal filler for wrinkle filler based on chitosan was compared to current hyaluronic acid-based dermal fillers by using a new rheological performance criterion based on viscosity during injection related to Newtonian viscosity. In addition an in vivo evaluation was performed for preclinical evidence of chitosan use as dermal filler. In this way, biocompatibility and dermis reconstruction was evaluated on a pig model.

The influence of the non-Newtonian properties of blood on blood-hammer through the posterior cerebral artery.

Science.gov (United States)

Tazraei, Pedram; Riasi, Alireza; Takabi, Behrouz

2015-06-01

This work investigates a two dimensional numerical analysis of blood hammer through the posterior cerebral artery. The non-Newtonian and usual Newtonian blood models are compared in the case of blood hammer through the posterior cerebral artery to quantify the differences between the models. In this way, a validated CFD simulation is used to study non-Newtonian shear-thinning effects of blood. The governing equations for the modeling of two-dimensional transient flow are solved using a combination of characteristics and central finite difference methods, respectively for the hyperbolic and parabolic parts. Herein, the non-Newtonian viscosity characteristic of blood is incorporated by using the Carreau model. To convert the nonlinear terms available in the characteristics equation into the linear ones, the Newton-Kantorovich method is implemented. The verification and validation of the numerical results are carried out in detail. Hemodynamic characteristics of blood hammer through the posterior cerebral artery are derived with both the Newtonian and non-Newtonian models, and the results are meticulously compared and discussed. The results show that when blood hammer occurs, the non-Newtonian properties greatly influence the velocity and shear stress profiles. At the early stages of blood hammer, there is a 64% difference between magnitudes of wall shear stress in these two models, and the magnitude of the wall shear stress for the shear-thinning blood flow is lower than the Newtonian one. Copyright © 2015 Elsevier Inc. All rights reserved.

Non-Newtonian fluid flow in an axisymmetric channel with porous wall

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M. Hosseini

2013-12-01

Full Text Available In the present article Optimal Homotopy Asymptotic Method (OHAM is used to obtain the solutions of momentum and heat transfer equations of non-Newtonian fluid flow in an axisymmetric channel with porous wall for turbine cooling applications. Numerical method is used for validity of this analytical method and excellent agreement is observed between the solutions obtained from OHAM and numerical results. Trusting to this validity, effects of some other parameters are discussed. The results show that Nusselt number increases with increase of Reynolds number, Prandtl number and power law index.

Comparison between different models for rheological characterization of sludge from settling tank

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Malczewska Beata

2017-09-01

Full Text Available The municipal sludge characterized non-Newtonian behaviour, therefore the viscosity of the sewage sludge is not a constant value. The laboratory investigation was made using coaxial cylinder with rotating torque and gravimetric concentration of the investigated sludge ranged from 4.40% to 2.09%. This paper presents the investigation on the effect of concentration of rheological sludge behaviour. The three different rheological models: Bingham (plastic model, Ostwald-de Waele (power-law, Hershel-Bulkley’s were calculated by fitting the experimental data of shear stress as a function of shear rate to these models. In this study, the 3-parameter Herschel- Bulkley’s model fits the experimental data best.

Determination of the Köthe-Toeplitz Duals over the Non-Newtonian Complex Field

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Uğur Kadak

2014-01-01

Full Text Available The important point to note is that the non-Newtonian calculus is a self-contained system independent of any other system of calculus. Therefore the reader may be surprised to learn that there is a uniform relationship between the corresponding operators of this calculus and the classical calculus. Several basic concepts based on non-Newtonian calculus are presented by Grossman (1983, Grossman and Katz (1978, and Grossman (1979. Following Grossman and Katz, in the present paper, we introduce the sets of bounded, convergent, null series and p-bounded variation of sequences over the complex field C* and prove that these are complete. We propose a quite concrete approach based on the notion of Köthe-Toeplitz duals with respect to the non-Newtonian calculus. Finally, we derive some inclusion relationships between Köthe space and solidness.

Conceptual Models of the Climate 2003 Program of Study: Non-Newtonian Geophysical Fluid Dynamics

National Research Council Canada - National Science Library

Balmforth, NeiI

2004-01-01

Non-Newtonian fluids occur commonly in our world. These fluids, such as toothpaste, saliva, oils, mud and lava, exhibit a number of behaviors that are different from Newtonian fluids and have a number of additional material properties...

Recommendations for rheological testing and modelling of DWPF melter feed slurries

International Nuclear Information System (INIS)

Shadday, M.A. Jr.

1994-08-01

The melter feed in the DWPF process is a non-Newtonian slurry. In the melter feed system and the sampling system, this slurry is pumped at a wide range of flow rates through pipes of various diameters. Both laminar and turbulent flows are encountered. Good rheology models of the melter feed slurries are necessary for useful hydraulic models of the melter feed and sampling systems. A concentric cylinder viscometer is presently used to characterize the stress/strain rate behavior of the melter feed slurries, and provide the data for developing rheology models of the fluids. The slurries exhibit yield stresses, and they are therefore modelled as Bingham plastics. The ranges of strain rates covered by the viscometer tests fall far short of the entire laminar flow range, and therefore hydraulic modelling applications of the present rheology models frequently require considerable extrapolation beyond the range of the data base. Since the rheology models are empirical, this cannot be done with confidence in the validity of the results. Axial pressure drop versus flow rate measurements in a straight pipe can easily fill in the rest of the laminar flow range with stress/strain rate data. The two types of viscometer tests would be complementary, with the concentric cylinder viscometer providing accurate data at low strain rates, near the yield point if one exists, and pipe flow tests providing data at high strain rates up to and including the transition to turbulence. With data that covers the laminar flow range, useful rheological models can be developed. In the Bingham plastic model, linear behavior of the shear stress as a function of the strain rate is assumed once the yield stress is exceeded. Both shear thinning and shear thickening behavior have been observed in viscometer tests. Bingham plastic models cannot handle this non-linear behavior, but a slightly more complicated yield/power law model can

Generation of Oil Droplets in a Non-Newtonian Liquid Using a Microfluidic T-Junction

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Enrico Chiarello

2015-11-01

Full Text Available We have compared the formation of oil drops in Newtonian and non-Newtonian fluids in a T-junction microfluidic device. As Newtonian fluids, we used aqueous solutions of glycerol, while as non-Newtonian fluids we prepared aqueous solutions of xanthan, a stiff rod-like polysaccharide, which exhibit strong shear-thinning effects. In the squeezing regime, the formation of oil droplets in glycerol solutions is found to scale with the ratio of the dispersed flow rate to the continuous one and with the capillary number associated to the continuous phase. Switching to xanthan solutions does not seem to significantly alter the droplet formation process. Any quantitative difference with respect to the Newtonian liquid can be accounted for by a suitable choice of the capillary number, corresponding to an effective xanthan viscosity that depends on the flow rates. We have deduced ample variations in the viscosity, on the order of 10 and more, during normal operation conditions of the T-junction. This allowed estimating the actual shear rates experienced by the xanthan solutions, which go from tens to hundreds of s−1.

Nonlinear shear wave in a non Newtonian visco-elastic medium

Energy Technology Data Exchange (ETDEWEB)

Banerjee, D.; Janaki, M. S.; Chakrabarti, N. [Saha Institute of Nuclear Physics, 1/AF Bidhannagar, Calcutta 700 064 (India); Chaudhuri, M. [Max-Planck-Institut fuer extraterrestrische Physik, 85741 Garching (Germany)

2012-06-15

An analysis of nonlinear transverse shear wave has been carried out on non-Newtonian viscoelastic liquid using generalized hydrodynamic model. The nonlinear viscoelastic behavior is introduced through velocity shear dependence of viscosity coefficient by well known Carreau-Bird model. The dynamical feature of this shear wave leads to the celebrated Fermi-Pasta-Ulam problem. Numerical solution has been obtained which shows that initial periodic solutions reoccur after passing through several patterns of periodic waves. A possible explanation for this periodic solution is given by constructing modified Korteweg de Vries equation. This model has application from laboratory to astrophysical plasmas as well as in biological systems.

A DNS Investigation of Non-Newtonian Turbulent Open Channel Flow

Science.gov (United States)

Guang, Raymond; Rudman, Murray; Chryss, Andrew; Slatter, Paul; Bhattacharya, Sati

2010-06-01

The flow of non-Newtonian fluids in open channels has great significance in many industrial settings from water treatment to mine waste disposal. The turbulent behaviour during transportation of these materials is of interest for many reasons, one of which is keeping settleable particles in suspension. The mechanism governing particle transport in turbulent flow has been studied in the past, but is not well understood. A better understanding of the mechanism operating in the turbulent flow of non-Newtonian suspensions in open channel would lead to improved design of many of the systems used in the mining and mineral processing industries. The objective of this paper is to introduce our work on the Direct Numerical Simulation of turbulent flow of non-Newtonian fluids in an open channel. The numerical method is based on spectral element/Fourier formulation. The flow simulation of a Herschel-Bulkley fluid agrees qualitatively with experimental results. The simulation results over-predict the flow velocity by approximately 15% for the cases considered, although the source of the discrepancy is difficult to ascertain. The effect of variation in yield stress and assumed flow depth are investigated and used to assess the sensitivity of the flow to these physical parameters. This methodology is seen to be useful in designing and optimising the transport of slurries in open channels.

Increasing heat transfer of non-Newtonian nanofluid in rectangular microchannel with triangular ribs

Science.gov (United States)

Shamsi, Mohammad Reza; Akbari, Omid Ali; Marzban, Ali; Toghraie, Davood; Mashayekhi, Ramin

2017-09-01

In this study, computational fluid dynamics and the laminar flow of the non-Newtonian fluid have been numerically studied. The cooling fluid includes water and 0.5 wt% Carboxy methyl cellulose (CMC) making the non-Newtonian fluid. In order to make the best of non-Newtonian nanofluid in this simulation, solid nanoparticles of Aluminum Oxide have been added to the non-Newtonian fluid in volume fractions of 0-2% with diameters of 25, 45 and 100 nm. The supposed microchannel is rectangular and two-dimensional in Cartesian coordination. The power law has been used to speculate the dynamic viscosity of the cooling nanofluid. The field of numerical solution is simulated in the Reynolds number range of 5 nanoparticles as well as the use for nanoparticles with smaller diameters lead to greater heat transfer. Among all the studied forms, the triangular rib from with an angle of attack 30° has the biggest Nusselt number and the smallest pressure drop along the microchannel. Also, an increase in the angle of attack and as a result of a sudden contact between the fluid and the ribs and also a reduction in the coflowing length (length of the rib) cause a cut in heat transfer by the fluid in farther parts from the solid wall (tip of the rib).

Numerical study on the heat transfer performance of non-Newtonian fluid flow in a manifold microchannel heat sink

International Nuclear Information System (INIS)

Li, Si-Ning; Zhang, Hong-Na; Li, Xiao-Bin; Li, Qian; Li, Feng-Chen; Qian, Shizhi; Joo, Sang Woo

2017-01-01

Highlights: • Heat transfer performance of non-Newtonian fluid flow in a MHS is studied. • Pseudo-plastic fluid flow can clearly promote the heat transfer efficiency in MMC. • Heat transfer enhancement is attributed to the emergence of secondary flow. • The heat transfer uniformity can also be improved by pseudo-plastic fluid flow. - Abstract: As the miniaturization and integration become the leading trend of the micro-electro-mechanical systems, it is of great significance to improve the microscaled heat transfer performance. This paper presents a three-dimensional (3D) numerical simulation on the flow characteristics and heat transfer performance of non-Newtonian fluid flow in a manifold microchannel (MMC) heat sink and traditional microchannel (TMC) heat sink. The non-Newtonian fluid was described by the power-law model. The analyses concentrated on the non-Newtonian fluid effect on the heat transfer performance, including the heat transfer efficiency and uniformity of temperature distribution, as well as the influence of inlet/outlet configurations on fluid flow and heat transfer. Comparing with Newtonian fluid flow, pseudo-plastic fluid could reduce the drag resistance in both MMC and TMC, while the dilatant fluid brought in quite larger drag resistance. For the heat transfer performance, the introduction of pseudo-plastic fluid flow greatly improved the heat transfer efficiency owing to the generation of secondary flow due to the shear-thinning property. Besides, the temperature distribution in MMC was more uniform by using pseudo-plastic fluid. Moreover, the inlet/outlet configuration was also important for the design and arrangement of microchannel heat sinks, since the present work showed that the maximum temperature was prone to locating in the corners near the inlet and outlet. This work provides guidance for optimal design of small-scale heat transfer devices in many cooling applications, such as biomedical chips, electronic systems, and

Influence of gamma radiation on the physicochemical and rheological properties of sterculia gum polysaccharides

International Nuclear Information System (INIS)

Singh, Baljit; Sharma, Vikrant

2013-01-01

Keeping in view the influence of gamma radiation on the physiochemical properties of the polysaccharides and their importance in the food and pharmaceutical industry, in the present study attempt has been made to investigate the effects of absorbed dose on FTIR, XRD, SEMs, absorbance, pH, solubility, water absorption capacity, emulsion stability and rheology of sterculia gum. Increase in solubility and decrease in swellability of gum has been observed on increasing the absorbed dose. The emulsion stability has improved for the gum sample irradiated with total dose of 8.1±0.2 kGy. Apparent viscosity of gum solution first increased with increase in dose from 0 to 8.1±0.2 kGy than decreased with regular trends with further increase in total absorbed dose. Flow behavior of gum solution shifted to Newtonian from non-Newtonian with increasing the dose. - Highlights: • Solubility increased and swellability decreased of gum on increasing the total dose. • Apparent viscosity of gum solution increased upto 8.1 kGy then decreased. • Emulsion stability improved for gum irradiated with total dose of 8.1 kGy. • Flow behavior shifted to Newtonian from non-Newtonian with increasing total dose

Determination of the diffusion coefficient of salts in non-Newtonian liquids by the Taylor dispersion method

Energy Technology Data Exchange (ETDEWEB)

Mey, Paula; Varges, Priscilla R.; Mendes, Paulo R. de Souza [Dept. of Mechanical Engineering. Pontificia Universidade Catolica do RJ (PUC-Rio), RJ (Brazil)], e-mails: prvarges@puc-rio.br, pmendes@puc-rio.br

2010-07-01

This research looked for a method to determine the binary diffusion coefficient D of salts in liquids (especially in drilling fluids) not only accurately, but in a reasonable time. We chose to use the Taylor Dispersion Method. This technique has been used for measuring binary diffusion coefficients in gaseous, liquid and supercritical fluids, due to its simplicity and accuracy. In the method, the diffusion coefficient is determined by the analysis of the dispersion of a pulse of soluble material in a solvent flowing laminarly through a tube. This work describes the theoretical basis and the experimental requirements for the application of the Taylor Dispersion Method, emphasizing the description of our experiment. A mathematical formulation for both Newtonian and non-Newtonian fluids is presented. The relevant sources of errors are discussed. The experimental procedure and associated analysis are validated by applying the method in well known systems, such as NaCl in water.D of salts in liquids (especially in drilling fluids) not only accurately, but in a reasonable time. We chose to use the Taylor Dispersion Method. This technique has been used for measuring binary diffusion coefficients in gaseous, liquid and supercritical fluids, due to its simplicity and accuracy. In the method, the diffusion coefficient is determined by the analysis of the dispersion of a pulse of soluble material in a solvent flowing laminarly through a tube. This work describes the theoretical basis and the experimental requirements for the application of the Taylor Dispersion Method, emphasizing the description of our experiment. A mathematical formulation for both Newtonian and non-Newtonian fluids is presented. The relevant sources of errors are discussed. The experimental procedure and associated analysis are validated by applying the method in well known systems, such as NaCl in water. (author)

Structural Optimization of non-Newtonian Microfluidics

DEFF Research Database (Denmark)

Jensen, Kristian Ejlebjærg

2013-01-01

Many of the biological fluids analyzed in Lab-on-a-Chip systems contain elastic components, which gives the fluids elastic character. Such fluids are said to be non-Newtonian or, more precisely, viscoelastic. They can give rise to exotic effects on the macroscale, which are never seen for fluids...... with components relying on viscoelastic effects, but the non-intuitive nature of these fluids complicates the design process. This thesis combines the method of topology optimization with differential constitutive equations, which govern the flow of viscoelastic fluids. The optimization method iteratively...... finite element package. The code is capable of calculating the viscoelastic flow in a benchmark geometry, and we hope that it will help newcomers as well as experienced researchers in the field of differential constitutive equations. v...

Problems in the extrapolation of laboratory rheological data

Science.gov (United States)

Paterson, M. S.

1987-02-01

The many types of variables and deformation regimes that need to be taken into account in extrapolating rheological behaviour from the laboratory to the earth are reviewed. The problems of extrapolation are then illustrated with two particular cases. In the case of divine-rich rocks, recent experimental work indicates that, within present uncertainties of extrapolation, the flow in the upper mantle could be either grain size dependent and near-Newtonian or grain size independent and distinctly non-Newtonian. Both types of behaviour would be influenced by the present of trace amounts of water. In the case of quartz-rich rocks, the uncertainties are even greater and it is still premature to attempt any extrapolation to geological conditions except as an upper bound; the fugacity and the scale of dispersion of the water are probably two important variables but the quantitative laws governing their influence are not yet clear.

COMPARISON BETWEEN DIFFERENT MODELS FOR RHEOLOGICAL CHARACTERIZATION OF ACTIVATED SLUDGE

Directory of Open Access Journals (Sweden)

A. H. Khalili Garakani

2011-09-01

Full Text Available Activated sludge flow rheology is a very complicated phenomenon. Studies related to activated sludge tend to classify sludge as non-Newtonian fluid. Until now, several theories have been built to describe the complex behavior of activated sludge with varying degrees of success. In this article, seven different models for viscosity of non-Newtonian fluids (i.e., Power law, Bingham plastic, Herschel-Bulkley, Casson, Sisko, Carreau and Cross were considered to evaluate their predictive capability of apparent viscosity of activated sludge. Results showed that although evaluating the constants in the four-parameter models is difficult, they provide the best prediction of viscosity in the whole range of shear rates for activated sludge. For easier prediction of viscosity at different mixed liquor suspended solids (2.74-31g/L, temperature (15-25°C and shear rate (1-1000/s, simple correlations were proposed. Comparing the results with the experimental data revealed that the proposed correlations are in good agreement with real apparent viscosities.

Physics of Life: A Model for Non-Newtonian Properties of Living Systems

Science.gov (United States)

Zak, Michail

2010-01-01

This innovation proposes the reconciliation of the evolution of life with the second law of thermodynamics via the introduction of the First Principle for modeling behavior of living systems. The structure of the model is quantum-inspired: it acquires the topology of the Madelung equation in which the quantum potential is replaced with the information potential. As a result, the model captures the most fundamental property of life: the progressive evolution; i.e. the ability to evolve from disorder to order without any external interference. The mathematical structure of the model can be obtained from the Newtonian equations of motion (representing the motor dynamics) coupled with the corresponding Liouville equation (representing the mental dynamics) via information forces. All these specific non-Newtonian properties equip the model with the levels of complexity that matches the complexity of life, and that makes the model applicable for description of behaviors of ecological, social, and economical systems. Rather than addressing the six aspects of life (organization, metabolism, growth, adaptation, response to stimuli, and reproduction), this work focuses only on biosignature ; i.e. the mechanical invariants of life, and in particular, the geometry and kinematics of behavior of living things. Living things obey the First Principles of Newtonian mechanics. One main objective of this model is to extend the First Principles of classical physics to include phenomenological behavior on living systems; to develop a new mathematical formalism within the framework of classical dynamics that would allow one to capture the specific properties of natural or artificial living systems such as formation of the collective mind based upon abstract images of the selves and non-selves; exploitation of this collective mind for communications and predictions of future expected characteristics of evolution; and for making decisions and implementing the corresponding corrections if

Rheology v.2 theory and applications

CERN Document Server

Eirich, Frederick

1958-01-01

Rheology: Theory and Applications, Volume II deals with the specific rheological subjects, such as deformational behavior in relation to the classic subjects and topics of rheology. This volume is divided into 13 chapters. Considerable chapters are devoted to the theory and aspects of viscoelastic and relaxation phenomena, as well as the applied theory concerning substances related to these phenomena, including elastomers, gelatins, and fibers. Other chapters cover the general principles of geological deformations derived from the study of less """"immobile"""" objects. The remaining chapt

On Laminar Flow of Non-Newtonian Fluids in Porous Media

KAUST Repository

Fayed, Hassan E.

2015-10-20

Flow of generalized Newtonian fluids in porous media can be modeled as a bundle of capillary tubes or a pore-scale network. In general, both approaches rely on the solution of Hagen–Poiseuille equation using power law to estimate the variations in the fluid viscosity due to the applied shear rate. Despite the effectiveness and simplicity, power law tends to provide unrealistic values for the effective viscosity especially in the limits of zero and infinite shear rates. Here, instead of using power law, Carreau model (bubbles, drops, and particles in non-Newtonian fluids. Taylor & Francis Group, New York, 2007) is used to determine the effective viscosity as a function of the shear strain rate. Carreau model can predict accurately the variation in the viscosity at all shear rates and provide more accurate solution for the flow physics in a single pore. Using the results for a single pore, normalized Fanning friction coefficient has been calculated and plotted as a function of the newly defined Reynolds number based on pressure gradient. For laminar flow, the variation in the friction coefficient with Reynolds number has been plotted and scaled. It is observed that generalized Newtonian fluid flows show Newtonian nature up to a certain Reynolds number. At high Reynolds number, deviation from the Newtonian behavior is observed. The main contribution of this paper is to present a closed-form solution for the flow in a single pore using Carreau model, which allows for fast evaluation of the relationship between flux and pressure gradient in an arbitrary pore diameter. In this way, we believe that our development will open the perspectives for using Carreau models in pore-network simulations at low computational costs to obtain more accurate prediction for generalized Newtonian fluid flows in porous media.

On Laminar Flow of Non-Newtonian Fluids in Porous Media

KAUST Repository

Fayed, Hassan E.; Sheikh, Nadeem A.; Iliev, Oleg

2015-01-01

Flow of generalized Newtonian fluids in porous media can be modeled as a bundle of capillary tubes or a pore-scale network. In general, both approaches rely on the solution of Hagen–Poiseuille equation using power law to estimate the variations in the fluid viscosity due to the applied shear rate. Despite the effectiveness and simplicity, power law tends to provide unrealistic values for the effective viscosity especially in the limits of zero and infinite shear rates. Here, instead of using power law, Carreau model (bubbles, drops, and particles in non-Newtonian fluids. Taylor & Francis Group, New York, 2007) is used to determine the effective viscosity as a function of the shear strain rate. Carreau model can predict accurately the variation in the viscosity at all shear rates and provide more accurate solution for the flow physics in a single pore. Using the results for a single pore, normalized Fanning friction coefficient has been calculated and plotted as a function of the newly defined Reynolds number based on pressure gradient. For laminar flow, the variation in the friction coefficient with Reynolds number has been plotted and scaled. It is observed that generalized Newtonian fluid flows show Newtonian nature up to a certain Reynolds number. At high Reynolds number, deviation from the Newtonian behavior is observed. The main contribution of this paper is to present a closed-form solution for the flow in a single pore using Carreau model, which allows for fast evaluation of the relationship between flux and pressure gradient in an arbitrary pore diameter. In this way, we believe that our development will open the perspectives for using Carreau models in pore-network simulations at low computational costs to obtain more accurate prediction for generalized Newtonian fluid flows in porous media.

Microrheological observations of the onset of non-Newtonian behavior in suspensions

Energy Technology Data Exchange (ETDEWEB)

Mondy, L A; Graham, A L; Gottlieb, M

1988-01-01

As the column fraction of solids increases above about 0.30, suspensions of non-Brownian, uniform spheres in Newtonian liquids begin to exhibit shear-thinning, normal stresses, and other non- Newtonian behavior. Here, we report on observations obtained from falling-ball and capillary rheometry at these high volume fractions. Specifically, we find that measured viscosity values are dependent on the size-scale of the viscometer (cylinder diameter, D, and falling- ball diameter, d) relative to the diameter of the suspended spheres d/sub s/. We report the dependence of the measured viscosity on the ratios d/d/sub s/, D/d, and D/d/sub s/, as well as critical values of these ratios above which the apparent viscosity is constant. 5 refs., 3 figs., 1 tab.

External gear pumps operating with non-Newtonian fluids: Modelling and experimental validation

Science.gov (United States)

Rituraj, Fnu; Vacca, Andrea

2018-06-01

External Gear Pumps are used in various industries to pump non-Newtonian viscoelastic fluids like plastics, paints, inks, etc. For both design and analysis purposes, it is often a matter of interest to understand the features of the displacing action realized by meshing of the gears and the description of the behavior of the leakages for this kind of pumps. However, very limited work can be found in literature about methodologies suitable to model such phenomena. This article describes the technique of modelling external gear pumps that operate with non-Newtonian fluids. In particular, it explains how the displacing action of the unit can be modelled using a lumped parameter approach which involves dividing fluid domain into several control volumes and internal flow connections. This work is built upon the HYGESim simulation tool, conceived by the authors' research team in the last decade, which is for the first time extended for the simulation of non-Newtonian fluids. The article also describes several comparisons between simulation results and experimental data obtained from numerous experiments performed for validation of the presented methodology. Finally, operation of external gear pump with fluids having different viscosity characteristics is discussed.

Rheological properties of salep powder-milk mixture.

Science.gov (United States)

Develi Işıklı, Nursel; Dönmez, Mehmet Necmi; Kozan, Nejat; Karababa, Erşan

2015-10-01

Rheological properties of salep-milk mixture as hot drink were evaluated using a rotational viscometer at different temperature (45, 50, 55, 60, and 65 °C) and salep concentration (0.75, 1.00, and 1.25 w/v, %). All salep-milk mixtures exhibited non-Newtonian behavior. The shear rate /shear stress data obtained from forward and backward directions were examined by common rheological models such as power law, Herschel-Bulkey, Casson and Bingham plastic models. Among the common models, the power-law model fitted the shear rate and shear stress data for 1.00 and 1.25 % salep concentration at all temperature. The Bingham plastic model described well the flow behavior of the salep-milk mixtures in 0.75 % salep concentration at all temperature. Flow behavior index (n), according to the power law and Herschel-Bulkey models decreased with an increase in salep concentration and a decrease of temperature. The consistency coefficient decreased with temperature and increased with salep concentration.

Aplicação de um Modelo Reológico Não-Linear em Sistemas Poliméricos Dilatantes Application of Non-Linear Rheological Model to Shear-Tickening Polymeric Systems

Directory of Open Access Journals (Sweden)

Rômulo F. Navarro

2002-01-01

Full Text Available A dilatância é um comportamento reológico comum a vários sistemas poliméricos embora não ocorra em polímeros puros. Existem várias teorias aplicáveis à explicação desse fenômeno e alguns modelos matemáticos para o ajuste de dados experimentais de quatro de suas seis formas de ocorrência. Neste trabalho é dado enfoque à dilatância antecedida por um comportamento newtoniano e sucedida pelo comportamento pseudoplástico. Para ajustar dados constantes da literatura para sistemas desse tipo, é apresentado um modelo híbrido e não-linear. Para o teste do modelo foram utilizados dados existentes na literatura para solução de alfa,ômega poli(t-butilestireno em óleo mineral e suspensão de partículas do copolímero de estireno com acrilato de metila em solução aquosa de poli(ácido acrílico. O modelo proposto apresenta boa concordância com os dados experimentais.Shear-thickening (dilatant behavior is common in several polymeric systems, but not in pure polymers. There are many theories that can be used to describe shear-thickening and some mathematical models that fit experimental data of three of its six types: dilatant, newtonian-dilatant, newtonian-dilatant-pseudoplastic, viscoplastic-dilatant, pseudoplastic-dilatant and newtonian-pseudoplastic-newtonian-dilatant sequences. This work deals with the behavior of newtonian-dilatant-pseudoplastic sequence behavior and proposes a hybrid, non-linear and viscous model to fit the experimental data from systems that present such rheological behavior. The systems under investigation were: a solution of alpha,omega poly(t-butylstyrene in a mineral oil (3g/dl (sample 1 and b suspension of styrene -- methyl acrylate copolymer (S-co-MA particles (15% vol. in a poly(acrylic acid (PAA (1% wt and water solution (sample 2. The proposed model agrees with the experimental data analysed.

Effect of the fructose and glucose concentration on the rheological ...

African Journals Online (AJOL)

Jose Luis Montañez Soto

2013-03-20

Mar 20, 2013 ... Key words: High fructose syrups, viscosity, rheological behavior, Newtonian fluids. ... demanded by the pharmaceuticals, food and beverage industries due to its ... determine the preferred quality by the consumer through.

Shear banding, discontinuous shear thickening, and rheological phase transitions in athermally sheared frictionless disks

Science.gov (United States)

Vâgberg, Daniel; Olsson, Peter; Teitel, S.

2017-05-01

We report on numerical simulations of simple models of athermal, bidisperse, soft-core, massive disks in two dimensions, as a function of packing fraction ϕ , inelasticity of collisions as measured by a parameter Q , and applied uniform shear strain rate γ ˙. Our particles have contact interactions consisting of normally directed elastic repulsion and viscous dissipation, as well as tangentially directed viscous dissipation, but no interparticle Coulombic friction. Mapping the phase diagram in the (ϕ ,Q ) plane for small γ ˙, we find a sharp first-order rheological phase transition from a region with Bagnoldian rheology to a region with Newtonian rheology, and show that the system is always Newtonian at jamming. We consider the rotational motion of particles and demonstrate the crucial importance that the coupling between rotational and translational degrees of freedom has on the phase structure at small Q (strongly inelastic collisions). At small Q , we show that, upon increasing γ ˙, the sharp Bagnoldian-to-Newtonian transition becomes a coexistence region of finite width in the (ϕ ,γ ˙) plane, with coexisting Bagnoldian and Newtonian shear bands. Crossing this coexistence region by increasing γ ˙ at fixed ϕ , we find that discontinuous shear thickening can result if γ ˙ is varied too rapidly for the system to relax to the shear-banded steady state corresponding to the instantaneous value of γ ˙.

Flow characteristics of Newtonian and non-Newtonian fluids in a vessel stirred by a 60° pitched blade impeller

Directory of Open Access Journals (Sweden)

Jamshid M. Nouri

2008-03-01

Full Text Available Mean and rms velocity characteristics of two Newtonian flows at Reynolds numbers of 12,800 (glycerin solution and 48,000 (water and of a non-Newtonian flow (0.2% CMC solution, at a power number similar to the Newtonian glycerin flow in a mixing vessel stirred by a 60° pitched blade impeller have been measured by laser Doppler velocimetry (LDV. The velocity measurements, resolved over 360° and 1.08° of impeller rotation, showed that the mean flow of the two power number matched glycerin and CMC flows were similar to within 3% of the impeller tip velocity and the turbulence intensities generally lower in the CMC flow by up to 5% of the tip velocity. The calculated mean flow quantities showed similar discharge coefficient and pumping efficiency in all three flows and similar strain rate between the two power number matched glycerin and CMC flows; the strain rate of the higher Reynolds number Newtonian flow was found to be slightly higher. The energy balance around the impeller indicated that the CMC flow dissipated up to 9% more of the total input power and converted 7% less into the turbulence compared to the glycerin flow with the same power input which could lead to less effective mixing processes where the micro-mixing is important.

Rheological Behaviour of Water-in-Light Crude Oil Emulsion

Science.gov (United States)

Husin, H.; Taju Ariffin, T. S.; Yahya, E.

2018-05-01

Basically, emulsions consist of two immiscible liquids which have different density. In petroleum industry, emulsions are undesirable due to their various costly problems in term of transportation difficulties and production loss. A study of the rheological behaviour of light crude oil and its mixture from Terengganu were carried out using Antoon Paar MCR 301 rheometer operated at pressure of 2.5 bar at temperature C. Water in oil emulsions were prepared by mixing light crude oil with different water volume fractions (20%, 30% and 40%). The objectives of present paper are to study the rheological behaviour of emulsion as a fuction of shear rate and model analysis that fitted with the experimental data. The rheological models of Ostwald-De-Waele and Herschel-Bulkley were fitted to the experimental results. All models represented well the rheological data, with high values for the correlation coefficients. The result indicated that variation of water content influenced shear rate-shear stress rheogram of the prepared emulsions. In the case of 100% light crude oil, the study demonstrated non-Newtonian shear thickening behavior. However, for emulsion with different volume water ratios, the rheological behaviour could be well described by Herschel-Bulkley models due to the present of yield stress parameter (R2 = 0.99807). As a conclusion, rheological studies showed that volume water ratio have a great impact on the shear stress and viscosity of water in oil emulsion and it is important to understand these factors to avoid various costly problems.

The application of silicon sol-gel technology to forensic blood substitute development: Mimicking aspects of whole human blood rheology.

Science.gov (United States)

Stotesbury, Theresa; Illes, Mike; Wilson, Paul; Vreugdenhil, Andrew J

2017-01-01

Solution-gelation chemistry has promising applications in forensic synthetic blood substitute development. This research offers a silicon-based sol-gel approach to creating stable materials that share similar rheological properties to that of whole human blood samples. Room temperature, high water content, silicon sol-gels were created using the organosilane precursors 3-glycidoxypropyltrimethoxysilane and tetraethylorthosilicate along with various concentrations of filler and pigment. Shear-thinning non-Newtonian properties were observed within most formulations of the presented materials. The effects of colloidal concentration, temperature, age and filler addition on the viscosity of the sol-gels were investigated. SEM-EDS analysis was used to identify the behavior of the fillers within the film and support their inclusion for basic bloodstain pattern simulation. A final proposed candidate sol-gel was assessed using a previously reported passive drip simulation test on a hard, dry surface and passed. This works represents encouraging development in providing safe material alternatives to using whole human blood for forensic training and research. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Hydrodynamically Coupled Brownian Dynamics simulations for flow on non-Newtonian fluids

NARCIS (Netherlands)

Ahuja, Vishal Raju

2018-01-01

This thesis deals with model development for particle-based flow simulations of non-Newtonian fluids such as polymer solutions. A novel computational technique called Hydrodynamically Coupled Brownian Dynamics (HCBD) is presented in this thesis. This technique essentially couples the Brownian motion

Similarity solution of axisymmetric non-Newtonian wall jets with swirl

Czech Academy of Sciences Publication Activity Database

Kolář, Václav

2011-01-01

Roč. 12, č. 6 (2011), s. 3413-3420 ISSN 1468-1218 R&D Projects: GA AV ČR IAA200600801 Institutional research plan: CEZ:AV0Z20600510 Keywords : similarity solution * wall jets * non-Newtonian fluids * power-law fluids * swirl Subject RIV: BK - Fluid Dynamics Impact factor: 2.043, year: 2011

Instrumentation to Monitor Transient Periodic Developing Flow in Non-Newtonian Slurries

Energy Technology Data Exchange (ETDEWEB)

Bamberger, Judith A.; Enderlin, Carl W.

2013-11-15

Staff at Pacific Northwest National Laboratory have conducted mixing and mobilization experiments with non-Newtonian slurries that exhibit Bingham plastic and shear thinning behavior and shear strength. This paper describes measurement techniques applied to identify the interface between flowing and stationary regions of non-Newtonian slurries that are subjected to transient, periodic, developing flows. Techniques were developed to identify the boundary between the flowing and stationary regions, time to mix, characteristic velocities of the flow field produced by the symmetrically spaced nozzles, and the velocity of the upwell formed in the center of the tank by the intersection of flow from four symmetrically spaced nozzles that impinge upon the tank floor. Descriptions of the instruments and instrument performance are presented. These techniques were an effective approach to characterize mixing phenomena, determine mixing energy required to fully mobilize vessel contents and to determine mixing times for process evaluation.

Non-Newtonian fluids: Frictional pressure loss prediction for fully-developed flow in straight pipes

Science.gov (United States)

1991-10-01

ESDU 91025 discusses models used to describe the rheology of time independent pseudohomogeneous non-Newtonian fluids (power-law, Bingham, Herschel-Bulkley and a generalized model due to Metzner and Reed); they are used to calculate the laminar flow pressure drop (which is independent of pipe roughness in this regime). Values of a generalized Reynolds number are suggested to define transitional and turbulent flow. For turbulent flow in smooth pipes, pressure loss is estimated on the basis of an experimentally determined rheogram using either the Dodge-Metzner or Bowen approach depending on the available measurements. Bowen requires results for at least two pipe diameters. The choice of Dodge-Metzner when data are limited is discussed; seven possible methods are assessed against five sets of experimental results drawn from the literature. No method is given for transitional flow, which it is suggested should be avoided, but the turbulent correlation is recommended because it will yield an overestimate. Suggestions are made for the treatment of roughness effects. Several worked examples illustrate the use of the methods and a flowchart guides the user through the process from experimentally characterizing the behavior of the fluid to determining the pressure drop. A computer program, ESDUpac A9125, is also provided.

Open mathematical problems regarding non-Newtonian fluids

International Nuclear Information System (INIS)

Wilson, Helen J

2012-01-01

We present three open problems in the mathematical modelling of the flow of non-Newtonian fluids. The first problem is rather long standing: a discontinuity in the dependence of the rise velocity of a gas bubble on its volume. This is very well characterized experimentally but not, so far, fully reproduced either numerically or analytically. The other two are both instabilities. The first is observed experimentally but never predicted analytically or numerically. In the second instability, numerical studies reproduce the experimental observations but there is as yet no analytical or semi-analytical prediction of the linear instability which must be present. (invited article)

Non-Newtonian Flow-Induced Deformation From Pressurized Cavities in Absorbing Porous Tissues

Science.gov (United States)

Ahmed, Aftab; Siddique, Javed

2017-11-01

We investigate the behavior of a spherical cavity in a soft biological tissue modeled as a deformable porous material during an injection of non-Newtonian fluid that follows a power law model. Fluid flows into the neighboring tissue due to high cavity pressure where it is absorbed by capillaries and lymphatics at a rate proportional to the local pressure. Power law fluid pressure and displacement of solid in the tissue are computed as function of radial distance and time. Numerical solutions indicate that shear thickening fluids exhibit less fluid pressure and induce small solid deformation as compared to shear thinning fluids. The absorption in the biological tissue increases as a consequence of flow induced deformation for power law fluids. In most cases non-Newtonian results are compared with viscous fluid case to magnify the differences.

Steady-state shear characteristics of Aspergillus niger broths

Energy Technology Data Exchange (ETDEWEB)

Svihla, C.K.; Dronawat, S.N.; Hanley, T.R. [Univ. of Louisville, KY (United States)

1995-12-31

It can be difficult to obtain reliable rheological data for filamentous fermentation broths using conventional instruments. One common approach is to measure the torque drawn by an impeller rotating in the suspension. Many previous workers have assumed that the applicable shear rate in such a device is related to the impeller speed by a fluid-independent constant determined by calibration with Newtonian and non-Newtonian fluids. The rheology of Aspergillus niger broths have been characterized using the impeller viscometer approach. The changes in the broth rheology were measured, and used to interpret the growth of biomass and the evolution of the microorganism morphology.

Non-Newtonian fluid flow in annular pipes and entropy generation ...

Indian Academy of Sciences (India)

analytical solution for the flow of third-grade non-Newtonian fluid in a pipe .... where c1,c2,d1,d2,t0,1,2...7,h1,h2,k1,2... ,12,m1 and m2 are defined as ..... Yurusoy M 2004 Flow of a third grade fluid between concentric circular cylinders. Math.

Non-newtonian deformation of co-based metallic glass at low stresses

NARCIS (Netherlands)

Fursova, YV; Khonik, VA; Csach, K; Ocelik, Vaclav

2000-01-01

The results of precision measurements of creep in Co-based metallic glass are presented. It is shown that, in spite of generally accepted concepts, plastic flow at low stresses under intense structural relaxation conditions is of a non-Newtonian type. Consequences of this fact are considered. (C)

Understanding the rheology of two and three-phase magmas

Science.gov (United States)

Coats, R.; Cai, B.; Kendrick, J. E.; Wallace, P. A.; Hornby, A. J.; Miwa, T.; von Aulock, F. W.; Ashworth, J. D.; Godinho, J.; Atwood, R. C.; Lee, P. D.; Lavallée, Y.

2017-12-01

The rheology of magma plays a fundamental role in determining the style of a volcanic eruption, be it explosive or effusive. Understanding how magmas respond to changes in stress/ strain conditions may help to enhance eruption forecast models. The presence of crystals and bubbles in magmas alter the viscosity of suspensions and favor a non-Newtonian response. Thus, with the aim of grasping the rheological behavior of volcanic materials, uniaxial compressive tests were performed on natural and synthetic samples. A suite of variably porous (10-32 vol.%), highly crystalline ( 50 vol.%) dacite from the 1991-95 eruption of Mt Unzen, Japan, was selected as the natural material, while synthetic samples were sintered with desired porosities (Diamond Light Source. Unexpectedly, these observations suggest that fractures nucleate in crystals due to crystal interactions, before propagating through the interstitial melt. This ongoing study promises to uncover the way crystal-bearing magmas flow or fail, necessary to constrain magmatic processes and volcanic hazards.

The rheological characterisation of non-newtonian slurries using a novel balanced beam tube viscometer

International Nuclear Information System (INIS)

Slatter, P.T.

1986-09-01

The novel Balanced Beam Tube Viscometer (BBTV), developed at the University of Cape Town, has been further developed and refined. Extensive work has been done in the following areas: (i) The effective length of BBTV tubes. (ii) Interpretation of the data obtained using the BBTV in both the laminar and turbulent flow regimes. (iii) Comparison with the rotary type viscometer. Kaolin clay and uranium tailings, slimes and slurries of different particle size range and concentration have been successfully characterised by yield-pseudoplastic rheologies using the BBTV. The BBTV is in fact a miniature pipeline and it has been shown that it is capable of producing valid turbulent flow data and indicating the laminar/turbulent transition region in the two tube sizes

Peristaltic Transport of a Rheological Fluid: Model for Movement of Food Bolus Through Esophagus

OpenAIRE

Misra, J. C.; Maiti, S.

2011-01-01

Fluid mechanical peristaltic transport through esophagus has been of concern in the paper. A mathematical model has been developed with an aim to study the peristaltic transport of a rheological fluid for arbitrary wave shapes and tube lengths. The Ostwald-de Waele power law of viscous fluid is considered here to depict the non-Newtonian behaviour of the fluid. The model is formulated and analyzed with the specific aim of exploring some important information concerning the movement of food bo...

Analysis of flow and LDL concentration polarization in siphon of internal carotid artery: Non-Newtonian effects.

Science.gov (United States)

Sharifi, Alireza; Niazmand, Hamid

2015-10-01

Carotid siphon is known as one of the risky sites among the human intracranial arteries, which is prone to formation of atherosclerotic lesions. Indeed, scientists believe that accumulation of low density lipoprotein (LDL) inside the lumen is the major cause of atherosclerosis. To this aim, three types of internal carotid artery (ICA) siphon have been constructed to examine variations of hemodynamic parameters in different regions of the arteries. Providing real physiological conditions, blood considered as non-Newtonian fluid and real velocity and pressure waveforms have been employed as flow boundary conditions. Moreover, to have a better estimation of risky sites, the accumulation of LDL particles has been considered, which has been usually ignored in previous relevant studies. Governing equations have been discretized and solved via open source OpenFOAM software. A new solver has been built to meet essential parameters related to the flow and mass transfer phenomena. In contrast to the common belief regarding negligible effect of blood non-Newtonian behavior inside large arteries, current study suggests that the non-Newtonian blood behavior is notable, especially on the velocity field of the U-type model. In addition, it is concluded that neglecting non-Newtonian effects underestimates the LDL accumulation up to 3% in the U-type model at the inner side of both its bends. However, in the V and C type models, non-Newtonian effects become relatively small. Results also emphasize that the outer part of the second bend at the downstream is also at risk similar to the inner part of the carotid bends. Furthermore, from findings it can be implied that the risky sites strongly depend on the ICA shape since the extension of the risky sites are relatively larger for the V-type model, while the LDL concentrations are higher for the C-type model. Copyright © 2015 Elsevier Ltd. All rights reserved.

Effect of Carreau-Yasuda rheological parameters on subcritical Lapwood convection in horizontal porous cavity saturated by shear-thinning fluid

Science.gov (United States)

Khechiba, Khaled; Mamou, Mahmoud; Hachemi, Madjid; Delenda, Nassim; Rebhi, Redha

2017-06-01

The present study is focused on Lapwood convection in isotropic porous media saturated with non-Newtonian shear thinning fluid. The non-Newtonian rheological behavior of the fluid is modeled using the general viscosity model of Carreau-Yasuda. The convection configuration consists of a shallow porous cavity with a finite aspect ratio and subject to a vertical constant heat flux, whereas the vertical walls are maintained impermeable and adiabatic. An approximate analytical solution is developed on the basis of the parallel flow assumption, and numerical solutions are obtained by solving the full governing equations. The Darcy model with the Boussinesq approximation and energy transport equations are solved numerically using a finite difference method. The results are obtained in terms of the Nusselt number and the flow fields as functions of the governing parameters. A good agreement is obtained between the analytical approximation and the numerical solution of the full governing equations. The effects of the rheological parameters of the Carreau-Yasuda fluid and Rayleigh number on the onset of subcritical convection thresholds are demonstrated. Regardless of the aspect ratio of the enclosure and thermal boundary condition type, the subcritical convective flows are seen to occur below the onset of stationary convection. Correlations are proposed to estimate the subcritical Rayleigh number for the onset of finite amplitude convection as a function of the fluid rheological parameters. Linear stability of the convective motion, predicted by the parallel flow approximation, is studied, and the onset of Hopf bifurcation, from steady convective flow to oscillatory behavior, is found to depend strongly on the rheological parameters. In general, Hopf bifurcation is triggered earlier as the fluid becomes more and more shear-thinning.

Thermal, emulsifying and rheological properties of polysaccharides sequentially extracted from Vaccinium bracteatum Thunb leaves.

Science.gov (United States)

Xu, Qi-Xin; Shi, Jun-Jun; Zhang, Jian-Guo; Li, Ling; Jiang, Li; Wei, Zhao-Jun

2016-12-01

Plant polysaccharides are widely used in food industry as thickening and gelling agents and these attributes largely depend on their thermal, emulsifying and rheological properties. As known, the extraction methods always bring about the diversification of property and functions of polysaccharides. Thus, the Vaccinium bracteatum Thunb leaves polysaccharides (VBTLP) were sequentially extracted using hot buffer (HBSS), chelating agent (CHSS), dilute alkaline (DASS) and concentrated alkaline (CASS). The thermal, emulsifying and rheological properties of VBTLP were investigated in the present study. Within the range of 20-225°C, CHSS showed the highest peak temperature, whereas HBSS displayed the highest endothermic enthalpy and highest emulsifying activity, while, CASS showed the longest emulsifying stability. The VBTLP solutions exhibited non-Newtonian shear-thinning behavior within the concentrations of 0.6-2.5%. The apparent viscosity of VBTLP solution decreased under following conditions: acidic pH (4.0), alkaline pH (10.0), in the presence of Ca 2+ and at high temperature, while it increased in the presence of Na + and at freezing conditions. The modulus G' and G″ of VBTLP solutions were increased with increasing oscillation frequency, and the crossover frequency shifted to lower values when the polysaccharide content increased. The above results of thermal, emulsifying and rheological properties of VBTLPs supplied the basis for V. bracteatum leaves in potential industrial applications of foods. Copyright © 2016 Elsevier B.V. All rights reserved.

Low Density Lipoprotein and Non-Newtonian Oscillating Flow Biomechanical Parameters for Normal Human Aorta.

Science.gov (United States)

Soulis, Johannes V; Fytanidis, Dimitrios K; Lampri, Olga P; Giannoglou, George D

2016-04-01

The temporal variation of the hemodynamic mechanical parameters during cardiac pulse wave is considered as an important atherogenic factor. Applying non-Newtonian blood molecular viscosity simulation is crucial for hemodynamic analysis. Understanding low density lipoprotein (LDL) distribution in relation to flow parameters will possibly spot the prone to atherosclerosis aorta regions. The biomechanical parameters tested were averaged wall shear stress (AWSS), oscillatory shear index (OSI) and relative residence time (RRT) in relation to the LDL concentration. Four non-Newtonian molecular viscosity models and the Newtonian one were tested for the normal human aorta under oscillating flow. The analysis was performed via computational fluid dynamic. Tested viscosity blood flow models for the biomechanical parameters yield a consistent aorta pattern. High OSI and low AWSS develop at the concave aorta regions. This is most noticeable in downstream flow region of the left subclavian artery and at concave ascending aorta. Concave aorta regions exhibit high RRT and elevated LDL. For the concave aorta site, the peak LDL value is 35.0% higher than its entrance value. For the convex site, it is 18.0%. High LDL endothelium regions located at the aorta concave site are well predicted with high RRT. We are in favor of using the non-Newtonian power law model for analysis. It satisfactorily approximates the molecular viscosity, WSS, OSI, RRT and LDL distribution. Concave regions are mostly prone to atherosclerosis. The flow biomechanical factor RRT is a relatively useful tool for identifying the localization of the atheromatic plaques of the normal human aorta.

Study of rheology and friction factor of natural food hydrocolloid gels

Directory of Open Access Journals (Sweden)

Vojtěch Kumbár

2017-01-01

Full Text Available Differences in the rheology and friction factor of natural food hydrocolloid gels were studied in this paper. The practical importance of the knowledge of the rheological parameters is quite evident. The experimental data were carried out using a concentric cylinder rotary viscometer. It was prepared 1% hydrocolloid solutions (hydrogels. Hydrogels of the natural gums extracted from the seeds of the plants and plant tubers have been used - carob gum (from the seeds of Ceratonia siliqua, guar gum (from the seeds of Cyamopsis tetragonoloba and tara gum (from the seeds of Caesalpinia spinosa. Rheological behaviour has non-Newtonian pseudoplastic character and the flow curves were fitted using the Otswald - de Waele (power law model and Herschel - Bulkley model. The hydrogels exhibit shear thinning behaviour. The meaning of the rheological parameters on the friction factors during flow of hydrocolloid gels in the tube has been shown. Information on time dependent behaviour of tested liquids has been also obtained. Time dependent curves were fitted by the Gaussian model. Preliminary results obtained for a constant shear rate showed the thixotropic and time-dependent behaviour of the hydrogels. These parameters can be especially used in much software dealing with a numerical simulation of the flow problems.

Flocking particles in a non-Newtonian shear thickening fluid

Science.gov (United States)

Mucha, Piotr B.; Peszek, Jan; Pokorný, Milan

2018-06-01

We prove the existence of strong solutions to the Cucker–Smale flocking model coupled with an incompressible viscous non-Newtonian fluid with the stress tensor of a power–law structure for . The fluid part of the system admits strong solutions while the solutions to the CS part are weak. The coupling is performed through a drag force on a periodic spatial domain . Additionally, we construct a Lyapunov functional determining the large time behavior of solutions to the system.

MHD free convection flow of a non-Newtonian power-law fluid over ...

African Journals Online (AJOL)

... flow have been presented for various parameters such as Prandtl number, flow behavior index (n), porous plate parameter and magnetic parameter. The local Nusselt number and skin friction coefficient is also presented graphically. Keywords: Magnetohydrodynamic flow; free convection flow; Non-Newtonian power-law

Supersoft Symmetry Energy Encountering Non-Newtonian Gravity in Neutron Stars

International Nuclear Information System (INIS)

Wen Dehua; Li Baoan; Chen Liewen

2009-01-01

Considering the non-Newtonian gravity proposed in grand unification theories, we show that the stability and observed global properties of neutron stars cannot rule out the supersoft nuclear symmetry energies at suprasaturation densities. The degree of possible violation of the inverse-square law of gravity in neutron stars is estimated using an equation of state of neutron-rich nuclear matter consistent with the available terrestrial laboratory data.

Solitons as Newtonian particles

International Nuclear Information System (INIS)

Eboli, O.J.P.; Marques, G.C.

1982-07-01

The effect of external electromagnetic fields on non relativistic solitons is studied. Although the solitons are distorted by external fields, they still exhibit a Newtonian behavior. Some explicit examples of such a phenomenon are given, presenting solutions which exhibit Newtonian behavior for simple external fields. Furthermore, general results like charge and flux quantization are shown. (Author) [pt

Newtonian and pseudo-Newtonian Hill problem

International Nuclear Information System (INIS)

Steklain, A.F.; Letelier, P.S.

2006-01-01

A pseudo-Newtonian Hill problem based on the Paczynski-Wiita pseudo-Newtonian potential that reproduces general relativistic effects is presented and compared with the usual Newtonian Hill problem. Poincare maps, Lyapunov exponents and fractal escape techniques are employed to study bounded and unbounded orbits. In particular we consider the systems composed by Sun, Earth and Moon and composed by the Milky Way, the M2 cluster and a star. We find that some pseudo-Newtonian systems-including the M2 system-are more stable than their Newtonian equivalent

Simulating non-Newtonian flows with the moving particle semi-implicit method with an SPH kernel

International Nuclear Information System (INIS)

Xiang, Hao; Chen, Bin

2015-01-01

The moving particle semi-implicit (MPS) method and smoothed particle hydrodynamics (SPH) are commonly used mesh-free particle methods for free surface flows. The MPS method has superiority in incompressible flow simulation and simple programing. However, the crude kernel function is not accurate enough for the discretization of the divergence of the shear stress tensor by the particle inconsistency when the MPS method is extended to non-Newtonian flows. This paper presents an improved MPS method with an SPH kernel to simulate non-Newtonian flows. To improve the consistency of the partial derivative, the SPH cubic spline kernel and the Taylor series expansion are combined with the MPS method. This approach is suitable for all non-Newtonian fluids that can be described with τ  = μ(|γ|) Δ (where τ is the shear stress tensor, μ is the viscosity, |γ| is the shear rate, and Δ is the strain tensor), e.g., the Casson and Cross fluids. Two examples are simulated including the Newtonian Poiseuille flow and container filling process of the Cross fluid. The results of Poiseuille flow are more accurate than the traditional MPS method, and different filling processes are obtained with good agreement with previous results, which verified the validation of the new algorithm. For the Cross fluid, the jet fracture length can be correlated with We 0.28 Fr 0.78 (We is the Weber number, Fr is the Froude number). (paper)

Break-up of a non-Newtonian jet injected downwards in a ...

Indian Academy of Sciences (India)

atomization and spray coating, crop spraying, ink jet printing, printing of polymer transis- tors, and ... particular ones used in printing and coating, the liquids encountered are non-Newtonian. For breakup of ...... In-Press. Sussman M and Pukett E G 2000 A coupled level set and volume-of-fluid method for computing 3D and.

Influence of gamma radiation on the physicochemical and rheological properties of sterculia gum polysaccharides

Science.gov (United States)

Singh, Baljit; Sharma, Vikrant

2013-11-01

Keeping in view the influence of gamma radiation on the physiochemical properties of the polysaccharides and their importance in the food and pharmaceutical industry, in the present study attempt has been made to investigate the effects of absorbed dose on FTIR, XRD, SEMs, absorbance, pH, solubility, water absorption capacity, emulsion stability and rheology of sterculia gum. Increase in solubility and decrease in swellability of gum has been observed on increasing the absorbed dose. The emulsion stability has improved for the gum sample irradiated with total dose of 8.1±0.2 kGy. Apparent viscosity of gum solution first increased with increase in dose from 0 to 8.1±0.2 kGy than decreased with regular trends with further increase in total absorbed dose. Flow behavior of gum solution shifted to Newtonian from non-Newtonian with increasing the dose.

Flow pattern-based mass and heat transfer and frictional drag of gas-non-Newtonian liquid flow in helical coil: two- and three-phase systems

Science.gov (United States)

Thandlam, Anil Kumar; Das, Chiranjib; Majumder, Subrata Kumar

2017-04-01

Investigation of wall-liquid mass transfer and heat transfer phenomena with gas-Newtonian and non-Newtonian fluids in vertically helical coil reactor have been reported in this article. Experiments were conducted to investigate the effect of various dynamic and geometric parameters on mass and heat transfer coefficients in the helical coil reactor. The flow pattern-based heat and mass transfer phenomena in the helical coil reactor are highlighted at different operating conditions. The study covered a wide range of geometric parameters such as diameter of the tube ( d t ), diameter of the coil ( D c ), diameter of the particle ( d p ), pitch difference ( p/D c ) and concentrations of non-Newtonian liquid. The correlation models for the heat and mass transfer coefficient based on the flow pattern are developed which may be useful in process scale-up of the helical coil reactor for industrial application. The frictional drag coefficient was also estimated and analyzed by mass transfer phenomena based on the electrochemical method.

Numerical Analyses of the Non-Newtonian Flow Performance and Thermal Effect on a Bearing Coated with a High Tin Content

Directory of Open Access Journals (Sweden)

K. Mehala

2016-12-01

Full Text Available The hydrodynamic bearings are stressed by severe workings conditions, such as speed, load, and the oil will be increasingly solicit by pressure and shear. The Newtonian behavior is far from being awarded in this case, the most loaded bearings operating at very high speeds; the shear rate of the oil is of higher order. A numerical analysis of the behavior of non-Newtonian fluid for plain cylindrical journal bearing finite dimension coated with antifriction material with a high tin content, for to facilitate the accommodation of the surfaces and save the silk of the shaft in the case of a contact. this analyses is implemented using the code-ANSYS CFX, by solving the energy equation with the finite difference method, considering that laminar regime and the fluid is non Newtonian by using the power law Ostwald model, the coefficient n is equal to 1.25 and for different model such as Bingham, cross and Hereshek-Bulkley model. This study aims to better predict the non-Newtonian behavior of the oil film in bearings operating under more severe conditions. The purpose conducted during this study is to predict the effect of non-Newtonian behavior of the film; the journal bearing operating under severe conditions, the speed of rotation varies from 1000 to 9000 rpm and the bearing working under radial load 2 to 10 kN. Temperature and the pressure within the fluid film assumed non-Newtonian are high, with a coefficient n greater than 1 that is to say for viscoelastic fluids.

Rheological and physical properties of spray-dried mucilage obtained from Hylocereus undatus cladodes.

Science.gov (United States)

García-Cruz, E E; Rodríguez-Ramírez, J; Méndez Lagunas, L L; Medina-Torres, L

2013-01-02

This study examines the rheological behavior of reconstituted spray-dried mucilage isolated from the cladodes of pitahaya (Hylocereus undatus), the effects of concentration and its relationship with physical properties were analyzed in reconstituted solutions. Drying process optimization was carried out through the surface response method, utilizing a factorial 2(3) design with three central points, in order to evaluate yield and rheological properties. The reconstituted mucilage exhibited non-Newtonian shear-thinning behavior, which adequately fit the Cross model (R(2)>0.95). This dynamic response suggests a random coil configuration. The steady-shear viscosity and dynamic response are suitably correlated through the Cox-Merz rule, confirming the mucilage's stability of flow. Analysis of the physical properties of the mucilage (Tg, DTP, and particle morphology) explains the shear-thinning behavior. Copyright © 2012 Elsevier Ltd. All rights reserved.

CFD-PBM Coupled Simulation of an Airlift Reactor with Non-Newtonian Fluid

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Han Mei

2017-09-01

Full Text Available Hydrodynamics of an AirLift Reactor (ALR with tap water and non-Newtonian fluid was studied experimentally and by numerical simulations. The Population Balance Model (PBM with multiple breakup and coalescence mechanisms was used to describe bubble size characteristics in the ALR. The interphase forces for closing the two-fluid model were formulated by considering the effect of Bubble Size Distribution (BSD. The BSD in the ALR obtained from the coupled Computational Fluid Dynamics (CFD-PBM model was validated against results from digital imaging measurements. The simulated velocity fields of both the gas and liquid phases were compared to measured fields obtained with Particle Image Velocimetry (PIV. The simulated results show different velocity field profile features at the top of the ALR between tap water and non-Newtonian fluid, which are in agreement with experiments. In addition, good agreement between simulations and experiments was obtained in terms of overall gas holdup and bubble Sauter mean diameter.

Orbit classification in an equal-mass non-spinning binary black hole pseudo-Newtonian system

Science.gov (United States)

Zotos, Euaggelos E.; Dubeibe, F. L.; González, Guillermo A.

2018-04-01

The dynamics of a test particle in a non-spinning binary black hole system of equal masses is numerically investigated. The binary system is modeled in the context of the pseudo-Newtonian circular restricted three-body problem, such that the primaries are separated by a fixed distance and move in a circular orbit around each other. In particular, the Paczyński-Wiita potential is used for describing the gravitational field of the two non-Newtonian primaries. The orbital properties of the test particle are determined through the classification of the initial conditions of the orbits, using several values of the Jacobi constant, in the Hill's regions of possible motion. The initial conditions are classified into three main categories: (i) bounded, (ii) escaping and (iii) displaying close encounters. Using the smaller alignment index (SALI) chaos indicator, we further classify bounded orbits into regular, sticky or chaotic. To gain a complete view of the dynamics of the system, we define grids of initial conditions on different types of two-dimensional planes. The orbital structure of the configuration plane, along with the corresponding distributions of the escape and collision/close encounter times, allow us to observe the transition from the classical Newtonian to the pseudo-Newtonian regime. Our numerical results reveal a strong dependence of the properties of the considered basins with the Jacobi constant as well as with the Schwarzschild radius of the black holes.

Modeling of rheological characteristics of the fermented dairy products obtained by novel and traditional starter cultures.

Science.gov (United States)

Vukić, Dajana V; Vukić, Vladimir R; Milanović, Spasenija D; Ilicić, Mirela D; Kanurić, Katarina G

2018-06-01

Tree different fermented dairy products obtained by conventional and non-conventional starter cultures were investigated in this paper. Textural and rheological characteristics as well as chemical composition during 21 days of storage were analysed and subsequent data processing was performed by principal component analysis. The analysis of samples` flow behaviour was focused on their time dependent properties. Parameters of Power law model described flow behaviour of samples depended on used starter culture and days of storage. The Power law model was applied successfully to describe the flow of the fermented milk, which had characteristics of shear thinning and non-Newtonian fluid behaviour.

Comparison of rheological evaluation techniques and turbulent flow prediction of a simulated nuclear waste melter slurry

International Nuclear Information System (INIS)

Carleson, T.E.; Hart, R.E.; Drown, D.C.; Peterson, M.E.

1987-03-01

An experimental study was performed on a simulated nuclear waste slurry containing the type of waste sludge and glass-forming chemicals that will be converted to a stable glass in a high-temperature furnace. The rheological properties of the slurry must be determined in order to design the transport and mixing systems. The rheological parameters for the slurry were determined by a variety of viscometers including a rotational viscometer, a capillary tube viscometer, and a pipe flow apparatus. Experiments revealed the absence of wall slip and sufficient non-Newtonian behavior to require adjustments of the results. The slurry was characterized as a yield pseudoplastic fluid. Different rheological constants were obtained for all three viscometers. Predictions of the shear stress as a function of shear rate showed good agreement between the constants determined by the rotational viscometer and the pipe loop apparatus. Laminar and turbulent flows in the pipe loop correlated closely with a recent theoretical model. 16 refs., 16 figs., 5 tabs

Preparation and rheological studies of uncoated and PVA-coated magnetite nanofluid

International Nuclear Information System (INIS)

Khosroshahi, M.E.; Ghazanfari, L.

2012-01-01

Experimental studies of rheological behavior of uncoated magnetite nanoparticles (MNPs)U and polyvinyl alcohol (PVA) coated magnetite nanoparticles (MNPs)C were performed. A Co-precipitation technique under N 2 gas was used to prevent undesirable critical oxidation of Fe 2+ . The results showed that smaller particles can be synthesized in both cases by decreasing the NaOH concentration which in our case this corresponded to 35 nm and 7 nm using 0.9 M NaOH at 750 rpm for (MNPs)U and (MNPs)C. The stable magnetic fluid contained well-dispersed Fe 3 O 4 /PVA nanocomposites which indicated fast magnetic response. The rheological measurement of magnetic fluid indicated an apparent viscosity range (0.1–1.2) pa s at constant shear rate of 20 s −1 with a minimum value in the case of (MNPs)U at 0 T and a maximum value for (MNPs)C at 0.5 T. Also, as the shear rate increased from 20 s −1 to 150 s −1 at constant magnetic field, the apparent viscosity also decreased correspondingly. The water-based ferrofluid exhibited the non-Newtonian behavior of shear thinning under magnetic field. - Highlights: ► The stable water-based magnetic fluid with fast magnetic response was synthesized. ► The shear rate was increased from 20 S −1 to 150 S −1 at constant magnetic field. ► The viscosity of magnetic fluid decreased with increasing of shear rate. ► Viscosity range (0.1–1.2) pa s was measured for (MNPs)U and (MNPs)C. ► The ferrofluid was non-Newtonian (shear thinning) under magnetic field.

Entropy generation in non-Newtonian fluid flow in a slider bearing

Indian Academy of Sciences (India)

In the present study, entropy production in flow fields due to slider bearings is formulated. The rate of entropy generation is computed for different fluid properties and geometric configurations of the slider bearing. In order to account for the non-Newtonian effect, a special type of third-grade fluid is considered. It is found that ...

Investigation of thermal conductivity and rheological properties of nanofluids containing graphene nanoplatelets

Science.gov (United States)

2014-01-01

In the present study, stable homogeneous graphene nanoplatelet (GNP) nanofluids were prepared without any surfactant by high-power ultrasonic (probe) dispersion of GNPs in distilled water. The concentrations of nanofluids were maintained at 0.025, 0.05, 0.075, and 0.1 wt.% for three different specific surface areas of 300, 500, and 750 m2/g. Transmission electron microscopy image shows that the suspensions are homogeneous and most of the materials have been well dispersed. The stability of nanofluid was investigated using a UV-visible spectrophotometer in a time span of 600 h, and zeta potential after dispersion had been investigated to elucidate its role on dispersion characteristics. The rheological properties of GNP nanofluids approach Newtonian and non-Newtonian behaviors where viscosity decreases linearly with the rise of temperature. The thermal conductivity results show that the dispersed nanoparticles can always enhance the thermal conductivity of the base fluid, and the highest enhancement was obtained to be 27.64% in the concentration of 0.1 wt.% of GNPs with a specific surface area of 750 m2/g. Electrical conductivity of the GNP nanofluids shows a significant enhancement by dispersion of GNPs in distilled water. This novel type of nanofluids shows outstanding potential for replacements as advanced heat transfer fluids in medium temperature applications including solar collectors and heat exchanger systems. PMID:24410867

Rheology of unstable mineral emulsions

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Sokolović Dunja S.

2013-01-01

Full Text Available In this paper, the rheology of mineral oils and their unstable water emulsion were investigated. The oil samples were domestic crude oil UA, its fractions UA1, UA4 and blend semi-product UP1, while the concentration of oil in water emulsions was in the range from 1 up to 30%. The results were analyzed based on shear stress. The oil samples UA, UA1 and UP1 are Newtonian fluids, while UA4 is pseudoplastic fluid. The samples UA and UA4 show higher value of shear stress (83.75 Pa, 297 Pa, then other two samples UA1 and UP1 (18.41 Pa, 17.52 Pa. Rheology of investigated oils due to its complex chemical composition should be analyzed as a simultaneous effect of all their components. Therefore, structural composition of the oils was determined, namely content of paraffins, naphthenes, aromatics and asphaltenes. All samples contain paraffins, naphthenes and aromatics but only oils UA and UA4 contain asphaltenes as well. All investigated emulsions except 30% EUA4 are Newtonian fluids. The EUA4 30% emulsion shows pseudoplastic behaviour, and it is the only 30% emulsion among investigated ones that achieves lower shear stress then its oil. The characteristics of oil samples that could have an influence on their properties and their emulsion rheology, were determined. These characteristics are: neutralization number, interfacial tension, dielectric constant, and emulsivity. Oil samples UA and UA4 have significantly higher values of neutralization number, dielectric constants, and emulsivity. The sample UA has the lowest value of interface tension and the greatest emulsivity, indicating that this oil, among all investigated, has the highest preference for building emulsion. This could be the reason why 20% and 30% emulsions of the oil UA achieve the highest shear stress among all investigated emulsions.

How to recover Newtonian mechanics from non-relative quantum mechanics in limit ℎ→0

International Nuclear Information System (INIS)

Mei Shizhong

2001-01-01

It is assumed that when ℎ→0, correct non-relative quantum mechanics should be equivalent to Newtonian mechanics. Starting from this point, the authors slightly revised the widely accepted non-relative quantum mechanics such that the mechanics after modification is strictly equivalent to that before the modification when ℎ≠0, and equivalent to Newtonian mechanics in the limit ℎ→0. The significance lies in the possibility that if authors further postulate that corrected relative quantum mechanics is equivalent to Einstein's theory of relativity in the case ℎ→0, then authors may obtain different predictions from what produced by the former that will help to verify or improve it

Rheological behavior, chemical and physical characterization of soybean and cottonseed methyl esters submitted to thermal oxidation process

Energy Technology Data Exchange (ETDEWEB)

Silva, Adriano Sant' ana; Silva, Flavio Luiz Honorato da; Lima, Ezenildo Emanuel de; Carvalho, Maria Wilma N.C. [Universidade Federal de Campina Grande (CCT/UFCG), PB (Brazil). Centro de Ciencia e Tecnologia; Dantas, Hemeval Jales; Farias, Paulo de Almeida [Universidade Federal de Campina Grande (CTRN/UFCG), PB (Brazil). Centro de Tecnologia e Recursos Naturais

2008-07-01

In this study the effect of antioxidant terc-butylhydroxyanisol (BHA) on the oxidative stability of soybean and cottonseed methyl esters subjected to thermal degradation at 100 deg C was studied. Soybean and cottonseed methyl esters specific mass, dynamic viscosity and rheological behavior were evaluated. According to results, antioxidant degraded samples specific mass and dynamic viscosity did not showed alterations, remaining statistically equal. Soybean and cottonseed methyl esters showed a Newtonian rheological behavior and degraded samples without adding BHA showed rheological behavior alterations. (author)

Was Newton right? A search for non-Newtonian behavior of weak-field gravity

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Boynton Paul

2014-06-01

Full Text Available Empirical tests of Einstein’s metric theory of gravitation, even in the non-relativistic, weak-field limit, could play an important role in judging theory-driven extensions of the current Standard Model of fundamental interactions. Guided by Galileo's work and his own experiments, Newton formulated a theory of gravity in which the force of attraction between two bodies is independent of composition and proportional to the inertia of each, thereby transparently satisfying Galileo's empirically informed conjecture regarding the Universality of Free Fall. Similarly, Einstein honored the manifest success of Newton’s theory by assuring that the linearized equations of GTR matched the Newtonian formalism under “classical” conditions. Each of these steps, however, was explicitly an approximation raised to the status of principle. Perhaps, at some level, Newtonian gravity does not accurately describe the physical interaction between uncharged, unmagnetized, macroscopic bits of ordinary matter. What if Newton were wrong? Detecting any significant deviation from Newtonian behavior, no matter how small, could provide new insights and possibly reveal new physics. In the context of physics as an empirical science, for us this yet unanswered question constitutes sufficient motivation to attempt precision measurements of the kind described here. In this paper we report the current status of a project to search for violation of the Newtonian inverse square law of gravity.

Introducing Non-Newtonian Fluid Mechanics Computations with Mathematica in the Undergraduate Curriculum

Science.gov (United States)

Binous, Housam

2007-01-01

We study four non-Newtonian fluid mechanics problems using Mathematica[R]. Constitutive equations describing the behavior of power-law, Bingham and Carreau models are recalled. The velocity profile is obtained for the horizontal flow of power-law fluids in pipes and annuli. For the vertical laminar film flow of a Bingham fluid we determine the…

Melt rheology and its applications in the plastics industry

CERN Document Server

Dealy, John M

2013-01-01

This is the second edition of Melt Rheology and its Role in Plastics Processing, although the title has changed to reflect its broadened scope. Advances in the recent years in rheometer technology and polymer science have greatly enhanced the usefulness of rheology in the plastics industry. It is now possible to design polymers having specific molecular structures and to predict the flow properties of melts having those structures. In addition, rheological properties now provide more precise information about molecular structure. This book provides all the information that is needed for the intelligent application of rheology in the development of new polymers, the determination of molecular structure and the correlation of processability with laboratory test data. Theory and equations are limited to what is essential for the use of rheology in the characterization of polymers, the development of new plastics materials and the prediction of plastics processing behavior. The emphasis is on information that wil...

Steady flow of non-Newtonian fluids - monotonicity methods in generalized orlicz spaces

Czech Academy of Sciences Publication Activity Database

Wróblewska, Aneta

2010-01-01

Roč. 72, č. 11 (2010), s. 4136-4147 ISSN 0362-546X Institutional research plan: CEZ:AV0Z10190503 Keywords : non-Newtonian fluid * Orlicz spaces * modular convergence of symmetric gradients * generalized Minty method * smart fluids Subject RIV: BA - General Mathematics Impact factor: 1.279, year: 2010 http://www.sciencedirect.com/science/article/pii/S0362546X10000568

Cosmology with modified Newtonian dynamics (MOND)

NARCIS (Netherlands)

Sanders, R. H.

1998-01-01

It is well known that the application of Newtonian dynamics to an expanding spherical region leads to the correct relativistic expression (the Friedmann equation) for the evolution of the cosmic scalefactor. Here, the cosmological implications of Milgrom's modified Newtonian dynamics (MOND) are

Viscoelastic capillary flow: the case of whole blood

Directory of Open Access Journals (Sweden)

David Rabaud

2016-07-01

Full Text Available The dynamics of spontaneous capillary flow of Newtonian fluids is well-known and can be predicted by the Lucas-Washburn-Rideal (LWR law. However a wide variety of viscoelastic fluids such as alginate, xanthan and blood, does not exhibit the same Newtonian behavior.In this work we consider the Herschel-Bulkley (HB rheological model and Navier-Stokes equation to derive a generic expression that predicts the capillary flow of non-Newtonian fluids. The Herschel-Bulkley rheological model encompasses a wide variety of fluids, including the Power-law fluids (also called Ostwald fluids, the Bingham fluids and the Newtonian fluids. It will be shown that the proposed equation reduces to the Lucas-Washburn-Rideal law for Newtonian fluids and to the Weissenberg-Rabinowitsch-Mooney (WRM law for power-law fluids. Although HB model cannot reduce to Casson’s law, which is often used to model whole blood rheology, HB model can fit the whole blood rheology with the same accuracy.Our generalized expression for the capillary flow of non-Newtonian fluid was used to accurately fit capillary flow of whole blood. The capillary filling of a cylindrical microchannel by whole blood was monitored. The blood first exhibited a Newtonian behavior, then after 7 cm low shear stress and rouleaux formation made LWR fails to fit the data: the blood could not be considered as Newtonian anymore. This non-Newtonian behavior was successfully fit by the proposed equation.

Viscosity of Heterogeneous Silicate Melts: A Non-Newtonian Model

Science.gov (United States)

Liu, Zhuangzhuang; Blanpain, Bart; Guo, Muxing

2017-12-01

The recently published viscosity data of heterogeneous silicate melts with well-documented structure and experimental conditions are critically re-analyzed and tabulated. By using these data, a non-Newtonian viscosity model incorporating solid fraction, solid shape, and shear rate is proposed on the basis of the power-law equation. This model allows calculating the viscosity of the heterogeneous silicate melts with solid fraction up to 34 vol pct. The error between the calculated and measured data is evaluated to be 32 pct, which is acceptable considering the large error in viscosity measurement of the completely liquid silicate melt.

Spreading law of non-Newtonian power-law liquids on a spherical substrate by an energy-balance approach.

Science.gov (United States)

Iwamatsu, Masao

2017-07-01

The spreading of a cap-shaped spherical droplet of non-Newtonian power-law liquids, both shear-thickening and shear-thinning liquids, that completely wet a spherical substrate is theoretically investigated in the capillary-controlled spreading regime. The crater-shaped droplet model with the wedge-shaped meniscus near the three-phase contact line is used to calculate the viscous dissipation near the contact line. Then the energy balance approach is adopted to derive the equation that governs the evolution of the contact line. The time evolution of the dynamic contact angle θ of a droplet obeys a power law θ∼t^{-α} with the spreading exponent α, which is different from Tanner's law for Newtonian liquids and those for non-Newtonian liquids on a flat substrate. Furthermore, the line-tension dominated spreading, which could be realized on a spherical substrate for late-stage of spreading when the contact angle becomes low and the curvature of the contact line becomes large, is also investigated.

Rheological and tribological behaviour of lubricating oils containing platelet MoS2 nanoparticles

Science.gov (United States)

Wan, Qingming; Jin, Yi; Sun, Pengcheng; Ding, Yulong

2014-05-01

This work concerns rheological and frictional behaviour of lubricating oils containing platelet molybdenum disulfide (MoS2) nanoparticles (average diameter 50 nm; single layer thickness 3 nm). Stable nano-MoS2 lubricants were formulated and measured for their rheological behaviour and tribological performance. Rheological experiments showed that the nano-MoS2 oils were non-Newtonian following the Bingham plastic fluid model. The viscosity data fitted the classic Hinch-Leal (H-L) model if an agglomeration factor of 1.72 was introduced. Tribological experiments indicated that the use of MoS2 nanoparticles could enhance significantly the tribological performance of the base lubricating oil (reduced frictional coefficient, reduced surface wear and increased stability). Scanning electron microscopy, laser confocal microscope and x-ray energy dispersive spectroscopy analyses suggested that the reduced frictional coefficient and surface wear be associated with surface patching effects. Such patching effects were shown to depend on the concentration of MoS2 nanoparticles, and an effective patching required a concentration over approximately 1 wt%. The increased stability could be attributed to the enhanced heat transfer and lubricating oil film strength due to the presence of nanoparticles.

Gas holdup in a reciprocating plate bioreactor: Non-Newtonian - liquid phase

Directory of Open Access Journals (Sweden)

Naseva Olivera S.

2002-01-01

Full Text Available The gas holdup was studied in non-newtonian liquids in a gas-liquid and gas-liquid-solid reciprocating plate bioreactor. Aqueous solutions of carboxy methyl cellulose (CMC; Lucel, Lučane, Yugoslavia of different degrees of polymerization (PP 200 and PP 1000 and concentration (0,5 and 1%, polypropylene spheres (diameter 8.3 mm; fraction of spheres: 3.8 and 6.6% by volume and air were used as the liquid, solid and gas phase. The gas holdup was found to be dependent on the vibration rate, the superficial gas velocity, volume fraction of solid particles and Theological properties of the liquid ohase. Both in the gas-liquid and gas-liquid-solid systems studied, the gas holdup increased with increasing vibration rate and gas flow rate. The gas holdup was higher in three-phase systems than in two-phase ones under otter operating conditions being the same. Generally the gas holdup increased with increasing the volume fraction of solid particles, due to the dispersion action of the solid particles, and decreased with increasing non-Newtonian behaviour (decreasing flow index i.e. with increasing degree of polymerization and solution concentration of CMC applied, as a result of gas bubble coalescence.

The Post-Newtonian Approximation for Relativistic Compact Binaries

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Futamase Toshifumi

2007-03-01

Full Text Available We discuss various aspects of the post-Newtonian approximation in general relativity. After presenting the foundation based on the Newtonian limit, we show a method to derive post-Newtonian equations of motion for relativistic compact binaries based on a surface integral approach and the strong field point particle limit. As an application we derive third post-Newtonian equations of motion for relativistic compact binaries which respect the Lorentz invariance in the post-Newtonian perturbative sense, admit a conserved energy, and are free from any ambiguity.

Steady flow of non-Newtonian fluids - monotonicity methods in generalized orlicz spaces

Czech Academy of Sciences Publication Activity Database

Wróblewska, Aneta

2010-01-01

Roč. 72, č. 11 (2010), s. 4136-4147 ISSN 0362-546X Institutional research plan: CEZ:AV0Z10190503 Keywords : non-Newtonian fluid * Orlicz spaces * modular convergence of symmetric gradients * general ized Minty method * smart fluids Subject RIV: BA - General Mathematics Impact factor: 1.279, year: 2010 http://www.sciencedirect.com/science/article/pii/S0362546X10000568

Rheology of Victorian brown coal slurries

Energy Technology Data Exchange (ETDEWEB)

Woskoboenko, F.; Siemon, S.R.; Creasy, D.E.

1987-09-01

Aqueous suspensions of finely ground raw brown coal from Victoria, Australia, have been tested in a Couette viscometer to evaluate their rheological properties. Shear rates covered the range 1-800s/sup -1/ and median particles were 6-41 ..mu..m. Concentrations up to 0.6 volume fraction were examined. The results were well represented by the two parameter Bingham model. It was found that the degree of non-Newtonian behaviour, as measured by yield stress, increased as the concentration was increased or the particle size decreased. The yield stress can be directly related to the volumetric solids concentration, particle size distribution and external specific area via a single, physically meaningful parameter - the mean distance separating the particles. The power law relationship between yield stress and inter-particle distance can be used to gauge the degree of flocculation of the system. As with non-interacting particle systems, the plastic viscosity of these suspensions increases in a logarithmic fashion as the concentration increases but is independent of the absolute particle size. 35 refs., 5 figs., 2 tabs.

Numerical study of entropy generation and melting heat transfer on MHD generalised non-Newtonian fluid (GNF): Application to optimal energy

Science.gov (United States)

Iqbal, Z.; Mehmood, Zaffar; Ahmad, Bilal

2018-05-01

This paper concerns an application to optimal energy by incorporating thermal equilibrium on MHD-generalised non-Newtonian fluid model with melting heat effect. Highly nonlinear system of partial differential equations is simplified to a nonlinear system using boundary layer approach and similarity transformations. Numerical solutions of velocity and temperature profile are obtained by using shooting method. The contribution of entropy generation is appraised on thermal and fluid velocities. Physical features of relevant parameters have been discussed by plotting graphs and tables. Some noteworthy findings are: Prandtl number, power law index and Weissenberg number contribute in lowering mass boundary layer thickness and entropy effect and enlarging thermal boundary layer thickness. However, an increasing mass boundary layer effect is only due to melting heat parameter. Moreover, thermal boundary layers have same trend for all parameters, i.e., temperature enhances with increase in values of significant parameters. Similarly, Hartman and Weissenberg numbers enhance Bejan number.

Post-Newtonian reference ellipsoid for relativistic geodesy

Science.gov (United States)

Kopeikin, Sergei; Han, Wenbiao; Mazurova, Elena

2016-02-01

We apply general relativity to construct the post-Newtonian background manifold that serves as a reference spacetime in relativistic geodesy for conducting a relativistic calculation of the geoid's undulation and the deflection of the plumb line from the vertical. We chose an axisymmetric ellipsoidal body made up of a perfect homogeneous fluid uniformly rotating around a fixed axis, as a source generating the reference geometry of the background manifold through Einstein's equations. We then reformulate and extend hydrodynamic calculations of rotating fluids done by a number of previous researchers for astrophysical applications to the realm of relativistic geodesy to set up algebraic equations defining the shape of the post-Newtonian reference ellipsoid. To complete this task, we explicitly perform all integrals characterizing gravitational field potentials inside the fluid body and represent them in terms of the elementary functions depending on the eccentricity of the ellipsoid. We fully explore the coordinate (gauge) freedom of the equations describing the post-Newtonian ellipsoid and demonstrate that the fractional deviation of the post-Newtonian level surface from the Maclaurin ellipsoid can be made much smaller than the previously anticipated estimate based on the astrophysical application of the coordinate gauge advocated by Bardeen and Chandrasekhar. We also derive the gauge-invariant relations of the post-Newtonian mass and the constant angular velocity of the rotating fluid with the parameters characterizing the shape of the post-Newtonian ellipsoid including its eccentricity, a semiminor axis, and a semimajor axis. We formulate the post-Newtonian theorems of Pizzetti and Clairaut that are used in geodesy to connect the geometric parameters of the reference ellipsoid to the physically measurable force of gravity at the pole and equator of the ellipsoid. Finally, we expand the post-Newtonian geodetic equations describing the post-Newtonian ellipsoid to

Gravitational radiation from nearly Newtonian systems

International Nuclear Information System (INIS)

Kirk, E.M.

1989-09-01

A method of examining gravitational radiation from nearly Newtonian systems is presented. Using the Cartan formulation of Newtonian gravity, a one parameter family of space-times which have a strict Newtonian limit is constructed. An expression for the initial null data in terms of the Newtonian potential is obtained in the Newtonian limit. Using this, the problem is formulated as a series in the Newtonian parameter. The series expansions for the sources of the Bianchi identities are obtained to third order in both the vacuum and non-vacuum cases. A simple technique is presented for determining whether a particular source term gives rise to asymptotically flat null data. The far field quadrupole formula is derived in a leading approximation and a method for obtaining error bounds is discussed. Additionally, a method for solving Einstein's equations is shown. This involves expressing the Ricci identities as a matrix, Riccati equation and a system of linear matrix equations. A comparison of the formalisms of Bondi and Newman Penrose is presented and explicit correspondences between the supersurface constrain equations and the Ricci identities are shown. (author)

Measurement of the Rheology of Crude Oil in Equilibrium with CO2 at Reservoir Conditions.

Science.gov (United States)

Hu, Ruien; Crawshaw, John

2017-06-06

A rheometer system to measure the rheology of crude oil in equilibrium with carbon dioxide (CO2) at high temperatures and pressures is described. The system comprises a high-pressure rheometer which is connected to a circulation loop. The rheometer has a rotational flow-through measurement cell with two alternative geometries: coaxial cylinder and double gap. The circulation loop contains a mixer, to bring the crude oil sample into equilibrium with CO2, and a gear pump that transports the mixture from the mixer to the rheometer and recycles it back to the mixer. The CO2 and crude oil are brought to equilibrium by stirring and circulation and the rheology of the saturated mixture is measured by the rheometer. The system is used to measure the rheological properties of Zuata crude oil (and its toluene dilution) in equilibrium with CO2 at elevated pressures up to 220 bar and a temperature of 50 °C. The results show that CO2 addition changes the oil rheology significantly, initially reducing the viscosity as the CO2 pressure is increased and then increasing the viscosity above a threshold pressure. The non-Newtonian response of the crude is also seen to change with the addition of CO2.

Non-Newtonian Hele-Shaw Flow and the Saffman-Taylor Instability

International Nuclear Information System (INIS)

Kondic, L.; Shelley, M.J.; Palffy-Muhoray, P.

1998-01-01

We explore the Saffman-Taylor instability of a gas bubble expanding into a shear thinning liquid in a radial Hele-Shaw cell. Using Darcy close-quote s law generalized for non-Newtonian fluids, we perform simulations of the full dynamical problem. The simulations show that shear thinning significantly influences the developing interfacial patterns. Shear thinning can suppress tip splitting, and produce fingers which oscillate during growth and shed side branches. Emergent length scales show reasonable agreement with a general linear stability analysis. copyright 1998 The American Physical Society

Drop Characteristics of non-Newtonian Impinging Jets at High Generalized Bird-Carreau Jet Reynolds Numbers

Science.gov (United States)

Sojka, Paul E.; Rodrigues, Neil S.

2015-11-01

The current study investigates the drop characteristics of three Carboxymethylcellulose (CMC) sprays produced by the impingement of two liquid jets. The three water-based solutions used in this work (0.5 wt.-% CMC-7MF, 0.8 wt.-% CMC-7MF, and 1.4 wt.-% CMC-7MF) exhibited strong shear-thinning, non-Newtonian behavior - characterized by the Bird-Carreau rheological model. A generalized Bird-Carreau jet Reynolds number was used as the primary parameter to characterize the drop size and the drop velocity, which were measured using Phase Doppler Anemometry (PDA). PDA optical configuration enabled a drop size measurement range of approximately 2.3 to 116.2 μm. 50,000 drops were measured at each test condition to ensure statistical significance. The arithmetic mean diameter (D10) , Sauter mean diameter (D32) , and mass median diameter (MMD) were used as representative diameters to characterize drop size. The mean axial drop velocity Uz -mean along with its root-mean square Uz -rms were used to characterize drop velocity. Incredibly, measurements for all three CMC liquids and reference DI water sprays seemed to follow a single curve for D32 and MMD drop diameters in the high generalized Bird-Carreau jet Reynolds number range considered in this work (9.21E +03

Accelerated lattice Boltzmann model for colloidal suspensions rheology and interface morphology

Science.gov (United States)

Farhat, Hassan

Colloids are ubiquitous in the food, medical, cosmetic, polymer, water purification and pharmaceutical industries. Colloids thermal, mechanical and storage properties are highly dependent on their interface morphology and their rheological behavior. Numerical methods provide a cheap and reliable virtual laboratory for the study of colloids. However efficiency is a major concern to address when using numerical methods for practical applications. This work introduces the main building-blocks for an improved lattice Boltzmann-based numerical tool designed for the study of colloidal rheology and interface morphology. The efficiency of the proposed model is enhanced by using the recently developed and validated migrating multi-block algorithms for the lattice Boltzmann method (LBM). The migrating multi-block was used to simulate single component, multi-component, multiphase and single component multiphase flows. Results were validated by experimental, numerical and analytical solutions. The contamination of the fluid-fluid interface influences the colloids morphology. This issue was addressed by the introduction of the hybrid LBM for surfactant-covered droplets. The module was used for the simulation of surfactant-covered droplet deformation under shear and uniaxial extensional flows respectively and under buoyancy. Validation with experimental and theoretical results was provided. Colloids are non-Newtonian fluids which exhibit rich rheological behavior. The suppression of coalescence module is the part of the proposed model which facilitates the study of colloids rheology. The model results for the relative viscosity were in agreement with some theoretical results. Biological suspensions such as blood are macro-colloids by nature. The study of the blood flow in the microvasculature was heuristically approached by assuming the red blood cells as surfactant covered droplets. The effects of interfacial tension on the flow velocity and the droplet exclusion from the walls

A Lagrangian finite element method for the simulation of flow of non-newtonian liquids

DEFF Research Database (Denmark)

Hassager, Ole; Bisgaard, C

1983-01-01

A Lagrangian method for the simulation of flow of non-Newtonian liquids is implemented. The fluid mechanical equations are formulated in the form of a variational principle, and a discretization is performed by finite elements. The method is applied to the slow of a contravariant convected Maxwell...

Free surface flow of a suspension of rigid particles in a non-Newtonian fluid

DEFF Research Database (Denmark)

Svec, Oldrich; Skocek, Jan; Stang, Henrik

2012-01-01

A numerical framework capable of predicting the free surface flow of a suspension of rigid particles in a non-Newtonian fluid is described. The framework is a combination of the lattice Boltzmann method for fluid flow, the mass tracking algorithm for free surface representation, the immersed...

Physically based model for extracting dual permeability parameters using non-Newtonian fluids

Science.gov (United States)

Abou Najm, M. R.; Basset, C.; Stewart, R. D.; Hauswirth, S.

2017-12-01

Dual permeability models are effective for the assessment of flow and transport in structured soils with two dominant structures. The major challenge to those models remains in the ability to determine appropriate and unique parameters through affordable, simple, and non-destructive methods. This study investigates the use of water and a non-Newtonian fluid in saturated flow experiments to derive physically-based parameters required for improved flow predictions using dual permeability models. We assess the ability of these two fluids to accurately estimate the representative pore sizes in dual-domain soils, by determining the effective pore sizes of macropores and micropores. We developed two sub-models that solve for the effective macropore size assuming either cylindrical (e.g., biological pores) or planar (e.g., shrinkage cracks and fissures) pore geometries, with the micropores assumed to be represented by a single effective radius. Furthermore, the model solves for the percent contribution to flow (wi) corresponding to the representative macro and micro pores. A user-friendly solver was developed to numerically solve the system of equations, given that relevant non-Newtonian viscosity models lack forms conducive to analytical integration. The proposed dual-permeability model is a unique attempt to derive physically based parameters capable of measuring dual hydraulic conductivities, and therefore may be useful in reducing parameter uncertainty and improving hydrologic model predictions.

The LS-STAG immersed boundary/cut-cell method for non-Newtonian flows in 3D extruded geometries

Science.gov (United States)

Nikfarjam, F.; Cheny, Y.; Botella, O.

2018-05-01

The LS-STAG method is an immersed boundary/cut-cell method for viscous incompressible flows based on the staggered MAC arrangement for Cartesian grids, where the irregular boundary is sharply represented by its level-set function, results in a significant gain in computer resources (wall time, memory usage) compared to commercial body-fitted CFD codes. The 2D version of LS-STAG method is now well-established (Cheny and Botella, 2010), and this paper presents its extension to 3D geometries with translational symmetry in the z direction (hereinafter called 3D extruded configurations). This intermediate step towards the fully 3D implementation can be applied to a wide variety of canonical flows and will be regarded as the keystone for the full 3D solver, since both discretization and implementation issues on distributed memory machines are tackled at this stage of development. The LS-STAG method is then applied to various Newtonian and non-Newtonian flows in 3D extruded geometries (axisymmetric pipe, circular cylinder, duct with an abrupt expansion) for which benchmark results and experimental data are available. The purpose of these investigations are (a) to investigate the formal order of accuracy of the LS-STAG method, (b) to assess the versatility of method for flow applications at various regimes (Newtonian and shear-thinning fluids, steady and unsteady laminar to turbulent flows) (c) to compare its performance with well-established numerical methods (body-fitted and immersed boundary methods).

Numerical methods for multi-scale modeling of non-Newtonian flows

Science.gov (United States)

Symeonidis, Vasileios

This work presents numerical methods for the simulation of Non-Newtonian fluids in the continuum as well as the mesoscopic level. The former is achieved with Direct Numerical Simulation (DNS) spectral h/p methods, while the latter employs the Dissipative Particle Dynamics (DPD) technique. Physical results are also presented as a motivation for a clear understanding of the underlying numerical approaches. The macroscopic simulations employ two non-Newtonian models, namely the Reiner-Ravlin (RR) and the viscoelastic FENE-P model. (1) A spectral viscosity method defined by two parameters ε, M is used to stabilize the FENE-P conformation tensor c. Convergence studies are presented for different combinations of these parameters. Two boundary conditions for the tensor c are also investigated. (2) Agreement is achieved with other works for Stokes flow of a two-dimensional cylinder in a channel. Comparison of the axial normal stress and drag coefficient on the cylinder is presented. Further, similar results from unsteady two- and three-dimensional turbulent flows past a flat plate in a channel are shown. (3) The RR problem is formulated for nearly incompressible flows, with the introduction of a mathematically equivalent tensor formulation. A spectral viscosity method and polynomial over-integration are studied. Convergence studies, including a three-dimensional channel flow with a parallel slot, investigate numerical problems arising from elemental boundaries and sharp corners. (4) The round hole pressure problem is presented for Newtonian and RR fluids in geometries with different hole sizes. Comparison with experimental data is made for the Newtonian case. The flaw in the experimental assumptions of undisturbed pressure opposite the hole is revealed, while good agreement with the data is shown. The Higashitani-Pritchard kinematical theory for RR, fluids is recovered for round holes and an approximate formula for the RR Stokes hole pressure is presented. The mesoscopic

Newtonian versus black-hole scattering

International Nuclear Information System (INIS)

Siopsis, G.

1999-01-01

We discuss non-relativistic scattering by a Newtonian potential. We show that the gray-body factors associated with scattering by a black hole exhibit the same functional dependence as scattering amplitudes in the Newtonian limit, which should be the weak-field limit of any quantum theory of gravity. This behavior arises independently of the presence of supersymmetry. The connection to two-dimensional conformal field theory is also discussed. copyright 1999 The American Physical Society

Modeling of flow of particles in a non-Newtonian fluid using lattice Boltzmann method

DEFF Research Database (Denmark)

Skocek, Jan; Svec, Oldrich; Spangenberg, Jon

2011-01-01

is necessary. In this contribution, the model at the scale of aggregates is introduced. The conventional lattice Boltzmann method for fluid flow is enriched with the immersed boundary method with direct forcing to simulate the flow of rigid particles in a non- Newtonian liquid. Basic ingredients of the model...

Mathematical model of microbicidal flow dynamics and optimization of rheological properties for intra-vaginal drug delivery: Role of tissue mechanics and fluid rheology.

Science.gov (United States)

Anwar, Md Rajib; Camarda, Kyle V; Kieweg, Sarah L

2015-06-25

Topically applied microbicide gels can provide a self-administered and effective strategy to prevent sexually transmitted infections (STIs). We have investigated the interplay between vaginal tissue elasticity and the yield-stress of non-Newtonian fluids during microbicide deployment. We have developed a mathematical model of tissue deformation driven spreading of microbicidal gels based on thin film lubrication approximation and demonstrated the effect of tissue elasticity and fluid yield-stress on the spreading dynamics. Our results show that both elasticity of tissue and yield-stress rheology of gel are strong determinants of the coating behavior. An optimization framework has been demonstrated which leverages the flow dynamics of yield-stress fluid during deployment to maximize retention while reaching target coating length for a given tissue elasticity. Copyright © 2015 Elsevier Ltd. All rights reserved.

Relation between rheological and structural properties of suspensions

Energy Technology Data Exchange (ETDEWEB)

Barcal, M; Sebor, G; Volsicky, Z

1982-01-01

The paper discusses results of investigations into separation processes for coal and kaolin suspensions. Effects of potassium chlorides and methanol additives on electrostatic potential of solid particles and on sedimentation rate are analyzed. Investigation results are shown in 5 diagrams. The relation between rheological and structural properties of coal and clay suspensions is investigated. Investigations show that the non-Newtonian behavior of suspensions cannot be attributed exclusively to the electrostatic and mechanical action of the solid phase particles. It is also caused by structure of the liquid phase, particularly on the surface of the solid particles, which depends mostly on hydrogen bonds. The internal structure of the liquid phase influences differential viscosity much more than the electrical surface properties of the solid phase. Bonds between the molecules of water and methanol are much stronger than bonds between water molecules alone. (9 refs.)

Rheological study of chitosan and its blends: An overview

Directory of Open Access Journals (Sweden)

Esam A. El-hefian

2010-06-01

Full Text Available Chitosan, a modified natural carbohydrate polymer derived from carapaces of crabs and shrimps, has received a great deal of attention for its applications in diverse fields owing to its biodegradability, biocompatibility, non-toxicity and anti-bacterial property. The wide-ranging applications involve a broad spectrum of characterisation techniques and rheology represents one technique of growing importance in this field. This paper is an attempt to review the latest development in the rheology of chitosan, either on its own or associated with other materials, including the parameters that strongly influence its rheological behaviour such as concentration, pH and temperature.

Textural, Rheological and Sensory Properties and Oxidative Stability of Nut Spreads—A Review

Directory of Open Access Journals (Sweden)

Hasanah Mohd Ghazali

2013-02-01

Full Text Available Tree nuts are rich in macro and micronutrients, phytochemicals, tocopherols and phenolic compounds. The development of nut spreads would potentially increase the food uses of nuts and introduce consumers with a healthier, non-animal breakfast snack food. Nut spreads are spreadable products made from nuts that are ground into paste. Roasting and milling (particle size reduction are two important stages for the production of nut spreads that affected the textural, rheological characteristic and overall quality of the nut spread. Textural, color, and flavor properties of nut spreads play a major role in consumer appeal, buying decisions and eventual consumption. Stability of nut spreads is influenced by its particle size. Proper combination of ingredients (nut paste, sweetener, vegetable oil and protein sources is also required to ensure a stable nut spread product is produced. Most of the nut spreads behaved like a non-Newtonian pseudo-plastic fluid under yield stress which help the producers how to start pumping and stirring of the nut spreads. Similar to other high oil content products, nut spreads are susceptible to autoxidation. Their oxidation can be controlled by application of antioxidants, using processing techniques that minimize tocopherol and other natural antioxidant losses.

Pseudo-Newtonian planar circular restricted 3-body problem

International Nuclear Information System (INIS)

Dubeibe, F.L.; Lora-Clavijo, F.D.; González, Guillermo A.

2017-01-01

We study the dynamics of the planar circular restricted three-body problem in the context of a pseudo-Newtonian approximation. By using the Fodor–Hoenselaers–Perjés procedure, we perform an expansion in the mass potential of a static massive spherical source up to the first non-Newtonian term, giving place to a gravitational potential that includes first-order general relativistic effects. With this result, we model a system composed by two pseudo-Newtonian primaries describing circular orbits around their common center of mass, and a test particle orbiting the system in the equatorial plane. The dynamics of the new system of equations is studied in terms of the Poincaré section method and the Lyapunov exponents, where the introduction of a new parameter ϵ, allows us to observe the transition from the Newtonian to the pseudo-Newtonian regime. We show that when the Jacobian constant is fixed, a chaotic orbit in the Newtonian regime can be either chaotic or regular in the pseudo-Newtonian approach. As a general result, we find that most of the pseudo-Newtonian configurations are less stable than their Newtonian equivalent.

Pseudo-Newtonian planar circular restricted 3-body problem

Energy Technology Data Exchange (ETDEWEB)

Dubeibe, F.L., E-mail: fldubeibem@unal.edu.co [Facultad de Ciencias Humanas y de la Educación, Universidad de los Llanos, Villavicencio (Colombia); Grupo de Investigación en Relatividad y Gravitación, Escuela de Física, Universidad Industrial de Santander, A.A. 678, Bucaramanga (Colombia); Lora-Clavijo, F.D., E-mail: fadulora@uis.edu.co [Grupo de Investigación en Relatividad y Gravitación, Escuela de Física, Universidad Industrial de Santander, A.A. 678, Bucaramanga (Colombia); González, Guillermo A., E-mail: guillermo.gonzalez@saber.uis.edu.co [Grupo de Investigación en Relatividad y Gravitación, Escuela de Física, Universidad Industrial de Santander, A.A. 678, Bucaramanga (Colombia)

2017-02-12

We study the dynamics of the planar circular restricted three-body problem in the context of a pseudo-Newtonian approximation. By using the Fodor–Hoenselaers–Perjés procedure, we perform an expansion in the mass potential of a static massive spherical source up to the first non-Newtonian term, giving place to a gravitational potential that includes first-order general relativistic effects. With this result, we model a system composed by two pseudo-Newtonian primaries describing circular orbits around their common center of mass, and a test particle orbiting the system in the equatorial plane. The dynamics of the new system of equations is studied in terms of the Poincaré section method and the Lyapunov exponents, where the introduction of a new parameter ϵ, allows us to observe the transition from the Newtonian to the pseudo-Newtonian regime. We show that when the Jacobian constant is fixed, a chaotic orbit in the Newtonian regime can be either chaotic or regular in the pseudo-Newtonian approach. As a general result, we find that most of the pseudo-Newtonian configurations are less stable than their Newtonian equivalent.

Investigation of the rheological properties of human semen

Energy Technology Data Exchange (ETDEWEB)

Dunn, P.F. (Purdue Univ., West Lafayette, IN); Picologlou, B.F.

1977-01-01

The results of an investigation of the previously undetermined rheological properties of human semen using a modified, multiple-point capillary viscometer are presented. The design of a viscometer, specifically constructed to give accurate, instantaneous pressure gradient and material flow rate records of biological viscoelastic fluids whose rheological properties are possibly changing with time is given. Using this device, measurements are made on human semen immediately following ejaculation. An analytical scheme for the data reduction, suitable for non-linear viscoelastic fluids of the Maxwell-type, is offered. An expression is developed for a non-linear Maxwell-type viscoelastic fluid flow in a circular tube, relating the material's elastic properties to the distance of recoil and the pressure gradient. In the case of a power-law elastic behavior this relation couples the wall shear stress with the recoil distance through an apparent shear modulus. Previously established procedures for the viscous response analysis are utilized and an approximate non-dimensional parameter is introduced allowing one to ascertain the relative contributions of the elastic and viscous components to the rate of flow. Results show the elastic and viscous properties of human semen to be functions of time following ejaculation and frequency of ejaculation. The elastic component is found to have a linear response over the shear stress range investigated, whereas the viscous component is found to exhibit a power-law behavior. The final equilibrium state is characterized by Newtonian behavior, with mean absolute viscosity of 3.37 centipoise. Finally, similarity among all cases examined is found for each material property through consideration of a non-dimensional time, t*, determined from semen liquefaction time and time post ejaculation.

Particle migration using local variation of the viscosity (LVOV) model in flow of a non-Newtonian fluid for ceramic tape casting

DEFF Research Database (Denmark)

Jabbaribehnam, Mirmasoud; Spangenberg, Jon; Hattel, Jesper Henri

2016-01-01

In this paper, the migration of secondary particles in a non-Newtonian ceramic slurry inthe tape casting process is investigated with the purpose of understanding the particle distribution patterns along the casting direction. The Ostwald-de Waele power law model for the non-Newtonian flow...... the substratevelocity (casting speed) leads to a more uniform distribution of the particles inside the ceramic slurry, in which case the shear induced particle migration is dominating over the gravity induced one....

Caracterização reológica de sorvetes Rheological characterization of ice cream

Directory of Open Access Journals (Sweden)

Katherine Helena Oliveira

2008-09-01

Full Text Available O conhecimento do comportamento reológico é de grande importância no processamento, manuseio, controle de qualidade e desenvolvimento de produtos alimentícios. A literatura relata que a maioria dos alimentos apresenta comportamento não newtoniano, em que a sua viscosidade pode variar com o tempo e com as condições de escoamento. Neste trabalho foi realizada a caracterização reológica de cinco diferentes tipos de sorvetes. As amostras nos sabores creme, creme light, limão, iogurte e soja banana foram fornecidas pela empresa Amoratto Sorvetes Artesanais, localizada na cidade de Florianópolis/SC. Os dados reológicos foram obtidos através de um reômetro com geometria de cilindros concêntricos. Os ensaios foram realizados em três diferentes temperaturas (-2, 0 e 2 °C e os resultados experimentais foram ajustados pelos modelos de Bingham, Casson, Herschel-Bulkley e Lei da Potência. As diferentes amostras apresentaram comportamento não newtoniano nas três temperaturas. Os parâmetros reológicos (K e n foram obtidos através do ajuste dos modelos e o da Lei da Potência mostrou o melhor ajuste aos resultados, com coeficientes de correlação (r iguais a 0,99 para quatro das cinco amostras, nas três diferentes temperaturas.The knowledge of rheological behavior is an important part of processing, handling, quality control and development of food products. Literature shows that most foodstuffs present non-Newtonian behavior, where their viscosity may vary with time, as well as with flow conditions. The rheological characterization of five different kinds of ice cream was carried out in this work. The samples studied were vanilla flavor, light vanilla flavor, lemon, yoghurt and banana soy, supplied by Amoratto Sorvetes Artesanais, located in Florianópolis/SC, Brazil. The rheological data were obtained using a rotational viscosimeter with concentric cylinder geometry. The trials were carried out at three different temperatures (-2, 0

CFD simulation of gas and non-Newtonian fluid two-phase flow in anaerobic digesters.

Science.gov (United States)

Wu, Binxin

2010-07-01

This paper presents an Eulerian multiphase flow model that characterizes gas mixing in anaerobic digesters. In the model development, liquid manure is assumed to be water or a non-Newtonian fluid that is dependent on total solids (TS) concentration. To establish the appropriate models for different TS levels, twelve turbulence models are evaluated by comparing the frictional pressure drops of gas and non-Newtonian fluid two-phase flow in a horizontal pipe obtained from computational fluid dynamics (CFD) with those from a correlation analysis. The commercial CFD software, Fluent12.0, is employed to simulate the multiphase flow in the digesters. The simulation results in a small-sized digester are validated against the experimental data from literature. Comparison of two gas mixing designs in a medium-sized digester demonstrates that mixing intensity is insensitive to the TS in confined gas mixing, whereas there are significant decreases with increases of TS in unconfined gas mixing. Moreover, comparison of three mixing methods indicates that gas mixing is more efficient than mixing by pumped circulation while it is less efficient than mechanical mixing.

Effect of dispersing and stabilizing additives on rheological characteristics of the upgraded brown coal water mixture

International Nuclear Information System (INIS)

Umar, Datin Fatia; Muta'alim; Usui, Hiromoto; Komoda, Yoshiyuki

2009-01-01

Upgraded brown coal water mixture (UBCWM) preparation by using an Indonesian upgraded coal produced by upgraded brown coal (UBC) process, was carried out to study the effect of dispersing and stabilizing additives on rheological behavior of the UBCWM. Three kinds of anionic dispersing additives, naphthalene sulfonic formaldehyde condensate (NSF), poly (meth) acrylate (PMA) and poly styrene sulfonic acid (PSS) and three kinds of stabilizing additives, carboxyl methyl cellulose (CMC), rhansam gum (S-194) and gellan gum (S-60) were used in this study. Results indicate that the addition of NSF 0.3 wt.% together with S-194 0.01 wt.% is effective in preparing UBCWM with good slurryability and stability, based on its rheological characteristics with the apparent viscosity at shear rate of 100 s - 1 and yield stress at zero point of shear rate. The rheological behavior of all of the UBCWM that prepared, exhibits non-Newtonian Bingham plastic. From the economical point of view, the price of S-194 is expensive. On the other hand, CMC is cheap and abundant. Therefore, the addition of CMC 0.01 wt.% together with NSF 0.3 wt.% is also effective in preparing UBCWM with good fluidity and stability. (author)

N-MODY: A Code for Collisionless N-body Simulations in Modified Newtonian Dynamics

Science.gov (United States)

Londrillo, Pasquale; Nipoti, Carlo

2011-02-01

N-MODY is a parallel particle-mesh code for collisionless N-body simulations in modified Newtonian dynamics (MOND). N-MODY is based on a numerical potential solver in spherical coordinates that solves the non-linear MOND field equation, and is ideally suited to simulate isolated stellar systems. N-MODY can be used also to compute the MOND potential of arbitrary static density distributions. A few applications of N-MODY indicate that some astrophysically relevant dynamical processes are profoundly different in MOND and in Newtonian gravity with dark matter.

Constraints on Non-Newtonian Gravity From the Experiment on Neutron Quantum States in the Earth's Gravitational Field.

Science.gov (United States)

Nesvizhevsky, V V; Protasov, K V

2005-01-01

An upper limit to non-Newtonian attractive forces is obtained from the measurement of quantum states of neutrons in the Earth's gravitational field. This limit improves the existing constraints in the nanometer range.

Experimental investigation of non-Newtonian/Newtonian liquid-liquid flow in microchannel

Science.gov (United States)

Roumpea, Eynagelia-Panagiota; Weheliye, Weheliye; Chinaud, Maxime; Angeli, Panagiota; Lyes Kahouadji Collaboration; Omar. K. Matar Collaboration

2015-11-01

Plug flow of an organic phase and an aqueous non-Newtonian solution was investigated experimentally in a quartz microchannel with I.D. 200 μm. The aqueous phase was a glycerol solution where 1000 and 2000 ppm of xanthan gum was added while the organic phase was silicon oil with 155 and 5 cSt viscosity. The two phases were brought together in a T-junction and their flowrates varied from 0.3 to 6 ml/hr. High speed imaging was used to study the characteristics of the plugs and the effect of the liquid properties on the flow patterns while a two-colour micro-PIV technique was used to investigate velocity profiles and circulation patterns within the plugs. The experimental results revealed that plug length was affected by both flowrate and viscosity. In all cases investigated, a film of the continuous phase always surrounded the plugs and its thickness was compared with existing literature models. Circulation patterns inside plugs were obtained by subtracting the plug velocity and found to be depended on the plug length and the amount of xanthan gum in the aqueous phase. Finally, the dimensionless circulation time was calculated and plotted as a function of the plug length. Department of Chemical Engineering South Kensington Campus Imperial College London SW7 2AZ.

Structure and rheology of nanoparticle–polymer suspensions

KAUST Repository

Srivastava, Samanvaya

2012-01-01

Structure and rheology of oligomer-tethered nanoparticles suspended in low molecular weight polymeric host are investigated at various particle sizes and loadings. Strong curvature effects introduced by the small size of the nanoparticle cores are found to be important for understanding both the phase stability and rheology of the materials. Small angle X-ray scattering (SAXS) and transmission electron microscopy measurements indicate that PEG-SiO 2/PEG suspensions are more stable against phase separation and aggregation than expected from theory for interacting brushes. SAXS and rheology measurements also reveal that at high particle loadings, the stabilizing oligomer brush is significantly compressed and produces jamming in the suspensions. The jamming transition is accompanied by what appears to be a unique evolution in the transient suspension rheology, along with large increments in the zero-shear, Newtonian viscosity. The linear and nonlinear flow responses of the jammed suspensions are discussed in the framework of the Soft Glassy Rheology (SGR) model, which is shown to predict many features that are consistent with experimental observations, including a two-step relaxation following flow cessation and a facile method for determining the shear-thinning coefficient from linear viscoelastic measurements. Finally, we show that the small sizes of the particles have a significant effect on inter-particle interactions and rheology, leading to stronger deviations from expectations based on planar brushes and hard-sphere suspension theories. In particular, we find that in the high volume fraction limit, tethered nanoparticles interact in their host polymer through short-range forces, which are more analogous to those between soft particles than between spherical polymer brushes. © 2012 The Royal Society of Chemistry.

Non-Newtonian Aspects of Artificial Intelligence

Science.gov (United States)

Zak, Michail

2016-05-01

The challenge of this work is to connect physics with the concept of intelligence. By intelligence we understand a capability to move from disorder to order without external resources, i.e., in violation of the second law of thermodynamics. The objective is to find such a mathematical object described by ODE that possesses such a capability. The proposed approach is based upon modification of the Madelung version of the Schrodinger equation by replacing the force following from quantum potential with non-conservative forces that link to the concept of information. A mathematical formalism suggests that a hypothetical intelligent particle, besides the capability to move against the second law of thermodynamics, acquires such properties like self-image, self-awareness, self-supervision, etc. that are typical for Livings. However since this particle being a quantum-classical hybrid acquires non-Newtonian and non-quantum properties, it does not belong to the physics matter as we know it: the modern physics should be complemented with the concept of the information force that represents a bridge to intelligent particle. As a follow-up of the proposed concept, the following question is addressed: can artificial intelligence (AI) system composed only of physical components compete with a human? The answer is proven to be negative if the AI system is based only on simulations, and positive if digital devices are included. It has been demonstrated that there exists such a quantum neural net that performs simulations combined with digital punctuations. The universality of this quantum-classical hybrid is in capability to violate the second law of thermodynamics by moving from disorder to order without external resources. This advanced capability is illustrated by examples. In conclusion, a mathematical machinery of the perception that is the fundamental part of a cognition process as well as intelligence is introduced and discussed.

Rheological properties of oil-in-water emulsions prepared with oil and protein isolates from sesame (Sesamum Indicum

Directory of Open Access Journals (Sweden)

David Ramirez BREWER

2016-01-01

Full Text Available In this study, food emulsions of oil in water from sesame (Sesamum indicum protein isolates and their oil were formulated and standardised. The effect of the concentrations of sesame (Sesamum indicum protein isolates and base oil and the speed of the emulsification process for the food emulsion stability was studied. The protein isolates were achieved from the defatted sesame flour (DSF, obtaining a percentage of 80% ± 0.05% of protein. Emulsions were formulated through a factorial design 23. The rheological behaviour of sesame (Sesamum indicum protein isolates-stabilised emulsions and microstructural composition were investigated. Stable emulsions with suitable rheological properties and microstructure were formulated at a concentration of 10% sesame oil and different concentrations of protein isolates, between 1.5% and 2.5%, with the best droplet distribution characteristics being shown for the 2.5% sesame protein isolates. The emulsions showed a non-Newtonian fluid behaviour, adjusting the Sisko model.

Rheology of Supramolecular Polymers

DEFF Research Database (Denmark)

Shabbir, Aamir

Supramolecular polymers are a broad class of materials that include all polymerscapable of associating via secondary interactions. These materials represent an emerging class of systems with superior versatility compared to classical polymers with applications in food stuff, coatings, cost...... efficient processes or biomedical areas. Design and development of supramolecular polymers using ionic, hydrogen bonding or transition metal complexes with tailored properties requires deep understanding of dynamics both in linear and non-linear deformations. While linear rheology is important to understand...... the dynamics under equilibrium conditions, extensional rheology is relevant during the processing or in the usage of polymers utilizing supramolecular associations for example, acrylic based pressure sensitive adhesives are subjected to extensional deformations during the peeling where strain hardening...

Droplet breakup driven by shear thinning solutions in a microfluidic T-junction

Science.gov (United States)

Chiarello, Enrico; Gupta, Anupam; Mistura, Giampaolo; Sbragaglia, Mauro; Pierno, Matteo

2017-12-01

Droplet-based microfluidics turned out to be an efficient and adjustable platform for digital analysis, encapsulation of cells, drug formulation, and polymerase chain reaction. Typically, for most biomedical applications, the handling of complex, non-Newtonian fluids is involved, e.g., synovial and salivary fluids, collagen, and gel scaffolds. In this study, we investigate the problem of droplet formation occurring in a microfluidic T-shaped junction, when the continuous phase is made of shear thinning liquids. At first, we review in detail the breakup process, providing extensive, side-by-side comparisons between Newtonian and non-Newtonian liquids over unexplored ranges of flow conditions and viscous responses. The non-Newtonian liquid carrying the droplets is made of Xanthan solutions, a stiff, rodlike polysaccharide displaying a marked shear thinning rheology. By defining an effective Capillary number, a simple yet effective methodology is used to account for the shear-dependent viscous response occurring at the breakup. The droplet size can be predicted over a wide range of flow conditions simply by knowing the rheology of the bulk continuous phase. Experimental results are complemented with numerical simulations of purely shear thinning fluids using lattice Boltzmann models. The good agreement between the experimental and numerical data confirm the validity of the proposed rescaling with the effective Capillary number.

Influence of clay and surfactant content in non-aqueous fluid rheology

International Nuclear Information System (INIS)

Guedes, I.C.; Gomes, N.L.; Menezes, R.R.; Campos, L.F.A.; Ferreira, H.S.

2012-01-01

The bentonite clay used as viscosity agent in the production of non-aqueous fluids cannot be used without organic treatment for their surfaces to become hydrophobic. These clays are called organophilic clays, and are generally obtained by adding, in an aqueous way, ionic or a nonionic surfactant. Recent studies of the variables involved in the dispersion of bentonite clays and in the process of organophilization, showed their lack of influence. This work aims to study the influence of clay content and surfactants on the rheology of nonaqueous fluids. To this end, the clays were treats and characterized, evidencing the incorporation of the surfactant, and then formulated non-aqueous fluids, following PETROBRAS standards, being possible to verify the influence of clay content and surfactant both from the point of view as the characterizing and rheological behavior. (author)

Rheological evaluation of polymers for EOR. Proper procedures for a laboratory approach

Energy Technology Data Exchange (ETDEWEB)

Kouchaki, S.; Hincapie-Reina, R.; Ganzer, L. [Technische Univ. Clausthal, Clausthal-Zellerfeld (Germany). ITE

2013-08-01

Some discrepancies exist in the literature concerning polymer EOR (Enhanced Oil Recovery) evaluation. Laboratory investigations are essentials for every particular flooding project, with proper preliminary lab evaluation techniques in order to study the polymer behavior and rheological properties at different reservoir conditions. Different research has been shown variation in procedures during polymer preparation and filtration; affecting the result in the field. Experience from field observation indicates that even high molecular weight (MW) polymers have filtration ratio (F.R) less than 1,5; in that way polymer solutions that are still in range cannot show a good approximation to the field behavior. To deal with the discrepancies, specific procedures based in rheological polymer characterization were adapted. Two different polymers were used for rheology study using a rotational rheometer analyzing some solutions at different conditions. Additionally rheological measurements was used to characterize the apparent viscosity of polymer as a shear rate function, salinity, temperature and polymer concentration, defining additional useful values for simulation evaluations and additionally Newtonian, non-Newtonian, shear viscosity and MW impact were also investigated. Quality control of the solutions was not limited to the conventional indicator 'filtrations ratio', but it was showed how important it is to consider two qualities check indicators, filterability ratio and filterability plot, simultaneously. Results indicated how stable the N-vinyl Pyrrolidone (NVP) Superpusher SAV301 could be in comparison to the Hydrolyzed Polyacrylamide polymer (HPAM) Flopaam 3630S. Despite the high viscosity results from HPAM Flopaam 3630S due to its high MW, the polymer is overly sensitive to factors like temperature, salinity and concentration. Quite the contrary was for polymer solutions with Superpusher SAV301; constant viscosity over a wide shear rate range which is the

Newtonian and post-Newtonian approximations are asymptotic to general relativity

International Nuclear Information System (INIS)

Futamase, T.; Schutz, B.F.

1983-01-01

A precise definition of the Newtonian and post-Newtonian hierarchy of approximations to general relativity is given by studying a C/sup infinity/ sequence of solutions to Einstein's equations that is defined by initial data having the Newtonian scaling property: v/sup i/approx.epsilon, rhoapprox.epsilon 2 , papprox.epsilon 4 , where epsilon is the parameter along the sequence. We map one solution in the sequence to another by identifying them at constant spatial position x/sup i/ and Newtonian dynamical time tau = epsilont. This mapping defines a congruence parametrized by epsilon, and the various post-Newtonian approximations emerge as derivatives of the relativistic solutions along this congruence. We thereby show for the first time that the approximations are genuine asymptotic approximations to general relativity. The proof is given in detail up to first post-Newtonian order, but is easily extended. The results will be applied in the following paper to radiation reaction in binary star systems, to give a proof of the validity of the ''quadrupole formula'' free from any divergences

Historical evolution of oil painting media: A rheological study

Science.gov (United States)

de Viguerie, Laurence; Ducouret, Guylaine; Lequeux, François; Moutard-Martin, Thierry; Walter, Philippe

2009-09-01

Rheology is the science of flow, which is a phenomenon found in every painting operation, such as decorative paintings or protective coatings. In this article, the principles of rheology as applied to paintings and coatings are recalled in a first part and the rheological criteria required in the paint industry presented. Indeed, different flow behaviours leads to different finishes. The same procedure and techniques as in industry can be employed to explain some evolutions in oil painting aspects over the centuries. The first recipes for oil painting indicate the use of treated oil, resins and spirits. This article deals with the evolution of the composition of these systems as media for oil painting, according to rheological clues. During the Renaissance period, the media used were Newtonian or slightly shear thinning and allowed one a perfect levelling. Then techniques changed, paints became more opaque with less addition of oil/resin media, and brushstrokes appeared visible. Some preparations containing lead, oil and mastic resin, whose flow behaviour is closed to those required in industry, may have appeared during the 17th century and are still used and sold today. To cite this article: L. de Viguerie et al., C. R. Physique 10 (2009).

Combinatorial Optimization for Energy Saving in Nickel Industry Non-Newtonian Fluid Pumping System

International Nuclear Information System (INIS)

Hernández Ramírez, Gabriel; Legra Lobaina, Aristides; Columbié Navarro, Angel; Marcos Aníbal León Segovia

2017-01-01

In the present work a study of the influence of the rheological parameters of the lateritic hydromixtures with the energetic ones of the pumping systems that guarantee the productivity of nickel company 'Commander Pedro Sotto Alba' is carried out. From an experimental study and through an estimator, the rheological parameters are modeled as a function of the factors: temperature, solids content, chemical and granulometric composition. From an appropriate discretization of the model of the lateritic hydrometer pumping system and the application of a Discrete Combination Optimization Double Sequencing procedure, the operating parameters of this system were obtained, in order to guarantee a flow rate of 1600 m3 / h and one Adequate solids concentration. It is concluded that the use of a mathematical model that relates the rheological parameters of the lateritic pulp and the energy parameters of the pumping system, guarantee the metallurgical and energy efficiency in the acid leaching process with an average increase in production between 1000-1500 T Ni + Co / y and an energy saving of 30 MWh /year. (author)

Natural convection heat transfer in shallow horizontal rectangular enclosures uniformly heated from the side and filled with non-Newtonian power law fluids

International Nuclear Information System (INIS)

Lamsaadi, M.; Naimi, M.; Hasnaoui, M.

2006-01-01

A combined analytical and numerical study is conducted for two dimensional, steady state, buoyancy driven flows of non-Newtonian power law fluids confined in a shallow rectangular cavity submitted to uniform fluxes of heat along both its short vertical sides, while its long horizontal walls are considered adiabatic. The effect of the non-Newtonian behavior on the fluid flow and heat transfer characteristics is examined. An approximate theoretical solution is developed on the basis of the parallel flow assumption and validated numerically by solving the full governing equations

Saffman-Taylor Instability for a non-Newtonian fluid

Science.gov (United States)

Daripa, Prabir

2013-11-01

Motivated by applications, we study classical Saffman-Taylor instability involving displacement of an Oldroyd-B fluid displaced by air in a Hele-Shaw cell. The lubrication approximation is used by neglecting the vertical component of the velocity. We obtain an explicit expression of one of the components of the extra-stress perturbations tensor in terms of the horizontal velocity perturbations. The main result is an explicit formula for the growth constant (in time) of perturbations, given by a ratio in which a term depending on the relaxation and retardation (time) constants appears in the denominator of the ratio. This exact result compares extremely well with known numerical results. It is found that flow is more unstable than the corresponding Newtonian case. This is a joint work with Gelu Pasa. The research has been made possible by an NPRP Grant # 08-777-1-141 from the Qatar National Research Fund (a member of the Qatar Foundation).

Irreversibility analysis for gravity driven non-Newtonian liquid film along an inclined isothermal plate

International Nuclear Information System (INIS)

Makinde, O.D.

2005-10-01

In this paper, the first and second law of thermodynamics are employed in order to study the inherent irreversibility for a gravity driven non-Newtonian Ostwald-de Waele power law liquid film along an inclined isothermal plate. Based on some simplified assumptions, the governing equations are obtained and solved analytically. Expressions for fluid velocity, temperature, volumetric entropy generation numbers, irreversibility distribution ratio and the Bejan number are also determined. (author)

Numerical investigation of non-Newtonian nanofluid flow in a converging microchannel

Energy Technology Data Exchange (ETDEWEB)

Mohsenian, S.; Ramiar, A.; Ranjbar, A. A. [Faculty of Mechanical Engineering, Babol Noshirvani University of Technology, Babol (Iran, Islamic Republic of)

2017-01-15

In the present study the flow of non-Newtonian nanofluid through a converging microchannel is investigated numerically. TiO{sub 2} nanoparticles with 10 nm diameter are dispersed in an aqueous solution of 0.5 %.wt Carboxymethyl cellulose (CMC) to produce the nanofluid. Both nanofluid and the base fluid show pseudoplastic behavior. The equations have been solved with finite volume approach using collocated grid. It has been found that by increasing the volume fraction and Reynolds number and the convergence angle, the Nusselt number increases. Also, it has been observed that by increasing convergence angle and decreasing aspect ratio of the channel, the velocity of the channel increases.

Novel nano-cellulose excipient for generating non-Newtonian droplets for targeted nasal drug delivery.

Science.gov (United States)

Young, Paul M; Traini, Daniela; Ong, Hui Xin; Granieri, Angelo; Zhu, Bing; Scalia, Santo; Song, Jie; Spicer, Patrick T

2017-10-01

Thickening polymers have been used as excipients in nasal formulations to avoid nasal run-off (nasal drip) post-administration. However, increasing the viscosity of the formulation can have a negative impact on the quality of the aerosols generated. Therefore, the study aims to investigate the use of a novel smart nano-cellulose excipient to generate suitable droplets for nasal drug delivery that simultaneously has only marginally increased viscosity while still reducing nasal drips. Nasal sprays containing nano-cellulose at different concentrations were investigated for the additive's potential as an excipient. The formulations were characterized for their rheological and aerosol properties. This was then compared to conventional nasal spray formulation containing the single-component hydroxyl-propyl methyl cellulose (HPMC) viscosity enhancing excipient. The HPMC-containing nasal formulations behave in a Newtonian manner while the nano-cellulose formulations have a yield stress and shear-thinning properties. At higher excipient concentrations and shear rates, the nano-cellulose solutions have significantly lower viscosities compared to the HPMC solution, resulting in improved droplet formation when actuated through conventional nasal spray. Nano-cellulose materials could potentially be used as a suitable excipient for nasal drug delivery, producing consistent aerosol droplet size, and enhanced residence time within the nasal cavity with reduced run-offs compared to conventional polymer thickeners.

Analysis of pressure falloff tests of non-Newtonian power-law fluids in naturally-fractured bounded reservoirs

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Omotayo Omosebi

2015-12-01

This article presents an analytic technique for interpreting pressure falloff tests of non-Newtonian Power-law fluids in wells that are located near boundaries in dual-porosity reservoirs. First, dimensionless pressure solutions are obtained and Stehfest inversion algorithm is used to develop new type curves. Subsequently, long-time analytic solutions are presented and interpretation procedure is proposed using direct synthesis. Two examples, including real field data from a heavy oil reservoir in Colombian eastern plains basin, are used to validate and demonstrate application of this technique. Results agree with conventional type-curve matching procedure. The approach proposed in this study avoids the use of type curves, which is prone to human errors. It provides a better alternative for direct estimation of formation and flow properties from falloff data.

Validation of a low field Rheo-NMR instrument and application to shear-induced migration of suspended non-colloidal particles in Couette flow

Science.gov (United States)

Colbourne, A. A.; Blythe, T. W.; Barua, R.; Lovett, S.; Mitchell, J.; Sederman, A. J.; Gladden, L. F.

2018-01-01

Nuclear magnetic resonance rheology (Rheo-NMR) is a valuable tool for studying the transport of suspended non-colloidal particles, important in many commercial processes. The Rheo-NMR imaging technique directly and quantitatively measures fluid displacement as a function of radial position. However, the high field magnets typically used in these experiments are unsuitable for the industrial environment and significantly hinder the measurement of shear stress. We introduce a low field Rheo-NMR instrument (1 H resonance frequency of 10.7MHz), which is portable and suitable as a process monitoring tool. This system is applied to the measurement of steady-state velocity profiles of a Newtonian carrier fluid suspending neutrally-buoyant non-colloidal particles at a range of concentrations. The large particle size (diameter > 200 μm) in the system studied requires a wide-gap Couette geometry and the local rheology was expected to be controlled by shear-induced particle migration. The low-field results are validated against high field Rheo-NMR measurements of consistent samples at matched shear rates. Additionally, it is demonstrated that existing models for particle migration fail to adequately describe the solid volume fractions measured in these systems, highlighting the need for improvement. The low field implementation of Rheo-NMR is complementary to shear stress rheology, such that the two techniques could be combined in a single instrument.

Rheological and phase behaviour of amphiphilic lipids

Directory of Open Access Journals (Sweden)

Alfaro, M. C.

2000-04-01

Full Text Available This chapter reviews the different association structures which are likely to be formed by amphiphilic lipids in the liquid-crystalline state and their corresponding shear flow properties. The structure and rheological behaviour of thermotropic liquid crystals, emphasizing the properties of smectic mesophases, and those of lyotropic liquid crystals such as: nematic, lamellar, diluted lamellar, lamellar dispersions, hexagonal and cubic mesophases are described. The importance of a comprehensive rheological characterisation, including rheo-optical techniques, is pointed out for their practical applications, development of formulations and as a useful technique to assist in the determination of phase diagrams. A historical approach has been used to discuss the evolving field of the rheology and structure identification of liquid crystals formed by amphiphilic lipids and surfactants. Non-Newtonian viscous shear flow, thixotropic and antithixotropic phenomena, linear viscoelastic properties -described by dynamic and creep compliance experiments- and non-linear viscoelastic properties - described by the difference of normal stresses and stress relaxation tests are interpreted on the basis of a microstructure-rheology relationship. The polycrystalline nature of liquid crystals turns out to be rather sensitive to shear due to the change of both size and orientation of the liquid-crystalline monodomains under flow.En este capítulo se realiza una revisión de las distintas estructuras coloidales de asociación que pueden formar los lípidos anfifílicos en estado líquido-cristalino y de sus correspondientes propiedades de flujo en cizalla. Se describe la estructura y comportamiento reológico de cristales líquidos termotrópicos, con énfasis en los de tipo esméctico, fases gel, y cristales líquidos liotrópicos: nemáticos, laminares, laminares diluidos, dispersiones de laminares, hexagonales y cúbicos. Se hace hincapié en la importancia de una

Simulation of forced convection in non-Newtonian fluid through sandstones

Science.gov (United States)

Gokhale, M. Y.; Fernandes, Ignatius

2017-11-01

Numerical simulation is carried out to study forced convection in non-Newtonian fluids flowing through sandstones. Simulation is carried out using lattice Boltzmann method (LBM) for both shear-thinning and shear-thickening, by varying the power law index from 0.5 to 1.5 in Carreau-Yasuda model. Parameters involved in LBM and Carreau model are identified to achieve numerical convergence. Permeability and porosity are varied in the range of 10-10-10-6 and 0.1-0.7, respectively, to match actual geometrical properties of sandstone. Numerical technology is validated by establishing Darcy's law by plotting the graph between velocity and pressure gradient. Consequently, investigation is carried out to study the influence of material properties of porous media on flow properties such as velocity profiles, temperature profiles, and Nusselt number.

ANALYSIS OF MARANGONI CONVECTION OF NON-NEWTONIAN POWER LAW FLUIDS WITH LINEAR TEMPERATURE DISTRIBUTION

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Yan Zhang

2011-01-01

Full Text Available The problem of steady, laminar, thermal Marangoni convection flow of non-Newtonian power law fluid along a horizontal surface with variable surface temperature is studied. The partial differential equations are transformed into ordinary differential equations by using a suitable similarity transformation and analytical approximate solutions are obtained by an efficient transformation, asymptotic expansion and Padé approximants technique. The effects of power law index and Marangoni number on velocity and temperature profiles are examined and discussed.

Stress analysis of mixing of non-newtonian flows in cylindrical vessel induced by co-rotating stirrers

International Nuclear Information System (INIS)

Memon, R.A.; Solangi, M.A.

2013-01-01

The impacts of rotational velocity and inertia on velocity gradients and stresses are addressed under present study. The non-Newtonian behaviour of inelastic rotating flows is predicted by employing Power law model. A numerical model has been developed for mixing flow within a cylindrical vessel along a couple of stirrers. A time marching FEM (Finite Element Method) is employed to predict the required solution. Predicted solutions are presented for minimum to maximum values in terms of contour plots of velocity gradients and shear stresses, over the range. The long term application of this research will be used to improve the design of mixers and processing products. The predicted results are used to generate the capability and are in good agreement with numerical results to the mixer design that will ultimately effect the processing of dough products. (author)

Newtonian cosmology with a quantum bounce

Energy Technology Data Exchange (ETDEWEB)

Bargueno, P.; Bravo Medina, S.; Nowakowski, M. [Universidad de los Andes, Departamento de Fisica, Bogota (Colombia); Batic, D. [University of West Indies, Department of Mathematics, Kingston 6 (Jamaica)

2016-10-15

It has been known for some time that the cosmological Friedmann equation deduced from general relativity can also be obtained within the Newtonian framework under certain assumptions. We use this result together with quantum corrections to the Newtonian potentials to derive a set a of quantum corrected Friedmann equations. We examine the behavior of the solutions of these modified cosmological equations paying special attention to the sign of the quantum corrections. We find different quantum effects crucially depending on this sign. One such a solution displays a qualitative resemblance to other quantum models like Loop quantum gravity or non-commutative geometry. (orig.)

Synthesis and characterization of magneto-rheological (MR fluids for MR brake application

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Bhau K. Kumbhar

2015-09-01

Full Text Available Magneto rheological (MR fluid technology has been proven for many industrial applications like shock absorbers, actuators, etc. MR fluid is a smart material whose rheological characteristics change rapidly and can be controlled easily in presence of an applied magnetic field. MR brake is a device to transmit torque by the shear stress of MR fluid. However, MR fluids exhibit yield stress of 50–90 kPa. In this research, an effort has been made to synthesize MR fluid sample/s which will typically meet the requirements of MR brake applications. In this study, various electrolytic and carbonyl iron powder based MR fluids have been synthesized by mixing grease as a stabilizer, oleic acid as an antifriction additive and gaur gum powder as a surface coating to reduce agglomeration of the MR fluid. MR fluid samples based on sunflower oil, which is bio-degradable, environmentally friendly and abundantly available have also been synthesized. These MR fluid samples are characterized for determination of magnetic, morphological and rheological properties. This study helps identify most suitable localized MR fluid meant for MR brake application.

Aerosol entrainment from a sparged non-Newtonian slurry

International Nuclear Information System (INIS)

Fritz, Brad G.

2006-01-01

Aerosol measurements were conducted above a half-scale air sparged mixing tank filled with simulated waste slurry. Three aerosol size fractions were measured at three sampling heights at three different sparging rates using a filter based ambient air sampling technique. Aerosol concentrations in the head space above the closed tank demonstrated a wide range, varying between 97 ?g m-3 for PM2.5 and 5650 ?g m-3 for TSP. The variation in concentrations was a function of sampling heights, size fraction and sparging rate. Measured aerosol entrainment coefficients showed good agreement with existing entrainment models. The models evaluated generally over predicted the entrainment, but were within a factor of two of the measured entrainment. This indicates that the range of applicability of the models may be extendable to include sparged slurries with Bingham plastic rheological properties

Influence of transglutaminase treatment on the physicochemical, rheological, and melting properties of ice cream prepared from goat milk

Directory of Open Access Journals (Sweden)

Hatice Şanlidere Aloğlu

2018-01-01

Full Text Available This study was conducted to evaluate the effects of the transglutaminase enzyme on the physicochemical characteristics, overrun, melting resistance, rheological and sensorial properties of ice cream made from goat’s milk. Different enzyme units (0.5, 1, 2, and 4 U/g milk protein and treatment times (20 min and 60 min were applied to determine the optimum process conditions. Treatment of the transglutaminase in the ice cream mix significantly affected the rheological and melting properties of the ice cream samples. The samples prepared with higher enzyme units and enzyme-treatment times showed higher melting resistance, consistency index, and viscoelastic modulus (G’ than the ice cream mix. The correlation coefficient between melting resistance and viscoelastic modulus was found to be high (0.76. The apparent viscosity of all samples decreased with increasing the shear rate, indicating that all samples exhibited non-Newtonian shear thinning flow behavior. The sensory, overrun, and physicochemical properties of samples were not affected by the enzyme treatment. This study showed that treatment times and enzyme units are essential factors in the processing of the transglutaminase enzyme for improving the rheological and melting properties of ice cream mixes. Another significant result was that desired melting resistance could be achieved for ice cream with lower stabilizer and fat content.

Gravitational Radiation from Post-Newtonian Sources and Inspiralling Compact Binaries

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Blanchet Luc

2006-06-01

Full Text Available The article reviews the current status of a theoretical approach to the problem of the emission of gravitational waves by isolated systems in the context of general relativity. Part A of the article deals with general post-Newtonian sources. The exterior field of the source is investigated by means of a combination of analytic post-Minkowskian and multipolar approximations. The physical observables in the far-zone of the source are described by a specific set of radiative multipole moments. By matching the exterior solution to the metric of the post-Newtonian source in the near-zone we obtain the explicit expressions of the source multipole moments. The relationships between the radiative and source moments involve many non-linear multipole interactions, among them those associated with the tails (and tails-of-tails of gravitational waves. Part B of the article is devoted to the application to compact binary systems. We present the equations of binary motion, and the associated Lagrangian and Hamiltonian, at the third post-Newtonian (3PN order beyond the Newtonian acceleration. The gravitational-wave energy flux, taking consistently into account the relativistic corrections in the binary moments as well as the various tail effects, is derived through 3.5PN order with respect to the quadrupole formalism. The binary's orbital phase, whose prior knowledge is crucial for searching and analyzing the signals from inspiralling compact binaries, is deduced from an energy balance argument.

Shear Rheology of a Suspension of Deformable Solids in Viscoelastic Fluid via Immersed Boundary Techniques

Science.gov (United States)

Guido, Christopher; Shaqfeh, Eric

2017-11-01

The simulation of fluids with suspended deformable solids is important to the design of microfluidic devices with soft particles and the examination of blood flow in complex channels. The fluids in these applications are often viscoelastic, motivating the development of a high-fidelity simulation tool with general constitutive model implementations for both the viscoelastic fluid and deformable solid. The Immersed Finite Element Method (IFEM) presented by Zhang et al. (2007) allows for distinct fluid and solid grids to be utilized reducing the need for costly re-meshing when particles translate. We discuss a modified version of the IFEM that allows for the simulation of deformable particles in viscoelastic flows. This simulation tool is validated for simple Newtonian shear flows with elastic particles that obey a Neo-Hookean Law. The tool is used to further explore the rheology of a dilute suspension of Neo-Hookean particles in a Giesekus fluid. The results show that dilute suspensions of soft particles have viscosities that decrease as the Capillary number becomes higher in both the case of a Newtonian and viscoelastic fluid. A discussion of multiple particle results will be included. NSF CBET-1066263 and 1066334.

Influence of ultrasonication and Fenton oxidation pre-treatment on rheological characteristics of wastewater sludge.

Science.gov (United States)

Pham, T T H; Brar, S K; Tyagi, R D; Surampalli, R Y

2010-01-01

The effect of ultrasonication and Fenton oxidation as physico-chemical pre-treatment processes on the change of rheology of wastewater sludge was investigated in this study. Pre-treated and raw sludges displayed non-Newtonian rheological behaviour with shear thinning as well as thixotropic properties for total solids ranging from 10 g/L to 40 g/L. The rheological models, namely, Bingham plastic, Casson law, NCA/CMA Casson, IPC Paste, and power law were also studied to characterize flow of raw and pre-treated sludges. Among all rheological models, the power law was more prominent in describing the rheology of the sludges. Pre-treatment processes resulted in a decrease in pseudoplasticity of sludge due to the decrease in consistency index K varying from 42.4 to 1188, 25.6 to 620.4 and 52.5 to 317.9; and increase in flow behaviour index n changing from 0.5 to 0.35, 0.62 to 0.55 and 0.63 to 0.58, for RS, UlS and FS, respectively at solids concentration 10-40 g/L. The correlation between improvement of biodegradability and dewaterability, decrease in viscosity, and change in particle size as a function of sludge pre-treatment process was also investigated. Fenton oxidation facilitated sludge filterability resulting in capillary suction time values which were approximately 50% of the raw sludges, whereas ultrasonication with high input energy deteriorated the filterability. Biodegradability was also enhanced by the pre-treatment processes and the maximum value was obtained (64%, 77% and 73% for raw, ultrasonicated and Fenton oxidized sludges, respectively) at total solids concentration of 25 g/L. Hence, pre-treatment of wastewater sludge modified the rheological properties so that: (1) the flowability of sludge was improved for transport through the treatment train (via pipes and pumps); (2) the dewaterability of wastewater sludge was enhanced for eventual disposal and; (3) the assimilation of nutrients by microorganisms for further value-addition was increased.

Rheological characterization of modified foodstuffs with food grade thickening agents

Science.gov (United States)

Reyes-Ocampo, I.; Aguayo-Vallejo, JP; Ascanio, G.; Córdova-Aguilar, MS

2017-01-01

This work describes a rheological characterization in terms of shear and extensional properties of whole milk, modified with food grade thickening agents (xanthan and carboxymethyl cellulose) with the purpose of being utilized in dysphagia treatment. Shear viscosity of the thickened fluids (2% wt. of xanthan and CMC) were measured in a stress-controlled rheometer and for extensional viscosity, a custom-built orifice flowmeter was used, with elongation rates from 20 to 3000 s-1. Such elongation-rate values represent the entire swallowing process, including the pharyngeal and esophageal phases. The steady-state shear and extensional flow curves were compared with the flow curve of a pudding consistency BaSO4 suspension (α=05), typically used as a reference fluid for the specialized commercial dysphagia products. The modified fluids presented non-Newtonian behavior in both, shear and extensional flows, and the comparison with the reference fluid show that the thickened milk prepared here, can be safely used for consumption by patients with severe dysphagia.

Rheological Characterization of Unusual DWPF Slurry Samples

International Nuclear Information System (INIS)

Koopman, D. C.

2005-01-01

A study was undertaken to identify and clarify examples of unusual rheological behavior in Defense Waste Processing Facility (DWPF) simulant slurry samples. Identification was accomplished by reviewing sludge, Sludge Receipt and Adjustment Tank (SRAT) product, and Slurry Mix Evaporator (SME) product simulant rheological results from the prior year. Clarification of unusual rheological behavior was achieved by developing and implementing new measurement techniques. Development of these new methods is covered in a separate report, WSRC-TR-2004-00334. This report includes a review of recent literature on unusual rheological behavior, followed by a summary of the rheological measurement results obtained on a set of unusual simulant samples. Shifts in rheological behavior of slurries as the wt. % total solids changed have been observed in numerous systems. The main finding of the experimental work was that the various unusual DWPF simulant slurry samples exhibit some degree of time dependent behavior. When a given shear rate is applied to a sample, the apparent viscosity of the slurry changes with time rather than remaining constant. These unusual simulant samples are more rheologically complex than Newtonian liquids or more simple slurries, neither of which shows significant time dependence. The study concludes that the unusual rheological behavior that has been observed is being caused by time dependent rheological properties in the slurries being measured. Most of the changes are due to the effect of time under shear, but SB3 SME products were also changing properties while stored in sample bottles. The most likely source of this shear-related time dependence for sludge is in the simulant preparation. More than a single source of time dependence was inferred for the simulant SME product slurries based on the range of phenomena observed. Rheological property changes were observed on the time-scale of a single measurement (minutes) as well as on a time scale of hours

Influence of hydroxypropylmethyl cellulose-sodium laurylsulfate interaction on rheological properties of the solution

Directory of Open Access Journals (Sweden)

Šaletić Jelena V.

2004-01-01

Full Text Available Interactions between the polymers and surfactants in solution have widely been investigated because of their scientific and technological importance. These interactions can be utilized to modify the physicochemical properties of system in many food products, pharmaceutical formulations, personal care products, paints, pesticides, etc. Interaction between nonionic polymer - hydroxypropylmethyl cellulose (HPMC and anionic surfactant - sodium laurylsulfate (SDS in solution has been investigated in this paper by rheological measurements. Rheological measurements are performed by rotational viscometer at 20°C and changes of rheological characteristics of HPMC solutions (0.5-1.5% with increasing SDS concentrations (0-4.0% were determined. The results of these investigations showed that viscosity of the solution is dependant on HPMC-SDS interaction. At particular SDS concentration viscosity increases, reach maximum and after that decreases until reach constant value. From the viscosity changes the characteristic concentrations of SDS, critical aggregation concentration (cac and polymer saturation point (psp, were determined. These concentrations are in linear relationships with HPMC concentrations. Rheological properties of the solution are strong influenced by HPMC-SDS interaction and exhibits more or less pronounced pseudoplastic behavior, which changes to Newtonian one after the psp has been reached.

The influence of pH on gas-liquid mass transfer in non-Newtonian fluids

OpenAIRE

Li Shaobai; Fan Jungeng; Xu Shuang; Li Rundong; Luan Jingde

2017-01-01

In this study, the effect of pH on the mass transfer of oxygen bubble swarms in non-Newtonian fluids was experimentally studied. The volumetric liquid side mass transfer coefficient (kLa), liquid side mass transfer coefficient (kL), and specific interfacial area (a) were investigated. The pH was regulated by the addition of hydrochloric acid and sodium hydroxide (NaOH). It was found that the kLa increased with the gas flow rate increasing and decreased with the apparent viscosity of the liqui...

Numerical investigation on hydraulic fracture cleanup and its impact on the productivity of a gas well with a non-Newtonian fluid model

Energy Technology Data Exchange (ETDEWEB)

Friedel, T. [Schlumberger Data and Consulting Services, Sugar Land, TX (United States)

2006-07-01

There are many damage mechanisms associated with hydraulically fractured gas wells. These include hydraulic damage caused by invading fluids during the treatment and damage due to the stresses exerted on the fracture face. Damage to the proppant pack can also reduce conductivity and non-Darcy flow. However, these are not the only impacts of impaired productivity in tight-gas reservoirs, which do not respond to hydraulic fracturing as expected. Some sustain a flat production profile or show only a slow increase in production rate for several weeks or months. This is due to poor rock quality, strong stress dependency in permeability, hydraulic and mechanical damage. Another reason for the poor performance is related to the cleanup of the cross-linked fracturing fluid with its non-Newtonian characteristics. This paper presented an improved 3-phase cleanup model for the investigation of polymer gel cleanup. Yield stress was considered according to the Herschel-Bulkley rheology model. The viscosity model is based on the exact analytical solution, including the plug flow zone. According to data in the published literature, half of the gel phase can be recovered. The gel saturation gradually increases towards the fracture tips, thereby lowering the fracture conductivities. The residing gel damages the permeability and porosity of the proppant pack or causes damage to the fracture face, thereby reducing production potential. These results are in agreement with field observations where fracture half-lengths, conductivities and productivity are also lower than expected. Preliminary results suggest that capillary forces and load-water recovery have little influence on gel cleanup. 16 refs., 2 tabs., 17 figs.

Complex rheological properties of a water-soluble extract from the fronds of the black tree fern, Cyathea medullaris.

Science.gov (United States)

Goh, Kelvin K T; Matia-Merino, Lara; Hall, Christopher E; Moughan, Paul J; Singh, Harjinder

2007-11-01

A water-soluble extract was obtained from the fronds of a New Zealand native black tree fern (Cyathea medullaris or Mamaku in Māori). The extract exhibited complex rheological behavior. Newtonian, shear-thinning, shear-thickening, thixotropic, antithixotropic, and viscoelastic behaviors were observed depending on polymer concentration, shear rate, and shear history. The extract also displayed rod-climbing and self-siphoning properties typical of viscoelastic fluids. Such complex rheological properties have been reported in synthetic or chemically modified polymers but are less frequent in unmodified biopolymers. Although Mamaku extract obtained from the pith of the fern has been traditionally used by the Māori in New Zealand for treating wounds and diarrhea among other ailments, this material has never been characterized before. This study reports on the chemical composition of the extract and on its viscoelastic properties through rotational and oscillatory rheological measurements. Explanations of the mechanism behind the rheological properties were based on transient network models for associating polymers.

Experimental study of physical and rheological properties of grape juice using different temperatures and concentrations. Part I: Cabernet Sauvignon.

Science.gov (United States)

de Castilhos, Maurício Bonatto Machado; Betiol, Lilian Fachin Leonardo; de Carvalho, Gisandro Reis; Telis-Romero, Javier

2017-10-01

The effect of the temperature and concentration on rheological behavior of Cabernet Sauvignon juice concentrates was assessed using a rheometer over a wide range of temperature (1-66°C) and concentrations (13.6-45.0Brix) at shear rates of 0.84-212.1 1/s. The Ostwald-De Waele was the best rheological model fitted the data (R 2 =0.99957 and relative error=7.77%). The Cabernet Sauvignon juice concentrates presented a non-Newtonian pseudoplastic behavior (n<1). The consistency levels were significantly reduced with the increase of temperature and increased with the increase of the concentrations. The flow activation energy ranged from 28.87 (45.0Brix) to 38.05KJ/mol (37.0Brix) with a R 2 =0.9798 for both cases. Density and specific heat were influenced by both temperature and concentration; however, thermal conductivity was only influenced by concentration. The Cabernet Sauvignon juice concentrates will be useful as wine chaptalization agent in future studies. Copyright © 2017 Elsevier Ltd. All rights reserved.

An integrated in-line fluid characterization system for industrial applications(In-situ fluid mechanics experiments)

OpenAIRE

Johan, Wiklund; Reinhardt, Kotze; Beat, Birkhofer; Stefano, Ricci; Valentino, Meacci; Mats, Stading; Rainer, Haldenwang; SP-Technical Research Institute of Sweden; FPRC, Cape Peninsula University of Technology; Sika Services AG; Information Engineering Department - University of Florence; Information Engineering Department - University of Florence; SP-Technical Research Institute of Sweden; FPRC, Cape Peninsula University of Technology

2015-01-01

In this work we have presented the world's first commercially available embedded in-line fluids characterization system, "Flow-Viz". It has been specifically designed for the non-invasive, in-line, continuous, real-time velocity profile and rheological assessment of opaque, non-Newtonian industrial fluids. The Flow-Viz system has been successfully installed in pilot plants of international companies and used also for academic research. The technology has been applied to a wide range of fluids...

Sugar Profile, Mineral Content, and Rheological and Thermal Properties of an Isomerized Sweet Potato Starch Syrup.

Science.gov (United States)

Dominque, Brunson; Gichuhi, Peter N; Rangari, Vijay; Bovell-Benjamin, Adelia C

2013-01-01

Currently, corn is used to produce more than 85% of the world's high fructose syrup (HFS). There is a search for alternative HFS substrates because of increased food demand and shrinking economies, especially in the developing world. The sweet potato is a feasible, alternative raw material. This study isomerized a high glucose sweet potato starch syrup (SPSS) and determined its sugar profile, mineral content, and rheological and thermal properties. Rheological and thermal properties were measured using a rheometer and DSC, respectively. Sweet potato starch was hydrolyzed to syrup with a mean fructose content of 7.6 ± 0.4%. The SPSS had significantly higher (P syrups. During 70 days of storage, the SPSS acted as a non-Newtonian, shear-thinning liquid in which the viscosity decreased as shear stress increased. Water loss temperature of the SPSS continually decreased during storage, while pancake and ginger syrups' peak water loss temperature decreased initially and then increased. Further and more detailed studies should be designed to further enhance the fructose content of the syrup and observe its stability beyond 70 days. The SPSS has the potential to be used in human food systems in space and on Earth.

Non-Newtonian flow of pathological bile in the biliary system: experimental investigation and CFD simulations

Science.gov (United States)

Kuchumov, Alex G.; Gilev, Valeriy; Popov, Vitaliy; Samartsev, Vladimir; Gavrilov, Vasiliy

2014-02-01

The paper presents an experimental study of pathological human bile taken from the gallbladder and bile ducts. The flow dependences were obtained for different types of bile from patients with the same pathology, but of different age and sex. The parameters of the Casson's and Carreau's equations were found for bile samples. Results on the hysteretic bile behavior at loading-unloading tests are also presented, which proved that the pathologic bile is a non-Newtonian thixotropic liquid. The viscosity of the gallbladder bile was shown to be higher compared to the duct bile. It was found that at higher shear stress the pathological bile behaves like Newtonian fluid, which is explained by reorientation of structural components. Moreover, some pathological bile flow in the biliary system CFD simulations were performed. The velocity and pressure distributions as well as flow rates in the biliary segments during the gallbladder refilling and emptying phases are obtained. The results of CFD simulations can be used for surgeons to assess the patient's condition and choose an adequate treatment.

Modeling of the blood rheology in steady-state shear flows

International Nuclear Information System (INIS)

Apostolidis, Alex J.; Beris, Antony N.

2014-01-01

We undertake here a systematic study of the rheology of blood in steady-state shear flows. As blood is a complex fluid, the first question that we try to answer is whether, even in steady-state shear flows, we can model it as a rheologically simple fluid, i.e., we can describe its behavior through a constitutive model that involves only local kinematic quantities. Having answered that question positively, we then probe as to which non-Newtonian model best fits available shear stress vs shear-rate literature data. We show that under physiological conditions blood is typically viscoplastic, i.e., it exhibits a yield stress that acts as a minimum threshold for flow. We further show that the Casson model emerges naturally as the best approximation, at least for low and moderate shear-rates. We then develop systematically a parametric dependence of the rheological parameters entering the Casson model on key physiological quantities, such as the red blood cell volume fraction (hematocrit). For the yield stress, we base our description on its critical, percolation-originated nature. Thus, we first determine onset conditions, i.e., the critical threshold value that the hematocrit has to have in order for yield stress to appear. It is shown that this is a function of the concentration of a key red blood cell binding protein, fibrinogen. Then, we establish a parametric dependence as a function of the fibrinogen and the square of the difference of the hematocrit from its critical onset value. Similarly, we provide an expression for the Casson viscosity, in terms of the hematocrit and the temperature. A successful validation of the proposed formula is performed against additional experimental literature data. The proposed expression is anticipated to be useful not only for steady-state blood flow modeling but also as providing the starting point for transient shear, or more general flow modeling

The Multiphase Rheology of Monte Nuovo's Eruption (Campi Flegrei, Italy)

Science.gov (United States)

Vona, A.; Romano, C.; Giordano, D.; Russell, K.

2011-12-01

We present a study of high-temperature, uniaxial deformation experiments of natural, partially crystallized samples from the Monte Nuovo (1538 AD) trachytic eruption. The experiments were performed at dry atmospheric conditions and controlled deformation rate using a high-temperature uniaxial Geocomp LoadTrac II press. Experiments were performed isothermally by deforming cores of the natural (i.e., crystal- and vesicle-bearing) samples at constant displacement rates (CDR) corresponding to constant strain rates between 10-7 and 10-4 s-1. The measurements were all performed in the viscous-flow regime and showed non-Newtonian shear thinning behavior. Measured viscosities vary between 1010 and 1013 Pa s. As no yield stress was detected, the flow behavior of the investigated specimens could be described with a simplified Herschel-Bulkley equation in terms of consistency K and flow index n. As the pure liquid and the liquid+crystal rheology of these samples were already measured in previous studies, we were able to estimate the net effects of crystals and vesicles on the rheology of the multiphase suspensions. The results revealed that the presence of vesicles has a major impact on the rheological response of magmas leading to a marked decrease of their viscosity, which partially balances the increase of viscosity due to the presence of crystals. At the same time, the presence of bubbles leads to a strong decrease in the shear strength of the magma inducing local and temporal variation in the deformation regimes (viscous vs. brittle). Brittle and ductile failure were in fact observed at T=600°C and strain rates of 10-5 s-1 and at T=800°C for the higher applied strain rate (10-4 s-1), respectively. During lava flow emplacement, this may explain the origin of the flow banding textures frequently observed in many silicic obsidian lava flows.

Rheological Flow Behavior of Structural Polysaccharides from Edible Tender Cladodes of Wild, Semidomesticated and Cultivated 'Nopal' (Opuntia) of Mexican Highlands.

Science.gov (United States)

López-Palacios, C; Peña-Valdivia, C B; Rodríguez-Hernández, A I; Reyes-Agüero, J A

2016-12-01

The aim of this study was to quantify the content of polysaccharides of edible tender cladodes (nopalitos) of three species of Opuntia and to evaluate the rheological flow behavior of isolated polysaccharides. A completely randomized experimental design was used to characterize a wild (O. streptacantha), a semidomesticated (O. megacantha) and a domesticated (O. ficus-indica) species. Mucilage content was higher (4.93 to 12.43 g 100 g -1 dry matter), tightly bound hemicelluloses were lower (3.32 to 1.81 g 100 g -1 dry matter) and pectins and loosely bound hemicelluloses were not different in wild than in domesticated species. Aqueous solution/suspensions of mucilage, pectins, hemicellulose and cellulose of all species showed non-Newtonian behavior under simple shear flow. The flow behavior of the structural polysaccharides was well described by the Ostwald de-Waele model. Pectins and mucilages exhibited the highest consistency indexes (K values ranged from 0.075 to 0.177 Pas n ) with a moderated shear-thinning behavior (n values ranged from 0.53 to 0.67). Cellulose dispersions exhibited the most shear-thinning behavior (n values ranged from 0.17 to 0.41) and hemicelluloses showed a tendency to Newtonian flow (n values ranged from 0.82 to 0.97). The rheological flow properties of these polysaccharides may be useful to improve the textural and sensory qualities of some foods and pharmaceutical materials. Moreover, they can emerge as functional ingredients mainly due to the nutraceutical properties that have been attributed to nopalitos.

Adding salt to a surfactant solution: Linear rheological response of the resulting morphologies

Energy Technology Data Exchange (ETDEWEB)

Gaudino, Danila; Pasquino, Rossana, E-mail: r.pasquino@unina.it; Grizzuti, Nino [DICMaPI, Università degli Studi di Napoli Federico II, P.le Tecchio 80, 80125 Napoli (Italy)

2015-11-15

The micellar system composed of Cetylpyridinium Chloride-Sodium Salicylate (CPyCl-NaSal) in brine aqueous solutions has been studied by systematically changing the salt concentration, in order to investigate the rheology of the arising morphologies. In particular, the zero-shear viscosity and the linear viscoelastic response have been measured as a function of the NaSal concentration (with [CPyCl] = 100 mM). The Newtonian viscosity shows a nonmonotonic dependence upon concentration, passing through a maximum at NaSal/CPyCl ≈ 0.6, and eventually dropping at higher salt concentrations. The progressive addition of salt determines first a transition from a Newtonian to a purely Maxwell-like behavior as the length of the micelles significantly increases. Beyond the peak viscosity, the viscoelastic data show two distinct features. On the one hand, the main relaxation time of the system strongly decreases, while the plateau modulus remains essentially constant. Calculations based on the rheological data show that, as the binding salt concentration increases, there is a decrease in micelles breaking rate and a decrease in their average length. On the other hand, in the same concentration region, a low-frequency elastic plateau is measured. Such a plateau is considered as the signature of a tenuous, but persistent branched network, whose existence is confirmed by cryo-transmission electron microscopy images.

Low-shear rheology and sedimentation stability of coal-oil dispersions

Energy Technology Data Exchange (ETDEWEB)

Rutter, P. R.; Davies, J. M.; Jones, T. E.R.

1984-10-15

Stable coal-oil mixtures can be prepared by grinding coal particles in fuel oil. These products have been prepared by the British Petroleum Company plc and are referred to as Coal-Oil Dispersions (COD). One of the major problems associated with the production of DOD is the rapid assessment of the length of time the coal particles are likely to remain in suspension under a particular set of storage conditions. This paper describes a number of measurements of the low-shear rheology and sedimentation stability of a series of CODs prepared by grinding two types of coal in two different fuel oils. The results suggest that two types of COD are possible. One type exhibits complex rheological properties at low shear rates and does not produce a coal sediment, even after prolonged storage at 80/sup 0/C under dynamic conditions. The other exhibits near Newtonian behaviour and appears to form a sedimented layer of coal during storage.

On a numerical strategy to compute gravity currents of non-Newtonian fluids

International Nuclear Information System (INIS)

Vola, D.; Babik, F.; Latche, J.-C.

2004-01-01

This paper is devoted to the presentation of a numerical scheme for the simulation of gravity currents of non-Newtonian fluids. The two dimensional computational grid is fixed and the free-surface is described as a polygonal interface independent from the grid and advanced in time by a Lagrangian technique. Navier-Stokes equations are semi-discretized in time by the Characteristic-Galerkin method, which finally leads to solve a generalized Stokes problem posed on a physical domain limited by the free surface to only a part of the computational grid. To this purpose, we implement a Galerkin technique with a particular approximation space, defined as the restriction to the fluid domain of functions of a finite element space. The decomposition-coordination method allows to deal without any regularization with a variety of non-linear and possibly non-differentiable constitutive laws. Beside more analytical tests, we revisit with this numerical method some simulations of gravity currents of the literature, up to now investigated within the simplified thin-flow approximation framework

Ferrocyanide Safety Program: Waste tank sludge rheology within a hot spot or during draining

International Nuclear Information System (INIS)

Fauske, H.K.; Cash, R.J.

1993-11-01

The conditions under which ferrocyanide waste sludge flows as a homogeneous non-Newtonian two-phase (solid precipitate-liquid) mixture rather than as a liquid through a porous medium (of stationary precipitate) are examined theoretically, based on the notion that the preferred rheological behavior of the sludge is the one which imposes the least resistance to the sludge flow. The homogeneous two-phase mixture is modeled as a power-law fluid and simple criteria are derived that show that the homogeneous power-law sludge-flow is a much more likely flow situation than the porous medium model of sludge flow. The implication of this finding is that the formation of a hot spot or the drainage of sludge from a waste tank are not likely to result in the uncovering (drying) and subsequent potential overheating of the reactive-solid component of the sludge

Chocolate rheology

Directory of Open Access Journals (Sweden)

Estela Vidal Gonçalves

2010-12-01

Full Text Available Rheology is the science that studies the deformation and flow of solids and fluids under the influence of mechanical forces. The rheological measures of a product in the stage of manufacture can be useful in quality control. The microstructure of a product can also be correlated with its rheological behavior allowing for the development of new materials. Rheometry permits attainment of rheological equations applied in process engineering, particularly unit operations that involve heat and mass transfer. Consumer demands make it possible to obtain a product that complies with these requirements. Chocolate industries work with products in a liquid phase in conching, tempering, and also during pumping operations. A good design of each type of equipment is essential for optimum processing. In the design of every process, it is necessary to know the physical characteristics of the product. The rheological behavior of chocolate can help to know the characteristics of application of the product and its consumers. Foods are generally in a metastable state. Their texture depends on the structural changes that occur during processing. Molten chocolate is a suspension with properties that are strongly affected by particle characteristics including not only the dispersed particles but also the fat crystals formed during chocolate cooling and solidification. Chocolate rheology is extensively studied, and it is known that chocolate texture and stability is strongly affected by the presence of specific crystals

Development of a fermented ice-cream as influenced by in situ exopolysaccharide production: Rheological, molecular, microstructural and sensory characterization.

Science.gov (United States)

Dertli, Enes; Toker, Omer S; Durak, M Zeki; Yilmaz, Mustafa T; Tatlısu, Nevruz Berna; Sagdic, Osman; Cankurt, Hasan

2016-01-20

This study aimed to investigate the role of in situ exopolysaccharide (EPS) production by EPS(+)Streptococcus thermophilus strains on physicochemical, rheological, molecular, microstructural and sensory properties of ice cream in order to develop a fermented and consequently functional ice-cream in which no stabilizers would be required in ice-cream production. For this purpose, the effect of EPS producing strains (control, strain 1, strain 2 and mixture) and fermentation conditions (fermentation temperature; 32, 37 and 42 °C and time; 2, 3 and 4h) on pH, S. thermophilus count, EPS amount, consistency coefficient (K), and apparent viscosity (η50) were investigated and optimized using single and multiple response optimization tools of response surface methodology. Optimization analyses indicated that functional ice-cream should be fermented with strain 1 or strain mixture at 40-42 °C for 4h in order to produce the most viscous ice-cream with maximum EPS content. Optimization analysis results also revealed that strain specific conditions appeared to be more effective factor on in situ EPS production amount, K and η50 parameters than did fermentation temperature and time. The rheological analysis of the ice-cream produced by EPS(+) strains revealed its high viscous and pseudoplastic non-Newtonian fluid behavior, which demonstrates potential of S. thermophilus EPS as thickening and gelling agent in dairy industry. FTIR analysis proved that the EPS in ice-cream corresponded to a typical EPS, as revealed by the presence of carboxyl, hydroxyl and amide groups with additional α-glycosidic linkages. SEM studies demonstrated that it had a web-like compact microstructure with pores in ice-cream, revealing its application possibility in dairy products to improve their rheological properties. Copyright © 2015. Published by Elsevier Ltd.

Effect of rheological parameters on curing rate during NBR injection molding

Science.gov (United States)

Kyas, Kamil; Stanek, Michal; Manas, David; Skrobak, Adam

2013-04-01

In this work, non-isothermal injection molding process for NBR rubber mixture considering Isayev-Deng curing kinetic model, generalized Newtonian model with Carreau-WLF viscosity was modeled by using finite element method in order to understand the effect of volume flow rate, index of non-Newtonian behavior and relaxation time on the temperature profile and curing rate. It was found that for specific geometry and processing conditions, increase in relaxation time or in the index of non-Newtonian behavior increases the curing rate due to viscous dissipation taking place at the flow domain walls.

Experimental model for non-Newtonian fluid viscosity estimation: Fit to mathematical expressions

Directory of Open Access Journals (Sweden)

Guillem Masoliver i Marcos

2017-01-01

Full Text Available The  construction  process  of  a  viscometer,  developed  in  collaboration  with  a  final  project  student,  is  here  presented.  It  is  intended  to  be  used  by   first  year's  students  to  know  the  viscosity  as  a  fluid  property, for  both  Newtonian  and  non-Newtonian  flows.  Viscosity  determination  is  crucial  for  the  fluids  behaviour knowledge  related  to  their  reologic  and  physical  properties.  These  have  great  implications  in  engineering aspects  such  as  friction  or  lubrication.  With  the  present  experimental  model  device  three  different fluids are  analyzed  (water,  kétchup  and  a  mixture  with  cornstarch  and  water.  Tangential stress is measured versus velocity in order to characterize all the fluids in different thermal conditions. A mathematical fit process is proposed to be done in order to adjust the results to expected analytical expressions, obtaining good results for these fittings, with R2 greater than 0.88 in any case.

Linking the fractional derivative and the Lomnitz creep law to non-Newtonian time-varying viscosity

OpenAIRE

Pandey, Vikash; Holm, Sverre

2016-01-01

Many of the most interesting complex media are non-Newtonian and exhibit time-dependent behavior of thixotropy and rheopecty. They may also have temporal responses described by power laws. The material behavior is represented by the relaxation modulus and the creep compliance. On the one hand, it is shown that in the special case of a Maxwell model characterized by a linearly time-varying viscosity, the medium's relaxation modulus is a power law which is similar to that of a fractional deriva...

Rheological studies of creams. I. Rheological functions and structure of creams.

Science.gov (United States)

Erös, I; Thaleb, A

1994-05-01

Large number of washable (o/w type) creams were prepared for rheological investigation. The rheological functions known from the literature were determined in our studies. Rheological constants were determined by measurements and calculations. From these, we selected those ones which were applicable to characterize the energy status of the coherent structure and which gave the most information for practical work, elaboration of composition and evaluation of stability. These functions and parameters are the following: flow curves, viscosity vs shear time and viscosity vs temperature functions, Bingham-type yield value, plastic viscosity, structure breakdown rate constant, activation energy.

Orbital motions as gradiometers for post-Newtonian tidal effects

Energy Technology Data Exchange (ETDEWEB)

Iorio, Lorenzo, E-mail: lorenzo.iorio@libero.it [Ministero dell' Istruzione, dell' Università e della Ricerca, Istruzione, Bari (Italy)

2014-08-14

The direct long-term changes occurring in the orbital dynamics of a local gravitationally bound binary system S due to the post-Newtonian tidal acceleration caused by an external massive source are investigated. A class of systems made of a test particle m rapidly orbiting with orbital frequency n{sub b} an astronomical body of mass M which, in turn, slowly revolves around a distant object of mass M′ with orbital frequency n{sub b}′ « n{sub b} is considered. The characteristic frequencies of the non-Keplerian orbital variations of m and of M itself are assumed to be negligible with respect to both n{sub b} and n{sub b}′. General expressions for the resulting Newtonian and post-Newtonian tidal orbital shifts of m are obtained. The future missions BepiColombo and JUICE to Mercury and Ganymede, respectively, are considered in view of a possible detection. The largest effects, of the order of ≈ 0.1-0.5 milliarcseconds per year (mas yr{sup −1}), occur for the Ganymede orbiter of the JUICE mission. Although future improvements in spacecraft tracking and orbit determination might, perhaps, reach the required sensitivity, the systematic bias represented by the other known orbital perturbations of both Newtonian and post-Newtonian origin would be overwhelming. The realization of a dedicated artificial mini-planetary system to be carried onboard and Earth-orbiting spacecraft is considered as well. Post-Newtonian tidal precessions as large as ≈ 1−10{sup 2} mas yr{sup −1} could be obtained, but the quite larger Newtonian tidal effects would be a major source of systematic bias because of the present-day percent uncertainty in the product of the Earth's mass times the Newtonian gravitational parameter.

Modelling of Emulsion Flow in Porous Media

Energy Technology Data Exchange (ETDEWEB)

Abou-Kassem, J.H. [UAE University (United Arab Emirates); Farouq Ali, S.M. [UAE University (United Arab Emirates)

1995-06-01

Oil recovery methods predominantly involve emulsion formation. Oil recovery simulation requires the incorporation of emulsion characteristics and flow in porous media, in order to optimize oil recovery from petroleum reservoirs. This paper explored the nature and rheology of emulsions, and evaluated several models of flow of Newtonian and non-Newtonian fluids in porous media. It also summarized in situ emulsion formation in porous media. A model for both Newtonian and non-Newtonian emulsion fluid flow was proposed, with special emphasis on pore size, and tortuosity in the porous media.

Newtonian cosmology Newton would understand

International Nuclear Information System (INIS)

Lemons, D.S.

1988-01-01

Isaac Newton envisioned a static, infinite, and initially uniform, zero field universe that was gravitationally unstable to local condensations of matter. By postulating the existence of such a universe and using it as a boundary condition on Newtonian gravity, a new field equation for gravity is derived, which differs from the classical one by a time-dependent cosmological term proportional to the average mass density of the universe. The new field equation not only makes Jeans' analysis of the gravitational instability of a Newtonian universe consistent, but also gives rise to a family of Newtonian evolutionary cosmologies parametrized by a time-invariant expansion velocity. This Newtonian cosmology contrasts with both 19th-century ones and with post general relativity Newtonian cosmology

The effect of epoxidized soybean oil on mechanical and rheological properties of poly(butylene succinate)/lignin via vane extruder

Science.gov (United States)

Liu, Huanyu; Huang, Zhaoxia; Qu, Jinping; Meng, Cong

2016-03-01

Epoxidized Soybean Oil (ESO) have been used as the compatilizer in the Poly (butylene succinate)/lignin (PBS/lignin) composites. Compatibilized composites were fabricated by a novel vane extruder (VE) which can generate global and dynamic elongational flow. The effects of ESO on the mechanical, rheological properties and morphology of PBS/lignin were studied. The results indicated that the use of ESO had plasticizing effect on the matrix PBS while the addition reduced tensile strength. From SEM micrographs it could be clearly observed that there was a better interfacial adhesion between lignin and matrix. Meanwhile, rheological tests showed the incorporation of ESO improved its Newtonian behavior and can enhance PBS's flexibility.

Orbital motions as gradiometers for post-Newtonian tidal effects

Directory of Open Access Journals (Sweden)

Lorenzo eIorio

2014-08-01

Full Text Available The direct long-term changes occurring in the orbital dynamics of a local gravitationally bound binary system S due to the post-Newtonian tidal acceleration caused by an external massive source are investigated. A class of systems made of a test particle m rapidly orbiting with orbital frequency nb an astronomical body of mass M which, in turn, slowly revolves around a distantobject of mass M with orbital frequency nb'<< □ nb is considered. The characteristic frequenciesof the non-Keplerian orbital variations of m and of M itself are assumed to be negligible withrespect to both nb and nb'. General expressions for the resulting Newtonian and post-Newtoniantidal orbital shifts of m are obtained. The future missions BepiColombo and JUICE to Mercuryand Ganymede, respectively, are considered in view of a possible detection. The largest effects,of the order of □ 0:1 □□ 0:5 milliarcseconds per year (mas yr□□1, occur for the Ganymede orbiterof the JUICE mission. Although future improvements in spacecraft tracking and orbit determina14tion might, perhaps, reach the required sensitivity, the systematic bias represented by the otherknown orbital perturbations of both Newtonian and post-Newtonian origin would be overwhel16ming. The realization of a dedicated artificial mini-planetary system to be carried onboard andEarth-orbiting spacecraft is considered as well. Post-Newtonian tidal precessions as large as1 □□ 102 mas yr□□1 could be obtained, but the quite larger Newtonian tidal effects would be amajor source of systematic bias because of the present-day percent uncertainty in the product of the Earth’s mass times the Newtonian gravitational parameter.

Designing shear-thinning

Science.gov (United States)

Nelson, Arif Z.; Ewoldt, Randy H.

2017-11-01

Design in fluid mechanics often focuses on optimizing geometry (airfoils, surface textures, microfluid channels), but here we focus on designing fluids themselves. The dramatically shear-thinning ``yield-stress fluid'' is currently the most utilized non-Newtonian fluid phenomenon. These rheologically complex materials, which undergo a reversible transition from solid-like to liquid-like fluid flow, are utilized in pedestrian products such as paint and toothpaste, but also in emerging applications like direct-write 3D printing. We present a paradigm for yield-stress fluid design that considers constitutive model representation, material property databases, available predictive scaling laws, and the many ways to achieve a yield stress fluid, flipping the typical structure-to-rheology analysis to become the inverse: rheology-to-structure with multiple possible materials as solutions. We describe case studies of 3D printing inks and other flow scenarios where designed shear-thinning enables performance remarkably beyond that of Newtonian fluids. This work was supported by Wm. Wrigley Jr. Company and the National Science Foundation under Grant No. CMMI-1463203.

Was Newtonian cosmology really inconsistent?

Science.gov (United States)

Vickers, Peter

This paper follows up a debate as to the consistency of Newtonian cosmology. Whereas Malament [(1995). Is Newtonian cosmology really inconsistent? Philosophy of Science 62, 489-510] has shown that Newtonian cosmology is not inconsistent, to date there has been no analysis of Norton's claim [(1995). The force of Newtonian cosmology: Acceleration is relative. Philosophy of Science 62, 511-522.] that Newtonian cosmology was inconsistent prior to certain advances in the 1930s, and in particular prior to Seeliger's seminal paper of Seeliger [(1895). Über das Newton'sche Gravitationsgesetz. Astronomische Nachrichten 137 (3273), 129-136.] In this paper I agree that there are assumptions, Newtonian and cosmological in character, and relevant to the real history of science, which are inconsistent. But there are some important corrections to make to Norton's account. Here I display for the first time the inconsistencies-four in total-in all their detail. Although this extra detail shows there to be several different inconsistencies, it also goes some way towards explaining why they went unnoticed for 200 years.

Effects of clove oil-phospholipid mixtures on rheology of gum tragacanth - possible application for surfactant action on mucus gel simulants.

Science.gov (United States)

Banerjee, R; Puniyani, R R

2000-01-01

The present study evaluates the effectiveness of specialised biomaterials consisting of clove oil- phospholipid mixtures as possible substitute surfactants in diseases of altered mucus viscosity by studying their effect on the viscosity of mucus gel simulants in vitro. Test surfactants consisting of phospholipid-clove oil mixtures in the ratio of 1 part of oil to 9 parts of phospholipid were prepared. The phospholipids used were dipalmitoyl phosphatidylcholine (PC), phosphatidylethanolamine (PE) and phosphatidylglycerol (PG) and binary mixtures of PC: PE and PC: PG in the ratio of 2 parts of PC to 3 parts of PE or PG. The effects of the phospholipid-clove oil mixtures on the viscosity of mucus gel simulant (MGS: a polymeric gel consisting predominantly of gum tragacanth and simulating respiratory mucus), was studied by application of steady shear rates ranging from 0.512 to 51.2/s in a concentric cylinder viscometer at 37 degrees C. The change in MGS viscosity, after incubation with surfactants, was found to have a non-Newtonian character and to follow the power law model with R2 values >0.8. The addition of clove oil-phospholipid mixtures caused a decrease in the MGS viscosity when compared with the effect of the phospholipid alone at low shear rates in case of PC, PG and PCPG. The combination of PC : PG with clove oil caused ratios of change in MGS viscosity < 1 i.e., caused a decrease in the MGS viscosity. PC: PG with clove oil was capable of lowering MGS viscosity and should be further researched as possible therapies for diseases of altered mucus rheology.

Second post-Newtonian Lagrangian dynamics of spinning compact binaries

Energy Technology Data Exchange (ETDEWEB)

Huang, Li; Wu, Xin [Nanchang University, Department of Physics and Institute of Astronomy, Nanchang (China); Ma, DaZhu [Hubei University for Nationalities, School of Science, Enshi (China)

2016-09-15

The leading-order spin-orbit coupling is included in a post-Newtonian Lagrangian formulation of spinning compact binaries, which consists of the Newtonian term, first post-Newtonian (1PN) and 2PN non-spin terms and 2PN spin-spin coupling. This leads to a 3PN spin-spin coupling occurring in the derived Hamiltonian. The spin-spin couplings are mainly responsible for chaos in the Hamiltonians. However, the 3PN spin-spin Hamiltonian is small and has different signs, compared with the 2PN spin-spin Hamiltonian equivalent to the 2PN spin-spin Lagrangian. As a result, the probability of the occurrence of chaos in the Lagrangian formulation without the spin-orbit coupling is larger than that in the Lagrangian formulation with the spin-orbit coupling. Numerical evidences support this claim. (orig.)

Perturbed Newtonian description of the Lemaître model with non-negligible pressure

International Nuclear Information System (INIS)

Yamamoto, Kazuhiro; Marra, Valerio; Mukhanov, Viatcheslav; Sasaki, Misao

2016-01-01

We study the validity of the Newtonian description of cosmological perturbations using the Lemaître model, an exact spherically symmetric solution of Einstein's equation. This problem has been investigated in the past for the case of a dust fluid. Here, we extend the previous analysis to the more general case of a fluid with non-negligible pressure, and, for the numerical examples, we consider the case of radiation (P=ρ/3). We find that, even when the density contrast has a nonlinear amplitude, the Newtonian description of the cosmological perturbations using the gravitational potential ψ and the curvature potential φ is valid as long as we consider sub-horizon inhomogeneities. However, the relation ψ+φ=O(φ 2 )—which holds for the case of a dust fluid—is not valid for a relativistic fluid, and an effective anisotropic stress is generated. This demonstrates the usefulness of the Lemaître model which allows us to study in an exact nonlinear fashion the onset of anisotropic stress in fluids with non-negligible pressure. We show that this happens when the characteristic scale of the inhomogeneity is smaller than the sound horizon and that the deviation is caused by the nonlinear effect of the fluid's fast motion. We also find that ψ+φ= [O(φ 2 ),O(c s 2φ  δ)] for an inhomogeneity with density contrast δ whose characteristic scale is smaller than the sound horizon, unless w is close to −1, where w and c s are the equation of state parameter and the sound speed of the fluid, respectively. On the other hand, we expect ψ+φ=O(φ 2 ) to hold for an inhomogeneity whose characteristic scale is larger than the sound horizon, unless the amplitude of the inhomogeneity is large and w is close to −1

On the existence of weak solution to the coupled fluid-structure interaction problem for non-Newtonian shear-dependent fluid

Czech Academy of Sciences Publication Activity Database

Hundertmark-Zaušková, A.; Lukáčová-Medviďová, M.; Nečasová, Šárka

2016-01-01

Roč. 68, č. 1 (2016), s. 193-243 ISSN 0025-5645 R&D Projects: GA ČR(CZ) GAP201/11/1304 Institutional support: RVO:67985840 Keywords : non-Newtonian fluids * fluid-structure interaction * shear-thinning fluids Subject RIV: BA - General Mathematics Impact factor: 0.592, year: 2016 http://projecteuclid.org/euclid.jmsj/1453731541

Pseudo-Newtonian Equations for Evolution of Particles and Fluids in Stationary Space-times

Energy Technology Data Exchange (ETDEWEB)

Witzany, Vojtěch; Lämmerzahl, Claus, E-mail: vojtech.witzany@zarm.uni-bremen.de, E-mail: claus.laemmerzahl@zarm.uni-bremen.de [ZARM, Universität Bremen, Am Fallturm, D-28359 Bremen (Germany)

2017-06-01

Pseudo-Newtonian potentials are a tool often used in theoretical astrophysics to capture some key features of a black hole space-time in a Newtonian framework. As a result, one can use Newtonian numerical codes, and Newtonian formalism, in general, in an effective description of important astrophysical processes such as accretion onto black holes. In this paper, we develop a general pseudo-Newtonian formalism, which pertains to the motion of particles, light, and fluids in stationary space-times. In return, we are able to assess the applicability of the pseudo-Newtonian scheme. The simplest and most elegant formulas are obtained in space-times without gravitomagnetic effects, such as the Schwarzschild rather than the Kerr space-time; the quantitative errors are smallest for motion with low binding energy. Included is a ready-to-use set of fluid equations in Schwarzschild space-time in Cartesian and radial coordinates.

Investigation of the fluid flow dynamic parameters for Newtonian and non-Newtonian materials: an approach to understanding the fluid flow-like structures within fault zones

Science.gov (United States)

Tanaka, H.; Shiomi, Y.; Ma, K.-F.

2017-11-01

To understand the fault zone fluid flow-like structure, namely the ductile deformation structure, often observed in the geological field (e.g., Ramsay and Huber The techniques of modern structure geology, vol. 1: strain analysis, Academia Press, London, 1983; Hobbs and Ord Structure geology: the mechanics of deforming metamorphic rocks, Vol. I: principles, Elsevier, Amsterdam, 2015), we applied a theoretical approach to estimate the rate of deformation, the shear stress and the time to form a streak-line pattern in the boundary layer of viscous fluids. We model the dynamics of streak lines in laminar boundary layers for Newtonian and pseudoplastic fluids and compare the results to those obtained via laboratory experiments. The structure of deformed streak lines obtained using our model is consistent with experimental observations, indicating that our model is appropriate for understanding the shear rate, flow time and shear stress based on the profile of deformed streak lines in the boundary layer in Newtonian and pseudoplastic viscous materials. This study improves our understanding of the transportation processes in fluids and of the transformation processes in fluid-like materials. Further application of this model could facilitate understanding the shear stress and time history of the fluid flow-like structure of fault zones observed in the field.[Figure not available: see fulltext.

Chemical and rheological properties of exopolysaccharides produced by four isolates of rhizobia.

Science.gov (United States)

Moretto, Cristiane; Castellane, Tereza Cristina Luque; Lopes, Erica Mendes; Omori, Wellington Pine; Sacco, Laís Postai; Lemos, Eliana Gertrudes de Macedo

2015-11-01

The rheological, physicochemical properties, emulsification and stability of exopolysaccharides (EPSs) from four rhizobia isolates (LBMP-C01, LBMP-C02, LBMP-C03 and LBMP-C04) were studied. The EPS yields of isolates under these experimental conditions were in the range of 1.5-6.63gL(-1). The LBMP-C04 isolate, which presented the highest EPS production (6.63gL(-1)), was isolated from Arachis pintoi and was identified as a Rhizobium sp. strain that could be explored as a possible potential source for the production of extracellular heteropolysaccharides. All polymers showed a pseudoplastic non-Newtonian fluid behavior or shear thinning property in aqueous solutions. Among the four EPS tested against hydrocarbons, EPS LBMP-C01 was found to be more effective against hexane, olive and soybean oils (89.94%, 82.75% and 81.15%, respectively). Importantly, we found that changes in pH (2-11) and salinity (0-30%) influenced the emulsification of diesel oil by the EPSs. EPSLBMP-C04 presented optimal emulsification capacity at pH 10 (E24=53%) and 30% salinity (E24=27%). These findings contribute to the understanding of the influence of the chemical composition, physical properties and biotechnology applications of rhizobial EPS solutions their bioemulsifying properties. Copyright © 2015 Elsevier B.V. All rights reserved.

Combined Effect of Piezoviscous Dependency and Non-Newtonian Couple Stress on Squeeze-Film Porous Annular Plate

Science.gov (United States)

Vasanth, K. R.; Hanumagowda, B. N.; Santhosh Kumar, J.

2018-04-01

Squeeze film investigations focus upon film pressure, load bearing quantity and the minimum thickness of film. The combined effect of pressure viscous dependent and non- Newtonian couple stress in porous annular plate is studied. The modified equations of one dimensional pressure, load bearing quantity, non dimensional squeeze time are obtained. The conclusions obtained in the study are found to be in very good agreement compared to the previous results which are published. The load carrying capacity is increased due to the variation in the pressure dependent viscosity and also due to the couple stress effect. Finally this results in change in the squeeze film timings.

Effect of ultrafiltration process on physico-chemical, rheological, microstructure and thermal properties of syrups from male and female date palm saps.

Science.gov (United States)

Makhlouf-Gafsi, Ines; Baklouti, Samia; Mokni, Abir; Danthine, Sabine; Attia, Hamadi; Blecker, Christophe; Besbes, Souhail; Masmoudi, Manel

2016-07-15

This study investigates the effect of the ultrafiltration process on physicochemical, rheological, microstructure and thermal properties of syrups from male and female date palm sap. All the studied syrups switched from pseudoplastic rheological behaviour (n=0.783) to Newtonian behaviour (n∼1) from 10 to 50 °C respectively and present similar thermal profiles. Results revealed that the ultrafiltration process significantly affects the rheological behaviour of the male and female syrups. These differences on rheological properties are attributed to the variation of chemical composition between sap and sap permeate syrups. Furthermore, the effect of temperature on viscosity of the syrups was investigated during heating and cooling processes at the same shear rate (50s(-1)). This study provides idea of the stability of the syrup by evaluating the area between heating and cooling curves. Actually, the syrup prepared from male sap permeate is the most stable between the four studied syrups. Copyright © 2016 Elsevier Ltd. All rights reserved.

Steady-shear rheological properties of graphene-reinforced epoxy resin for manufacturing of aerospace composite films

Science.gov (United States)

Clausi, Marialaura; Santonicola, M. Gabriella; Laurenzi, Susanna

2016-05-01

The aim of this work is to analyze the steady-shear rheological behavior and the absolute viscosity of epoxy matrix reinforced with graphene nanoplatelets (xGnP) before cure. Three different grades of xGnP (grades C, M and H) were dispersed homogenously at different weight percentages (wt%) into the epoxy matrix, ranging from 0.5 to 5 wt%. It is found that nanocomposite fluids with xGnP-C exhibit a Newtonian behavior at shear rate in the range 0.1-100 s-1, conversely, nanocomposite fluids with xGnP of grade M and H exhibit a shear-thinning behavior with the increase of nanoplatelet loading. Results from this analysis indicate how the steady shear rheological properties of the nano-reinforced polymer fluids depend on the geometrical characteristics of the graphene nanoplatelets.

Post-Newtonian Jeans Analysis

International Nuclear Information System (INIS)

Nazari, Elham; Kazemi, Ali; Roshan, Mahmood; Abbassi, Shahram

2017-01-01

The Jeans analysis is studied in the first post-Newtonian limit. In other words, the relativistic effects on local gravitational instability are considered for systems whose characteristic velocities and corresponding gravitational fields are higher than those permitted in the Newtonian limit. The dispersion relation for the propagation of small perturbations is found in the post-Newtonian approximation using two different techniques. A new Jeans mass is derived and compared to the standard Jeans mass. In this limit, the relativistic effects make the new Jeans mass smaller than the Newtonian Jeans mass. Furthermore, the fractional difference between these two masses increases when the temperature/pressure of the system increases. Interestingly, in this limit, pressure can enhance gravitational instability instead of preventing it. Finally, the results are applied to high-temperature astrophysical systems, and the possibility of local fragmentation in some relativistic systems is investigated.

Post-Newtonian Jeans Analysis

Energy Technology Data Exchange (ETDEWEB)

Nazari, Elham; Kazemi, Ali; Roshan, Mahmood; Abbassi, Shahram, E-mail: mroshan@um.ac.ir [Department of Physics, Ferdowsi University of Mashhad, P.O. Box 1436, Mashhad (Iran, Islamic Republic of)

2017-04-20

The Jeans analysis is studied in the first post-Newtonian limit. In other words, the relativistic effects on local gravitational instability are considered for systems whose characteristic velocities and corresponding gravitational fields are higher than those permitted in the Newtonian limit. The dispersion relation for the propagation of small perturbations is found in the post-Newtonian approximation using two different techniques. A new Jeans mass is derived and compared to the standard Jeans mass. In this limit, the relativistic effects make the new Jeans mass smaller than the Newtonian Jeans mass. Furthermore, the fractional difference between these two masses increases when the temperature/pressure of the system increases. Interestingly, in this limit, pressure can enhance gravitational instability instead of preventing it. Finally, the results are applied to high-temperature astrophysical systems, and the possibility of local fragmentation in some relativistic systems is investigated.

Rheological effects of micropolar slime on the gliding motility of bacteria with slip boundary condition

Science.gov (United States)

Asghar, Z.; Ali, N.; Anwar Bég, O.; Javed, T.

2018-06-01

Gliding bacteria are virtually everywhere. These organisms are phylogenetically diverse with their hundreds of types, different shapes and several modes of motility. One possible mode of gliding motility in the rod shaped bacteria is that they propel themselves by producing undulating waves in their body. Few bacteria glides near the solid surface over the slime without any aid of flagella so the classical Navier-Stokes equations are incapable of explaining the slime rheology at the microscopic level. Micropolar fluid dynamics however provides a solid framework for mimicking bacterial physical phenomena at both micro and nano-scales, and therefore we use the micropolar fluid to characterize the rheology of a thin layer of slime and its dominant microrotation effects. It is also assumed that there is a certain degree of slip between slime and bacterial undulating surface and also between slime and solid substrate. The flow equations are formulated under long wavelength and low Reynolds number assumptions. Exact expressions for stream function and pressure gradient are obtained. The speed of the gliding bacteria is numerically calculated by using a modified Newton-Raphson method. Slip effects and effects of non-Newtonian slime parameters on bacterial speed and power are also quantified. In addition, when the glider is fixed, the effects of slip and rheological properties of micropolar slime parameters on the velocity, micro-rotation (angular velocity) of spherical slime particles, pressure rise per wavelength, pumping and trapping phenomena are also shown graphically and discussed in detail. The study is relevant to emerging biofuel cell technologies and also bacterial biophysics.

Non-Linear Rheological Properties and Neutron Scattering Investigation on Dilute Ring-Linear Blends

DEFF Research Database (Denmark)

Pyckhout-Hintzen, W.; Bras, A.R.; Wischnewski, A.

in a filament stretching rheometer, followed by quenching, strong anisotropic scattering patterns were obtained which were described by affinely deformed rings which function as giant, polymeric chemical crosslinks or sliplinks and more or less isotropic topological contributions from the entangling...... with interpenetrating linear chains. At the same time the non-linear rheological and mechanical data fit to a non-affine slip-tube model as for moderately crosslinked networks and to interchain pressure models or a modified non-linear Doi-Edwards description for the observed strain hardening during the extensional...

On a criterion of incipient motion and entrainment into suspension of a particle from cuttings bed in shear flow of non-Newtonian fluid

Science.gov (United States)

Ignatenko, Yaroslav; Bocharov, Oleg; May, Roland

2017-10-01

Solids transport is a major issue in high angle wells. Bed-load forms by sediment while transport and accompanied by intermittent contact with stream-bed by rolling, sliding and bouncing. The study presents the results of a numerical simulation of a laminar steady-state flow around a particle at rest and in free motion in a shear flow of Herschel-Bulkley fluid. The simulation was performed using the OpenFOAM open-source CFD package. A criterion for particle incipient motion and entrainment into suspension from cuttings bed (Shields criteria) based on forces and torques balance is discussed. Deflection of the fluid parameters from the ones of Newtonian fluid leads to decreasing of the drag and lift forces and the hydrodynamic moment. Thus, the critical shear stress (Shields parameter) for the considered non-Newtonian fluid must be greater than the one for a Newtonian fluid.

Review Of Applied Mathematical Models For Describing The Behaviour Of Aqueous Humor In Eye Structures

Science.gov (United States)

Dzierka, M.; Jurczak, P.

2015-12-01

In the paper, currently used methods for modeling the flow of the aqueous humor through eye structures are presented. Then a computational model based on rheological models of Newtonian and non-Newtonian fluids is proposed. The proposed model may be used for modeling the flow of the aqueous humor through the trabecular meshwork. The trabecular meshwork is modeled as an array of rectilinear parallel capillary tubes. The flow of Newtonian and non-Newtonian fluids is considered. As a results of discussion mathematical equations of permeability of porous media and velocity of fluid flow through porous media have been received.

Linear and Nonlinear Rheology Combined with Dielectric Spectroscopy of Hybrid Polymer Nanocomposites for Semiconductive Applications

Science.gov (United States)

Kádár, Roland; Abbasi, Mahdi; Figuli, Roxana; Rigdahl, Mikael; Wilhelm, Manfred

2017-01-01

The linear and nonlinear oscillatory shear, extensional and combined rheology-dielectric spectroscopy of hybrid polymer nanocomposites for semiconductive applications were investigated in this study. The main focus was the influence of processing conditions on percolated poly(ethylene-butyl acrylate) (EBA) nanocomposite hybrids containing graphite nanoplatelets (GnP) and carbon black (CB). The rheological response of the samples was interpreted in terms of dispersion properties, filler distortion from processing, filler percolation, as well as the filler orientation and distribution dynamics inside the matrix. Evidence of the influence of dispersion properties was found in linear viscoelastic dynamic frequency sweeps, while the percolation of the nanocomposites was detected in nonlinearities developed in dynamic strain sweeps. Using extensional rheology, hybrid samples with better dispersion properties lead to a more pronounced strain hardening behavior, while samples with a higher volume percentage of fillers caused a drastic reduction in strain hardening. The rheo-dielectric time-dependent response showed that in the case of nanocomposites containing only GnP, the orientation dynamics leads to non-conductive samples. However, in the case of hybrids, the orientation of the GnP could be offset by the dispersing of the CB to bridge the nanoplatelets. The results were interpreted in the framework of a dual PE-BA model, where the fillers would be concentrated mainly in the BA regions. Furthermore, better dispersed hybrids obtained using mixing screws at the expense of filler distortion via extrusion processing history were emphasized through the rheo-dielectric tests. PMID:28336857

Linear and Nonlinear Rheology Combined with Dielectric Spectroscopy of Hybrid Polymer Nanocomposites for Semiconductive Applications

Directory of Open Access Journals (Sweden)

Roland Kádár

2017-01-01

Full Text Available The linear and nonlinear oscillatory shear, extensional and combined rheology-dielectric spectroscopy of hybrid polymer nanocomposites for semiconductive applications were investigated in this study. The main focus was the influence of processing conditions on percolated poly(ethylene-butyl acrylate (EBA nanocomposite hybrids containing graphite nanoplatelets (GnP and carbon black (CB. The rheological response of the samples was interpreted in terms of dispersion properties, filler distortion from processing, filler percolation, as well as the filler orientation and distribution dynamics inside the matrix. Evidence of the influence of dispersion properties was found in linear viscoelastic dynamic frequency sweeps, while the percolation of the nanocomposites was detected in nonlinearities developed in dynamic strain sweeps. Using extensional rheology, hybrid samples with better dispersion properties lead to a more pronounced strain hardening behavior, while samples with a higher volume percentage of fillers caused a drastic reduction in strain hardening. The rheo-dielectric time-dependent response showed that in the case of nanocomposites containing only GnP, the orientation dynamics leads to non-conductive samples. However, in the case of hybrids, the orientation of the GnP could be offset by the dispersing of the CB to bridge the nanoplatelets. The results were interpreted in the framework of a dual PE-BA model, where the fillers would be concentrated mainly in the BA regions. Furthermore, better dispersed hybrids obtained using mixing screws at the expense of filler distortion via extrusion processing history were emphasized through the rheo-dielectric tests.

Rheological Behavior, Granule Size Distribution and Differential Scanning Calorimetry of Cross-Linked Banana (Musa paradisiaca) Starch.

Science.gov (United States)

Núñez-Santiago, María C.; Maristany-Cáceres, Amira J.; Suárez, Francisco J. García; Bello-Pérez, Arturo

2008-07-01

Rheological behavior at 60 °C, granule size distribution and Differential Scanning Calorimetry (DSC) tests were employed to study the effect of diverse reaction conditions: adipic acid concentration, pH and temperature during cross-linking of banana (Musa paradisiaca) starch. These properties were determined in native banana starch pastes for the purpose of comparison. Rheological behavior from pastes of cross-linked starch at 60 °C did not show hysteresis, probably due the cross-linkage of starch that avoided disruption of granules, elsewhere, native starch showed hysteresis in a thixotropic loop. All pastes exhibited non-Newtonian shear thinning behavior. In all cases, size distribution showed a decrease in the median diameter in cross-linked starches. This condition produces a decrease in swelling capacity of cross-linked starch. The median diameter decreased with an increase of acid adipic concentration; however, an increase of pH and Temperature produced an increase in this variable. Finally, an increase in gelatinization temperature and entalphy (ΔH) were observed as an effect of cross-linkage. An increase in acid adipic concentration produced an increase in Tonset and a decrease in ΔH. pH and temperature. The cross-linked of banana starch produced granules more resistant during the pasting procedure.

Sugar Profile, Mineral Content, and Rheological and Thermal Properties of an Isomerized Sweet Potato Starch Syrup

Directory of Open Access Journals (Sweden)

Brunson Dominque

2013-01-01

Full Text Available Currently, corn is used to produce more than 85% of the world’s high fructose syrup (HFS. There is a search for alternative HFS substrates because of increased food demand and shrinking economies, especially in the developing world. The sweet potato is a feasible, alternative raw material. This study isomerized a high glucose sweet potato starch syrup (SPSS and determined its sugar profile, mineral content, and rheological and thermal properties. Rheological and thermal properties were measured using a rheometer and DSC, respectively. Sweet potato starch was hydrolyzed to syrup with a mean fructose content of 7.6±0.4%. The SPSS had significantly higher (P<0.05 mineral content when compared to commercial ginger and pancake syrups. During 70 days of storage, the SPSS acted as a non-Newtonian, shear-thinning liquid in which the viscosity decreased as shear stress increased. Water loss temperature of the SPSS continually decreased during storage, while pancake and ginger syrups’ peak water loss temperature decreased initially and then increased. Further and more detailed studies should be designed to further enhance the fructose content of the syrup and observe its stability beyond 70 days. The SPSS has the potential to be used in human food systems in space and on Earth.

Newtonian and non-newtonian limits of gravitational fields

International Nuclear Information System (INIS)

Koppel', A.A.

1975-01-01

The nonrelativistic limit of the exact stationary axially-symmetric vacuum solution to Einstein equations, which is called the unified (generalized) Kerr-NUT solution, is investigated. Potentials for nonrelativistic gravitational fields, corresponding to this solution, have been calculated. The character of the c→infinity limit (c is the velocity of light) has been shown to depend on the structure of parameters of the Kerr-NUT solution. An example is given that shows the possibility of the existence of a nonrelativistic limit having an absolutely new, non-Newton (vortex) character. From the mathematically proved possibility of the existence of nonrelativistic vortex fields there follow also some implications of a more fundamental character. The Newton limit is commonly supposed to be the only nonrelativistic limit in the Einstein theory. Now there arises a dilemma: either gravitational fields having a non-Newton limit exist in nature and thus the Newton theory does not embrace all gravitational phenomena of nonrelativistic character or in the Newton solutions to the nonrelativistic gravitational equations a certain element of the Einstein theory is revealed that is alien to the true nonrelativistic theory of gravitation. In the former case, one cannot exclude the possibility that owing to a comprehensive analysis of properties, possible sources, etc. the vortex soltions to Einstein equations may prove important in cosmological and astrophysical applications of the general relativity theory. In the latter case, a detailed analysis of the non-Newton-limit solutions will at least enable one to gain a deeper insight into the structure of Einstein equations and their solutions

Newtonian and non-newtonian limits of gravitational fields

Energy Technology Data Exchange (ETDEWEB)

Koppel, A A [Tartuskij Gosudarstvennyj Univ., (USSR)

1975-09-01

The nonrelativistic limit of the exact stationary axially-symmetric vacuum solution to Einstein equations, which is called the unified (generalized) Kerr-NUT solution, is investigated. Potentials for nonrelativistic gravitational fields, corresponding to this solution, have been calculated. The character of the c..-->..infinity limit (c is the velocity of light) has been shown to depend on the structure of parameters of the Kerr-NUT solution. An example is given that shows the possibility of the existence of a nonrelativistic limit having an absolutely new, non-Newton (vortex) character. From the mathematically proved possibility of the existence of nonrelativistic vortex fields there follow also some implications of a more fundamental character. The Newton limit is commonly supposed to be the only nonrelativistic limit in the Einstein theory. Now there arises a dilemma: either gravitational fields having a non-Newton limit exist in nature and thus the Newton theory does not embrace all gravitational phenomena of nonrelativistic character or in the Newton solutions to the nonrelativistic gravitational equations a certain element of the Einstein theory is revealed that is alien to the true nonrelativistic theory of gravitation. In the former case, one cannot exclude the possibility that owing to a comprehensive analysis of properties, possible sources, etc. the vortex soltions to Einstein equations may prove important in cosmological and astrophysical applications of the general relativity theory. In the latter case, a detailed analysis of the non-Newton-limit solutions will at least enable one to gain a deeper insight into the structure of Einstein equations and their solutions.

Presenting Newtonian gravitation

International Nuclear Information System (INIS)

Counihan, Martin

2007-01-01

The basic principles of the Newtonian theory of gravitation are presented in a way which students may find more logically coherent, mathematically accessible and physically interesting than other approaches. After giving relatively simple derivations of the circular hodograph and the elliptical orbit from the inverse-square law, the concept of gravitational energy is developed from vector calculus. It is argued that the energy density of a gravitational field may reasonably be regarded as -g 2 /8πG, and that the inverse-square law may be replaced by a Schwarzschild-like force law without the need to invoke non-Euclidean geometry

Newtonian heating effects in three-dimensional flow of viscoelastic fluid

International Nuclear Information System (INIS)

Qayyum, A.; Hayat, T.; Alhuthali, M. S.; Malaikah, H. M.

2014-01-01

A mathematical model is constructed to investigate the three-dimensional flow of a non-Newtonian fluid. An incompressible viscoelastic fluid is used in mathematical formulation. The conjugate convective process (in which heat the transfer rate from the bounding surface with a finite capacity is proportional to the local surface temperature) in three-dimensional flow of a differential type of non-Newtonian fluid is analyzed for the first time. Series solutions for the nonlinear differential system are computed. Plots are presented for the description of emerging parameters entering into the problem. It is observed that the conjugate heating phenomenon causes an appreciable increase in the temperature at the stretching wall. (electromagnetism, optics, acoustics, heat transfer, classical mechanics, and fluid dynamics)

Physics of non-Newtonian fluids and interdisciplinary relations (biology and criminology)

Science.gov (United States)

Holubova, R.

2018-03-01

The aim of the paper is the presentation of an interdisciplinary topic that allows applying content knowledge in physics, mathematics and biology in real life environment. Students use to play games and view crime scenes but in common they have little knowledge about the science used during crime scene investigation. In this paper the science background of blood spatter analysis is presented—the physics of non-Newtonian fluids, the biology of blood and mathematics—the measurement and calculation of the angle of inpact, the relationship between height and spatter diameter. This topic was choosen according to the analysis of interviews with secondary and high school learners realized at four schools in Moravia, Czech Republic. The topic can be taught at secondary schools so as at a higher level at high schools. Hands-on activities are included. The teaching strategy supports group work. The appropriateness and reasonableness of the topic was checked in the real teaching process and the activities have had a positive feedback.

Magneto-rheological suspensions for improving ground vehicle's ride comfort, stability, and handling

Science.gov (United States)

Ahmadian, Mehdi

2017-10-01

A state-of-the-art discussion on the applications of magneto-rheological (MR) suspensions for improving ride comfort, handling, and stability in ground vehicles is discussed for both road and rail applications. A historical perspective on the discovery and engineering development of MR fluids is presented, followed by some of the common methods for modelling their non-Newtonian behaviour. The common modes of the MR fluids are discussed, along with the application of the fluid in valve mode for ground vehicles' dampers (or shock absorbers). The applications span across nearly all road vehicles, including automobiles, trains, semi-trucks, motorcycles, and even bicycles. For each type of vehicle, the results of some of the past studies is presented briefly, with reference to the originating study. It is discussed that Past experimental and modelling studies have indicated that MR suspensions provide clear advantages for ground vehicles that far surpasses the performance of passive suspension. For rail vehicles, the primary advantage is in terms of increasing the speed at which the onset of hunting occurs, whereas for road vehicles - mainly automobiles - the performance improvements are in terms of a better balance between vehicle ride, handling, and stability. To further elaborate on this point, a single-suspension model is used to develop an index-based approach for studying the compromise that is offered by vehicle suspensions, using the H2 optimisation approach. Evaluating three indices based on the sprung-mass acceleration, suspension rattlespace, and tyre deflection, it is clearly demonstrated that MR suspensions significantly improve road vehicle's ride comfort, stability, and handling in comparison with passive suspensions. For rail vehicles, the simulation results indicate that using MR suspensions with an on-off switching control can increase the speed at which the on-set of hunting occurs by as much as 50% to more than 300%.

Molecularly thin fluoro-polymeric nanolubricant films: tribology, rheology, morphology, and applications.

Science.gov (United States)

Chung, Pil Seung; Jhon, Myung S; Choi, Hyoung Jin

2016-03-21

Molecularly thin perfluoropolyether (PFPE) has been used extensively as a high-performance lubricant in various applications and, more importantly, on carbon overcoats to enhance the reliability and lubrication of micro-/nanoelectro-mechanical systems, where the tribological performance caused by its molecular architecture is a critical issue, as are its physical properties and rheological characteristics. This Highlight addresses recent trends in the development of fluoro-polymeric lubricant films with regard to their tribology, rheology, and physio-chemical properties as they relate to heat-assisted magnetic recording. Nanorheology has been employed to examine the dynamic response of nonfunctional and functional PFPEs, while the viscoelastic properties of nanoscale PFPE films and the relaxation processes as a function of molecular structure and end-group functionality were analyzed experimentally; furthermore, the characteristics of binary blends were reported.

Two parameters Lie group analysis and numerical solution of unsteady free convective flow of non-Newtonian fluid

Directory of Open Access Journals (Sweden)

M.J. Uddin

2016-09-01

Full Text Available The two-dimensional unsteady laminar free convective heat and mass transfer fluid flow of a non-Newtonian fluid adjacent to a vertical plate has been analyzed numerically. The two parameters Lie group transformation method that transforms the three independent variables into a single variable is used to transform the continuity, the momentum, the energy and the concentration equations into a set of coupled similarity equations. The transformed equations have been solved by the Runge–Kutta–Fehlberg fourth-fifth order numerical method with shooting technique. Numerical calculations were carried out for the various parameters entering into the problem. The dimensionless velocity, temperature and concentration profiles were shown graphically and the skin friction, heat and mass transfer rates were given in tables. It is found that friction factor and heat transfer (mass transfer rate for methanol are higher (lower than those of hydrogen and water vapor. Friction factor decreases while heat and mass transfer rate increase as the Prandtl number increases. Friction (heat and mass transfer rate factor of Newtonian fluid is higher (lower than the dilatant fluid.

SYMMETRY CLASSIFICATION OF NEWTONIAN INCOMPRESSIBLEFLUID’S EQUATIONS FLOW IN TURBULENT BOUNDARY LAYERS

Directory of Open Access Journals (Sweden)

Nadjafikhah M.

2017-07-01

Full Text Available Lie group method is applicable to both linear and non-linear partial differential equations, which leads to find new solutions for partial differential equations. Lie symmetry group method is applied to study Newtonian incompressible fluid’s equations flow in turbulent boundary layers. The symmetry group and its optimal system are given, and group invariant solutions associated to the symmetries are obtained. Finally the structure of the Lie algebra such as Levi decomposition, radical subalgebra, solvability and simplicity of symmetries is given.

Reconciling laboratory and observational models of mantle rheology in geodynamic modelling

Science.gov (United States)

King, Scott D.

2016-10-01

-stress regions of the lower mantle, may be in the dislocation creep (power-law) regime. Due to our limited knowledge of mantle grain size, the best hope to resolve the question of whether a region is in diffusion creep (Newtonian rheology) or dislocation or grain-boundary creep (power-law rheology), may be the presence of absence of seismic anisotropy, because there is no mechanism to rotate crystals in diffusion creep which would be necessary to develop anisotropy from lattice preferred orientation. While non-intuitive, the presence or absence of a weak region in the upper mantle has a profound effect on lower mantle flow. With an asthenosphere, the lower mantle organizes into a long-wavelength plan form with one or two (degree 1 or degree 2) large downwellings and updrafts, which may contain a cluster of plumes. The boundary between the long-wavelength lower mantle flow and upper region flow may be deeper, likely 800-1200 km, than the usually assumed base of the transition zone. There are competing hypotheses as to whether this change in flow pattern is caused by a change in rheology, composition, or phase.

Interplay between inertial and non-Newtonian effects on the flow in weakly modulated channel

International Nuclear Information System (INIS)

Abu-Ramadan, E.; Khayat, R.E.

2002-01-01

The flow inside a spatially modulated channel is examined for shear-thinning and shear-thickening fluids. The modulation amplitude is assumed to be small. A regular perturbation expansion of the flow field is used, coupled to a variable-step finite-difference scheme, to solve the problem. Since this method is intended to provide a fast and accurate alternative to conventional methods in the limit of small modulation amplitude, establishing the accuracy of the solution is critical. Numerical accuracy and convergence will be assessed, therefore. The influence of the wall geometry, inertia and non-Newtonian effects are investigated systematically. In particular, the influence of the flow and fluid parameters is examined on the conditions for the onset of separation. (author)

The influence of pH on gas-liquid mass transfer in non-Newtonian fluids

Directory of Open Access Journals (Sweden)

Li Shaobai

2017-01-01

Full Text Available In this study, the effect of pH on the mass transfer of oxygen bubble swarms in non-Newtonian fluids was experimentally studied. The volumetric liquid side mass transfer coefficient (kLa, liquid side mass transfer coefficient (kL, and specific interfacial area (a were investigated. The pH was regulated by the addition of hydrochloric acid and sodium hydroxide (NaOH. It was found that the kLa increased with the gas flow rate increasing and decreased with the apparent viscosity of the liquid increasing. In the case of pH 7 was attributed to the decomposition of the Xanthan molecular structure by the hydroxyl of NaOH.

Gravitational Radiation from Post-Newtonian Sources and Inspiralling Compact Binaries

Directory of Open Access Journals (Sweden)

Luc Blanchet

2014-02-01

Full Text Available To be observed and analyzed by the network of gravitational wave detectors on ground (LIGO, VIRGO, etc. and by the future detectors in space (eLISA, etc., inspiralling compact binaries -- binary star systems composed of neutron stars and/or black holes in their late stage of evolution -- require high-accuracy templates predicted by general relativity theory. The gravitational waves emitted by these very relativistic systems can be accurately modelled using a high-order post-Newtonian gravitational wave generation formalism. In this article, we present the current state of the art on post-Newtonian methods as applied to the dynamics and gravitational radiation of general matter sources (including the radiation reaction back onto the source and inspiralling compact binaries. We describe the post-Newtonian equations of motion of compact binaries and the associated Lagrangian and Hamiltonian formalisms, paying attention to the self-field regularizations at work in the calculations. Several notions of innermost circular orbits are discussed. We estimate the accuracy of the post-Newtonian approximation and make a comparison with numerical computations of the gravitational self-force for compact binaries in the small mass ratio limit. The gravitational waveform and energy flux are obtained to high post-Newtonian order and the binary's orbital phase evolution is deduced from an energy balance argument. Some landmark results are given in the case of eccentric compact binaries -- moving on quasi-elliptical orbits with non-negligible eccentricity. The spins of the two black holes play an important role in the definition of the gravitational wave templates. We investigate their imprint on the equations of motion and gravitational wave phasing up to high post-Newtonian order (restricting to spin-orbit effects which are linear in spins, and analyze the post-Newtonian spin precession equations as well as the induced precession of the orbital plane.

Perturbed Newtonian description of the Lemaître model with non-negligible pressure

Energy Technology Data Exchange (ETDEWEB)

Yamamoto, Kazuhiro [Department of Physical Sciences, Hiroshima University, Higashi-hiroshima, Kagamiyama 1-3-1, 739-8526 (Japan); Marra, Valerio [Departamento de Física, Universidade Federal do Espírito Santo, Av. F. Ferrari, 514, 29075-910, Vitória, ES (Brazil); Mukhanov, Viatcheslav [Theoretical Physics, Ludwig Maxmillians University, Theresienstr. 37, 80333 Munich (Germany); Sasaki, Misao, E-mail: kazuhiro@hiroshima-u.ac.jp, E-mail: valerio.marra@me.com, E-mail: Viatcheslav.Mukhanov@physik.lmu.de, E-mail: misao@yukawa.kyoto-u.ac.jp [Yukawa Institute for Theoretical Physics, Kyoto University, Kitashirakawa-Oiwakecho, Sakyo-Ku, Kyoto 606-8502 (Japan)

2016-03-01

We study the validity of the Newtonian description of cosmological perturbations using the Lemaître model, an exact spherically symmetric solution of Einstein's equation. This problem has been investigated in the past for the case of a dust fluid. Here, we extend the previous analysis to the more general case of a fluid with non-negligible pressure, and, for the numerical examples, we consider the case of radiation (P=ρ/3). We find that, even when the density contrast has a nonlinear amplitude, the Newtonian description of the cosmological perturbations using the gravitational potential ψ and the curvature potential φ is valid as long as we consider sub-horizon inhomogeneities. However, the relation ψ+φ=O(φ{sup 2})—which holds for the case of a dust fluid—is not valid for a relativistic fluid, and an effective anisotropic stress is generated. This demonstrates the usefulness of the Lemaître model which allows us to study in an exact nonlinear fashion the onset of anisotropic stress in fluids with non-negligible pressure. We show that this happens when the characteristic scale of the inhomogeneity is smaller than the sound horizon and that the deviation is caused by the nonlinear effect of the fluid's fast motion. We also find that ψ+φ= [O(φ{sup 2}),O(c{sub s}{sup 2φ} δ)] for an inhomogeneity with density contrast δ whose characteristic scale is smaller than the sound horizon, unless w is close to −1, where w and c{sub s} are the equation of state parameter and the sound speed of the fluid, respectively. On the other hand, we expect ψ+φ=O(φ{sup 2}) to hold for an inhomogeneity whose characteristic scale is larger than the sound horizon, unless the amplitude of the inhomogeneity is large and w is close to −1.

Influence of high power ultrasound on rheological and foaming properties of model ice-cream mixtures

Directory of Open Access Journals (Sweden)

Verica Batur

2010-03-01

Full Text Available This paper presents research of the high power ultrasound effect on rheological and foaming properties of ice cream model mixtures. Ice cream model mixtures are prepared according to specific recipes, and afterward undergone through different homogenization techniques: mechanical mixing, ultrasound treatment and combination of mechanical and ultrasound treatment. Specific diameter (12.7 mm of ultrasound probe tip has been used for ultrasound treatment that lasted 5 minutes at 100 percent amplitude. Rheological parameters have been determined using rotational rheometer and expressed as flow index, consistency coefficient and apparent viscosity. From the results it can be concluded that all model mixtures have non-newtonian, dilatant type behavior. The highest viscosities have been observed for model mixtures that were homogenizes with mechanical mixing, and significantly lower values of viscosity have been observed for ultrasound treated ones. Foaming properties are expressed as percentage of increase in foam volume, foam stability index and minimal viscosity. It has been determined that ice cream model mixtures treated only with ultrasound had minimal increase in foam volume, while the highest increase in foam volume has been observed for ice cream mixture that has been treated in combination with mechanical and ultrasound treatment. Also, ice cream mixtures having higher amount of proteins in composition had shown higher foam stability. It has been determined that optimal treatment time is 10 minutes.

Craton stability and continental lithosphere dynamics during plume-plate interaction

Science.gov (United States)

Wang, H.; Van Hunen, J.; Pearson, D.

2013-12-01

Survival of thick cratonic roots in a vigorously convecting mantle system for billions of years has long been studied by the geodynamical community. A high cratonic root strength is generally considered to be the most important factor. We first perform and discuss new numerical models to investigate craton stability in both Newtonian and non-Newtonian rheology in the stagnant lid regime. The results show that only a modest compositional rheological factor of Δη=10 with non-Newtonian rheology is required for the survival of cratonic roots in a stagnant lid regime. A larger rheological factor (100 or more) is needed to maintain similar craton longevity in a Newtonian rheology environment. Furthermore, chemical buoyancy plays an important role on craton stability and its evolution, but could only work with suitable compositional rheology. During their long lifespan, cratons experienced a suite of dynamic, tectonothermal events, such as nearby subduction and mantle plume activity. Cratonic nuclei are embedded in shorter-lived, more vulnerable continental areas of different thickness, composition and rheology, which would influence the lithosphere dynamic when tectonothermal events happen nearby. South Africa provides a very good example to investigate such dynamic processes as it hosts several cratons and there are many episodic thermal events since the Mesozoic as indicated by a spectrum of magmatic activity. We numerically investigate such an integrated system using the topographic evolution of cratons and surrounding lithosphere as a diagnostic observable. The post-70Ma thinning of pericratonic lithosphere by ~50km around Kaapvaal craton (Mather et al., 2011) is also investigated through our numerical models. The results show that the pericratonic lithosphere cools and grows faster than cratons do, but is also more likely to be effected by episodic thermal events. This leads to surface topography change that is significantly larger around the craton than within

Rheological properties of disintegrated sewage sludge

Science.gov (United States)

Wolski, Paweł

2017-11-01

The rheology of the sludge provides information about the capacity and the flow, which in the case of project tasks for the hydraulic conveying installation is an important control parameter. Accurate knowledge of the rheological properties of sludge requires the designation of rheological models. Models single and multiparameter (Ostwald, Bingham, Herschel-Bulkley'a, and others) allow an approximation of flow curves, and the determination of the boundaries of the flow of modified sludge allows you to control the process compaction or are dewatered sludge undergoing flow. The aim of the study was to determine the rheological parameters and rheological models of sludge conditioned by physical methods before and after the process of anaerobic digestion. So far, studies have shown that the application of conditioning in the preparation of sewage sludge increases shear stress, viscosity as well as the limits of flow in relation to the untreated sludge. Offset yield point by the application of a conditioning agent is associated with decreased flowability tested sludge, which has also been observed by analyzing the structure of the prepared samples. Lowering the yield point, and thus the shear stress was recorded as a result of the fermentation test of disintegrated sludge.

Textural Properties of Agarose Gels described by FT-Rheology

NARCIS (Netherlands)

Klein, C.O.; Venema, P.; Sagis, L.M.C.; Linden, van der E.

2008-01-01

Large Amplitude Oscillatory Shear was used to determine the non-linear rheological properties of agarose gels. The analysis was performed with the characteristic functions method based on FT-Rheology, that gives access to a physical interpretation of the non-linear regime. This analysis was then

Field and experimental constraints on the rheology of arc basaltic lavas: the January 2014 Eruption of Pacaya (Guatemala)

Science.gov (United States)

Soldati, A.; Sehlke, A.; Chigna, G.; Whittington, A.

2016-06-01

We estimated the rheology of an active basaltic lava flow in the field, and compared it with experimental measurements carried out in the laboratory. In the field we mapped, sampled, and recorded videos of the 2014 flow on the southern flank of Pacaya, Guatemala. Velocimetry data extracted from videos allowed us to determine that lava traveled at ˜2.8 m/s on the steep ˜45° slope 50 m from the vent, while 550 m further downflow it was moving at only ˜0.3 m/s on a ˜4° slope. Estimates of effective viscosity based on Jeffreys' equation increased from ˜7600 Pa s near the vent to ˜28,000 Pa s downflow. In the laboratory, we measured the viscosity of a representative lava composition using a concentric cylinder viscometer, at five different temperatures between 1234 and 1199 °C, with crystallinity increasing from 0.1 to 40 vol%. The rheological data were best fit by power law equations, with the flow index decreasing as crystal fraction increased, and no detectable yield strength. Although field-based estimates are based on lava characterized by a lower temperature, higher crystal and bubble fraction, and with a more complex petrographic texture, field estimates and laboratory measurements are mutually consistent and both indicate shear-thinning behavior. The complementary field and laboratory data sets allowed us to isolate the effects of different factors in determining the rheological evolution of the 2014 Pacaya flows. We assess the contributions of cooling, crystallization, and changing ground slope to the 3.7-fold increase in effective viscosity observed in the field over 550 m, and conclude that decreasing slope is the single most important factor over that distance. It follows that the complex relations between slope, flow velocity, and non-Newtonian lava rheology need to be incorporated into models of lava flow emplacement.

Post-Newtonian gravitational bremsstrahlung

International Nuclear Information System (INIS)

Turner, M.; Will, C.M.

1977-07-01

Formulae and numerical results are presented for the gravitational radiation emitted during a low-deflection encounter between two massive bodies. Results are valid through post-Newtonian order within general relativity. The gravitational waveform, the total luminosity and total emitted energy, the angular distribution of emitted energy, and the frequency spectrum are discussed in detail. A method boosting the accuracy of these quantities to post Newtonian order is also presented. A numerical comparison of results with those of Peters, and of Kovacs and Thorne shows that the post Newtonian method is reliable to better than 0.1 percent at v = 0.1 c, to a few percent at v = 0.35 c, and to 10 to 20 percent at v = 0.5 c

On multiple solutions of non-Newtonian Carreau fluid flow over an inclined shrinking sheet

Science.gov (United States)

Khan, Masood; Sardar, Humara; Gulzar, M. Mudassar; Alshomrani, Ali Saleh

2018-03-01

This paper presents the multiple solutions of a non-Newtonian Carreau fluid flow over a nonlinear inclined shrinking surface in presence of infinite shear rate viscosity. The governing boundary layer equations are derived for the Carreau fluid with infinite shear rate viscosity. The suitable transformations are employed to alter the leading partial differential equations to a set of ordinary differential equations. The consequential non-linear ODEs are solved numerically by an active numerical approach namely Runge-Kutta Fehlberg fourth-fifth order method accompanied by shooting technique. Multiple solutions are presented graphically and results are shown for various physical parameters. It is important to state that the velocity and momentum boundary layer thickness reduce with increasing viscosity ratio parameter in shear thickening fluid while opposite trend is observed for shear thinning fluid. Another important observation is that the wall shear stress is significantly decreased by the viscosity ratio parameter β∗ for the first solution and opposite trend is observed for the second solution.

Nonrotating black hole in a post-Newtonian tidal environment

International Nuclear Information System (INIS)

Taylor, Stephanne; Poisson, Eric

2008-01-01

We examine the motion and tidal dynamics of a nonrotating black hole placed within a post-Newtonian external spacetime. The black hole's gravity is described accurately to all orders in Gm/c 2 r, where m is the black-hole mass and r is the distance to the black hole. The tidal perturbation created by the external environment is treated as a small perturbation. At a large distance from the black hole, the gravitational field of the external distribution of matter is assumed to be sufficiently weak to be adequately described by the (first) post-Newtonian approximation to general relativity. There, the black hole is treated as a monopole contribution to the total gravitational field. There exists an overlap in the domains of validity of each description, and the black-hole and post-Newtonian metrics are matched in the overlap. The matching procedure produces (i) a justification of the statement that a nonrotating black hole is a post-Newtonian monopole; (ii) a complete characterization of the coordinate transformation between the inertial, barycentric frame and the accelerated, black-hole frame; (iii) the equations of motion for the black hole; and (iv) the gravito-electric and gravito-magnetic tidal fields acting on the black hole. We first calculate the equations of motion and tidal fields by making no assumptions regarding the nature of the post-Newtonian environment; this could contain a continuous distribution of matter (so as to model a galactic core) or any number of condensed bodies. We next specialize our discussion to a situation in which the black hole is a member of a post-Newtonian two-body system. As an application of our results, we examine the geometry of the deformed event horizon and calculate the tidal heating of the black hole, the rate at which it acquires mass as a result of its tidal interaction with the companion body.

Effect of rock rheology on fluid leak- off during hydraulic fracturing

Science.gov (United States)

Yarushina, V. M.; Bercovici, D.; Oristaglio, M. L.

2012-04-01

In this communication, we evaluate the effect of rock rheology on fluid leak­off during hydraulic fracturing of reservoirs. Fluid leak-off in hydraulic fracturing is often nonlinear. The simple linear model developed by Carter (1957) for flow of fracturing fluid into a reservoir has three different regions in the fractured zone: a filter cake on the fracture face, formed by solid additives from the fracturing fluid; a filtrate zone affected by invasion of the fracturing fluid; and a reservoir zone with the original formation fluid. The width of each zone, as well as its permeability and pressure drop, is assumed to remain constant. Physical intuition suggests some straightforward corrections to this classical theory to take into account the pressure dependence of permeability, the compressibility or non-Newtonian rheology of fracturing fluid, and the radial (versus linear) geometry of fluid leak­off from the borehole. All of these refinements, however, still assume that the reservoir rock adjacent to the fracture face is non­deformable. Although the effect of poroelastic stress changes on leak-off is usually thought to be negligible, at the very high fluid pressures used in hydraulic fracturing, where the stresses exceed the rock strength, elastic rheology may not be the best choice. For example, calculations show that perfectly elastic rock formations do not undergo the degree of compaction typically seen in sedimentary basins. Therefore, pseudo-elastic or elastoplastic models are used to fit observed porosity profiles with depth. Starting from balance equations for mass and momentum for fluid and rock, we derive a hydraulic flow equation coupled with a porosity equation describing rock compaction. The result resembles a pressure diffusion equation with the total compressibility being a sum of fluid, rock and pore-space compressibilities. With linear elastic rheology, the bulk formation compressibility is dominated by fluid compressibility. But the possibility

Quasi-local mass in the covariant Newtonian spacetime

International Nuclear Information System (INIS)

Wu, Y-H; Wang, C-H

2008-01-01

In general relativity, quasi-local energy-momentum expressions have been constructed from various formulae. However, the Newtonian theory of gravity gives a well-known and a unique quasi-local mass expression (surface integration). Since geometrical formulation of Newtonian gravity has been established in the covariant Newtonian spacetime, it provides a covariant approximation from relativistic to Newtonian theories. By using this approximation, we calculate the Komar integral, the Brown-York quasi-local energy and the Dougan-Mason quasi-local mass in the covariant Newtonian spacetime. It turns out that the Komar integral naturally gives the Newtonian quasi-local mass expression; however, further conditions (spherical symmetry) need to be made for Brown-York and Dougan-Mason expressions

Gass-Assisted Displacement of Non-Newtonian Fluids

DEFF Research Database (Denmark)

Rasmussen, Henrik Koblitz; Eriksson, Torbjörn Gerhard

2003-01-01

in a circular cylinder. This is a simple model system used to investigate the gas-fluid displacement, as the problem is reduced to an axis-symmetric flow problem. The understanding of this process is relevant for the geometrically much more complex polymer processing operation Gas-assisted injection moulding...... (GAIM). This is a process, where a mould is filled partly with a polymer melt followed by the injection of inert gas into the core of the polymer melt. The numerical analysis of the fluid flow concerning the experimental observations data in these publications is all based on Newtonian or general...... equation of Boger fluids is the Oldroyd-B model. This model has, with success, been able to describe the complex flow behaviours of Boger fluid. Though, refinements in the flow analysis can be obtained using more complex constitutive models. To keep the flow analysis as simple as possible the Oldroyd...

Laminar flow of a shear-thickening fluid in a 90∘ pipe bend

Science.gov (United States)

Marn, Jure; Ternik, Primož

2006-05-01

The non-Newtonian fluid flow in a sharp 90∘ curved pipe is studied numerically to obtain the pressure loss coefficient prompted by disagreement between the existing empirical correlations and results obtained by computer codes. This disagreement results from presumption of fully developed flow throughout the curvature (correlations) while the actual flow is partially developed for the Newtonian and sharp 90∘ curved bend non-Newtonian flows, and fully developed for slightly bent 90∘ curvature non-Newtonian flow. The Quadratic model is employed to accommodate the shear-thickening behavior of an electrostatic ash and water mixture. Numerical results are obtained for different values of Reynolds number. Finally, results for local pressure loss coefficient are compared with values obtained for the Power law rheological model.

Stronger constraints on non-Newtonian gravity from the Casimir effect

Energy Technology Data Exchange (ETDEWEB)

Mostepanenko, V M; Klimchitskaya, G L [Center of Theoretical Studies and Institute for Theoretical Physics, Leipzig University, D-04009, Leipzig (Germany); Decca, R S [Department of Physics, Indiana University-Purdue University Indianapolis, Indianapolis, IN 46202 (United States); Fischbach, E; Krause, D E [Department of Physics, Purdue University, West Lafayette, IN 47907 (United States); Lopez, D [Bell Laboratories, Lucent Technologies, Murray Hill, NJ 07974 (United States)

2008-04-25

We review new constraints on the Yukawa-type corrections to Newtonian gravity obtained recently from gravitational experiments and from the measurements of the Casimir force. Special attention is paid to the constraints following from the most precise dynamic determination of the Casimir pressure between the two parallel plates by means of a micromechanical torsional oscillator. The possibility of setting limits on the predictions of chameleon field theories using the results of gravitational experiments and Casimir force measurements is discussed.

A Finite Difference Scheme for Double-Diffusive Unsteady Free Convection from a Curved Surface to a Saturated Porous Medium with a Non-Newtonian Fluid

KAUST Repository

El-Amin, Mohamed

2011-05-14

In this paper, a finite difference scheme is developed to solve the unsteady problem of combined heat and mass transfer from an isothermal curved surface to a porous medium saturated by a non-Newtonian fluid. The curved surface is kept at constant temperature and the power-law model is used to model the non-Newtonian fluid. The explicit finite difference method is used to solve simultaneously the equations of momentum, energy and concentration. The consistency of the explicit scheme is examined and the stability conditions are determined for each equation. Boundary layer and Boussinesq approximations have been incorporated. Numerical calculations are carried out for the various parameters entering into the problem. Velocity, temperature and concentration profiles are shown graphically. It is found that as time approaches infinity, the values of wall shear, heat transfer coefficient and concentration gradient at the wall, which are entered in tables, approach the steady state values.

Rheological properties of concentrated alumina slurries: influence of ph and dispersant agent

International Nuclear Information System (INIS)

Ewais, E.M.M.

2004-01-01

The relationship between the ph, the electrolyte concentrations and the rheological properties of high concentrated alumina slurries in aqueous medium is of great importance because it is considered to be the key to control the stability of the slurries from flocculation. Zeta potential of alumina slurries with and without Duramax C (dispersant agent) as a function of ph was studied. Two ph around the zero point of charge of alumina slurries were selected for the investigation of rheological properties. The rheological properties of aqueous alumina slurries with respect to different parameters, e.g.: viscosity, elastic modulus (storage modulus G) and viscous modulus (loss modulus G), were investigated. Viscosity measurements of the slurries as a function of Duramax C content at both ph 8.4 and 9.4) were used to determine the state of slurries. Three states of slurries, termed flocculated, partially de flocculated and fully de flocculated, were selected for further investigation. The viscosity of the three slurries at both ph as a function of shear rate was determined. Fully de flocculated slurry shows Newtonian behavior at all shear rates at both tested ph compared by the partial de flocculated and flocculated system. Results of investigation of G and G at ph of 9.4 as a function of applied stress explored the critical stress

Motion of charged suspended particle in a non-Newtonian fluid between two long parallel plates

Energy Technology Data Exchange (ETDEWEB)

Abd Elkhalek, M M [Nuclear Research Center-Atomic Energy Authority, Cairo (Egypt)

1997-12-31

The motion of charged suspended particle in a non-Newtonian fluid between two long parallel plates is discussed. The equation of motion of a suspended particle was suggested by Closkin. The equations of motion are reduced to ordinary differential equations by similarity transformation and solved numerically by using Runge-Kutta method. The trajectories of particles are calculated by integrating the equation of motion of a single particle. The present simulation requires some empirical parameters concerning the collision of the particles with the wall. The effect of solid particles on flow properties are discussed. Some typical results for both fluid and particle phases and density distributions of the particles are presented graphically. 4 figs.

Motion of Charged Suspended Particle in a Non-Newtonian Fluid between Two Long Parallel Plated

International Nuclear Information System (INIS)

Abd-El Khalek, M.M.

1998-01-01

The motion of charged suspended particle in a non-Newtonian fluid between two long parallel plates is discussed. The equation of motion of a suspended particle was suggested by Closkin. The equations of motion are reduced to ordinary differential equations by similarity transformations and solved numerically by using the Runge-Kutta method. The trajectories of particles are calculated by integrating the equation of motion of a single particle. The present simulation requires some empirical parameters concerning the collision of the particles with the wall. The effects of solid particles on flow properties are discussed. Some typical results for both fluid and particle phases and density distributions of the particles are presented graphically

Effects of aspect ratio and concentration on rheology of epoxy suspensions containing model plate-like nanoparticles

Energy Technology Data Exchange (ETDEWEB)

White, K. L.; Takahara, A. [International Institute for Carbon-Neutral Energy Research (WPI-I2CNER), Kyushu University, Fukuoka 819-0395 (Japan); Institute for Materials Chemistry and Engineering, Kyushu University, Fukuoka 819-0395 (Japan); Hawkins, S.; Sue, H.-J., E-mail: hjsue@tamu.edu [Department of Materials Science and Engineering, Texas A& M University, College Station, Texas 77843 (United States); Miyamoto, M. [Kaneka US Materials Research Center, Kaneka America Holdings, Inc., College Station, Texas 77843 (United States)

2015-12-15

Hexagonal 2-dimensional α-zirconium phosphate crystals were prepared with lateral diameters ranging from 110 nm to 1.5 μm to investigate the effect of particle size on suspension rheology. The nanoplatelets were exfoliated to individual sheets with monodisperse thickness and dispersed in a Newtonian epoxy fluid. The steady shear response of dilute and semi-dilute suspensions was measured and compared to expressions obtained from theory for infinitely dilute suspensions. For suspensions containing the smaller nanoplatelets, aspect ratio ∼160, the low shear rate viscosity and transition to shear thinning behavior were well described by theory for loadings up to 0.5 vol. %. The agreement was improved by assuming a moderate polydispersity in lateral diameter, ∼30%–50%, which is consistent with experimental observation. For the higher aspect ratio nanoplatelets, good agreement between theory and experiment was observed only at high shear rates. At lower shear rate, theory consistently over-predicted viscosity, which was attributed to a progressive shift to non-isotropic initial conditions with increasing particle size. The results suggest that at a fixed Peclet number, there is an increasing tendency for the nanoplatelets to form transient, local stacks as particle size increases. The largest particles, aspect ratio ∼2200, showed unusual shear thinning and thickening behaviors that were attributed to particle flexibility. The findings demonstrate the surprising utility of theory for infinitely dilute suspensions to interpret, and in some cases quantitatively describe, the non-Newtonian viscosity of real suspensions containing high aspect ratio plate-like particles. A simple framework is proposed to interpret deviations from ideal behavior based on the local and collective behavior of the suspended nanoplatelets.

The turbulent mixing of non-Newtonian fluids

Science.gov (United States)

Demianov, A. Yu; Doludenko, A. N.; Inogamov, N. A.; Son, E. E.

2013-07-01

The turbulence caused by the Rayleigh-Taylor instability represents a complicated phenomenon. It is usually related to the major hydrodynamic activities, the tangling of the media contact boundary, merging, separation and intermixing of originally smoothed initial structures. An important role in the theory of the Rayleigh-Taylor instability is played by the discontinuity of density on a contact interface between two homogeneous (in terms of density) fluids. A numerical modeling of the intermixing of two fluids with different rheology whose densities differ twice as a result of the Rayleigh-Taylor instability has been carried out. The coefficients of turbulent intermixing in a multimode statement of the problem for the Bingham, dilatant and pseudo-plastic fluids have been obtained.

A Symmetry Particle Method towards Implicit Non‐Newtonian Fluids

Directory of Open Access Journals (Sweden)

Yalan Zhang

2017-02-01

Full Text Available In this paper, a symmetry particle method, the smoothed particle hydrodynamics (SPH method, is extended to deal with non‐Newtonian fluids. First, the viscous liquid is modeled by a non‐Newtonian fluid flow and the variable viscosity under shear stress is determined by the Carreau‐Yasuda model. Then a pressure correction method is proposed, by correcting density error with individual stiffness parameters for each particle, to ensure the incompressibility of fluid. Finally, an implicit method is used to improve efficiency and stability. It is found that the nonNewtonian behavior can be well displayed in all cases, and the proposed SPH algorithm is stable and efficient.

Nonlinear viscoplasticity in ASPECT: benchmarking and applications to subduction

Science.gov (United States)

Glerum, Anne; Thieulot, Cedric; Fraters, Menno; Blom, Constantijn; Spakman, Wim

2018-03-01

ASPECT (Advanced Solver for Problems in Earth's ConvecTion) is a massively parallel finite element code originally designed for modeling thermal convection in the mantle with a Newtonian rheology. The code is characterized by modern numerical methods, high-performance parallelism and extensibility. This last characteristic is illustrated in this work: we have extended the use of ASPECT from global thermal convection modeling to upper-mantle-scale applications of subduction.Subduction modeling generally requires the tracking of multiple materials with different properties and with nonlinear viscous and viscoplastic rheologies. To this end, we implemented a frictional plasticity criterion that is combined with a viscous diffusion and dislocation creep rheology. Because ASPECT uses compositional fields to represent different materials, all material parameters are made dependent on a user-specified number of fields.The goal of this paper is primarily to describe and verify our implementations of complex, multi-material rheology by reproducing the results of four well-known two-dimensional benchmarks: the indentor benchmark, the brick experiment, the sandbox experiment and the slab detachment benchmark. Furthermore, we aim to provide hands-on examples for prospective users by demonstrating the use of multi-material viscoplasticity with three-dimensional, thermomechanical models of oceanic subduction, putting ASPECT on the map as a community code for high-resolution, nonlinear rheology subduction modeling.

Post-Newtonian gravitational bremsstrahlung

International Nuclear Information System (INIS)

Turner, M.; Will, C.M.

1978-01-01

We present formulae and numerical results for the gravitational radiation emitted during a low-deflection encounter between two massive bodies (''gravitational bremsstrahlung''). Our results are valid through post-Newtonian order within general relativity. We discuss in detail the gravitational waveform (transverse-traceless part of the metric perturbation tensor), the toal luminosity and total emitted energy, the angular distribution of emitted energy (antenna pattern), and the frequency spectrum. We also present a method of ''boosting'' the accuracy of these quantities to post-3/2-Newtonian order. A numerical comparison of our results with those of Peters and of Kovacs and Thorne shows that the post-Newtonian method is reliable to better than 0.1% at v=0.1c, to a few percent at v=0.35c, and to 10--20% at v=0.5c. We also compare our results with those of Smarr

Rheological measurements on cement grouts

International Nuclear Information System (INIS)

Dalton, M.J.

1986-06-01

This report describes the techniques which have been developed at Winfrith for assessing the rheological properties of cement grouts. A discussion of the theory of rheology and its application to cement is given and the methodology for calibrating a special paddle measuring system for a commercial viscometer is described. The use of the system for determining flow curves, equilibrium viscosity, viscosity as a function of shearing time and structure changes is also discussed. (author)

Minimal gravitational coupling in the Newtonian theory and the covariant Schroedinger equation

International Nuclear Information System (INIS)

Duval, C.; Kuenzle, H.P.

1983-02-01

The role of the Bargmann group (11-dimensional extended Galilei group) in non relativistic gravitation theory is investigated. The generalized Newtonian gravitation theory (Newton-Cartan theory) achieves the status of a gauge theory about as much as General Relativity and couples minimally to a complex scalar field leading to a fourdimensionally covariant Schroedinger equation. Matter current and stress-energy tensor follow correctly from the Lagrangian. This theory on curved Newtonian space-time is also shown to be a limit of the Einstein-Klein-Gordon theory

The Effect of Polymer Content on the Non-Newtonian Behavior of Acetaminophen Suspension

Directory of Open Access Journals (Sweden)

Eskandar Moghimipour

2013-01-01

Full Text Available Acetaminophen is used as an analgesic and antipyretic agent. The aim of the study was evaluation of the effect of different polymers on rheological behavior of acetaminophen suspension. In order to achieve controlled flocculation, sodium chloride was added. Then structural vehicles such as carboxymethyl cellulose (CMC, polyvinyl pyrrolidone (PVP, tragacanth, and magnesium aluminum silicate (Veegum were evaluated individually and in combination. Physical stability parameters such as sedimentation volume (F, redispersibility (n, and growth of crystals of the suspensions were determined. Also, the rheological properties of formulations were studied. The results of this study showed that the combination of suspending agents had the most physical stability and pseudoplastic behavior with some degree of thixotropy. Viscosity of suspensions was increased by adding NaCl 0.02%. Presence of PVP is necessary for improving rheological behavior of suspensions by NaCl. This may be related to the cross-linking between the carbonyl group in the PVP segment and Na+ ions.

The Effect of Polymer Content on the Non-Newtonian Behavior of Acetaminophen Suspension

Science.gov (United States)

Moghimipour, Eskandar; Kouchak, Maryam; Salimi, Anayatollah; Bahrampour, Saeed; Handali, Somayeh

2013-01-01

Acetaminophen is used as an analgesic and antipyretic agent. The aim of the study was evaluation of the effect of different polymers on rheological behavior of acetaminophen suspension. In order to achieve controlled flocculation, sodium chloride was added. Then structural vehicles such as carboxymethyl cellulose (CMC), polyvinyl pyrrolidone (PVP), tragacanth, and magnesium aluminum silicate (Veegum) were evaluated individually and in combination. Physical stability parameters such as sedimentation volume (F), redispersibility (n), and growth of crystals of the suspensions were determined. Also, the rheological properties of formulations were studied. The results of this study showed that the combination of suspending agents had the most physical stability and pseudoplastic behavior with some degree of thixotropy. Viscosity of suspensions was increased by adding NaCl 0.02%. Presence of PVP is necessary for improving rheological behavior of suspensions by NaCl. This may be related to the cross-linking between the carbonyl group in the PVP segment and Na+ ions. PMID:24109512

Unexpected Rheological Behavior of Hydrophobic Associative Shellac-based Oligomeric Food Thickener.

Science.gov (United States)

Gao, Jianan; Li, Kun; Xu, Juan; Zhang, Wen-Wen; Ma, Jinju; Liu, Lanxiang; Sun, Yanlin; Zhang, Hong; Li, Kai

2018-06-07

The sodium shellac constituting of "surfactant" monomer, which is sensitive to shear stress, exhibits shear-thickening behavior at low concentration (5 wt%), and reacts with H+ to retain the transient high viscosity under shear, is introduced in this study. The appearance of the sodium shellac with different concentrations in aqueous mode also could be described. The steady-shear flow test proved that under high shear rate, sodium shellac suspension could change from Newtonian fluid to continuous shear thickening of non-Newtonian fluid. Dynamic oscillation test suggested that the sodium shellac solution at low concentration (0.1 and 1 wt%) under low shear rate represented classic viscous fluid behavior (G´´G´), and the solution at high concentration (5, 10 and 15 wt%) represented the classic the elastic gel behavior (G´´G´). Moreover, high shear rate caused a cross-linking point between G´´and G´ curve; at the low concentration, this could be the gel point and at high concentration, it could be attributed to the broken of gel. All of these transforming points were relating to the interaction between the sodium clusters. This interaction should be the hydrophobic association between the particles. In order to prove phenomenon, classic hydrophilic polymer PEO was employed as the disrupting factor to the hydrophobic association. As expected, the shear-thickening behavior vanished after mixing with PEO, which verified our assumption. On the other hand, the high viscosity of the suspension under shear could be retained by reaction with H+ to solidify the transient hydroclusters under shear, meanwhile, sodium shellac had great potential as the functional shear-thickener which could modify the rheological property of the polymer with carboxyl groups, e.g. pectin, alginate or polyacrylic acid. Thus, this natural and green thicker has great potential in food, medical gel, green adhesive, or cosmetic products.

Rheology of irradiated honey from Parana region

Energy Technology Data Exchange (ETDEWEB)

Sabato, S.F. E-mail: sfsabato@ipen.br

2004-10-01

Viscosity characteristics can be governed by the molecular chain length of sugars present in the honey. Honey is essentially a mixture of sugar and water. When a physical treatment, as gamma radiation, is applied to food, some changes on its viscosity may occur. Viscosity is one of the important properties of honey and depends on water and sugar quantities. The objective of this work was to verify the rheological behavior of irradiated honey from Parana region in comparison to the unirradiated one. Each rheogram was measured at different shear rates that was increased to a certain value then immediately decreased to the starting point ('up and down curves'). These measurements were made for control and irradiated samples (5 and 10 kGy) in different temperatures (30 deg. C, 35 deg. C and 40 deg. C). The curves constructed with shear stress against shear rate presented linearity. Honey, irradiated and control, showed a Newtonian behavior and gamma radiation did not affect it.

On the Newtonian limit of emergent NC gravity and long-distance corrections

International Nuclear Information System (INIS)

Steinacker, Harold

2009-01-01

We show how Newtonian gravity emerges on 4-dimensional non-commutative spacetime branes in Yang-Mills matrix models. Large matter clusters such as galaxies are embedded in large-scale harmonic deformations of the space-time brane, which screen gravity for long distances. On shorter scales, the local matter distribution reproduces Newtonian gravity via local deformations of the brane and its metric. The harmonic 'gravity bag' acts as a halo with effective positive energy density. This leads in particular to a significant enhancement of the orbital velocities around galaxies at large distances compared with the Newtonian case, before dropping to zero as the geometry merges with a Milne-like cosmology. Besides these 'harmonic' solutions, there is another class of solutions which is more similar to Einstein gravity. Thus the IKKT model provides an accessible candidate for a quantum theory of gravity.

Measurement and characterization of slippage and slip-law using a rigorous analysis in dynamics of oscillating rheometer: Newtonian fluid

Science.gov (United States)

Azese, Martin Ndi

2018-02-01

This article presents a rigorous calculation involving velocity slip of Newtonian fluid where we analyze and solve the unsteady Navier-Stokes equation with emphasis on its rheological implication. The goal of which is to model a simple yet effective non-invasive way of quantifying and characterizing slippage. Indeed this contrasts with previous techniques that exhibit inherent limitations whereby injecting foreign objects usually alter the flow. This problem is built on the Couette rheological flow system such that μ-Newton force and μ-stress are captured and processed to obtain wall slip. Our model leads to a linear partial differential equation and upon enforcing linear-Navier slip boundary conditions (BC) yields inhomogeneous and unsteady "Robin-type" BC. A dimensional analysis reveals salient dimensionless parameters: Roshko, Strouhal, and Reynolds while highlighting slip-numbers from BC. We also solve the slip-free case to corroborate and validate our results. Several graphs are generated showing slip effects, particularly, studying how slip-numbers, a key input, differentiate themselves to the outputs. We also confirm this in a graphical fashion by presenting the flow profile across channel width, velocity, and stress at both walls. A perturbation scheme is introduced to calculate long-time behavior when the system seats for long. More importantly, in the end, we justify the existence of a reverse mechanism, where an inverse transformation like Fourier transform uses the output data to retrieve slip-numbers and slip law, thus quantifying and characterizing slip. Therefore, we not only substantiate our analysis, but we also justify our claim, measurement and characterization, and theorize realizability of our proposition.

Rheology of Indian Honey: Effect of Temperature and Gamma Radiation

Directory of Open Access Journals (Sweden)

Sudhanshu Saxena

2014-01-01

Full Text Available Honey brands commonly available in Indian market were characterized for their rheological and thermal properties. Viscosity of all the honey samples belonging to different commercial brands was found to decrease with increase in temperature (5–40°C and their sensitivity towards temperature varied significantly as explained by calculating activation energy based on Arrhenius model and ranged from 54.0 to 89.0 kJ/mol. However, shear rate was not found to alter the viscosity of honey indicating their Newtonian character and the shear stress varied linearly with shear rate for all honey samples. Honey is known to contain pathogenic microbial spores and in our earlier study gamma radiation was found to be effective in achieving microbial decontamination of honey. The effect of gamma radiation (5–15 kGy on rheological properties of honey was assessed, and it was found to remain unchanged upon radiation treatment. The glass transition temperatures (Tg of these honey analyzed by differential scanning calorimetry varied from −44.1 to −54.1°C and remained unchanged upon gamma radiation treatment. The results provide information about some key physical properties of commercial Indian honey. Radiation treatment which is useful for ensuring microbial safety of honey does not alter these properties.

Rheological and thermal properties of suspensions of microcapsules containing phase change materials.

Science.gov (United States)

Cao, Vinh Duy; Salas-Bringas, Carlos; Schüller, Reidar Barfod; Szczotok, Anna M; Hiorth, Marianne; Carmona, Manuel; Rodriguez, Juan F; Kjøniksen, Anna-Lena

2018-01-01

The thermal and rheological properties of suspensions of microencapsulated phase change materials (MPCM) in glycerol were investigated. When the microcapsule concentration is raised, the heat storage capacity of the suspensions becomes higher and a slight decline in the thermal conductivity of the suspensions is observed. The temperature-dependent shear-thinning behaviour of the suspensions was found to be strongly affected by non-encapsulated phase change materials (PCM). Accordingly, the rheological properties of the MPCM suspensions could be described by the Cross model below the PCM melting point while a power law model best described the data above the PCM melting point. The MPCM suspensions are interesting for energy storage and heat transfer applications. However, the non-encapsulated PCM contributes to the agglomeration of the microcapsules, which can lead to higher pumping consumption and clogging of piping systems.

Chemical and rheological properties of a starch-rich fraction from the pulp of the fruit cupuassu (Theobroma grandiflorum)

International Nuclear Information System (INIS)

Vriesmann, Lucia C.; Silveira, Joana L.M.; Petkowicz, Carmen L. de O

2009-01-01

The pulp obtained from the fruit of cupuassu (Theobroma grandiflorum) was extracted with hot aqueous 0.1% citric acid to give fraction 0.1CA-2 in 15% yield. This was the predominant component polysaccharide, 91% of which was composed of starch, by an iodine test and monosaccharide composition, and its 13 C NMR spectrum was consistent with that of a high amylose starch. The content of amylose found in fraction 0.1CA-2 was 71%. This value is higher than those of common starches of cereal grains, tubers, roots, and other fruits. The fraction was submitted to rheological examination, gels being prepared on heating with concentrations of 4 to 7% (w/w). A non-Newtonian behavior was observed, and gel viscosity and strength depended on the concentration. The presence of starch, as well as the presence of previously investigated pectin, conferred the high viscosity and gelling capability of the pulp

Chemical and rheological properties of a starch-rich fraction from the pulp of the fruit cupuassu (Theobroma grandiflorum)

Energy Technology Data Exchange (ETDEWEB)

Vriesmann, Lucia C.; Silveira, Joana L.M. [Universidade Federal do Parana, Departamento de Bioquimica e Biologia Molecular, CP 19046, CEP 81531-990, Curitiba-PR (Brazil); Petkowicz, Carmen L. de O [Universidade Federal do Parana, Departamento de Bioquimica e Biologia Molecular, CP 19046, CEP 81531-990, Curitiba-PR (Brazil)], E-mail: clop@ufpr.br

2009-03-01

The pulp obtained from the fruit of cupuassu (Theobroma grandiflorum) was extracted with hot aqueous 0.1% citric acid to give fraction 0.1CA-2 in 15% yield. This was the predominant component polysaccharide, 91% of which was composed of starch, by an iodine test and monosaccharide composition, and its {sup 13}C NMR spectrum was consistent with that of a high amylose starch. The content of amylose found in fraction 0.1CA-2 was 71%. This value is higher than those of common starches of cereal grains, tubers, roots, and other fruits. The fraction was submitted to rheological examination, gels being prepared on heating with concentrations of 4 to 7% (w/w). A non-Newtonian behavior was observed, and gel viscosity and strength depended on the concentration. The presence of starch, as well as the presence of previously investigated pectin, conferred the high viscosity and gelling capability of the pulp.

Viscosity characteristics of selected volcanic rock melts

Science.gov (United States)

Hobiger, Manuel; Sonder, Ingo; Büttner, Ralf; Zimanowski, Bernd

2011-02-01

A basic experimental study of the behavior of magma rheology was carried out on remelted volcanic rocks using wide gap viscometry. The complex composition of magmatic melts leads to complicated rheologic behavior which cannot be described with one simple model. Therefore, measurement procedures which are able to quantify non-Newtonian behavior have to be employed. Furthermore, the experimental apparatus must be able to deal with inhomogeneities of magmatic melts. We measured the viscosity of a set of materials representing a broad range of volcanic processes. For the lower viscous melts (low-silica compositions), non-Newtonian behavior is observed, whereas the high-silica melts show Newtonian behavior in the measured temperature and shear rate range (T = 1423 K - 1623 K, γ˙ = 10 - 2 s - 1 - 20 s - 1 ). The non-Newtonian materials show power-law behavior. The measured viscosities η and power-law indexes m lie in the intervals 8 Pa s ≤ η ≤ 210 3 Pa s, 0.71 ≤ m ≤ 1.0 (Grímsvötn basalt), 0.9 Pa s ≤ η ≤ 350 Pa s, 0.61 ≤ m ≤ 0.93 (Hohenstoffeln olivine-melilitite), and 8 Pa s ≤ η ≤ 1.510 4 Pa s, 0.55 ≤ m ≤ 1.0 (Sommata basalt). Measured viscosities of the Newtonian high-silica melts lie in the range 10 4 Pa s ≤ η ≤ 310 5 Pa s.

Rheology modification in mixed shape colloidal dispersions. Part I: pure components

NARCIS (Netherlands)

ten Brinke, A.J.W.; Bailey, L.; Lekkerkerker, H.N.W.; Matiland, G.C.

2007-01-01

The flow behaviour and rheology of colloidal dispersions are of considerable interest in many applications, for example colloidal clay particles find applications in oilfield and constructiondrilling fluids. The rheological properties of such fluids can be enhanced significantly by adding colloidal

Comparing scalar-tensor gravity and f(R)-gravity in the Newtonian limit

International Nuclear Information System (INIS)

Capozziello, S.; Stabile, A.; Troisi, A.

2010-01-01

Recently, a strong debate has been pursued about the Newtonian limit (i.e. small velocity and weak field) of fourth order gravity models. According to some authors, the Newtonian limit of f(R)-gravity is equivalent to the one of Brans-Dicke gravity with ω BD =0, so that the PPN parameters of these models turn out to be ill-defined. In this Letter, we carefully discuss this point considering that fourth order gravity models are dynamically equivalent to the O'Hanlon Lagrangian. This is a special case of scalar-tensor gravity characterized only by self-interaction potential and that, in the Newtonian limit, this implies a non-standard behavior that cannot be compared with the usual PPN limit of General Relativity. The result turns out to be completely different from the one of Brans-Dicke theory and in particular suggests that it is misleading to consider the PPN parameters of this theory with ω BD =0 in order to characterize the homologous quantities of f(R)-gravity. Finally the solutions at Newtonian level, obtained in the Jordan frame for an f(R)-gravity, reinterpreted as a scalar-tensor theory, are linked to those in the Einstein frame.

Flow and Displacement of Non-Newtonian Fluid(Power-Law Model) by Surface Tension and Gravity Force in Inclined Circular Tube

International Nuclear Information System (INIS)

Moh, Jeong Hah; Cho, Y. I.

2014-01-01

This paper presents the theoretical analysis of a flow driven by surface tension and gravity in an inclined circular tube. A governing equation is developed for describing the displacement of a non-Newtonian fluid(Power-law model) that continuously flows into a circular tube owing to surface tension, which represents a second-order, nonlinear, non-homogeneous, and ordinary differential form. It was found that quantitatively, the theoretical predictions of the governing equation were in excellent agreement with the solutions of the equation for horizontal tubes and the past experimental data. In addition, the predictions compared very well with the results of the force balance equation for steady

Low-cost viscometer based on energy dissipation in viscous liquids

Science.gov (United States)

Hashimoto, C.; Cristobal, G.; Nicolas, A.; Panizza, P.; Rouch, J.; Ushiki, H.

2001-04-01

We describe a new type of low-cost easy-to-use viscometer based on the temperature elevation in a liquid under shear flow. After calibration, this instrument can be used to measure the apparent steady state viscosity for both Newtonian and non-Newtonian liquids with no yield stress. We compute the rise in temperature due to viscous dissipation in a Couette cell and compare it to experimental results for different fluids. We show that the variation of the temperature with shear rate can be used to characterize the rheological behaviour of viscous fluids and to evaluate their viscosity in a large domain, from typically a few cP up to more than 10 P, with an accuracy of about ±5%. In contrast to simple viscometers, non-Newtonian fluids can be studied with this apparatus. We give experimental results for Newtonian and non-Newtonian liquids and show that they are very similar to those given in the literature by using much more sophisticated instruments.

Simulating single-phase and two-phase non-Newtonian fluid flow of a digital rock scanned at high resolution

Science.gov (United States)

Tembely, Moussa; Alsumaiti, Ali M.; Jouini, Mohamed S.; Rahimov, Khurshed; Dolatabadi, Ali

2017-11-01

Most of the digital rock physics (DRP) simulations focus on Newtonian fluids and overlook the detailed description of rock-fluid interaction. A better understanding of multiphase non-Newtonian fluid flow at pore-scale is crucial for optimizing enhanced oil recovery (EOR). The Darcy scale properties of reservoir rocks such as the capillary pressure curves and the relative permeability are controlled by the pore-scale behavior of the multiphase flow. In the present work, a volume of fluid (VOF) method coupled with an adaptive meshing technique is used to perform the pore-scale simulation on a 3D X-ray micro-tomography (CT) images of rock samples. The numerical model is based on the resolution of the Navier-Stokes equations along with a phase fraction equation incorporating the dynamics contact model. The simulations of a single phase flow for the absolute permeability showed a good agreement with the literature benchmark. Subsequently, the code is used to simulate a two-phase flow consisting of a polymer solution, displaying a shear-thinning power law viscosity. The simulations enable to access the impact of the consistency factor (K), the behavior index (n), along with the two contact angles (advancing and receding) on the relative permeability.

Analogy between dynamics of thermo-rheological and piezo-rheological pendulums

International Nuclear Information System (INIS)

Hedrih, K

2008-01-01

The constitutive stress-strain relations of the standard thermo-rheological and piezo-rheological hereditary element in differential form as well as in two different integro-differential forms are defined. The considered problem of a thermo-rheological hereditary discrete system nonlinear dynamics in the form of thermo-rheological double pendulum system with coupled pendulums gets the significance of two constrained bodies in plane motion problem, as a problem important for studying a sensor dynamics or actuator dynamics in active structure dynamics. System of the averaged equations in the first approximation for amplitudes and phases are derived and qualitatively analyzed. Analogy between nonlinear dynamics of the double pendulum systems with thermo-rheological and piezo-rheological properties between pendulums is pointed out

Relativistic generalization of the Newtonian force

International Nuclear Information System (INIS)

Qadir, A.; Quamar, J.

1982-06-01

Whereas there is no denying the essential contribution of geometrodynamics, it must be admitted that our physical intuition is still firmly based in the Newtonian concept of force. Here we extend some earlier work re-introducing the Newtonian force concept into relativity theory. Some fundamentally new insights into the relativistic effects due to charge and rotation are presented. (author)

Rheological Behavior and Microstructure of Ceramic Particulate/Aluminum Alloy Composites. Ph.D. Thesis Final Technical Report

Science.gov (United States)

Moon, Hee-Kyung

1990-01-01

The rheological behavior and microstructure were investigated using a concentric cylinder viscometer for three different slurries: semi-solid alloy slurries of a matrix alloy, Al-6.5wt percent Si: composite slurries, SiC (sub p) (8.5 microns)/Al-6.5wt percent Si, with the same matrix alloy in the molten state, and composite slurries of the same composition with the matrix alloy in the semi-solid state. The pseudoplasticity of these slurries was obtained by step changes of the shear rate from a given initial shear rate. To study the thixotropic behavior of the system, a slurry was allowed to rest for different periods of time, prior to shearing at a given initial shear rate. In the continuous cooling experiments, the viscosities of these slurries were dependent on the shear rate, cooling rate, volume fraction of the primary solid of the matrix alloy, and volume fraction of silicon carbide. In the isothermal experiments, all three kinds of slurries exhibited non-Newtonian behavior, depending on the volume fraction of solid particles.

Influence of the aspect ratio of bioactive nanofillers on rheological behavior of PMMA-based orthopedic materials.

Science.gov (United States)

Liu, Tse-Ying; Chen, San-Yuan; Liu, Dean-Mo

2004-10-15

In this investigation, calcium-deficient hydroxyapatite (CDHA) nanocrystals with needle-like geometry were synthesized and incorporated with Poly(methyl methacrylate), PMMA, to form CDHA-PMMA nanocomposites. Rheological behaviors of the PMMA-CDHA melting suspensions were systematically investigated in terms of solid loading and aspect ratio of the CDHA nanoparticles. The maximum solid loadings of nano-CDHA particles with aspect ratios of 7.2, 10.4, and 17 were determined to be 28, 31, and 57%, respectively. An increase in solid concentrations causes pronounced shear-thinning behavior. This result suggests that a strong interaction, including Van der Waals attraction and mechanical interlocking, between the nano-CDHA particles makes the nanocomposite mixture more non-Newtonian. Furthermore, it was found that packing efficiency and yield strength in the suspension were strongly influenced by the aspect ratio, especially above the critical value of 8.8. The obtained critical aspect ratio and solid content provide not only appropriate design in the PMMA-CDHA polymeric suspension for fabrication process but also optimal conditions for the fabrication of orthopedic devices via injection molding or extrusion.

Applications of Monte Carlo method to nonlinear regression of rheological data

Science.gov (United States)

Kim, Sangmo; Lee, Junghaeng; Kim, Sihyun; Cho, Kwang Soo

2018-02-01

In rheological study, it is often to determine the parameters of rheological models from experimental data. Since both rheological data and values of the parameters vary in logarithmic scale and the number of the parameters is quite large, conventional method of nonlinear regression such as Levenberg-Marquardt (LM) method is usually ineffective. The gradient-based method such as LM is apt to be caught in local minima which give unphysical values of the parameters whenever the initial guess of the parameters is far from the global optimum. Although this problem could be solved by simulated annealing (SA), the Monte Carlo (MC) method needs adjustable parameter which could be determined in ad hoc manner. We suggest a simplified version of SA, a kind of MC methods which results in effective values of the parameters of most complicated rheological models such as the Carreau-Yasuda model of steady shear viscosity, discrete relaxation spectrum and zero-shear viscosity as a function of concentration and molecular weight.

On Dual Phase-Space Relativity, the Machian Principle and Modified Newtonian Dynamics

CERN Document Server

Castro, C

2004-01-01

We investigate the consequences of the Mach's principle of inertia within the context of the Dual Phase Space Relativity which is compatible with the Eddington-Dirac large numbers coincidences and may provide with a physical reason behind the observed anomalous Pioneer acceleration and a solution to the riddle of the cosmological constant problem ( Nottale ). The cosmological implications of Non-Archimedean Geometry by assigning an upper impassible scale in Nature and the cosmological variations of the fundamental constants are also discussed. We study the corrections to Newtonian dynamics resulting from the Dual Phase Space Relativity by analyzing the behavior of a test particle in a modified Schwarzschild geometry (due to the the effects of the maximal acceleration) that leads in the weak-field approximation to essential modifications of the Newtonian dynamics and to violations of the equivalence principle. Finally we follow another avenue and find modified Newtonian dynamics induced by the Yang's Noncommut...

Computational simulation of a non-newtonian model of the blood separation process.

Science.gov (United States)

De Gruttola, Sandro; Boomsma, Kevin; Poulikakos, Dimos

2005-12-01

The aim of this work is to construct a computational fluid dynamics model capable of simulating the transient non-Newtonian process of apheresis. A Lagrangian-Eulerian model has been developed which tracks the blood particles within a two-dimensional flow configuration. Within the Eulerian method, the fluid mass and momentum conservation equations within the separator are solved using the density and the viscosity is calculated from the blood particle concentrations. Subsequently, the displacement of the blood particles is calculated with a Lagrangian method. Hawksley's model for the density of supensions is used in the variable density calculation. The viscosity is calculated with two models based on Vand's rigid particle suspension viscosity concepts, followed by the flow field calculation in the separator. Simulations were performed for various inlet hematocrit values and separator lengths. The simulations are in satisfactory agreement with experimental results reported in literature, indicating a complete separation of plasma and red blood cells (RBCs), as well as nearly complete separation of red blood cells and platelets. No hemolysis was observed in the simulations because the shear rate remained under the critical value of 150 N/m2.

Effect of magneto rheological damper on tool vibration during hard turning

Science.gov (United States)

Paul, P. Sam; Varadarajan, A. S.

2012-12-01

Recently, the concept of hard turning has gained considerable attention in metal cutting as it can apparently replace the traditional process cycle of turning, heat treating, and finish grinding for assembly of hard wear resistant steel parts. The present investigation aims at developing a magneto rheological (MR) fluid damper for suppressing tool vibration and promoting better cutting performance during hard turning. The magneto rheological Fluid acts as a viscoelastic spring with non-linear vibration characteristics that are controlled by the composition of the magneto rheological fluid, the shape of the plunger and the electric parameters of the magnetizing field. Cutting experiments were conducted to arrive at a set of electrical, compositional and shape parameters that can suppress tool vibration and promote better cutting performance during turning of AISI 4340 steel of 46 HRC with minimal fluid application using hard metal insert with sculptured rake face. It was observed that the use of MR fluid damper reduces tool vibration and improves the cutting performance effectively. Also commercialization of this idea holds promise to the metal cutting industry.

Synthesis and characterization of carboxymethyl cellulose from office waste paper: A greener approach towards waste management

International Nuclear Information System (INIS)

Joshi, Gyanesh; Naithani, Sanjay; Varshney, V.K.; Bisht, Surendra S.; Rana, Vikas; Gupta, P.K.

2015-01-01

Highlights: • Carboxymethyl cellulose (CMC) was successfully prepared from waste paper. • CMC had maximum degree of substitution (DS) 1.07. • Rheological studies of CMC (DS, 1.07) showed non-Newtonian pseudoplastic behavior. • Characterization of CMC was done by FT-IR and NMR techniques. • Morphology of prepared CMC was studied by SEM. - Abstract: In the present study, functionalization of mixed office waste (MOW) paper has been carried out to synthesize carboxymethyl cellulose, a most widely used product for various applications. MOW was pulped and deinked prior to carboxymethylation. The deinked pulp yield was 80.62 ± 2.0% with 72.30 ± 1.50% deinkability factor. The deinked pulp was converted to CMC by alkalization followed by etherification using NaOH and ClCH 2 COONa respectively, in an alcoholic medium. Maximum degree of substitution (DS) (1.07) of prepared CMC was achieved at 50 °C with 0.094 M and 0.108 M concentrations of NaOH and ClCH 2 COONa respectively for 3 h reaction time. The rheological characteristics of 1–3% aqueous solution of optimized CMC product showed the non-Newtonian pseudoplastic behavior. Fourier transform infra red (FTIR), nuclear magnetic resonance (NMR) and scanning electron microscope (SEM) study were used to characterize the CMC product

Does general relativity theory possess the classical newtonian limit

International Nuclear Information System (INIS)

Denisov, V.I.; Logunov, A.A.

1980-01-01

A detailed comparison of newtonian approximation of the Einstein theory and the Newton theory of gravity is made. A difference of principle between these two theories is clarified at the stage of obtaining integrals of motion. Exact eqautions of motion and Einstein equations shows the existence only zero integrals of motion as well as in the newtonian approximation. A conclusion is that GRT has no classical newtonian limit, since the integrals of motion in the Newton theory of gravity and in the newtonian approximation of the Einstein theory do not coincide [ru

Effect of thermal radiation and chemical reaction on non-Newtonian fluid through a vertically stretching porous plate with uniform suction

Science.gov (United States)

Khan, Zeeshan; Khan, Ilyas; Ullah, Murad; Tlili, I.

2018-06-01

In this work, we discuss the unsteady flow of non-Newtonian fluid with the properties of heat source/sink in the presence of thermal radiation moving through a binary mixture embedded in a porous medium. The basic equations of motion including continuity, momentum, energy and concentration are simplified and solved analytically by using Homotopy Analysis Method (HAM). The energy and concentration fields are coupled with Dankohler and Schmidt numbers. By applying suitable transformation, the coupled nonlinear partial differential equations are converted to couple ordinary differential equations. The effect of physical parameters involved in the solutions of velocity, temperature and concentration profiles are discussed by assign numerical values and results obtained shows that the velocity, temperature and concentration profiles are influenced appreciably by the radiation parameter, Prandtl number, suction/injection parameter, reaction order index, solutal Grashof number and the thermal Grashof. It is observed that the non-Newtonian parameter H leads to an increase in the boundary layer thickness. It was established that the Prandtl number decreases thee thermal boundary layer thickness which helps in maintaining system temperature of the fluid flow. It is observed that the temperature profiles higher for heat source parameter and lower for heat sink parameter throughout the boundary layer. Fromm this simulation it is analyzed that an increase in the Schmidt number decreases the concentration boundary layer thickness. Additionally, for the sake of comparison numerical method (ND-Solve) and Adomian Decomposition Method are also applied and good agreement is found.

Newtonian heating effect on unsteady hydromagnetic Casson fluid flow past a flat plate with heat and mass transfer

Directory of Open Access Journals (Sweden)

M. Das

2015-12-01

Full Text Available The influence of Newtonian heating on heat and mass transfer in unsteady hydromagnetic flow of a Casson fluid past a vertical plate in the presence of thermal radiation and chemical reaction is studied. The Casson fluid model is used to distinguish the non-Newtonian fluid behavior. The fluid flow is induced due to periodic oscillations of the plate along its length and a uniform transverse magnetic field is applied in a direction which is normal to the direction of fluid flow. The partial differential equations governing the flow, heat, and mass transfer are transformed to non-dimensional form using suitable non-dimensional variables which are then solved analytically by using Laplace transform technique. The numerical values of the fluid velocity, fluid temperature, and species concentration are depicted graphically whereas the values of skin-friction, Nusselt number, and Sherwood number are presented in tabular form. It is noticed that the fluid velocity and temperature decrease with increasing values of Casson parameter while concentration decreases with increasing values of chemical reaction parameter and Schmidt number. Such a fluid flow model has several industrial and medical applications such as in glass manufacturing, paper production, purification of crude oil and study of blood flow in the cardiovascular system.

Experimental study on the rheological behaviour of coal ash slurries

Directory of Open Access Journals (Sweden)

Assefa K.M.

2015-12-01

Full Text Available Extensive experimental investigations were carried out to evaluate the rheological behaviour of fly ash (FA slurry without and with the addition of bottom ash (BA and BA slurry without and with the addition of FA. The FA slurries exhibited Bingham behaviour at solid mass concentrations ranging from 60–65% and mixing proportions from 10– 40%. A substantial reduction in yield stress was observed except for mixing proportion of 40% on which the yield stress and viscosity were increased drastically for all solid concentrations. Hence, it can be concluded that the yield stress and viscosity of FA slurry were very much influenced by adding BA up to the mixing proportion of 30%. The rheological behaviour of BA slurries with and without the addition of FA in proportions of 10–50% was investigated and exhibited Newtonian behaviours for solid mass concentrations ranging from 30–50% without and with the addition of FA. The viscosity increases with increasing the solid concentrations and proportion of FA. Based on these experimental data, a correlation was developed to predict the relative viscosity of BA slurries as a function of solid volume fraction and FA mass proportion of 0–50% and the RMSE and R2 values showed good agreement between the experimental and the predicted data.

State of the art of medical devices featuring smart electro-rheological and magneto-rheological fluids

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Jong-Seok Oh

2017-10-01

Full Text Available Recently, smart fluids have drawn significant attention and growing a great interest in a broad range of engineering applications such as automotive and medical areas. In this article, two smart fluids called electro-rheological (ER fluid and magneto-rheological (MR fluid are reviewed in terms of medical applications. Especially, this article describes the attributes and inherent properties of individual medical and rehabilitation devices. The devices surveyed in this article include multi-degree-of-freedom haptic masters for robot surgery, thin membrane touch panels for braille readers, sponge-like tactile sensors to feel human tissues such as liver, rehabilitation systems such as prosthetic leg, and haptic interfaces for dental implant surgery. The operating principle, inherent characteristics and practical feasibility of each medical device or system are fully discussed in details.

Rheological characterisation of biologically treated and non-treated putrescible food waste.

Science.gov (United States)

Baroutian, Saeid; Munir, M T; Sun, Jiyang; Eshtiaghi, Nicky; Young, Brent R

2018-01-01

Food waste is gaining increasing attention worldwide due to growing concerns over its environmental and economic costs. Understanding the rheological behaviour of food waste is critical for effective processing so rheological measurements were carried out for different food waste compositions at 25, 35 and 45 °C. Food waste samples of various origins (carbohydrates, vegetables & fruits, and meat), anaerobically digested and diluted samples were used in this study. The results showed that food waste exhibits shear-thinning flow behaviour and viscosity of food waste is a function of temperature and composition. The composition of food waste affected the flow properties. Viscosity decreased at a given temperature as the proportion of carbohydrate increased. This may be due to the high water content of vegetable & fruits as the total solids fraction is likely to be a key controlling factor of the rheology. The Herschel-Bulkley model was used successfully to model food waste flow behaviour. Also, a higher strain was needed to break down the structure of the food waste as digestion time increased. Copyright © 2017 Elsevier Ltd. All rights reserved.

Rheology for chemists an introduction

CERN Document Server

Goodwin, J W

2000-01-01

Rheology is an integral part of life, from decorative paint and movement of volcanic lava to the flow of blood in our veins. This book describes, without the use of complex mathematics, how atoms and molecules interact to control the handling properties of materials ranging from simple ionic crystals through polymers to colloidal dispersions.Beginning with an introduction to essential terminology, Rheology for Chemists goes on to discuss limiting behaviour, temporal behaviour and non-linear behaviour. Throughout, examples of everyday experiments are provided to illustrate the theory, which increases in complexity with each discrete chapter. Ideas are developed in a systematic fashion so that the mechanisms responsible for the elastic, viscous or viscoelastic behaviour of systems are understood. The text thus progresses in a manner that makes it an ideal introduction to rheology for any scientist who needs to use the ideas to modify systems.Comprehensive and unique in approach, this book will provide the neces...

Rheological study of chitosan in solution

International Nuclear Information System (INIS)

Silva, Italo Guimaraes Medeiros da; Alves, Keila dos Santos; Balaban, Rosangela de Carvalho

2009-01-01

Chitosan is an abundant biopolymer with remarkable physicochemical and biological properties, usually employed in a wide range of applications. It acts as a cationic polyelectrolyte in aqueous acid solutions, leading to unique characteristics. In this work, chitosan was characterized by 1 H NMR and its rheological behavior were studied as function of chitosan sample, shear rate, polymer concentration, ionic strength, time and temperature. In order to calculate rheological parameters and to understand the macromolecular dynamic in solution, the Otswald-de Waele model was fitted. (author)

PREFACE: 1st International Conference on Rheology and Modeling of Materials

Science.gov (United States)

Gömze, László A.

2015-04-01

Understanding the rheological properties of materials and their rheological behaviors during their manufacturing processes and in their applications in many cases can help to increase the efficiency and competitiveness not only of the finished goods and products but the organizations and societies also. The more scientific supported and prepared organizations develop more competitive products with better thermal, mechanical, physical, chemical and biological properties and the leading companies apply more competitive knowledge, materials, equipment and technology processes. The idea to organize in Hungary the 1st International Conference on Rheology and Modeling of Materials we have received from prospective scientists, physicists, chemists, mathematicians and engineers from Asia, Europe, North and South America including India, Korea, Russia, Turkey, Estonia, France, Italy, United Kingdom, Chile, Mexico and USA. The goals of ic-rmm1 the 1st International Conference on Rheology and Modeling of Materials are the following: • Promote new methods and results of scientific research in the fields of modeling and measurements of rheological properties and behavior of materials under processing and applications. • Change information between the theoretical and applied sciences as well as technical and technological implantations. • Promote the communication between the scientists of different disciplines, nations, countries and continents. The international conference ic-rmm1 provides a platform among the leading international scientists, researchers, PhD students and engineers for discussing recent achievements in measurement, modeling and application of rheology in materials technology and materials science of liquids, melts, solids, crystals and amorphous structures. Among the major fields of interest are the influences of material structures, mechanical stresses temperature and deformation speeds on rheological and physical properties, phase transformation of

Rheological State Diagrams for Rough Colloids in Shear Flow.

Science.gov (United States)

Hsiao, Lilian C; Jamali, Safa; Glynos, Emmanouil; Green, Peter F; Larson, Ronald G; Solomon, Michael J

2017-10-13

To assess the role of particle roughness in the rheological phenomena of concentrated colloidal suspensions, we develop model colloids with varying surface roughness length scales up to 10% of the particle radius. Increasing surface roughness shifts the onset of both shear thickening and dilatancy towards lower volume fractions and critical stresses. Experimental data are supported by computer simulations of spherical colloids with adjustable friction coefficients, demonstrating that a reduction in the onset stress of thickening and a sign change in the first normal stresses occur when friction competes with lubrication. In the quasi-Newtonian flow regime, roughness increases the effective packing fraction of colloids. As the shear stress increases and suspensions of rough colloids approach jamming, the first normal stresses switch signs and the critical force required to generate contacts is drastically reduced. This is likely a signature of the lubrication films giving way to roughness-induced tangential interactions that bring about load-bearing contacts in the compression axis of flow.

Rheological State Diagrams for Rough Colloids in Shear Flow

Science.gov (United States)

Hsiao, Lilian C.; Jamali, Safa; Glynos, Emmanouil; Green, Peter F.; Larson, Ronald G.; Solomon, Michael J.

2017-10-01

To assess the role of particle roughness in the rheological phenomena of concentrated colloidal suspensions, we develop model colloids with varying surface roughness length scales up to 10% of the particle radius. Increasing surface roughness shifts the onset of both shear thickening and dilatancy towards lower volume fractions and critical stresses. Experimental data are supported by computer simulations of spherical colloids with adjustable friction coefficients, demonstrating that a reduction in the onset stress of thickening and a sign change in the first normal stresses occur when friction competes with lubrication. In the quasi-Newtonian flow regime, roughness increases the effective packing fraction of colloids. As the shear stress increases and suspensions of rough colloids approach jamming, the first normal stresses switch signs and the critical force required to generate contacts is drastically reduced. This is likely a signature of the lubrication films giving way to roughness-induced tangential interactions that bring about load-bearing contacts in the compression axis of flow.

A methodology to define the flow rate and pressure requirements for transfer of double-shell tank waste slurries

International Nuclear Information System (INIS)

Bamberger, J.A.; Liljegren, L.M.

1993-04-01

This document presents an analysis of the pressure drop and flow rate double-shell tank slurries. Experiments to requirements for transport of characterize the transport of double-shell tank slurries through piping networks and to resuspend materials that settle during pump outages are proposed. Reported values of physical properties of double-shell tank slurries were analyzed to evaluate the flow regimes that are likely to occur during transport. The results of these evaluations indicate that the slurry will be pseudohomogeneous during transport and that the slurry rheology is sufficiently non-Newtonian to affect both the pressure drop achieved during transport and the critical Reynolds number. The transport data collected in the non-Newtonian experiment will be used to determine whether a non-Newtonian correlation developed by Hanks (1978) adequately describes the experimental results

A statistical investigation of the rheological properties of magnesium phosphate cement

OpenAIRE

Yue, Y.; Bai, Y.; Hu, W.; You, C.; Qian, J.; McCague, C.; Jin, F.; Al-Tabbaa, A.; Mo, L.; Deng, M.

2016-01-01

Magnesium phosphate cement (MPC) is a promising material applied for rapid patch repairing in civil engineering and waste immobilisation in nuclear industry. However, the rheological properties of this new binder material which highly affects its engineering application, is to be explored. The current work aims at investigating the rheological properties of MPC along 98 with determining the optimum conditions to obtain MPC materials with desirable rheological performances. ...

Turbulent structures of non-Newtonian solutions containing rigid polymers

Science.gov (United States)

Mohammadtabar, M.; Sanders, R. S.; Ghaemi, S.

2017-10-01

The turbulent structure of a channel flow of Xanthan Gum (XG) polymer solution is experimentally investigated and compared with water flow at a Reynolds number of Re = 7200 (based on channel height and properties of water) and Reτ = 220 (based on channel height and friction velocity, uτ0). The polymer concentration is varied from 75, 100, and 125 ppm to reach the point of maximum drag reduction (MDR). Measurements are carried out using high-resolution, two-component Particle Image Velocimetry (PIV) to capture the inner and outer layer turbulence. The measurements showed that the logarithmic layer shifts away from the wall with increasing polymer concentration. The slopes of the mean velocity profile for flows containing 100 and 125 ppm XG are greater than that measured for XG at 75 ppm, which is parallel with the slope obtained for deionized water. The increase in slope results in thickening buffer layer. At MDR, the streamwise Reynolds stresses are as large as those of the Newtonian flow while the wall-normal Reynolds stresses and Reynolds shear stresses are significantly attenuated. The sweep-dominated region in the immediate vicinity of the wall extends further from the wall with increasing polymer concentration. The near-wall skewness intensifies towards positive streamwise fluctuations and covers a larger wall-normal length at larger drag reduction values. The quadrant analysis at y + 0 = 25 shows that the addition of polymers inclines the principal axis of v versus u plot to almost zero (horizontal) as the joint probability density function of fluctuations becomes symmetric with respect to the u axis at MDR. The reduction of turbulence production is mainly associated with the attenuation of the ejection motions. The spatial-correlation of the fluctuating velocity field shows that increasing the polymer concentration increases the spatial coherence of u fluctuations in the streamwise direction while they appear to have the opposite effect in the wall

Dumbbell shaped polystyrene : synthesis and solution rheology

NARCIS (Netherlands)

Rajan, M.

2006-01-01

Polymeric additives profoundly influence fluid rheological properties; hence finding applications in fuels, lubricants, coatings, sprays, enhanced oil recovery, turbulent drag reduction etc. Several of these applications are based on the coil-stretch transition and subsequent stretching of polymer

Thermophysical and rheological properties of dulce de leche with and without coconut flakes as a function of temperature

Directory of Open Access Journals (Sweden)

Vanessa Camarinha Barbosa

2013-03-01

Full Text Available Dulce de leche (DL, a dairy dessert highly appreciated in Brazil, is a concentrated product containing about 70% m/m of total solids. Thermophysical and rheological properties of two industrial Brazilian Dulce de leche formulations (classic Dulce de leche and Dulce de leche added with coconut flakes 1.5% m/m were determined at temperatures comprised between 28.4 and 76.4 °C. In general, no significant differences (p < 0.05 were observed in the presence of coconut flakes in the two formulations. Heat capacity varied from 2633.2 to 3101.8 J/kg.°C; thermal conductivity from 0.383 to 0.452 W/m.°C; specific mass from 1350.7 to 1310.7 kg/m³; and, thermal diffusivity from (1.082 × 10-7 to 1.130 × 10-7 m²/s. The Bingham model was used to properly describe the non-Newtonian behavior of both formulations, with yielding stress values varying from 27.3 to 17.6 Pa and plastic viscosity from 19.9 to 5.9 Pa.s.

Chemical, Sensorial and Rheological Properties of a New Organic Rice Bran Beverage

Directory of Open Access Journals (Sweden)

Gerson Luis FACCIN

2009-09-01

Full Text Available Rice bran is a solid residue from rice polishing that is used in animal nutrition and rice oil production. Cultivation conditions with agro-toxics, lipids instability, and tendency for mycotoxin contamination restrict its application in human nutrition. Therefore, organic agriculture is an alternative to use the properties of rice bran. Rice bran beverage is a new cereal product from organic rice. This work presents the preliminary results of the chemical and rheological studies of a bath pasteurized rice bran beverage. Compared with integral defatted milk, soy extracts, and brown rice low-fat milk, the rice bran beverage studied in this work presents itself as an important source of minerals and unsaturated lipids. All essential amino acids were found in this product. Glutamic and aspartic acids were predominant. Bath pasteurization at boiling water temperature for 15 and 30 min was adequate for microbiological safety. Refrigeration storage for 20 days, evaluated by pH and acidity variations, was ideal for assessment of the beverage conservation time. The beverage viscosity was of the Newtonian standard behavior, and its viscosity during storage was not a good parameter to evaluate shelf life. Sensory preference tests showed positive perspectives for this new beverage.

Influence of extrusion rate and magma rheology on the growth of lava domes: Insights from particle-dynamics modeling

Science.gov (United States)

Husain, Taha; Elsworth, Derek; Voight, Barry; Mattioli, Glen; Jansma, Pamela

2014-09-01

Lava domes are structures that grow by the extrusion of viscous silicic or intermediate composition magma from a central volcanic conduit. Repeated cycles of growth are punctuated by collapse, as the structure becomes oversized for the strength of the composite magma that rheologically stiffens and strengthens at its surface. Here we explore lava dome growth and failure mechanics using a two-dimensional particle-dynamics model. The model follows the evolution of fractured lava, with solidification driven by degassing induced crystallization of magma. The particle-dynamics model emulates the natural development of dome growth and rearrangement of the lava dome which is difficult in mesh-based analyses due to mesh entanglement effects. The deformable talus evolves naturally as a frictional carapace that caps a ductile magma core. Extrusion rate and magma rheology together with crystallization temperature and volatile content govern the distribution of strength in the composite structure. This new model is calibrated against existing observational models of lava dome growth. Results show that the shape and extent of the ductile core and the overall structure of the lava dome are strongly controlled by the infusion rate. The effects of extrusion rate on magma rheology are sensitive to material stiffness, which in turn is a function of volatile content and crystallinity. Material stiffness and material strength are key model parameters which govern magma rheology and subsequently the morphological character of the lava dome and in turn stability. Degassing induced crystallization causes material stiffening and enhances material strength reflected in non-Newtonian magma behavior. The increase in stiffness and strength of the injected magma causes a transition in the style of dome growth, from endogenous expansion of a ductile core, to stiffer and stronger intruding material capable of punching through the overlying material and resulting in the development of a spine or

Effect of thermal radiation and chemical reaction on non-Newtonian fluid through a vertically stretching porous plate with uniform suction

Directory of Open Access Journals (Sweden)

Zeeshan Khan

2018-06-01

Full Text Available In this work, we discuss the unsteady flow of non-Newtonian fluid with the properties of heat source/sink in the presence of thermal radiation moving through a binary mixture embedded in a porous medium. The basic equations of motion including continuity, momentum, energy and concentration are simplified and solved analytically by using Homotopy Analysis Method (HAM. The energy and concentration fields are coupled with Dankohler and Schmidt numbers. By applying suitable transformation, the coupled nonlinear partial differential equations are converted to couple ordinary differential equations. The effect of physical parameters involved in the solutions of velocity, temperature and concentration profiles are discussed by assign numerical values and results obtained shows that the velocity, temperature and concentration profiles are influenced appreciably by the radiation parameter, Prandtl number, suction/injection parameter, reaction order index, solutal Grashof number and the thermal Grashof. It is observed that the non-Newtonian parameter H leads to an increase in the boundary layer thickness. It was established that the Prandtl number decreases thee thermal boundary layer thickness which helps in maintaining system temperature of the fluid flow. It is observed that the temperature profiles higher for heat source parameter and lower for heat sink parameter throughout the boundary layer. Fromm this simulation it is analyzed that an increase in the Schmidt number decreases the concentration boundary layer thickness. Additionally, for the sake of comparison numerical method (ND-Solve and Adomian Decomposition Method are also applied and good agreement is found. Keywords: Unsteady flow, Viscous fluid, Thermal radiation, Porous plate, Arrhenius kinetics, HAM and numerical method

High shear microfluidics and its application in rheological measurement

Science.gov (United States)

Kang, Kai; Lee, L. James; Koelling, Kurt W.

2005-02-01

High shear rheology was explored experimentally in microchannels (150×150 μm). Two aqueous polymer solutions, polyethylene oxide (viscoelastic fluid) and hydroxyethyl cellulose (viscous fluid) were tested. Bagley correction was applied to remove the end effect. Wall slip was investigated with Mooney’s analysis. Shear rates as high as 106 s-1 were obtained in the pressure-driven microchannel flow, allowing a smooth extension of the low shear rheological data obtained from the conventional rheometers. At high shear rates, polymer degradation was observed for PEO solutions at a critical microchannel wall shear stress of 4.1×103 Pa. Stresses at the ends of the microchannel also contributed to PEO degradation significantly.

Rheological behaviour of hydrocolloids for oil recovery; Comportamento reologico de hidrocoloides para recuperacao de oleo

Energy Technology Data Exchange (ETDEWEB)

Correia, Denise Z.; Franca, Francisca P. de; Mothe, Cheila G. [Universidade Federal do Rio de Janeiro (UFRJ), RJ (Brazil). Escola de Quimica; Dutra, Eduardo S.S. [Pontificia Univ. Catolica do Rio de Janeiro, RJ (Brazil); Naccache, Monica F. [Pontificia Univ. Catolica do Rio de Janeiro, RJ (Brazil). Dept. de Engenharia Mecanica

2004-07-01

In crude oil extraction, water can be injected into the well (secondary oil recovery). The amount of the oil extracted decrease after some operation time. In order to improve the oil recovery, polymer flooding would subsequently be used (tertiary oil recovery). The aim of this work was to study the rheological behavior of polyacrylamide, xanthan gum, guar gum and their blends in seawater solutions, and the rheology of a crude oil. Dynamic measurements of the pure polymers (1000 ppm) and blends (2000 ppm) exhibited G' values lower than G'' in low frequencies, and inversion of G' and G'' curves in frequencies between 20 and 30 rad/s. The xanthan gum presented the greatest values of G' when compared to the other polymers, which means that its structure is more rigid. The oil showed G' values lower than G'' values in low and high frequencies of oscillation. Steady measurements revealed pseudoplastic behavior for polymers and Newtonian behavior for the oil. In shear rates around 10 s{sup -1}, polyacrylamide/xanthan blend would be the most appropriate for the extraction of the oil presented. (author)

An analytical investigation on unsteady motion of vertically falling spherical particles in non-Newtonian fluid by Collocation Method

Directory of Open Access Journals (Sweden)

M. Rahimi-Gorji

2015-06-01

Full Text Available An analytical investigation is applied for unsteady motion of a rigid spherical particle in a quiescent shear-thinning power-law fluid. The results were compared with those obtained from Collocation Method (CM and the established Numerical Method (Fourth order Runge–Kutta scheme. It was shown that CM gave accurate results. Collocation Method (CM and Numerical Method are used to solve the present problem. We obtained that the CM which was used to solve such nonlinear differential equation with fractional power is simpler and more accurate than series method such as HPM which was used in some previous works by others but the new method named Akbari-Ganji’s Method (AGM is an accurate and simple method which is slower than CM for solving such problems. The terminal settling velocity—that is the velocity at which the net forces on a falling particle eliminate—for three different spherical particles (made of plastic, glass and steel and three flow behavior index n, in three sets of power-law non-Newtonian fluids was investigated, based on polynomial solution (CM. Analytical results obtained indicated that the time of reaching the terminal velocity in a falling procedure is significantly increased with growing of the particle size that validated with Numerical Method. Further, with approaching flow behavior to Newtonian behavior from shear-thinning properties of flow (n → 1, the transient time to achieving the terminal settling velocity is decreased.

Hyperdiffusive Dynamics in Newtonian Nanoparticle Fluids

KAUST Repository

Srivastava, Samanvaya

2015-10-20

© 2015 American Chemical Society. Hyperdiffusive relaxations in soft glassy materials are typically associated with out-of-equilibrium states, and nonequilibrium physics and aging are often invoked in explaining their origins. Here, we report on hyperdiffusive motion in model soft materials comprised of single-component polymer-tethered nanoparticles, which exhibit a readily accessible Newtonian flow regime. In these materials, polymer-mediated interactions lead to strong nanoparticle correlations, hyperdiffusive relaxations, and unusual variations of properties with temperature. We propose that hyperdiffusive relaxations in such materials can arise naturally from nonequilibrium or non-Brownian volume fluctuations forced by equilibrium thermal rearrangements of the particle pair orientations corresponding to equilibrated shear modes.

Hyperdiffusive Dynamics in Newtonian Nanoparticle Fluids

KAUST Repository

Srivastava, Samanvaya; Agarwal, Praveen; Mangal, Rahul; Koch, Donald L.; Narayanan, Suresh; Archer, Lynden A.

2015-01-01

© 2015 American Chemical Society. Hyperdiffusive relaxations in soft glassy materials are typically associated with out-of-equilibrium states, and nonequilibrium physics and aging are often invoked in explaining their origins. Here, we report on hyperdiffusive motion in model soft materials comprised of single-component polymer-tethered nanoparticles, which exhibit a readily accessible Newtonian flow regime. In these materials, polymer-mediated interactions lead to strong nanoparticle correlations, hyperdiffusive relaxations, and unusual variations of properties with temperature. We propose that hyperdiffusive relaxations in such materials can arise naturally from nonequilibrium or non-Brownian volume fluctuations forced by equilibrium thermal rearrangements of the particle pair orientations corresponding to equilibrated shear modes.

Stability, rheology and thermal analysis of functionalized alumina- thermal oil-based nanofluids for advanced cooling systems

International Nuclear Information System (INIS)

Ilyas, Suhaib Umer; Pendyala, Rajashekhar; Narahari, Marneni; Susin, Lim

2017-01-01

Highlights: • Alumina nanoparticles are functionalized with oleic acid. • Functionalization of alumina nanoparticles gives better dispersion in thermal oil. • Thermophysical properties of nanofluids are experimentally measured. • TGA confirms the improvement in life of nanofluids. - Abstract: Thermal oils are widely used as cooling media in heat transfer processes. However, their potential has not been utilised exquisitely in many applications due to low thermal properties. Thermal oil-based nanofluids are prepared by dispersing functionalized alumina with varying concentrations of 0.5–3 wt.% to enhance thermal properties of oil for advanced cooling systems. The oleic acid coated alumina is prepared and then dispersed in the oil to overcome the aggregation of nanoparticles in base fluid. The surface characterizations of functionalized nanoparticles are performed using different analysis such as XRD, EDS, SEM, TEM and FTIR. Dispersion behaviour and agglomeration studies are conducted at natural and functionalized conditions using different analysis to ensure long-term stability of nanofluids. In addition, rheological behaviour of non-Newtonian nanofluids is studied at high shear rates (100–2000 s"−"1). Effective densities and enhancement in thermal conductivities are measured for different nanofluids concentrations. Specific heat capacity is measured using Differential Scanning Calorimetry. The correlations are developed for thermophysical properties of nanofluids. Thermogravimetric analysis is performed with respect to temperature and time to exploit the effect of the addition of nanoparticles on the degradation of nanofluids. Significant improvement in the thermal properties of oil is observed using highly stable functionalized alumina nano-additives.

Dynamics of magnetic nano-flake vortices in Newtonian fluids

Energy Technology Data Exchange (ETDEWEB)

Bazazzadeh, Nasim, E-mail: n.bazazzadeh@gmail.com [Department of Physics, Shahid Beheshti University, G.C., Evin, Tehran 19839 (Iran, Islamic Republic of); Mohseni, Seyed Majid, E-mail: m-mohseni@sbu.ac.ir [Department of Physics, Shahid Beheshti University, G.C., Evin, Tehran 19839 (Iran, Islamic Republic of); Khavasi, Amin, E-mail: khavasi@sharif.edu [Department of Electrical Engineering, Sharif University of Technology, Tehran 11555-4363 (Iran, Islamic Republic of); Zibaii, Mohammad Ismail, E-mail: mizibaye@gmail.com [Laser and Plasma Research Institute, Shahid Beheshti University, G.C., Evin, Tehran 19839 (Iran, Islamic Republic of); Movahed, S.M.S., E-mail: m_movahed@sbu.ac.ir [Department of Physics, Shahid Beheshti University, G.C., Evin, Tehran 19839 (Iran, Islamic Republic of); Jafari, G.R., E-mail: gjafari@gmail.com [Department of Physics, Shahid Beheshti University, G.C., Evin, Tehran 19839 (Iran, Islamic Republic of)

2016-12-01

We study the rotational motion of nano-flake ferromagnetic disks suspended in a Newtonian fluid, as a potential material owing the vortex-like magnetic configuration. Using analytical expressions for hydrodynamic, magnetic and Brownian torques, the stochastic angular momentum equation is determined in the dilute limit conditions under applied magnetic field. Results are compared against experimental ones and excellent agreement is observed. We also estimate the uncertainty in the orientation of the disks due to the Brownian torque when an external magnetic field aligns them. Interestingly, this uncertainty is roughly proportional to the ratio of thermal energy of fluid to the magnetic energy stored in the disks. Our approach can be implemented in many practical applications including biotechnology and multi-functional fluidics. - Highlights: • The rotational motion of magnetic-vortex microdiscs in a Newtonian fluid is studied. • Results are compared against experimental ones and excellent agreement is observed. • The uncertainty in the orientation of the microdiscs is analytically derived.

High shear microfluidics and its application in rheological measurement

Energy Technology Data Exchange (ETDEWEB)

Kang, Kai; Lee, L.James; Koelling, Kurt W. [The Ohio State University, Department of Chemical Engineering, Columbus, OH (United States)

2005-02-01

High shear rheology was explored experimentally in microchannels (150 x 150 {mu}m). Two aqueous polymer solutions, polyethylene oxide (viscoelastic fluid) and hydroxyethyl cellulose (viscous fluid) were tested. Bagley correction was applied to remove the end effect. Wall slip was investigated with Mooney's analysis. Shear rates as high as 10{sup 6} s {sup -1} were obtained in the pressure-driven microchannel flow, allowing a smooth extension of the low shear rheological data obtained from the conventional rheometers. At high shear rates, polymer degradation was observed for PEO solutions at a critical microchannel wall shear stress of 4.1 x 10 {sup 3} Pa. Stresses at the ends of the microchannel also contributed to PEO degradation significantly. (orig.)

Rheology of planetary ices

Energy Technology Data Exchange (ETDEWEB)

Durham, W.B. [Lawrence Livermore National Lab., CA (United States); Kirby, S.H.; Stern, L.A. [Geological Survey, Menlo Park, CA (United States)

1996-04-24

The brittle and ductile rheology of ices of water, ammonia, methane, and other volatiles, in combination with rock particles and each other, have a primary influence of the evolution and ongoing tectonics of icy moons of the outer solar system. Laboratory experiments help constrain the rheology of solar system ices. Standard experimental techniques can be used because the physical conditions under which most solar system ices exist are within reach of conventional rock mechanics testing machines, adapted to the low subsolidus temperatures of the materials in question. The purpose of this review is to summarize the results of a decade-long experimental deformation program and to provide some background in deformation physics in order to lend some appreciation to the application of these measurements to the planetary setting.

The Rheology of Acoustically Fluidized Sand

Science.gov (United States)

Conrad, J. W.; Melosh, J.

2013-12-01

The collapse of large craters and the formation of central peaks and peak rings is well modeled by numerical computer codes that incorporate the acoustic fluidization mechanism to temporarily allow the fluid-like flow of rock debris immediately after crater excavation. Furthermore, long runout landslides require a similar mechanism to explain their almost frictionless movement, which is probably also a consequence of their granular composition coupled with internal vibrations. Many different investigators have now confirmed the ability of vibrations to fluidize granular materials. Yet it still remains to fully describe the rheology of vibrated sand as a function of stress, frequency and amplitude of the vibrations in the sand itself. We constructed a rotational viscometer to quantitatively investigate the relation between the stress and strain rate in a horizontal bed of strongly vibrated sand. In addition to the macroscopic stain rate, the amplitude and frequency of the vibrations produced by a pair of pneumatic vibrators were also measured with the aid of miniaturized piezoelectric accelerometers (B&K 4393) whose output was recorded on a digital storage oscilloscope. The initial gathering of the experimental data was difficult due to granular memory, but by having the sand compacted vibrationally for 8 minutes before each run the scatter of data was reduced and we were able to obtain consistent results. Nevertheless, our major source of uncertainty was variations in strain rate from run to run. We find that vibrated sand flows like a highly non-Newtonian fluid, in which the shear strain rate is proportional to stress to a power much greater than one, where the precise power depends on the amplitude and frequency of the applied vibrations. Rapid flow occurs at stresses less than half of the static yield stress (that is, the yield stress when no vibration is applied) when strong vibrations are present. For a Newtonian fluid, such as water, the relation between

Synthesis and characterization of carboxymethyl cellulose from office waste paper: A greener approach towards waste management

Energy Technology Data Exchange (ETDEWEB)

Joshi, Gyanesh, E-mail: joshig@icfre.org [Cellulose and Paper Division, Forest Research Institute, Dehradun 248006 (India); Naithani, Sanjay [Chemistry of Forest Products Division, Institute of Wood Science & Technology, Bangalore 560003 (India); Varshney, V.K. [Chemistry Division, Forest Research Institute, Dehradun 248006 (India); Bisht, Surendra S. [Chemistry of Forest Products Division, Institute of Wood Science & Technology, Bangalore 560003 (India); Rana, Vikas; Gupta, P.K. [Cellulose and Paper Division, Forest Research Institute, Dehradun 248006 (India)

2015-04-15

Highlights: • Carboxymethyl cellulose (CMC) was successfully prepared from waste paper. • CMC had maximum degree of substitution (DS) 1.07. • Rheological studies of CMC (DS, 1.07) showed non-Newtonian pseudoplastic behavior. • Characterization of CMC was done by FT-IR and NMR techniques. • Morphology of prepared CMC was studied by SEM. - Abstract: In the present study, functionalization of mixed office waste (MOW) paper has been carried out to synthesize carboxymethyl cellulose, a most widely used product for various applications. MOW was pulped and deinked prior to carboxymethylation. The deinked pulp yield was 80.62 ± 2.0% with 72.30 ± 1.50% deinkability factor. The deinked pulp was converted to CMC by alkalization followed by etherification using NaOH and ClCH{sub 2}COONa respectively, in an alcoholic medium. Maximum degree of substitution (DS) (1.07) of prepared CMC was achieved at 50 °C with 0.094 M and 0.108 M concentrations of NaOH and ClCH{sub 2}COONa respectively for 3 h reaction time. The rheological characteristics of 1–3% aqueous solution of optimized CMC product showed the non-Newtonian pseudoplastic behavior. Fourier transform infra red (FTIR), nuclear magnetic resonance (NMR) and scanning electron microscope (SEM) study were used to characterize the CMC product.

RESONANT POST-NEWTONIAN ECCENTRICITY EXCITATION IN HIERARCHICAL THREE-BODY SYSTEMS

Energy Technology Data Exchange (ETDEWEB)

Naoz, Smadar; Kocsis, Bence; Loeb, Abraham [Institute for Theory and Computation, Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Yunes, Nicolas, E-mail: snaoz@cfa.harvard.edu [Department of Physics, Montana State University, Bozeman, MT 59718 (United States)

2013-08-20

We study the secular, hierarchical three-body problem to first-order in a post-Newtonian expansion of general relativity (GR). We expand the first-order post-Newtonian Hamiltonian to leading-order in the ratio of the semi-major axis of the two orbits. In addition to the well-known terms that correspond to the GR precession of the inner and outer orbits, we find a new secular post-Newtonian interaction term that can affect the long-term evolution of the triple. We explore the parameter space for highly inclined and eccentric systems, where the Kozai-Lidov mechanism can produce large-amplitude oscillations in the eccentricities. The standard lore, i.e., that GR effects suppress eccentricity, is only consistent with the parts of phase space where the GR timescales are several orders of magnitude shorter than the secular Newtonian one. In other parts of phase space, however, post-Newtonian corrections combined with the three-body ones can excite eccentricities. In particular, for systems where the GR timescale is comparable to the secular Newtonian timescales, the three-body interactions give rise to a resonant-like eccentricity excitation. Furthermore, for triples with a comparable-mass inner binary, where the eccentric Kozai-Lidov mechanism is suppressed, post-Newtonian corrections can further increase the eccentricity and lead to orbital flips even when the timescale of the former is much longer than the timescale of the secular Kozai-Lidov quadrupole perturbations.

Dynamics of continua and particles from general covariance of Newtonian gravitation theory

International Nuclear Information System (INIS)

Duval, C.; Kunzle, H.P.

1976-07-01

The principle of general covariance, which states that the total action functional in General Relativity is independent of coordinate transformations, is shown to be also applicable to the four-dimensional geometric theory of Newtonian gravitation. It leads to the correct conservation (or balance) equations of continuum mechanics as well as the equations of motion of test particles in a gravitational field. The degeneracy of the ''metric'' of Newtonian space-time forces to introduce a ''gauge field'' which fixes the connection and leads to a conserved current, the mass flow. The particle equations are also derived from an invariant Hamiltonian structure on the extended Galilei group and a minimal interaction principle. One not only finds the same equations of motion but even the same gauge fields

Aspects of the motion of extended bodies in the post-Newtonian approximation to general relativity

Science.gov (United States)

Racine, Etienne

We give a surface integral derivation of post-1-Newtonian translational equations of motion for a system of arbitrarily structured bodies, including the coupling to all the bodies' mass and current multipole moments. The explicit form of these translational equations of motion has not been previously derived. The derivation requires only that the post-1-Newtonian vacuum field equations are satisfied in weak-field regions between the bodies; the bodies' internal gravity can be arbitrarily strong. In particular black holes are not excluded. The derivation extends previous results due to Damour, Soffel and Xu (DSX) for weakly self-gravitating bodies in which the post-1- Newtonian field equations are satisfied everywhere. We also give a surface integral derivation of the leading-order evolution equations for the spin and energy of a relativistic body interacting with other bodies in the post-Newtonian expansion. As part of the computational method, new explicit expansions of general solutions of post-2-Newtonian vacuum field equations are derived. These expansions can serve as foundation for future work in a number of directions, including for example conserved quantities at post- 2-Newtonian order, definitions of angular momentum and studies of gauge invariance of tidal heating. As an astrophysical application of the translational equations of motion, we study gravitomagnetic resonant tidal excitations of r -modes in neutron star binary coalescence. We show that the effect of the resonance on the phase of the binary can be parametrized by a single number. We compute this number explicitly and discuss the detectability of this effect from its imprint on the gravitational wave signal emitted by the binary.

A Conditionally Stable Scheme for a Transient Flow of a Non-Newtonian Fluid Saturating a Porous Medium

KAUST Repository

El-Amin, Mohamed

2012-06-02

The problem of thermal dispersion effects on unsteady free convection from an isothermal horizontal circular cylinder to a non-Newtonian fluid saturating a porous medium is examined numerically. The Darcy-Brinkman-Forchheimer model is employed to describe the flow field. The thermal diffusivity coefficient has been assumed to be the sum of the molecular diffusivity and the dynamic diffusivity due to mechanical dispersion. The simultaneous development of the momentum and thermal boundary layers are obtained by using finite difference method. The stability conditions are determined for each difference equation. Using an explicit finite difference scheme, solutions at each time-step have been found and then stepped forward in time until reaching steady state solution. Velocity and temperature profiles are shown graphically. It is found that as time approaches infinity, the values of friction factor and heat transfer coefficient approach the steady state values.

A Conditionally Stable Scheme for a Transient Flow of a Non-Newtonian Fluid Saturating a Porous Medium

KAUST Repository

El-Amin, Mohamed; Salama, Amgad; Sun, Shuyu

2012-01-01

The problem of thermal dispersion effects on unsteady free convection from an isothermal horizontal circular cylinder to a non-Newtonian fluid saturating a porous medium is examined numerically. The Darcy-Brinkman-Forchheimer model is employed to describe the flow field. The thermal diffusivity coefficient has been assumed to be the sum of the molecular diffusivity and the dynamic diffusivity due to mechanical dispersion. The simultaneous development of the momentum and thermal boundary layers are obtained by using finite difference method. The stability conditions are determined for each difference equation. Using an explicit finite difference scheme, solutions at each time-step have been found and then stepped forward in time until reaching steady state solution. Velocity and temperature profiles are shown graphically. It is found that as time approaches infinity, the values of friction factor and heat transfer coefficient approach the steady state values.

Flow-induced structure in colloidal suspensions

Energy Technology Data Exchange (ETDEWEB)

Vermant, J [Department of Chemical Engineering, K U Leuven, W de Croylaan 46, B-3001 Leuven (Belgium); Solomon, M J [Department of Chemical Engineering, University of Michigan, Ann Arbor, MI 48109-2136 (United States)

2005-02-02

We review the sequences of structural states that can be induced in colloidal suspensions by the application of flow. Structure formation during flow is strongly affected by the delicate balance among interparticle forces, Brownian motion and hydrodynamic interactions. The resulting non-equilibrium microstructure is in turn a principal determinant of the suspension rheology. Colloidal suspensions with near hard-sphere interactions develop an anisotropic, amorphous structure at low dimensionless shear rates. At high rates, clustering due to strong hydrodynamic forces leads to shear thickening rheology. Application of steady-shear flow to suspensions with repulsive interactions induces a rich sequence of transitions to one-, two-and three-dimensional order. Oscillatory-shear flow generates metastable ordering in suspensions with equilibrium liquid structure. On the other hand, short-range attractive interactions can lead to a fluid-to-gel transition under quiescent suspensions. Application of flow leads to orientation, breakup, densification and spatial reorganization of aggregates. Using a non-Newtonian suspending medium leads to additional possibilities for organization. We examine the extent to which theory and simulation have yielded mechanistic understanding of the microstructural transitions that have been observed. (topical review)

Physicochemical and Rheological Properties of a Dairy Dessert, Enriched with Chickpea Flour

Directory of Open Access Journals (Sweden)

Victoria Guadalupe Aguilar-Raymundo

2018-02-01

Full Text Available Dairy desserts are complex mixtures and matrices including main components such as milk, sugar, starch, hydrocolloids, colorants and flavors, with a proteinaceous structure; they are widely consumed and present a semisolid consistency. In this work, the physicochemical and rheological properties of a dairy dessert with the addition of chickpea flour (raw and cooked, at four concentrations were studied to determine the effect of the flour. The results indicated that luminosity (L*: 62.75–83.29, pH (6.35–7.11 and acidity (1.56–3.56 changed with the type of flour. The flow properties of the custards exhibited a non-Newtonian behavior that was well fitted by three flow models. The studied custard systems were stored for twelve days at 4 °C. The physicochemical and flow properties of the custards changed notably as a function of flour addition and storage time. From all samples, only four were analyzed with oscillatory tests, showing their mechanical spectra with elastic behavior. The dessert texture was also measured, founding that those formulated with Blanco Noroeste chickpea flour exhibited the highest values of hardness (0.356–0.391 N through the twelve days. It can be concluded that those custard systems with the highest content of flour presented a very good response as a potential new dairy product.

Physicochemical and Rheological Properties of a Dairy Dessert, Enriched with Chickpea Flour

Science.gov (United States)

Aguilar-Raymundo, Victoria Guadalupe; Vélez-Ruiz, Jorge Fernando

2018-01-01

Dairy desserts are complex mixtures and matrices including main components such as milk, sugar, starch, hydrocolloids, colorants and flavors, with a proteinaceous structure; they are widely consumed and present a semisolid consistency. In this work, the physicochemical and rheological properties of a dairy dessert with the addition of chickpea flour (raw and cooked, at four concentrations) were studied to determine the effect of the flour. The results indicated that luminosity (L*: 62.75–83.29), pH (6.35–7.11) and acidity (1.56–3.56) changed with the type of flour. The flow properties of the custards exhibited a non-Newtonian behavior that was well fitted by three flow models. The studied custard systems were stored for twelve days at 4 °C. The physicochemical and flow properties of the custards changed notably as a function of flour addition and storage time. From all samples, only four were analyzed with oscillatory tests, showing their mechanical spectra with elastic behavior. The dessert texture was also measured, founding that those formulated with Blanco Noroeste chickpea flour exhibited the highest values of hardness (0.356–0.391 N) through the twelve days. It can be concluded that those custard systems with the highest content of flour presented a very good response as a potential new dairy product. PMID:29463036

Non-Newtonian stress tensor and thermal conductivity tensor in granular plane shear flow

Science.gov (United States)

Alam, Meheboob; Saha, Saikat

2014-11-01

The non-Newtonian stress tensor and the heat flux in the plane shear flow of smooth inelastic disks are analysed from the Grad-level moment equations using the anisotropic Gaussian as a reference. Closed-form expressions for shear viscosity, pressure, first normal stress difference (N1) and the dissipation rate are given as functions of (i) the density or the area fraction (ν), (ii) the restitution coefficient (e), (iii) the dimensionless shear rate (R), (iv) the temperature anisotropy [ η, the difference between the principal eigenvalues of the second moment tensor] and (v) the angle (ϕ) between the principal directions of the shear tensor and the second moment tensor. Particle simulation data for a sheared hard-disk system is compared with theoretical results, with good agreement for p, μ and N1 over a large range of density. In contrast, the predictions from a Navier-Stokes order constitutive model are found to deviate significantly from both the simulation and the moment theory even at moderate values of e. We show that the gradient of the deviatoric part of the kinetic stress drives a heat current and the thermal conductivity is characterized by an anisotropic 2nd rank tensor for which explicit expressions are derived.

CFD study of the thermal transfer of a non-Newtonian fluid within a tank mechanically stirred by an anchor-shaped impeller

Science.gov (United States)

Rahmani, L.; Seghier, O.; Benmoussa, A.; Draoui, B.

2018-06-01

The most of operations of chemical, biochemical or petrochemical industries are carried out in tanks or in reactors which are mechanically-controlled. The optimum mode of operation of these devices requires a finalized knowledge of the thermo-hydrodynamic behavior induced by the agitator. In the present work, the characterization of the incompressible hydrodynamic and thermal fields of a non-Newtonian fluid (Bingham) in a flat, non-baffled cylindrical vessel fitted with anchor agitator was undertaken by numerical simulation, using the CFD code Fluent (6.3.26) based on the finite volume discretization method of the energy equation and the Navier-Stokes equations which are formulated in (U.V.P) variables. We have summarized this simulated system by comparing of the consumed power and the Nusselt number for this type of mobile (Anchor agitator).

Introducing Students to Rheological Classification of Foods, Cosmetics, and Pharmaceutical Excipients Using Common Viscous Materials

Science.gov (United States)

Faustino, Ce´lia; Bettencourt, Ana F.; Alfaia, Anto´nio; Pinheiro, Lídia

2015-01-01

Rheological measurements are very important tools for the characterization of the flow and deformation of a material, as well as for optimization of the rheological parameters. The application and acceptance of pharmaceutical formulations, cosmetics, and foodstuffs depends upon their rheological characteristics, such as texture, consistency, or…

Scaling of Structural and Rheological Responde of L3 Sponge Phases in the 'Sweetened' Cetylpyridinium/Hexanol/Dextrose/Brine System

International Nuclear Information System (INIS)

Porcar, L.; Hamilton, William A.; Butler, Paul D.; Warr, G.G.

2003-01-01

We report a study of the shear response of sponge phases in cetylpyridinium chloride (CPCl)/hexanol/brine/dextrose systems by parallel measurements of rheology and structure by small angle neutron scattering (SANS). Our measurements show that this dextrose added to the extensively studied CPCl/hexanol/brine system is taken up exclusively by the brine solvent, resulting in an equivalent CPCl/hexanol membrane structure and phase behavior for this modified system. Adding dextrose to the brine in these systems to volume fractions up to 0.4 allows us to increase the solvent viscosity by more than an order of magnitude. This lowers the cooperative membrane diffusion coefficient in this system as measured by dynamic light scattering by the same factor, resulting in a corresponding slowing of the Helfrich fluctuation dominated membrane dynamics. Our results show clear and consistent evidence of shear-induced sponge to lamellar phase transformations in these systems. Further, both the rheological and microstructural responses of these systems follow universal master curves when plotted against a rescaled applied shear γ η s /φ 3 , where φ is the membrane volume fraction and η s is the viscosity of the brine/dextrose solvent. This well-defined shear response is characterized by three distinct regimes. At low shear rates the sponge phases exhibit Newtonian flow behavior and no structural change is observed. For intermediate shear rates, the systems shear thin and SANS measurements show that the sponge phases are progressively transformed into lamellar phases with the CPCl/hexanol membrane normals aligned parallel to the velocity gradient. This continuous process and the absence of a stress plateau in the rheological measurements both rule out the existence of a biphasic state in this region and thus of a first-order transition between sponge and lamellar phases as is observed in equilibrium phase diagrams. At higher shear rates, the systems are apparently again Newtonian

Modeling and analysis rheology of polymers for application in technologies “self-crimping” and its adaptation to the practices of Polymer Materials Engineering

OpenAIRE

N. Montanes; L. Sánchez-Nacher; M.J. Reig; O. Fenollar; T. Boronat

2017-01-01

[EN] Polymers are manufactured in molted state, so the rheological properties are mandatory in order to analyzeand evaluate its processability. The prediction of the viscoelastic response of a material and the simulationof the behavior of the same when it is processed is achieved with the application of the rheological models.In the preparation by extrusion of bicomponent polymer bers with self-crimping e ect it is essentialthat the two components have the same viscosity...

Rheological Principles for Food Analysis

Science.gov (United States)

Daubert, Christopher R.; Foegeding, E. Allen

Food scientists are routinely confronted with the need to measure physical properties related to sensory texture and processing needs. These properties are determined by rheological methods, where rheology is a science devoted to the deformation and flow of all materials. Rheological properties should be considered a subset of the textural properties of foods, because the sensory detection of texture encompasses factors beyond rheological properties. Specifically, rheological methods accurately measure "force," "deformation," and "flow," and food scientists and engineers must determine how best to apply this information. For example, the flow of salad dressing from a bottle, the snapping of a candy bar, or the pumping of cream through a homogenizer are each related to the rheological properties of these materials. In this chapter, we describe fundamental concepts pertinent to the understanding of the subject and discuss typical examples of rheological tests for common foods. A glossary is included as Sect. 30.6 to clarify and summarize rheological definitions throughout the chapter.

5th European Rheology Conference

CERN Document Server

1998-01-01

Global sustainable development of the world economy requires better understanding and utilization of natural recourses. In this endeavor rheology has an indispensable role. The Rheology Conferences are therefore always an important event for science and technology. The Fifth European Rheology Conference, held from September 6 to 11 in the Portoro-z, Slovenia, will be the first AlI-European rheology meeting after the formal constitution of the European Society ofRheology. As such it will be a special historical event. At this meeting the European Society of Rheology will introduce the Weissenberg Medal, to be bestowed every four years to an individual for hislhers contribution to the field of Rheology. The recipient ofthe first award will be professor G. Marrucci ofthe Universita degli Studi di Napoli, Italy. Two mini Symposia will be part of the Conference. The first, on Industrial Rheology, will commemorate the late professor G. Astarita. The second will honor the eightieth birthday of professor N.W. Tschoeg...

Rheological changes in irradiated chicken eggs

Science.gov (United States)

Ferreira, Lúcia F. S.; Del Mastro, Nélida L.

1998-06-01

Pathogenic bacteria may cause foodborne illnesses. Humans may introduce pathogens into foods during production, processing, distribution and or preparation. Some of these microorganisms are able to survive conventional preservation treatments. Heat pasteurization, which is a well established and satisfactory means of decontamination/disinfection of liquid foods, cannot efficiently achieve a similar objective for solid foods. Extensive work carried out worldwide has shown that irradiation is efficient in eradicating foodborne pathogens like Salmonella spp. that can contaminate poultry products. In this work Co-60 gamma irradiation was applied to samples of industrial powder white, yolk and whole egg at doses between 0 and 25 kGy. Samples were rehydrated and the viscosity measured in a Brookfield viscosimeter, model DV III at 5, 15 and 25°C. The rheological behaviour among the various kinds of samples were markedly different. Irradiation with doses up to 5 kGy, known to reduced bacterial contamination to non-detectable levels, showed almost no variation of viscosity of irradiated egg white samples. On the other hand, whole or yolk egg samples showed some changes in rheological properties depending on the dose level, showing the predominance of whether polimerization or degradation as a result of the irradiation. Additionally, irradiation of yolk egg powder reduced yolk color as a function of the irradiation exposure implemented. The importance of these results are discussed in terms of possible industrial applications.

Rheological changes in irradiated chicken eggs

International Nuclear Information System (INIS)

Ferreira, Lucia F. S.; Del Mastro, Nelida L.

1998-01-01

Pathogenic bacteria may cause foodborne illnesses. Humans may introduce pathogens into foods during production, processing, distribution and or preparation. Some of these microorganisms are able to survive conventional preservation treatments. Heat pasteurization, which is a well established and satisfactory means of decontamination/disinfection of liquid foods, cannot efficiently achieve a similar objective for solid foods. Extensive work carried out worldwide has shown that irradiation is efficient in eradicating foodborne pathogens like Salmonella spp. that can contaminate poultry products. In this work Co-60 gamma irradiation was applied to samples of industrial powder white, yolk and whole egg at doses between 0 and 25 kGy. Samples were rehydrated and the viscosity measured in a Brookfield viscosimeter, model DV III at 5, 15 and 25 degree sign C. The rheological behaviour among the various kinds of samples were markedly different. Irradiation with doses up to 5 kGy, known to reduced bacterial contamination to non-detectable levels, showed almost no variation of viscosity of irradiated egg white samples. On the other hand, whole or yolk egg samples showed some changes in rheological properties depending on the dose level, showing the predominance of whether polimerization or degradation as a result of the irradiation. Additionally, irradiation of yolk egg powder reduced yolk color as a function of the irradiation exposure implemented. The importance of these results are discussed in terms of possible industrial applications

Entropy Generation Analysis of Power-Law Non-Newtonian Fluid Flow Caused by Micropatterned Moving Surface

Directory of Open Access Journals (Sweden)

M. H. Yazdi

2014-01-01

Full Text Available In the present study, the first and second law analyses of power-law non-Newtonian flow over embedded open parallel microchannels within micropatterned permeable continuous moving surface are examined at prescribed surface temperature. A similarity transformation is used to reduce the governing equations to a set of nonlinear ordinary differential equations. The dimensionless entropy generation number is formulated by an integral of the local rate of entropy generation along the width of the surface based on an equal number of microchannels and no-slip gaps interspersed between those microchannels. The velocity, the temperature, the velocity gradient, and the temperature gradient adjacent to the wall are substituted into this equation resulting from the momentum and energy equations obtained numerically by Dormand-Prince pair and shooting method. Finally, the entropy generation numbers, as well as the Bejan number, are evaluated. It is noted that the presence of the shear thinning (pseudoplastic fluids creates entropy along the surface, with an opposite effect resulting from shear thickening (dilatant fluids.

Linking the fractional derivative and the Lomnitz creep law to non-Newtonian time-varying viscosity

Science.gov (United States)

Pandey, Vikash; Holm, Sverre

2016-09-01

Many of the most interesting complex media are non-Newtonian and exhibit time-dependent behavior of thixotropy and rheopecty. They may also have temporal responses described by power laws. The material behavior is represented by the relaxation modulus and the creep compliance. On the one hand, it is shown that in the special case of a Maxwell model characterized by a linearly time-varying viscosity, the medium's relaxation modulus is a power law which is similar to that of a fractional derivative element often called a springpot. On the other hand, the creep compliance of the time-varying Maxwell model is identified as Lomnitz's logarithmic creep law, making this possibly its first direct derivation. In this way both fractional derivatives and Lomnitz's creep law are linked to time-varying viscosity. A mechanism which yields fractional viscoelasticity and logarithmic creep behavior has therefore been found. Further, as a result of this linking, the curve-fitting parameters involved in the fractional viscoelastic modeling, and the Lomnitz law gain physical interpretation.

Moving interface problems and applications in fluid dynamics

CERN Document Server

Khoo, Boo Cheong; Lin, Ping

2008-01-01

This volume is a collection of research papers presented at the program on Moving Interface Problems and Applications in Fluid Dynamics, which was held between January 8 and March 31, 2007 at the Institute for Mathematical Sciences (IMS) of the National University of Singapore. The topics discussed include modeling and simulations of biological flow coupled to deformable tissue/elastic structure, shock wave and bubble dynamics and various applications including biological treatments with experimental verification, multi-medium flow or multi-phase flow and various applications including cavitation/supercavitation, detonation problems, Newtonian and non-Newtonian fluid, and many other areas. Readers can benefit from some recent research results in these areas.

A rheological and microscopical characterization of biocompatible ferrofluids

International Nuclear Information System (INIS)

Nowak, J.; Wolf, D.; Odenbach, S.

2014-01-01

There is an increasing interest in suspensions of magnetic nanoparticles in the biomedical area. Those ferrofluids are e.g. used for magnetic resonance imaging and emerging research focuses on employing the fluids for magnetic drug targeting or magnetic particle heating as a potential treatment for cancer. For these applications the knowledge of the suspensions' thermophysical properties is of major interest to guarantee a safe and effective application. Therefore the flow behavior cannot be neglected as it might significantly influence the execution of the aforementioned applications. In this experimental study two biocompatible ferrofluids were investigated. Rheological measurements were carried out using rotational rheometry. To allow an interpretation of the fluids' behavior the microscopic make-up was investigated using dynamic light scattering and transmission electron microscopy. Measurements of diluted ferrofluids were carried out as a first step to simulate the rheological behavior reflecting the concentration of magnetic nanoparticles found in blood flow for most biomedical applications of such fluids. The detected strong effects show the potential to significantly influence application and handling of the biocompatible ferrofluids in the medical area and should therefore be taken into account for further research as well as for the application of such fluids. - Highlights: • The rheology of biocompatible multicore ferrofluids is influenced by magnetic fields. • The flow curves can be described by the Herschel–Bulkley model. • A connection between the magnetoviscous effect and the particle size is found. • The strong magnetoviscous effect exists even if the fluids are diluted. • The connection between the effect and the dilution is mathematically described

Unsteady boundary layer flow and heat transfer of a Casson fluid past an oscillating vertical plate with Newtonian heating.

Science.gov (United States)

Hussanan, Abid; Zuki Salleh, Mohd; Tahar, Razman Mat; Khan, Ilyas

2014-01-01

In this paper, the heat transfer effect on the unsteady boundary layer flow of a Casson fluid past an infinite oscillating vertical plate with Newtonian heating is investigated. The governing equations are transformed to a systems of linear partial differential equations using appropriate non-dimensional variables. The resulting equations are solved analytically by using the Laplace transform method and the expressions for velocity and temperature are obtained. They satisfy all imposed initial and boundary conditions and reduce to some well-known solutions for Newtonian fluids. Numerical results for velocity, temperature, skin friction and Nusselt number are shown in various graphs and discussed for embedded flow parameters. It is found that velocity decreases as Casson parameters increases and thermal boundary layer thickness increases with increasing Newtonian heating parameter.

Temperature Effect on Rheological Behavior of Portuguese Honeys

Directory of Open Access Journals (Sweden)

Afonso Maria João

2018-09-01

Full Text Available In the present work the temperature effect on rheological properties of Portuguese honeys was studied for the first time. Two unifloral honeys – heather and rosemary – and a polyflower honey were analyzed. All honeys showed flow independence over time and behaved as Newtonian fluids at the studied temperature and shear rate ranges. For all honeys it was found that the viscosity decreased with temperature and the rosemary honey was the one that always presented the lowest viscosity at 30°C (6120 mPa·s, 50°C (603 mPa·s and 70°C (145 mPa·s. The temperature dependence of viscosity was well described by the K0×eAT-B$K_0 \\times e^{{A \\over {T - B}}} $ equation. Nevertheless, good regression coefficients were also obtained when fitting the experimental data to the Arrhenius model, showing the rosemary honey to be less temperature sensitive. The results obtained in this study are of great interest to beekeepers and industrials that handle and prepare eatable honey-based products because they will be better informed about the best type of honey to use.

Pore scale simulations for the extension of the Darcy-Forchheimer law to shear thinning fluids

Science.gov (United States)

Tosco, Tiziana; Marchisio, Daniele; Lince, Federica; Boccardo, Gianluca; Sethi, Rajandrea

2014-05-01

Flow of non-Newtonian fluids through porous media at high Reynolds numbers is often encountered in chemical, pharmaceutical and food as well as petroleum and groundwater engineering and in many other industrial applications (1 - 2). In particular, the use of shear thinning polymeric solutions has been recently proposed to improve colloidal stability of micro- and nanoscale zerovalent iron particles (MZVI and NZVI) for groundwater remediation. In all abovementioned applications, it is of paramount importance to correctly predict the pressure drop resulting from non-Newtonian fluid flow through the porous medium. For small Reynolds numbers, usually up to 1, typical of laboratory column tests, the extended Darcy law is known to be applicable also to non Newtonian fluids, provided that all non-Newtonian effects are lumped together into a proper viscosity parameter (1,3). For higher Reynolds numbers (eg. close to the injection wells) non linearities between pressure drop and flow rate arise, and the Darcy-Forchheimer law holds for Newtonian fluids, while for non-Newtonian fluids, it has been demonstrated that, at least for simple rheological models (eg. power law fluids) a generalized Forchheimer law can be applied, even if the determination of the flow parameters (permeability K, inertial coefficient β, and equivalent viscosity) is not straightforward. This work (co-funded by European Union project AQUAREHAB FP7 - Grant Agreement Nr. 226565) aims at proposing an extended formulation of the Darcy-Forchheimer law also for shear-thinning fluids, and validating it against results of pore-scale simulations via computational fluid dynamics (4). Flow simulations were performed using Fluent 12.0 on four different 2D porous domains for Newtonian and non-Newtonian fluids (Cross, Ellis and Carreau models). The micro-scale flow simulation results are analyzed in terms of 'macroscale' pressure drop between inlet and outlet of the model domain as a function of flow rate. The

On the normal stress effect in grease-lubricated bearing seals

NARCIS (Netherlands)

Baart, P.; Lugt, Pieter Martin; Prakash, B.

2014-01-01

The film formation in lip seals, due to the non-Newtonian rheology of the lubricant, has been a topic of speculation. Earlier work suggests that normal stresses in grease would be favorable for the film buildup between the seal lip and shaft or bearing ring. In the current article, we evaluate this

Dramatic effect of fluid chemistry on cornstarch suspensions : Linking particle interactions to macroscopic rheology

NARCIS (Netherlands)

Oyarte Galvez, Loreto; de Beer, Sissi; van der Meer, Devaraj; Pons, Adeline

2017-01-01

Suspensions of cornstarch in water exhibit strong dynamic shear-thickening. We show that partly replacing water by ethanol strongly alters the suspension rheology. We perform steady and non-steady rheology measurements combined with atomic force microscopy to investigate the role of fluid chemistry

Rheology and structure of aqueous bentonite–polyvinyl alcohol ...

Indian Academy of Sciences (India)

Keywords. Bentonite–polyvinyl alcohol dispersions; rheology; zeta potential; particle size analysis; SEM; FTIR studies. 1. .... sity and interception of the linear portion of the curve ..... applications for decolourizing or moisture absorption purpose.

Effect of smectite clays storage in their rheological properties

International Nuclear Information System (INIS)

Silva, I.A. da; Sousa, F.K.A. de; Neves, G. de A.; Ferreira, H.C.; Ferreira, H.S.; Ferreira, H.S.

2017-01-01

This work investigates the storage influence of natural and industrial smectite clays in their rheological properties, since the salt metathesis reaction that occurs following treatment of polycationic clays with Na_2 CO_3 is reversible. The phenomena involved in this reaction are not yet fully known and previous studies show improvement in some properties. The rheological properties were determined in sodium-clays in 1995 and polycationic clays added with sodium carbonate (Na_2 CO_3 ) in 2015. Physical, chemical and mineralogical characterizations of the samples were performed using the following techniques: particle size analysis by laser diffraction, chemical composition by X-ray fluorescence, X-ray diffraction and thermal analysis (DTA and TGA). The rheology of dispersions was determined by the apparent viscosity, plastic viscosity and filtrate volume, which were later considered the oil industry standards only as a benchmark. The results showed that the storage conditions, humidity and particle size of the samples resulted in improvements in their rheological properties over the years, indicating the non-reversibility of the reaction of cation exchange, which is important in their validity after manufacturing. (author)

Unsteady boundary layer flow and heat transfer of a Casson fluid past an oscillating vertical plate with Newtonian heating.

Directory of Open Access Journals (Sweden)

Abid Hussanan

Full Text Available In this paper, the heat transfer effect on the unsteady boundary layer flow of a Casson fluid past an infinite oscillating vertical plate with Newtonian heating is investigated. The governing equations are transformed to a systems of linear partial differential equations using appropriate non-dimensional variables. The resulting equations are solved analytically by using the Laplace transform method and the expressions for velocity and temperature are obtained. They satisfy all imposed initial and boundary conditions and reduce to some well-known solutions for Newtonian fluids. Numerical results for velocity, temperature, skin friction and Nusselt number are shown in various graphs and discussed for embedded flow parameters. It is found that velocity decreases as Casson parameters increases and thermal boundary layer thickness increases with increasing Newtonian heating parameter.

Shear and elongational rheology of photo-oxidative degraded HDPE and LLDPE

Science.gov (United States)

Wagner, Manfred Hermann; Zheng, Wang; Wang, Peng; Talamante, Sebastián Ramos; Narimissa, Esmaeil

2017-05-01

The effect of photo-oxidative degradation of high-density polyethylene (HDPE) and linear low-density polyethylene (LLDPE) was investigated by linear and non-linear rheological measurements. The linear-viscoelastic rheological measurements were performed at different temperatures, while the elongational viscosity was measured at 170°C and at different strain rates. The rheological data are indicative of structural changes caused by photo-oxidative degradation including formation of long-chain branches (LCB), cross-linking, and chain scission, and they revealed a cyclic and continuing competition between chain scission and LCB/gel formation. These findings are supported by additional FTIR measurements and direct measurements of the gel content of the degraded samples.

Theoretical frameworks for testing relativistic gravity. V - Post-Newtonian limit of Rosen's theory

Science.gov (United States)

Lee, D. L.; Ni, W.-T.; Caves, C. M.; Will, C. M.

1976-01-01

The post-Newtonian limit of Rosen's theory of gravity is evaluated and is shown to be identical to that of general relativity, except for the post-Newtonian parameter alpha sub 2 (which is related to the difference in propagation speeds for gravitational and electromagnetic waves). Both the value of alpha sub 2 and the value of the Newtonian gravitational constant depend on the present cosmological structure of the Universe. If the cosmological structure has a specific (but presumably special) form, the Newtonian gravitational constant assumes its current value, alpha sub 2 is zero, the post-Newtonian limit of Rosen's theory is identical to that of general relativity - and standard solar system experiments cannot distinguish between the two theories.

Parameterized Post-Newtonian Expansion of Scalar-Vector-Tensor Theory of Gravity

International Nuclear Information System (INIS)

Arianto; Zen, Freddy P.; Gunara, Bobby E.; Hartanto, Andreas

2010-01-01

We investigate the weak-field, post-Newtonian expansion to the solution of the field equations in scalar-vector-tensor theory of gravity. In the calculation we restrict ourselves to the first post Newtonian. The parameterized post Newtonian (PPN) parameters are determined by expanding the modified field equations in the metric perturbation. Then, we compare the solution to the PPN formalism in first PN approximation proposed by Will and Nordtvedt and read of the coefficients (the PPN parameters) of post Newtonian potentials of the theory. We find that the values of γ PPN and β PPN are the same as in General Relativity but the coupling functions β 1 , β 2 , and β 3 are the effect of the preferred frame.

Influence of vibration on structure rheological properties of a highly concentrated suspension

Science.gov (United States)

Ouriev Uriev, Boris N.; Uriev, Naum B.

2005-08-01

The influence of mechanical vibration on the flow properties of a highly concentrated multiphase food system is explored in this work. An experimental set-up was designed and adapted to a conventional rotational rheometer with precise rheological characterization capability. A number of calibration tests were performed prior to fundamental experiments with a highly concentrated chocolate suspension. Also, the prediction of wall slippage in shear flow under vibration was evaluated. Analysis of the boundary conditions shows that no side effects such as wall slippage or the Taylor effect were present during the shear experiment under vibration. It was found that superposition of mechanical vibration and shear flow radically decreases the shear viscosity. Comparison between reference shear viscosities at specified shear rates and those measured under vibration shows considerable differences in flow properties. Conversion of the behaviour of the concentrated suspension from strongly shear-thinning to Newtonian flow is reported. Also, the appearance of vibration-induced dilatancy as a new phenomenon is described. It is suggested to relate such phenomena to the non-equilibrium between structure formation and disintegration under vibration and hydrodynamic forces of shear flow. The influence of vibration on structure formation can be well observed during measurement of the yield value of the chocolate suspension under vibration. Comparison with reference data shows how sensitive the structure of the concentrated suspension is to vibration in general. The effects and observations revealed provide a solid basis for further fundamental investigations of structure formation regularities in the flow of any highly concentrated system. The results also show the technological potential for non-conventional treatment of concentrated, multiphase systems.

Silk Electrogel Rheology

Science.gov (United States)

Tabatabai, A. P.; Urbach, J. S.; Blair, D. L.; Kaplan, D. L.

2014-03-01

We present experimental results on the rheology on electrogels derived from aqueous solutions of reconstituted Bombyx Mori silk fibroin protein. Through electrochemistry, the silk protein solution develops local pH changes resulting in the assembly of protein into a weak gel. We determine the physical properties of the electrogels by performing rheology and observe that they exhibit the characteristics of a crosslinked biopolymer network. Interestingly, we find that these silk gels exhibit linear elasticity over a range of up to two orders of magnitude larger than most crosslinked biopolymer networks. Moreover, the nonlinear rheology exhibits a strain-stiffening behavior that is fundamentally different than the strain-stiffening observed in crosslinked biopolymers. Through rheological techniques we aim to understand this distinctive material that cannot be explained by current polymeric models. This work is supported by a grant from the AFOSR FA9550-07-1-0130.

Newtonian quantum gravity

International Nuclear Information System (INIS)

Jones, K.R.W.

1995-01-01

We develop a nonlinear quantum theory of Newtonian gravity consistent with an objective interpretation of the wavefunction. Inspired by the ideas of Schroedinger, and Bell, we seek a dimensional reduction procedure to map complex wavefunctions in configuration space onto a family of observable fields in space-time. Consideration of quasi-classical conservation laws selects the reduced one-body quantities as the basis for an explicit quasi-classical coarse-graining. These we interpret as describing the objective reality of the laboratory. Thereafter, we examine what may stand in the role of the usual Copenhagen observer to localise this quantity against macroscopic dispersion. Only a tiny change is needed, via a generically attractive self-potential. A nonlinear treatment of gravitational self-energy is thus advanced. This term sets a scale for all wavepackets. The Newtonian cosmology is thus closed, without need of an external observer. Finally, the concept of quantisation is re-interpreted as a nonlinear eigenvalue problem. To illustrate, we exhibit an elementary family of gravitationally self-bound solitary waves. Contrasting this theory with its canonically quantised analogue, we find that the given interpretation is empirically distinguishable, in principle. This result encourages deeper study of nonlinear field theories as a testable alternative to canonically quantised gravity. (author). 46 refs., 5 figs

Mixed Convection Flow of Magnetic Viscoelastic Polymer from a Nonisothermal Wedge with Biot Number Effects

Directory of Open Access Journals (Sweden)

S. Abdul Gaffar

2015-01-01

Full Text Available Magnetic polymers are finding increasing applications in diverse fields of chemical and mechanical engineering. In this paper, we investigate the nonlinear steady boundary layer flow and heat transfer of such fluids from a nonisothermal wedge. The incompressible Eyring-Powell non-Newtonian fluid model is employed and a magnetohydrodynamic body force is included in the simulation. The transformed conservation equations are solved numerically subject to physically appropriate boundary conditions using a second-order accurate implicit finite difference Keller Box technique. The numerical code is validated with previous studies. The influence of a number of emerging nondimensional parameters, namely, the Eyring-Powell rheological fluid parameter (ε, local non-Newtonian parameter based on length scale (δ, Prandtl number (Pr, Biot number (γ, pressure gradient parameter (m, magnetic parameter (M, mixed convection parameter (λ, and dimensionless tangential coordinate (ξ, on velocity and temperature evolution in the boundary layer regime is examined in detail. Furthermore, the effects of these parameters on surface heat transfer rate and local skin friction are also investigated.

Entropy analysis of convective MHD flow of third grade non-Newtonian fluid over a stretching sheet

Directory of Open Access Journals (Sweden)

M.M. Rashidi

2017-03-01

Full Text Available The purpose of this article is to study and analyze the convective flow of a third grade non-Newtonian fluid due to a linearly stretching sheet subject to a magnetic field. The dimensionless entropy generation equation is obtained by solving the reduced momentum and energy equations. The momentum and energy equations are reduced to a system of ordinary differential equations by a similarity method. The optimal homotopy analysis method (OHAM is used to solve the resulting system of ordinary differential equations. The effects of the magnetic field, Biot number and Prandtl number on the velocity component and temperature are studied. The results show that the thermal boundary-layer thickness gets decreased with increasing the Prandtl number. In addition, Brownian motion plays an important role to improve thermal conductivity of the fluid. The main purpose of the paper is to study the effects of Reynolds number, dimensionless temperature difference, Brinkman number, Hartmann number and other physical parameters on the entropy generation. These results are analyzed and discussed.

A measurement of LAGEOS II pericenter shift with a 1% accuracy and its constraints on non-Newtonian gravity

Science.gov (United States)

Peron, Roberto; Lucchesi, David

The pericenter shift of a binary system represents a suitable observable to be used to test for possible deviations from the Newtonian gravitational inverse—square—law in favor of pos-sible new weak interactions between macroscopic objects. These very weak and long-range interactions are usually described by means of a Yukawa—like potential with strength α and range λ. Moreover, these supplementary interactions may be either consistent with Einstein Equivalence Principle or not. In this work, we analyzed 11 years of LAGEOS II normal points using the GEODYN II code with suitable models for both gravitational and non—gravitational perturbations. However, we do not included in the models the general relativity corrections to Newtonian gravity, such as the ones due to the Earth's gravitoelectric and gravitomagnetic fields. From the fit of the satellite pericenter residuals we have been able to obtain a 99% agreement with the predictions of Einstein theory of gravitation. Therefore, the present mea-surement of the LAGEOS II pericenter shift represents a 1% measurement in the field of the Earth of the combination of the Parametrized Post—Newtonian parameters g and b of general relativity. This result may be also used to put limits on the strength α of a possible Yukawa— like interaction with a characteristic range of about 1 Earth radii. We obtained |α| ≈ 4 · 10-11 , that represents a significant improvement with respect to the previous constraints based on Earth—LAGEOS or Lunar—LAGEOS data.

State of the art of control schemes for smart systems featuring magneto-rheological materials

International Nuclear Information System (INIS)

Choi, Seung-Bok; Do, Phu Xuan; Li, Weihua; Yu, Miao; Fu, Jie; Du, Haiping

2016-01-01

This review presents various control strategies for application systems utilizing smart magneto-rheological fluid (MRF) and magneto-rheological elastomers (MRE). It is well known that both MRF and MRE are actively studied and applied to many practical systems such as vehicle dampers. The mandatory requirements for successful applications of MRF and MRE include several factors: advanced material properties, optimal mechanisms, suitable modeling, and appropriate control schemes. Among these requirements, the use of an appropriate control scheme is a crucial factor since it is the final action stage of the application systems to achieve the desired output responses. There are numerous different control strategies which have been applied to many different application systems of MRF and MRE, summarized in this review. In the literature review, advantages and disadvantages of each control scheme are discussed so that potential researchers can develop more effective strategies to achieve higher control performance of many application systems utilizing magneto-rheological materials. (topical review)

Newtonian hydrodynamic equations with relativistic pressure and velocity

Energy Technology Data Exchange (ETDEWEB)

Hwang, Jai-chan [Department of Astronomy and Atmospheric Sciences, Kyungpook National University, Daegu 702-701 (Korea, Republic of); Noh, Hyerim [Korea Astronomy and Space Science Institute, Daejeon 305-348 (Korea, Republic of); Fabris, Júlio; Piattella, Oliver F.; Zimdahl, Winfried, E-mail: jchan@knu.ac.kr, E-mail: hr@kasi.re.kr, E-mail: fabris@pq.cnpq.br, E-mail: oliver.piattella@pq.cnpq.br, E-mail: winfried.zimdahl@pq.cnpq.br [Departamento de Fisica, Universidade Federal do Espirito Santo, Vitória (Brazil)

2016-07-01

We present a new approximation to include fully general relativistic pressure and velocity in Newtonian hydrodynamics. The energy conservation, momentum conservation and two Poisson's equations are consistently derived from Einstein's gravity in the zero-shear gauge assuming weak gravity and action-at-a-distance limit. The equations show proper special relativity limit in the absence of gravity. Our approximation is complementary to the post-Newtonian approximation and the equations are valid in fully nonlinear situations.

Cohesive granular media modelization with non-convex particles shape: Application to UO2 powder compaction

International Nuclear Information System (INIS)

Saint-Cyr, B.

2011-01-01

We model in this work granular materials composed of non-convex and cohesive aggregates, in view of application to the rheology of UO 2 powders. The effect of non convexity is analyzed in terms of bulk quantities (Coulomb internal friction and cohesion) and micromechanical parameters such as texture anisotropy and force transmission. In particular, we find that the packing fraction evolves in a complex manner with the shape non convexity and the shear strength increases but saturates due to interlocking between the aggregates. We introduce simple models to describe these features in terms of micro-mechanical parameters. Furthermore, a systematic investigation of shearing, uniaxial compaction and simple compression of cohesive packings show that bulk cohesion increases with non-convexity but is strongly influenced by the boundary conditions and shear bands or stress concentration. (author) [fr

2nd International Conference on Rheology and Modeling of Materials (IC-RMM2)

International Nuclear Information System (INIS)

2017-01-01

Understanding the rheological properties of materials and their rheological behaviors during their manufacturing processes and in their applications in many cases can help to increase the efficiency and competitiveness not only of the finished goods and products but the organizations and societies also. The more scientific supported and prepared organizations develop more competitive products with better thermal, mechanical, physical, chemical and biological properties and the leading companies apply more competitive equipment and technology processes. The aims of the 2 nd International Conference on Rheology and Modeling of Materials (ic-rmm2) and the parallel organized symposiums of the 1 st International Symposium on Powder Injection Molding (is-pim1) and the 1 st International Symposium on Rheology and Fracture of Solids (is-rfs1) are the followings: Promote new methods and results of scientific research in the fields of modeling and measurements of rheological properties and behavior of materials under processing and applications; Change information between the theoretical and applied sciences as well as technical and technological implantations. Promote the communication and collaboration between the scientists, researchers and engineers of different disciplines, different nations, countries and continents. The international conference ic-rmm2 and symposiums of is-pim1 and is-rfs1 provide a platform among the leading international scientists, researchers, PhD students and engineers for discussing recent achievements in measurement, modeling and application of rheology in materials technology and materials science of liquids, melts, solids, crystals and amorphous structures. Among thr major fields of interest are the influence of materials structures, mechanical stresses, temperatures, deformation speeds and shear rates on rheological and physical properties, phase transformation of foams, foods, polymers, plastics and other competitive materials like ceramics

2nd International Conference on Rheology and Modeling of Materials (IC-RMM2)

Science.gov (United States)

2017-01-01

Understanding the rheological properties of materials and their rheological behaviors during their manufacturing processes and in their applications in many cases can help to increase the efficiency and competitiveness not only of the finished goods and products but the organizations and societies also. The more scientific supported and prepared organizations develop more competitive products with better thermal, mechanical, physical, chemical and biological properties and the leading companies apply more competitive equipment and technology processes. The aims of the 2nd International Conference on Rheology and Modeling of Materials (ic-rmm2) and the parallel organized symposiums of the 1st International Symposium on Powder Injection Molding (is-pim1) and the 1st International Symposium on Rheology and Fracture of Solids (is-rfs1) are the followings: Promote new methods and results of scientific research in the fields of modeling and measurements of rheological properties and behavior of materials under processing and applications; Change information between the theoretical and applied sciences as well as technical and technological implantations. Promote the communication and collaboration between the scientists, researchers and engineers of different disciplines, different nations, countries and continents. The international conference ic-rmm2 and symposiums of is-pim1 and is-rfs1 provide a platform among the leading international scientists, researchers, PhD students and engineers for discussing recent achievements in measurement, modeling and application of rheology in materials technology and materials science of liquids, melts, solids, crystals and amorphous structures. Among thr major fields of interest are the influence of materials structures, mechanical stresses, temperatures, deformation speeds and shear rates on rheological and physical properties, phase transformation of foams, foods, polymers, plastics and other competitive materials like ceramics

Acetylation of banana (Musa paradisiaca L.) and corn (Zea mays L.) starches using a microwave heating procedure and iodine as catalyst: II. Rheological and structural studies.

Science.gov (United States)

Sánchez-Rivera, Mirna M; Almanza-Benitez, Sirlen; Bello-Perez, Luis A; Mendez-Montealvo, Guadalupe; Núñez-Santiago, María C; Rodriguez-Ambriz, Sandra L; Gutierrez-Meráz, Felipe

2013-02-15

The effect of iodine concentration on the acetylation of starches with low and moderate degree of substitution (DS<0.5) and its impact on the physicochemical feature and structural features was evaluated. The acetylated starches were prepared with 0.03 mol anhydroglucose unit, 0.12 mol of anhydride acetic, and 0.6, 0.9 or 1.4 mM of molecular iodine as catalyst in a sealed Teflon vessel using microwave heating (600 W/2 min). Pasting profile and rheological properties were obtained under steady flow; dynamic oscillatory test was used. Structural features were obtained by HPSEC-RI. In acetylated starches, DS and acetyl groups increased when the iodine concentration increased, corn starch showed higher values than banana starch. The viscosity of acetylated starches decreased relative to unmodified starches while, acetylated corn starch had lower value than acetylated banana starch. In the flow curves, a non-Newtonian pattern (shear-thinning) was shown in the pastes of native and modified starches. Storage modulus (G') and loss modulus (G") showed low dependence on frequency (G'αω(0.1); G"αω(0.2)) on frequency sweep test, which is characteristic of a viscoelastic gel. Debranched native banana and corn starches presented trimodal chain-length distribution. The pattern was maintained in the acetylated starches, but with different level of short and long chains. The structural differences in native and acetylated samples explain the rheological characteristics in both starches. Copyright © 2012 Elsevier Ltd. All rights reserved.

Design and analysis of a magneto-rheological damper for an all terrain vehicle

Science.gov (United States)

Krishnan Unni, R.; Tamilarasan, N.

2018-02-01

A shock absorber design intended to replace the existing conventional shock absorber with a controllable system using a Magneto-rheological damper is introduced for an All Terrain Vehicle (ATV) that was designed for Baja SAE competitions. Suspensions are a vital part of an All Terrain Vehicles as it endures various surfaces and requires utmost attention while designing. COMSOL multi-physics software is used for applications that have coupled physics problems and is a unique tool that is used for the designing and analysis phase of the Magneto-rheological damper for the considered application and the model is optimized based on Taguchi using DOE software. The magneto-rheological damper is designed to maximize the damping force with the measured geometric constraints for the All Terrain Vehicle.

Simulation of melt spreading in consideration of phase transitions

Energy Technology Data Exchange (ETDEWEB)

Spengler, C. [Gesellschaft fuer Anlagen- und Reaktorsicherheit (GRS) mbH, Koeln (Germany)

2002-07-01

The analysis of melt spreading and relocation phenomena in the containment of LWR power plants in case of hypothetical severe accidents leading to core melting is an important issue for reactor safety investigations. For the simulation of melt spreading the code LAVA has been developed on the basis of a method from the related subject of volcanology by adding more detailed models for heat transfer phenomena and flow rheology. The development is supported by basic analysis of the spreading of gravity currents as well as experimental investigations of the rheology of solidifying melts. These exhibit strong non-Newtonian effects in case of a high content of solids in the freezing melt. The basic model assumption in LAVA is the ideal Bingham plastic approach to the non-Newtonian, shear-thinning characteristic of solidifying melts. For the recalculation of melt spreading experiments, the temperature-dependent material properties for solidifying melt mixtures have been calculated using correlations from the literature. With the parameters and correlations for the rheological material properties approached by results from literature, it was possible to recalculate successfully recent spreading experiments with simulant materials and prototypic reactor core materials. An application to the behaviour of core melt in the reactor cavity assumed a borderline case for the issue of spreading. This limit is represented by melt conditions (large solid fraction, low volume flux), under which the melt is hardly spreadable. Due to the persistent volume flux the reactor cavity is completely, but inhomogeneously filled with melt. The degree of inhomogeneity is rather small, so it is concluded, that for the long-term coolability of a melt pool in narrow cavities the spreading of melt will probably have only negligible influence. (orig.)

Semisolid Metal Processing Consortium

Energy Technology Data Exchange (ETDEWEB)

Apelian,Diran

2002-01-10

Mathematical modeling and simulations of semisolid filling processes remains a critical issue in understanding and optimizing the process. Semisolid slurries are non-Newtonian materials that exhibit complex rheological behavior. There the way these slurries flow in cavities is very different from the way liquid in classical casting fills cavities. Actually filling in semisolid processing is often counter intuitive

Achieving effective confinement through utilization of non-Newtonian fluid mixture as stemming structure

Directory of Open Access Journals (Sweden)

Luís Felipe Gomes Marinho

Full Text Available Abstract The economics of a mining operation is directly influenced by blasting outcomes, where blasting aims to comminute the rock mass in order to attain smaller grain sizes to be loaded and hauled at a minimum cost for its first processing stage. In order to promote adequate rock breakage, the stemming structure needs to provide proper confinement for the borehole charged with explosives, reflecting the energy released during the detonation in form of shock waves and gases to act throughout the in situ rock mass, enlarging its failures and fractures, and also creating new ones. To build up a stemming column, literature recommends the usage of dry granular materials instead of elements with plastic behavior. However, a study was performed using Gypsum plaster as stemming; a kind of material that exhibits solid-like behavior when it is dry. Following this theory, this test verified improvements regarding confinement effectiveness and energy propagation throughout the rock mass when a non-Newtonian mixture (NNM was applied as stemming; a material that shows a solid-like behavior when is under shear stress. When the stemming arrangement was composed of NNM, it was able to reduce energy and gas losses to the atmosphere, because of the liquid's property of filling voids into the borehole. The NNM yielded high results due to its better confinement effectiveness, a reduction of air overpressure, and an increase of the strain propagation and ground vibration throughout the rock.

The parameterized post-Newtonian limit of bimetric theories of gravity

International Nuclear Information System (INIS)

Clifton, Timothy; Banados, Maximo; Skordis, Constantinos

2010-01-01

We consider the post-Newtonian limit of a general class of bimetric theories of gravity, in which both metrics are dynamical. The established parameterized post-Newtonian approach is followed as closely as possible, although new potentials are found that do not exist within the standard framework. It is found that these theories can evade solar system tests of post-Newtonian gravity remarkably well. We show that perturbations about Minkowski space in these theories contain both massless and massive degrees of freedom, and that in general there are two different types of massive mode, each with a different mass parameter. If both of these masses are sufficiently large then the predictions of the most general class of theories we consider are indistinguishable from those of general relativity, up to post-Newtonian order in a weak-field, low-velocity expansion. In the limit that the massive modes become massless, we find that these general theories do not exhibit a van Dam-Veltman-Zakharov-like discontinuity in their γ parameter, although there are discontinuities in other post-Newtonian parameters as the massless limit is approached. This smooth behaviour in γ is due to the discontinuities from each of the two different massive modes cancelling each other out. Such cancellations cannot occur in special cases with only one massive mode, such as the Isham-Salam-Strathdee theory.

Error analysis for reducing noisy wide-gap concentric cylinder rheometric data for nonlinear fluids - Theory and applications

Science.gov (United States)

Borgia, Andrea; Spera, Frank J.

1990-01-01

This work discusses the propagation of errors for the recovery of the shear rate from wide-gap concentric cylinder viscometric measurements of non-Newtonian fluids. A least-square regression of stress on angular velocity data to a system of arbitrary functions is used to propagate the errors for the series solution to the viscometric flow developed by Krieger and Elrod (1953) and Pawlowski (1953) ('power-law' approximation) and for the first term of the series developed by Krieger (1968). A numerical experiment shows that, for measurements affected by significant errors, the first term of the Krieger-Elrod-Pawlowski series ('infinite radius' approximation) and the power-law approximation may recover the shear rate with equal accuracy as the full Krieger-Elrod-Pawlowski solution. An experiment on a clay slurry indicates that the clay has a larger yield stress at rest than during shearing, and that, for the range of shear rates investigated, a four-parameter constitutive equation approximates reasonably well its rheology. The error analysis presented is useful for studying the rheology of fluids such as particle suspensions, slurries, foams, and magma.

Topics in the Foundations of General Relativity and Newtonian Gravitation Theory

CERN Document Server

Malament, David B

2012-01-01

In Topics in the Foundations of General Relativity and Newtonian Gravitation Theory, David B. Malament presents the basic logical-mathematical structure of general relativity and considers a number of special topics concerning the foundations of general relativity and its relation to Newtonian gravitation theory. These special topics include the geometrized formulation of Newtonian theory (also known as Newton-Cartan theory), the concept of rotation in general relativity, and Gödel spacetime. One of the highlights of the book is a no-go theorem that can be understood to show that there is

Soil Mechanics

DEFF Research Database (Denmark)

Gottlieb, Sara Wisbech Jacobsen; Hededal, Ole; Foged, Niels Nielsen

by stress and strain and their behaviour is convergent. Numerical models exist that simulate clay behaviour over time, the majority derived from Perzyna (1966). An empirical expression for the ‘index of viscosity’ was derived by Leinenkugel (1976). This suggests the change of strain rate is proportional......It is widely accepted that there is a connection between the undrained shear strength and the strain rate. Thixotropy and creep behaviour are connected to the mechanical properties of clay. Thixotropy is the ability of clay to recover its shear strength over time when the shear stress is released...... of equilibrium in viscosity over time at a given stress level for a thixotropic fluid. In rheology, this type of material is known as a non-Newtonian thixotropic fluid. A Newtonian fluid has no yield stress, resembling a strictly elastic material; whereas a non-Newtonian fluid cannot be expressed by a direct...

Rheology essentials of cosmetic and food emulsions

CERN Document Server

Brummer, Rüdiger

2006-01-01

Cosmetic emulsions exist today in many forms for a wide variety of applications, including face and hand creams for normal, dry or oily skin, body milks and lotions, as well as sun-block products. Keeping track of them and their properties is not always easy despite informative product names or partial names (e.g. hand or face cream) that clearly indicate their use and properties. This practical manual provides a detailed overview that describes the key properties and explains how to measure them using modern techniques. Written by an expert in flows and flow properties, it focuses on the application of rheological (flow) measurements to cosmetic and food emulsions and the correlation of these results with findings from other tests. Beginning with a brief history of rheology and some fundamental principles, the manual describes in detail the use of modern viscometers and rheometers, including concise explanations of the different available instruments. But the focus remains on practical everyday lab procedure...

Differences in rheological profile of regular diesel and bio-diesel fuel

Directory of Open Access Journals (Sweden)

Jiří Čupera

2010-01-01

Full Text Available Biodiesel represents a promising alternative to regular fossil diesel. Fuel viscosity markedly influences injection, spraying and combustion, viscosity is thus critical factor to be evaluated and monitored. This work is focused on quantifying the differences in temperature dependent kinematic viscosity regular diesel fuel and B30 biodiesel fuel. The samples were assumed to be Newtonian fluids. Vis­co­si­ty was measured on a digital rotary viscometer in a range of 0 to 80 °C. More significant difference between minimum and maximum values was found in case of diesel fuel in comparison with biodiesel fuel. Temperature dependence of both fuels was modeled using several mathematical models – polynomial, power and Gaussian equation. The Gaussian fit offers the best match between experimental and computed data. Description of viscosity behavior of fuels is critically important, e.g. when considering or calculating running efficiency and performance of combustion engines. The models proposed in this work may be used as a tool for precise prediction of rheological behavior of diesel-type fuels.

Activated Sludge Rheology

DEFF Research Database (Denmark)

Ratkovich, Nicolas Rios; Horn, Willi; Helmus, Frank

2013-01-01

Rheological behaviour is an important fluid property that severely impacts its flow behaviour and many aspects related to this. In the case of activated sludge, the apparent viscosity has an influence on e.g. pumping, hydrodynamics, mass transfer rates, sludge-water separation (settling and filtr...... rheological measurements. Moreover, the rheological models are not very trustworthy and remain very “black box”. More insight in the physical background needs 30 to be gained. A model-based approach with dedicated experimental data collection is the key to address this.......Rheological behaviour is an important fluid property that severely impacts its flow behaviour and many aspects related to this. In the case of activated sludge, the apparent viscosity has an influence on e.g. pumping, hydrodynamics, mass transfer rates, sludge-water separation (settling......, leading to varying results and conclusions. In this paper, a vast amount of papers are critically reviewed with respect to this and important flaws are highlighted with respect to rheometer choice, rheometer settings and measurement protocol. The obtained rheograms from experimental efforts have...

A note on the post-Newtonian limit of quasi-local energy expressions

International Nuclear Information System (INIS)

Frauendiener, Jörg; Szabados, László B

2011-01-01

An 'effective' quasi-local energy expression, motivated by the (relativistically corrected) Newtonian theory, is introduced in exact general relativity as the volume integral of all the source terms in the field equation for the Newtonian potential in static spacetimes. In particular, we exhibit a new post-Newtonian correction in the source term in the field equation for the Newtonian gravitational potential. In asymptotically flat spacetimes, this expression tends to the Arnowitt-Deser-Misner energy at spatial infinity as a monotonically decreasing set function. We prove its positivity in spherically symmetric spacetimes under certain energy conditions, and that its vanishing characterizes flatness. We argue that any physically acceptable quasi-local energy expression should behave qualitatively like this 'effective' energy expression in this limit. (paper)

The rheological and fracture properties of Gouda cheese

NARCIS (Netherlands)

Luyten, H.

1988-01-01

The rheological and fracture behaviour of Gouda cheese was studied. Methods for determining these properties of visco-elastic materials are described. Application of the theory of fracture mechanics, after modification and expansion, to visco-elastic materials with a

Relativistic gravitation theory for the modified Newtonian dynamics paradigm

International Nuclear Information System (INIS)

Bekenstein, Jacob D.

2004-01-01

The modified Newtonian dynamics (MOND) paradigm of Milgrom can boast of a number of successful predictions regarding galactic dynamics; these are made without the assumption that dark matter plays a significant role. MOND requires gravitation to depart from Newtonian theory in the extragalactic regime where dynamical accelerations are small. So far relativistic gravitation theories proposed to underpin MOND have either clashed with the post-Newtonian tests of general relativity, or failed to provide significant gravitational lensing, or violated hallowed principles by exhibiting superluminal scalar waves or an a priori vector field. We develop a relativistic MOND inspired theory which resolves these problems. In it gravitation is mediated by metric, a scalar, and a 4-vector field, all three dynamical. For a simple choice of its free function, the theory has a Newtonian limit for nonrelativistic dynamics with significant acceleration, but a MOND limit when accelerations are small. We calculate the β and γ parameterized post-Newtonian coefficients showing them to agree with solar system measurements. The gravitational light deflection by nonrelativistic systems is governed by the same potential responsible for dynamics of particles. To the extent that MOND successfully describes dynamics of a system, the new theory's predictions for lensing by that system's visible matter will agree as well with observations as general relativity's predictions made with a dynamically successful dark halo model. Cosmological models based on the theory are quite similar to those based on general relativity; they predict slow evolution of the scalar field. For a range of initial conditions, this last result makes it easy to rule out superluminal propagation of metric, scalar, and vector waves

Hereditary effects in eccentric compact binary inspirals to third post-Newtonian order

Science.gov (United States)

Loutrel, Nicholas; Yunes, Nicolás

2017-02-01

While there has been much success in understanding the orbital dynamics and gravitational wave emission of eccentric compact binaries in the post-Newtonian formalism, some problems still remain. The largest of these concerns hereditary effects: non-linear phenomena related to the scattering off of the background curved spacetime (tails) and to the generation of gravitational waves by gravitational waves (memory). Currently, these hereditary effects are only known numerically for arbitrary eccentricity through infinite sums of Bessel functions, with closed-form, analytic results only available in the small eccentricity limit. We here calculate, for the first time, closed-form, analytic expressions for all hereditary effects to third post-Newtonian order in binaries with arbitrary eccentricity. For the tails, we first asymptotically expand all Bessel functions in high eccentricity and find a superasymptotic series for each enhancement factor, accurate to better than 10-3 relative to post-Newtonian numerical calculations at all eccentricities. We further improve the small-eccentricity behavior of the superasymptotic series by generating hyperasymptotic expressions for each enhancement factor, typically accurate to better than 10-8 at all eccentricities. For the memory, we discuss its computation within the context of an osculating approximation of the binary’s orbit and the difficulties that arise. Our closed-form analytic expressions for the hereditary fluxes allow us to numerically compute orbital phases that are identical to those found using an infinite sum of Bessel functions to double numerical precision.

Hereditary effects in eccentric compact binary inspirals to third post-Newtonian order

International Nuclear Information System (INIS)

Loutrel, Nicholas; Yunes, Nicolás

2017-01-01

While there has been much success in understanding the orbital dynamics and gravitational wave emission of eccentric compact binaries in the post-Newtonian formalism, some problems still remain. The largest of these concerns hereditary effects: non-linear phenomena related to the scattering off of the background curved spacetime (tails) and to the generation of gravitational waves by gravitational waves (memory). Currently, these hereditary effects are only known numerically for arbitrary eccentricity through infinite sums of Bessel functions, with closed-form, analytic results only available in the small eccentricity limit. We here calculate, for the first time, closed-form, analytic expressions for all hereditary effects to third post-Newtonian order in binaries with arbitrary eccentricity. For the tails, we first asymptotically expand all Bessel functions in high eccentricity and find a superasymptotic series for each enhancement factor, accurate to better than 10 −3 relative to post-Newtonian numerical calculations at all eccentricities. We further improve the small-eccentricity behavior of the superasymptotic series by generating hyperasymptotic expressions for each enhancement factor, typically accurate to better than 10 −8 at all eccentricities. For the memory, we discuss its computation within the context of an osculating approximation of the binary’s orbit and the difficulties that arise. Our closed-form analytic expressions for the hereditary fluxes allow us to numerically compute orbital phases that are identical to those found using an infinite sum of Bessel functions to double numerical precision. (paper)

The Effect of non-Newtonian Behavior of Fluid on the Tubular Reactor Performance and Studying Different Variables in Relation to the Degree of Conversion

Directory of Open Access Journals (Sweden)

Keivan Shayesteh

2015-02-01

Full Text Available In tubular reactors, there are different parameters which can affect the degree of conversion. The type of fluid motion and velocity profile of substances in the reactor are of most central measures. Different rheological models can be employed to study the behavior of fluids; power law model is one of the most commonly used models. In this study, the rheological behaviour of polymerization reaction of methyl methacrylate was examined. Due to the similarity function of tubular and batch reactors, the number of test tubes are used to prepare the solution. After preparation of the reactor solution, the n value of power law model was estimated within the span of 0.3492 to 0.9889 by curve fitting. Employing these rheological data, a reactor has been designed. Moreover, the effects of parameters such as reaction temperature, initiator wt%, the concentration of monomer and reactor’s radius on the degree of conversion have been studied. The obtained results in the research indicate a direct proportionality of conversion with the reaction temperature, initiator wt% and the concentration of monomer and also an inverse proportionality of conversion with reactor’s radius. Finally, the amount of conversion was obtained equal to 56.47% and according to its laboratory proportion which was 55.88% we have reached the conclusion that the modeling duly undertaken is applicable and valid.

Transport phenomena in Newtonian fluids a concise primer

CERN Document Server

Olsson, Per

2013-01-01

This short primer provides a concise and tutorial-style introduction to transport phenomena in Newtonian fluids , in particular the transport of mass, energy and momentum.  The reader will find detailed derivations of the transport equations for these phenomena, as well as selected analytical solutions to the transport equations in some simple geometries. After a brief introduction to the basic mathematics used in the text, Chapter 2, which deals with momentum transport, presents a derivation of the Navier-Stokes-Duhem equation describing the basic flow in a Newtonian fluid.  Also provided at

Large strain deformation behavior of polymeric gels in shear- and cavitation rheology

Science.gov (United States)

Hashemnejad, Seyed Meysam; Kundu, Santanu

Polymeric gels are used in many applications including in biomedical and in food industries. Investigation of mechanical responses of swollen polymer gels and linking that to the polymer chain dynamics are of significant interest. Here, large strain deformation behavior of two different gel systems and with different network architecture will be presented. We consider biologically relevant polysaccharide hydrogels, formed through ionic and covalent crosslinking, and physically associating triblock copolymer gels in a midblock selective solvent. Gels with similar low-strain shear modulus display distinctly different non-linear rheological behavior in large strain shear deformation. Both these gels display strain-stiffening behavior in shear-deformation prior to macroscopic fracture of the network, however, only the alginate gels display negative normal stress. The cavitation rheology data show that the critical pressure for cavitation is higher for alginate gels than that observed for triblock gels. These distinctly different large-strain deformation behavior has been related to the gel network structure, as alginate chains are much stiffer than the triblock polymer chains.

Rheological phenomena in focus

CERN Document Server

Boger, DV

1993-01-01

More than possibly any other scientific discipline, rheology is easily visualized and the relevant literature contains many excellent photographs of unusual and often bizarre phenomena. The present book brings together these photographs for the first time. They are supported by a full explanatory text. Rheological Phenomena in Focus will be an indispensable support manual to all those who teach rheology or have to convince colleagues of the practical relevance of the subject within an industrial setting. For those who teach fluid mechanics, the book clearly illustrates the difference be

Mudflow rheology in a vertically rotating flume

Science.gov (United States)

Holmes, Robert R.; Westphal, Jerome A.; Jobson, Harvey E.; ,

1990-01-01

Joint research by the U.S. Geological Survey and the University of Missouri-Rolla currently (1990) is being conducted on a 3.05 meters in diameter vertically rotating flume used to simulate mudflows under steady-state conditions. Observed mudflow simulations indicate flow patterns in the flume are similar to those occurring in natural mudflows. Variables such as mean and surface velocity, depth, and average boundary shear stress can be measured in this flume more easily than in the field or in a traditional tilting flume. Sensitive variables such as sediment concentration, grain-size distribution, and Atterberg limits also can be precisely and easily controlled. A known Newtonian fluid, SAE 30 motor oil, was tested in the flume and the computed value for viscosity was within 12.5 percent of the stated viscosity. This provided support that the data from the flume can be used to determine the rheological properties of fluids such as mud. Measurements on mud slurries indicate that flows with sediment concentrations ranging from 81 to 87 percent sediment by weight can be approximated as Bingham plastic for strain rates greater than 1 per second. In this approximation, the yield stress and Bingham viscosity were extremely sensitive to sediment concentration. Generally, the magnitude of the yield stress was large relative to the change in shear stress with increasing mudflow velocity.

Parameterised post-Newtonian expansion in screened regions

Science.gov (United States)

McManus, Ryan; Lombriser, Lucas; Peñarrubia, Jorge

2017-12-01

The parameterised post-Newtonian (PPN) formalism has enabled stringent tests of static weak-field gravity in a theory-independent manner. Here we incorporate screening mechanisms of modified gravity theories into the framework by introducing an effective gravitational coupling and defining the PPN parameters as functions of position. To determine these functions we develop a general method for efficiently performing the post-Newtonian expansion in screened regimes. For illustration, we derive all the PPN functions for a cubic galileon and a chameleon model. We also analyse the Shapiro time delay effect for these two models and find no deviations from General Relativity insofar as the signal path and the perturbing mass reside in a screened region of space.

Engineering Fracking Fluids with Computer Simulation

Science.gov (United States)

Shaqfeh, Eric

2015-11-01

There are no comprehensive simulation-based tools for engineering the flows of viscoelastic fluid-particle suspensions in fully three-dimensional geometries. On the other hand, the need for such a tool in engineering applications is immense. Suspensions of rigid particles in viscoelastic fluids play key roles in many energy applications. For example, in oil drilling the ``drilling mud'' is a very viscous, viscoelastic fluid designed to shear-thin during drilling, but thicken at stoppage so that the ``cuttings'' can remain suspended. In a related application known as hydraulic fracturing suspensions of solids called ``proppant'' are used to prop open the fracture by pumping them into the well. It is well-known that particle flow and settling in a viscoelastic fluid can be quite different from that which is observed in Newtonian fluids. First, it is now well known that the ``fluid particle split'' at bifurcation cracks is controlled by fluid rheology in a manner that is not understood. Second, in Newtonian fluids, the presence of an imposed shear flow in the direction perpendicular to gravity (which we term a cross or orthogonal shear flow) has no effect on the settling of a spherical particle in Stokes flow (i.e. at vanishingly small Reynolds number). By contrast, in a non-Newtonian liquid, the complex rheological properties induce a nonlinear coupling between the sedimentation and shear flow. Recent experimental data have shown both the shear thinning and the elasticity of the suspending polymeric solutions significantly affects the fluid-particle split at bifurcations, as well as the settling rate of the solids. In the present work, we use the Immersed Boundary Method to develop computer simulations of viscoelastic flow in suspensions of spheres to study these problems. These simulations allow us to understand the detailed physical mechanisms for the remarkable physical behavior seen in practice, and actually suggest design rules for creating new fluid recipes.

Landslides and tsunamis predicted by incompressible smoothed particle hydrodynamics (SPH) with application to the 1958 Lituya Bay event and idealized experiment.

Science.gov (United States)

Xenakis, A M; Lind, S J; Stansby, P K; Rogers, B D

2017-03-01

Tsunamis caused by landslides may result in significant destruction of the surroundings with both societal and industrial impact. The 1958 Lituya Bay landslide and tsunami is a recent and well-documented terrestrial landslide generating a tsunami with a run-up of 524 m. Although recent computational techniques have shown good performance in the estimation of the run-up height, they fail to capture all the physical processes, in particular, the landslide-entry profile and interaction with the water. Smoothed particle hydrodynamics (SPH) is a versatile numerical technique for describing free-surface and multi-phase flows, particularly those that exhibit highly nonlinear deformation in landslide-generated tsunamis. In the current work, the novel multi-phase incompressible SPH method with shifting is applied to the Lituya Bay tsunami and landslide and is the first methodology able to reproduce realistically both the run-up and landslide-entry as documented in a benchmark experiment. The method is the first paper to develop a realistic implementation of the physics that in addition to the non-Newtonian rheology of the landslide includes turbulence in the water phase and soil saturation. Sensitivity to the experimental initial conditions is also considered. This work demonstrates the ability of the proposed method in modelling challenging environmental multi-phase, non-Newtonian and turbulent flows.

Theoretical frameworks for testing relativistic gravity. 5: Post-Newtonian limit of Rosen's theory

Science.gov (United States)

Lee, D. L.; Caves, C. M.

1974-01-01

The post-Newtonian limit of Rosen's theory of gravity is evaluated and is shown to be identical to that of general relativity, except for the PPN parameter alpha sub 2, which is related to the difference in propagation speeds for gravitational and electromagnetic waves. Both the value of alpha sub 2 and the value of the Newtonian gravitational constant depend on the present cosmological structure of the Universe. If the cosmological structure has a specific but presumably special form, the Newtonian gravitational constant assumes its current value, alpha sub 2 is zero, the post-Newtonian limit of Rosen's theory is identical to that of general relativity--and standard solar system experiments cannot distinguish between the two theories.

Rheological behavior of mammalian cells.

Science.gov (United States)

Stamenović, D

2008-11-01

Rheological properties of living cells determine how cells interact with their mechanical microenvironment and influence their physiological functions. Numerous experimental studies have show that mechanical contractile stress borne by the cytoskeleton and weak power-law viscoelasticity are governing principles of cell rheology, and that the controlling physics is at the level of integrative cytoskeletal lattice properties. Based on these observations, two concepts have emerged as leading models of cytoskeletal mechanics. One is the tensegrity model, which explains the role of the contractile stress in cytoskeletal mechanics, and the other is the soft glass rheology model, which explains the weak power-law viscoelasticity of cells. While these two models are conceptually disparate, the phenomena that they describe are often closely associated in living cells for reasons that are largely unknown. In this review, we discuss current understanding of cell rheology by emphasizing the underlying biophysical mechanism and critically evaluating the existing rheological models.

Rheology of Biopolymer Solutions and Gels

Directory of Open Access Journals (Sweden)

David R. Picout

2003-01-01

Full Text Available Rheological techniques and methods have been employed for many decades in the characterization of polymers. Originally developed and used on synthetic polymers, rheology has then found much interest in the field of natural (bio polymers. This review concentrates on introducing the fundamentals of rheology and on discussing the rheological aspects and properties of the two major classes of biopolymers: polysaccharides and proteins. An overview of both their solution properties (dilute to semi-dilute and gel properties is described.

Post-Newtonian approximation of the maximum four-dimensional Yang-Mills gauge theory

International Nuclear Information System (INIS)

Smalley, L.L.

1982-01-01

We have calculated the post-Newtonian approximation of the maximum four-dimensional Yang-Mills theory proposed by Hsu. The theory contains torsion; however, torsion is not active at the level of the post-Newtonian approximation of the metric. Depending on the nature of the approximation, we obtain the general-relativistic values for the classical Robertson parameters (γ = β = 1), but deviations for the Nordtvedt effect and violations of post-Newtonian conservation laws. We conclude that in its present form the theory is not a viable theory of gravitation

Newtonian gravity and the Bargmann algebra

NARCIS (Netherlands)

Andringa, Roel; Bergshoeff, Eric; Panda, Sudhakar; de Roo, Mees

2011-01-01

We show how the Newton-Cartan formulation of Newtonian gravity can be obtained from gauging the Bargmann algebra, i.e. the centrally extended Galilean algebra. In this gauging procedure several curvature constraints are imposed. These convert the spatial (time) translational symmetries of the

Nonlinear convective flow of Powell-Erying magneto nanofluid with Newtonian heating

Directory of Open Access Journals (Sweden)

Sajid Qayyum

Full Text Available Objective of present article is to describe magnetohydrodynamic (MHD non-linear convective flow of Powell-Erying nanofluid over a stretching surface. Characteristics of Newtonian heat and mass conditions in this attempt is given attention. Heat and mass transfer analysis is examined in the frame of thermal radiation and chemical reaction. Brownian motion and thermophoresis concept is introduced due to presence of nanoparticles. Nonlinear equations of momentum, energy and concentration are transformed into dimensionless expression by invoking suitable variables. The series solutions are obtained through homotopy analysis method (HAM. Impact of embedded variables on the velocity, temperature and nanoparticles concentration is graphically presented. Numerical values of skin friction coefficient, local Nusselt and Sherwood numbers are computed and analyzed. It is concluded that velocity field enhances for fluid variable while reverse situation is noticed regarding Hartman number. Temperature and heat transfer rate behave quite reverse for Prandtl number. It is also noted that the concentration and local Sherwood number have opposite behavior in the frame of Brownian motion. Keywords: Powell-Erying nanofluid, Magnetohydrodynamic (MHD, Nonlinear convection, Thermal radiation, Chemical reaction, Newtonian heat and mass conditions

Active and Passive Microrheology: Theory and Simulation

Science.gov (United States)

Zia, Roseanna N.

2018-01-01

Microrheological study of complex fluids traces its roots to the work of the botanist Robert Brown in the early nineteenth century. Indeed, passive microrheology and Brownian motion are one and the same. Once thought to reveal a fundamental life force, the phenomenon was ultimately leveraged by Einstein in proof of the atomic nature of matter ( Haw 2006 ). His work simultaneously paved the way for modern-day passive microrheology by connecting observable particle motion—diffusion—to solvent properties—the viscosity—via the well-known Stokes-Einstein relation. Advances in microscopy techniques in the last two decades have prompted extensions of the original model to generalized forms for passive probing of complex fluids. In the last decade, active microrheology has emerged as a means by which to interrogate the nonequilibrium behavior of complex fluids, in particular, the non-Newtonian rheology of dynamically heterogeneous and microscopically small systems. Here we review theoretical and computational approaches and advances in both passive and active microrheology, with a focus on the extent to which these techniques preserve the connection between single-particle motion and flow properties, as well as the rather surprising recovery of non-Newtonian flow behavior observed in bulk rheology.

Novel design of a self powered and self sensing magneto-rheological damper

International Nuclear Information System (INIS)

Ferdaus, Mohammad Meftahul; Rashid, M M; Bhuiyan, M M I; Muthalif, Asan Gani Bin Abdul; Hasan, M R

2013-01-01

Magneto-rheological (MR) dampers are semi-active control devices and use MR fluids. Magneto-rheological dampers have successful applications in mechatronics engineering, civil engineering and numerous areas of engineering. At present, traditional MR damper systems, require a isolated power supply and dynamic sensor. This paper presents the achievability and accuracy of a self- powered and self-sensing magneto-rheological damper using harvested energy from the vibration and shock environment in which it is deployed and another important part of this paper is the increased yield stress of the Magneto rheological Fluids. Magneto rheological fluids using replacement of glass beads for Magnetic Particles to surge yield stress is implemented here. Clearly this shows better result on yield stress, viscosity, and settling rate. Also permanent magnet generator (PMG) is designed and attached to a MR damper. For evaluating the self-powered MR damper's vibration mitigating capacity, an Engine Mount System using the MR damper is simulated. The ideal stiffness of the PMG for the Engine Mount System (EMS) is calculated by numerical study. The vibration mitigating performance of the EMS employing the self-powered and self sensing MR damper is theoretically calculated and evaluated in the frequency domain

Novel design of a self powered and self sensing magneto-rheological damper

Science.gov (United States)

Meftahul Ferdaus, Mohammad; Rashid, M. M.; Bhuiyan, M. M. I.; Muthalif, Asan Gani Bin Abdul; Hasan, M. R.

2013-12-01

Magneto-rheological (MR) dampers are semi-active control devices and use MR fluids. Magneto-rheological dampers have successful applications in mechatronics engineering, civil engineering and numerous areas of engineering. At present, traditional MR damper systems, require a isolated power supply and dynamic sensor. This paper presents the achievability and accuracy of a self- powered and self-sensing magneto-rheological damper using harvested energy from the vibration and shock environment in which it is deployed and another important part of this paper is the increased yield stress of the Magneto rheological Fluids. Magneto rheological fluids using replacement of glass beads for Magnetic Particles to surge yield stress is implemented here. Clearly this shows better result on yield stress, viscosity, and settling rate. Also permanent magnet generator (PMG) is designed and attached to a MR damper. For evaluating the self-powered MR damper's vibration mitigating capacity, an Engine Mount System using the MR damper is simulated. The ideal stiffness of the PMG for the Engine Mount System (EMS) is calculated by numerical study. The vibration mitigating performance of the EMS employing the self-powered & self sensing MR damper is theoretically calculated and evaluated in the frequency domain.

Numerical simulation of bubble induced shear in membrane bioreactors: effects of mixed liquor rheology and membrane configuration.

Science.gov (United States)

Liu, Xuefei; Wang, Yuan; Waite, T David; Leslie, Greg

2015-05-15

A CFD model, incorporating an empirically determined rheology model and a porous media model, was developed to simulate bubble induced surface shear in membrane bioreactors configured with hollow fibre membranes with outer diameters ranging from 1.3 to 2.4 mm, arranged in vertically orientated modules with packing density from 200 to 560 m(2)/m(3). The rheology model was developed for mixed liquor suspended solids (MLSS) concentrations of 3 to 16 gL(-1) in the presence and absence of coagulant (generated by addition of a ferrous salt) for shear rates ranging from 0 to 500 s(-1). Experimentally determined particle relaxation times for the biological flocs in the mixed liquor, both in the absence and presence of iron, were negligible, consistent with an environment where positive buoyancy forces were greater than negative settling forces thereby allowing the sludge mixture to be modelled as a single continuous phase. The non-Newtonian behaviour of the mixed liquor was incorporated into the CFD simulations using an Ostwald-de Waele rheology model. Interactions between mixed liquor and hollow fibre membranes of different fibre size and packing density were described using a porous media model that was calibrated by empirical measurement of inertial loss coefficients over a range of viscosities (0.8 × 10(-3) to 2.1 × 10(-3) Pa.s) and velocities (0 to 0.35 m/s) typically encountered in full scale MBRs. Experimental results indicated that addition of iron salts resulted in an increase in MLSS and sludge viscosity. Shear stress is affected by both velocity and viscosity. The increase in sludge viscosity resulted in an increase in resistance to flow through the hollow fibre membrane bundles and, as a result, decreased the liquid flow velocities. CFD simulations provided insight on the effects of point of coagulant addition and MLSS concentration on bubble-induced shear over a range of industrially relevant conditions. A 12% increase in shear stress was observed when

Rheological and structural studies of carboxymethyl derivatives of chitosan

Science.gov (United States)

Winstead, Cherese; Katagumpola, Pushpika

2014-05-01

The degrees of substitution of chitosan derivatives were varied and the viscoelastic behavior of these biopolymer solutions was studied using rheology. Chitosan is a cationic copolymer of glucosamine and N-acetylglucosamine obtained by alkaline deacetylation of chitin. Due to its inherent non-toxicity, biocompatibility, and biodegradability, chitosan has gained much interest. However, the poor solubility of the biopolymer in water and most common organic solvents limits its applications. Therefore, the focus of this work is the chemical modification of chitosan via carboxymethylation as well as studying the viscoelastic behavior of these polymer solutions. Varying degrees of substitution (DS) of carboxymethyl chitosan derivatives were synthesized by treating chitosan with monochloroacetic acid under alkylated medium varying the reaction time and temperature. The effect of degree of substitution on the rheology of these polymer solutions was studied as a function of concentration. The viscosity of chitosan derivatives sharply increased with increase in degree of substitution. G' and G" dependence on strain and angular frequency were studied and were found to exhibit predominantly viscous behavior. Additional characterization of the derivatized products were further studied using Fourier transform infrared (FT-IR), 1H Nuclear Magnetic Resonance (1H NMR) spectroscopy, X-ray diffraction (XRD), and thermal gravimetric analysis as well as differential scanning calorimetry (DSC). Degree of substitution (DS) was calculated by titrimetric method.

Rheological and structural studies of carboxymethyl derivatives of chitosan

International Nuclear Information System (INIS)

Winstead, Cherese; Katagumpola, Pushpika

2014-01-01

The degrees of substitution of chitosan derivatives were varied and the viscoelastic behavior of these biopolymer solutions was studied using rheology. Chitosan is a cationic copolymer of glucosamine and N-acetylglucosamine obtained by alkaline deacetylation of chitin. Due to its inherent non-toxicity, biocompatibility, and biodegradability, chitosan has gained much interest. However, the poor solubility of the biopolymer in water and most common organic solvents limits its applications. Therefore, the focus of this work is the chemical modification of chitosan via carboxymethylation as well as studying the viscoelastic behavior of these polymer solutions. Varying degrees of substitution (DS) of carboxymethyl chitosan derivatives were synthesized by treating chitosan with monochloroacetic acid under alkylated medium varying the reaction time and temperature. The effect of degree of substitution on the rheology of these polymer solutions was studied as a function of concentration. The viscosity of chitosan derivatives sharply increased with increase in degree of substitution. G' and G' dependence on strain and angular frequency were studied and were found to exhibit predominantly viscous behavior. Additional characterization of the derivatized products were further studied using Fourier transform infrared (FT-IR), 1 H Nuclear Magnetic Resonance ( 1 H NMR) spectroscopy, X-ray diffraction (XRD), and thermal gravimetric analysis as well as differential scanning calorimetry (DSC). Degree of substitution (DS) was calculated by titrimetric method

Influence of clay, surfactant and presence of dispersant in the non-aqueous fluids rheology

International Nuclear Information System (INIS)

Gomes, N.L.; Guedes, I.C.; Menezes, R.R.; Campos, L.F.A.; Ferreira, H.S.

2012-01-01

The bentonite clay used as a thickening agent in production of non-aqueous fluids and can not be used without a prior treatment to their organic surfaces become hydrophobic. These treated clays are called organoclays, and are usually obtained by adding, in aqueous solution, a quaternary ammonium salt. This work makes a detailed study of the variables involved in the dispersion of the bentonite clays in organophilization process, as well, the type of clay, type of surfactant and the presence of dispersant. It was observed this study that the process variables involved in the dispersion of the clays and organophilization, observed through characterization, have low influence on the peaks related to interplanar basal distance caused by the incorporation of the surfactant and bentonite clays been influential the type of clay and surfactant and the presence of sodium as dispersant agent, on the rheological properties. (author)

Waxy crude oil flow restart ability

Energy Technology Data Exchange (ETDEWEB)

Sierra, Andre Gaona; Varges, Priscilla Ribeiro; Mendes, Paulo Roberto de Souza [Dept. of Mechanical Engineering. Pontificia Universidade Catolica do Rio de Janeiro, RJ (Brazil)], e-mails: prvarges@puc-rio.br, pmendes@puc-rio.br; Ziglio, Claudio [PETROBRAS S.A, R.J., Rio de Janeiro, RJ (Brazil)], e-mail: ziglio@petrobras.com.br

2010-07-01

Under the hot reservoir conditions, waxy crudes behave like Newtonian fluids but once they experience very cold temperatures on the sea floor, the heavy paraffin's begin to precipitate from the solution impacting non- Newtonian flow behavior to the crude (Chang 2000, Lee 2009, Davidson 2004) and begin to deposit on the pipe wall leave blocked of pipeline. This gel cannot be broken with the original steady state flow operating pressure applied before gelation (Chang 1998). Restarting waxy crude oil flows in pipelines is a difficult issue because of the complex rheological behavior of the gelled oil. Indeed, below the WAT, the gelled oil exhibits viscoplastic, thixotropic, temperature-dependent, and compressible properties due to the interlocking gel-like structure formed by the crystallized paraffin compounds and the thermal shrinkage of the oil. The main objective of this work is to determine the minimal pressure to restart the flow, and the relationship between the fluid rheology , pipe geometry and the restart pressure of the flow. Experiments will be performed to investigate the displacement of carbopol aqueous solutions (viscoplastic fluid without thixotropic effects) by Newtonian oil flowing through a strait pipe to validate the experimental apparatus. Therefore, tests will be made with different fluids, like Laponite and waxy crude oils. (author)

Constraining Relativistic Generalizations of Modified Newtonian Dynamics with Gravitational Waves.

Science.gov (United States)

Chesler, Paul M; Loeb, Abraham

2017-07-21

In the weak-field limit of general relativity, gravitational waves obey linear equations and propagate at the speed of light. These properties of general relativity are supported by the observation of ultrahigh-energy cosmic rays as well as by LIGO's recent detection of gravitation waves. We argue that two existing relativistic generalizations of modified Newtonian dynamics, namely, the generalized Einstein-aether theory and bimetric modified Newtonian dynamics, display fatal inconsistencies with these observations.

Post-Newtonian celestial dynamics in cosmology: Field equations

Science.gov (United States)

Kopeikin, Sergei M.; Petrov, Alexander N.

2013-02-01

Post-Newtonian celestial dynamics is a relativistic theory of motion of massive bodies and test particles under the influence of relatively weak gravitational forces. The standard approach for development of this theory relies upon the key concept of the isolated astronomical system supplemented by the assumption that the background spacetime is flat. The standard post-Newtonian theory of motion was instrumental in the explanation of the existing experimental data on binary pulsars, satellite, and lunar laser ranging, and in building precise ephemerides of planets in the Solar System. Recent studies of the formation of large-scale structures in our Universe indicate that the standard post-Newtonian mechanics fails to describe more subtle dynamical effects in motion of the bodies comprising the astronomical systems of larger size—galaxies and clusters of galaxies—where the Riemann curvature of the expanding Friedmann-Lemaître-Robertson-Walker universe interacts with the local gravitational field of the astronomical system and, as such, cannot be ignored. The present paper outlines theoretical principles of the post-Newtonian mechanics in the expanding Universe. It is based upon the gauge-invariant theory of the Lagrangian perturbations of cosmological manifold caused by an isolated astronomical N-body system (the Solar System, a binary star, a galaxy, and a cluster of galaxies). We postulate that the geometric properties of the background manifold are described by a homogeneous and isotropic Friedmann-Lemaître-Robertson-Walker metric governed by two primary components—the dark matter and the dark energy. The dark matter is treated as an ideal fluid with the Lagrangian taken in the form of pressure along with the scalar Clebsch potential as a dynamic variable. The dark energy is associated with a single scalar field with a potential which is hold unspecified as long as the theory permits. Both the Lagrangians of the dark matter and the scalar field are

RHEOLOGIC BEHAVIOR OF PASTRY CREAMS

Directory of Open Access Journals (Sweden)

Camelia Vizireanu

2012-03-01

Full Text Available The increased social and economic importance of ready–made food production, together with the complexity of production technology, processing, handling and acceptance of these fragile and perishable products requires extensive knowledge of their physical properties. Viscoelastic properties play an important role in the handling and quality attributes of creams.Our study was to investigate the rheological properties of different confectionary creams, by scanning the field of shear rates at constant temperature and frequency, angular frequency scanning at small deformations and quantification of rheological changes during application of deformation voltages. The creams tested were made in the laboratory using specific concentrates as fine powders, marketed by the company “Dr. Oetker” compared with similar creams based on traditional recipes and techniques. Following the researches conducted we could conclude that both traditional creams and the instant ones are semi fluid food products with pseudoplastic and thixotropic shear flow behavior, with structural viscosity. Instant and traditional creams behaved as physical gels with links susceptible to destruction, when subjected to deformation forces.

Rheological behavior of drilling fluids under low temperatures

Energy Technology Data Exchange (ETDEWEB)

Lomba, Rosana F.T.; Sa, Carlos H.M. de; Brandao, Edimir M. [PETROBRAS, Rio de Janeiro, RJ (Brazil). Centro de Pesquisas]. E-mails: rlomba, chsa, edimir@cenpes.petrobras.com.br

2000-07-01

The so-called solid-free fluids represent a good alternative to drill through productive zones. These drill-in fluids are known to be non-damaging to the formation and their formulation comprise polymers, salts and acid soluble solids. Xanthan gum is widely used as viscosifier and modified starch as fluid loss control additive. The salts most commonly used are sodium chloride and potassium chloride, although the use of organic salt brines has been increasing lately. Sized calcium carbonate is used as bridging material, when the situation requires. The low temperatures encountered during deep water drilling demand the knowledge of fluid rheology at this temperature range. The rheological behavior of drill-in fluids at temperatures as low as 5 deg C was experimentally evaluated. Special attention was given to the low shear rate behavior of the fluids. A methodology was developed to come up with correlations to calculate shear stress variations with temperature. The developed correlations do not depend on a previous choice of a rheological model. The results will be incorporated in a numerical simulator to account for temperature effects on well bore cleaning later on. (author)

The interaction of two spheres in a simple-shear flow of complex fluids

Science.gov (United States)

Firouznia, Mohammadhossein; Metzger, Bloen; Ovarlez, Guillaume; Hormozi, Sarah

2017-11-01

We study the interaction of two small freely-moving spheres in a linear flow field of Newtonian, shear thinning and yield stress fluids. We perform a series of experiments over a range of shear rates as well as different shear histories using an original apparatus and with the aid of conventional rheometry, Particle Image Velocimetry and Particle Tracking Velocimetry. Showing that the non-Newtonian nature of the suspending fluid strongly affects the shape of particle trajectories and the irreversibility. An important point is that non-Newtonian effects can be varied and unusual. Depending on the shear rate, nonideal shear thinning and yield stress suspending fluids might show elasticity that needs to be taken into account. The flow field around one particle is studied in different fluids when subjected to shear. Then using these results to explain the two particle interactions in a simple-shear flow we show how particle-particle contact and non-Newtonian behaviors result in relative trajectories with fore-aft asymmetry. Well-resolved velocity and stress fields around the particles are presented here. Finally, we discuss how the relative particle trajectories may affect the microstructure of complex suspensions and consequently the bulk rheology. NSF (Grant No. CBET-1554044-CAREER).

Nonlinear oscillatory rheology and structure of wormlike micellar solutions and colloidal suspensions

Science.gov (United States)

Gurnon, Amanda Kate

The complex, nonlinear flow behavior of soft materials transcends industrial applications, smart material design and non-equilibrium thermodynamics. A long-standing, fundamental challenge in soft-matter science is establishing a quantitative connection between the deformation field, local microstructure and macroscopic dynamic flow properties i.e., the rheology. Soft materials are widely used in consumer products and industrial processes including energy recovery, surfactants for personal healthcare (e.g. soap and shampoo), coatings, plastics, drug delivery, medical devices and therapeutics. Oftentimes, these materials are processed by, used during, or exposed to non-equilibrium conditions for which the transient response of the complex fluid is critical. As such, designing new dynamic experiments is imperative to testing these materials and further developing micromechanical models to predict their transient response. Two of the most common classes of these soft materials stand as the focus of the present research; they are: solutions of polymer-like micelles (PLM or also known as wormlike micelles, WLM) and concentrated colloidal suspensions. In addition to their varied applications these two different classes of soft materials are also governed by different physics. In contrast, to the shear thinning behavior of the WLMs at high shear rates, the near hard-sphere colloidal suspensions are known to display increases, sometimes quite substantial, in viscosity (known as shear thickening). The stress response of these complex fluids derive from the shear-induced microstructure, thus measurements of the microstructure under flow are critical for understanding the mechanisms underlying the complex, nonlinear rheology of these complex fluids. A popular micromechanical model is reframed from its original derivation for predicting steady shear rheology of polymers and WLMs to be applicable to weakly nonlinear oscillatory shear flow. The validity, utility and limits of

Aggregation in concentrated protein solutions: Insights from rheology, neutron scattering and molecular simulations

Science.gov (United States)

Castellanos, Maria Monica

-angle neutron scattering experiments were used to characterize the antibody aggregates responsible for this non-Newtonian response. From the neutron scattering data, a weak barrier leading to reversible aggregation is identified. Therefore, proteins aggregate weakly after colliding hydrodynamically, unless they find a favorable contact with high binding energy. Two types of antibody aggregates were identified: oligomers with average radius of gyration of ˜10 nm, and fractal aggregates larger than ˜ 0.1 microm formed by a reaction-limited aggregation process. A characteristic upturn in the scattered intensity at low wavevector and a low shear viscosity increase are observed in aggregated protein solutions. These features are removed by filtering with a 0.2 microm filter, which also eliminates the submicron fractal aggregates. Biophysical characterization supports the conclusions from the rheology and neutron scattering experiments. Finally, molecular dynamics simulations were used to understand the effects of disulfide bonds on the conformational stability of serum albumin. Changes in disulfide bonds in the native structure could lead to partial unfolding, and the formation of aggregates through inter-molecular disulfide bonds. Therefore, it is important to understand the role of each disulfide bond on the structure and dynamics of the protein. After removing disulfide bonds, changes occur in the dynamic correlations between different residues, and the secondary and tertiary structure of albumin. However, not all disulfide bonds affect the conformation of the protein, suggesting that other interactions are more relevant to keep the stability in certain regions. Removal of all disulfide bonds using molecular dynamics is proposed as a practical prescreening tool to identify disulfide bonds that are important for the conformational stability. As a result, some disulfide bonds can be mutated without affecting the conformation of the protein.

Hydrodynamic characteristics and mixing behaviour of Sclerotium glucanicum culture fluids in an airlift reactor with an internal loop used for scleroglucan production.

Science.gov (United States)

Kang, X; Wang, H; Wang, Y; Harvey, L M; McNeil, B

2001-10-01

The filamentous fungus, Sclerotium glucanicum NRRL 3006, was cultivated in a 0.008 m(3) airlift bioreactor with internal recirculation loop (ARL-IL) for production of the biopolymer, scleroglucan. The rheological behaviour of the culture fluid was characterised by measurement of the fluid consistency coefficient (K) and the flow behaviour index (n). Based on these measurements, the culture fluid changed from a low viscosity Newtonian system early in the process, to a viscous non-Newtonian (pseudoplastic) system. In addition, reactor hydrodynamics and mixing behaviour were characterised by measurement of whole mean gas hold-up (epsilon(g)), liquid re-circulation velocity (U(ld)) and mixing time (t(m)). Under identical process conditions, the effects of the viscosity of the culture fluid and air flow rate on epsilon(g), U(ld) and t(m) were examined and empirical correlations for epsilon(g), U(ld) and t(m) with both superficial velocity U(g) and consistency coefficient K were obtained and expressed separately. The correlations obtained are likely to describe the behaviour of real fungal culture fluids more accurately than previous correlations based on Newtonian or simulated non-Newtonian systems.

Theoretical Tools for Relativistic Gravimetry, Gradiometry and Chronometric Geodesy and Application to a Parameterized Post-Newtonian Metric

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Pacôme Delva

2017-03-01

Full Text Available An extensive review of past work on relativistic gravimetry, gradiometry and chronometric geodesy is given. Then, general theoretical tools are presented and applied for the case of a stationary parameterized post-Newtonian metric. The special case of a stationary clock on the surface of the Earth is studied.

Surface rheology and interface stability.

Energy Technology Data Exchange (ETDEWEB)

Yaklin, Melissa A.; Cote, Raymond O.; Moffat, Harry K.; Grillet, Anne Mary; Walker, Lynn; Koehler, Timothy P.; Reichert, Matthew D. (Carnegie Mellon University, Pittsburgh, PA); Castaneda, Jaime N.; Mondy, Lisa Ann; Brooks, Carlton, F.

2010-11-01

We have developed a mature laboratory at Sandia to measure interfacial rheology, using a combination of home-built, commercially available, and customized commercial tools. An Interfacial Shear Rheometer (KSV ISR-400) was modified and the software improved to increase sensitivity and reliability. Another shear rheometer, a TA Instruments AR-G2, was equipped with a du Nouey ring, bicone geometry, and a double wall ring. These interfacial attachments were compared to each other and to the ISR. The best results with the AR-G2 were obtained with the du Nouey ring. A Micro-Interfacial Rheometer (MIR) was developed in house to obtain the much higher sensitivity given by a smaller probe. However, it was found to be difficult to apply this technique for highly elastic surfaces. Interfaces also exhibit dilatational rheology when the interface changes area, such as occurs when bubbles grow or shrink. To measure this rheological response we developed a Surface Dilatational Rheometer (SDR), in which changes in surface tension with surface area are measured during the oscillation of the volume of a pendant drop or bubble. All instruments were tested with various surfactant solutions to determine the limitations of each. In addition, foaming capability and foam stability were tested and compared with the rheology data. It was found that there was no clear correlation of surface rheology with foaming/defoaming with different types of surfactants, but, within a family of surfactants, rheology could predict the foam stability. Diffusion of surfactants to the interface and the behavior of polyelectrolytes were two subjects studied with the new equipment. Finally, surface rheological terms were added to a finite element Navier-Stokes solver and preliminary testing of the code completed. Recommendations for improved implementation were given. When completed we plan to use the computations to better interpret the experimental data and account for the effects of the underlying bulk

The Newtonian Moment - Isaac Newton and the Making of Modern Culture

Science.gov (United States)

Feingold, Mordechai

2004-12-01

Isaac Newton is a legendary figure whose mythical dimension threatens to overshadow the actual man. The story of the apple falling from the tree may or may not be true, but Isaac Newton's revolutionary discoveries and their importance to the Enlightenment era and beyond are undeniable. The Newtonian Moment , a companion volume to a forthcoming exhibition by the New York Public Library, investigates the effect that Newton's theories and discoveries had, not only on the growth of science, but also on the very shape of modern culture and thought. Newton's scientific work at Cambridge was groundbreaking. From his optical experiments with prisms during the 1660s to the publication of both Principia (1687) and Opticks (1704), Newton's achievements were widely disseminated, inciting tremendous interest and excitement. Newtonianism developed into a worldview marked by many tensions: between modernity and the old guard, between the humanities and science, and the public battles between great minds. The Newtonian Moment illuminates the many facets of his colossal accomplishments, as well as the debates over the kind of knowledge that his accomplishments engendered. The book contributes to a greater understanding of the world today by offering a panoramic view of the profound impact of Newtonianism on the science, literature, art, and religion of the Enlightenment. Copiously illustrated with items drawn from the collections of the New York Public Library as well as numerous other libraries and museums, The Newtonian Moment enlightens its audience with a guided and in-depth look at the man, his world, and his enduring legacy.

Actual Romanian research in post-newtonian dynamics

Science.gov (United States)

Mioc, V.; Stavinschi, M.

2007-05-01

We survey the recent Romanian results in the study of the two-body problem in post-Newtonian fields. Such a field is characterized, in general, by a potential of the form U(q)=|q|^{-1}+ something (small, but not compulsorily). We distinguish some classes of post-Newtonian models: relativistic (Schwarzschild, Fock, Einstein PN, Reissner-Nordström, Schwarzschild - de Sitter, etc.) and nonrelativistic (Manev, Mücket-Treder, Seeliger, gravito-elastic, etc.). Generalized models (the zonal-satellite problem, quasihomogeneous fields), as well as special cases (anisotropic Manev-type and Schwarzschild-type models, Popovici or Popovici-Manev photogravitational problem), were also tackled. The methods used in such studies are various: analytical (using mainly the theory of perturbations, but also other theories: functions of complex variable, variational calculus, etc.), geometric (qualitative approach of the theory of dynamical systems), and numerical (especially using the Poincaré-section technique). The areas of interest and the general results obtained focus on: exact or approximate analytical solutions; characteristics of local flows (especially at limit situations: collision and escape); quasiperiodic and periodic orbits; equilibria; symmetries; chaoticity; geometric description of the global flow (and physical interpretation of the phase-space structure). We emphasize some special features, which cannot be met within the Newtonian framework: black-hole effect, oscillatory collisions, radial librations, bounded orbits for nonnegative energy, existence of unstable circular motion (or unstable rest), symmetric periodic orbits within anisotropic models, etc.

Research of rheological characteristics and determination of rational parameters of drying process of activated ferment for bakery products

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D. M. Borodulin

2017-01-01

Full Text Available The work is aimed at investigating the rheological properties of the ferment in the process of maturation and storage with subsequent determination of the rational parameters of its drying in various drying plants with the analysing of microflora of dried samples. We studied the rheological properties of the ferment using the strain of the lactobacilli L. Acidothilus 146A (activator and without it, which showed that the ferment for the production of special purpose bakery products to non-Newtonian or anomalously viscous liquids described by the Osthald-de-Vale rheological equation. We found that the introduction the strain of the lactobacilli L. Acidothilus 146A helps to reduce the viscosity during maturation by almost 3 times, and when storing the samples – in 2 times, this is indicated by the value of the consistency coefficient. The activator reduces the influence of temperature, so the structure of the ferment becomes more stable. It is easier to further process in this state. Consequently, the energy consumption for production is significantly reduced and the increases expiration date after the strain of the lactobacilli L. Acidothilus 146A is added to the starter for the production of special purpose bakery products. We detected kinetic patterns of drying of the activated ferment in thermoradiation, convective and sublimation dryers under different temperature operating conditions. We have determined the rational parameters of drying the ferment for the production of bakery products of specialized purpose. We analyzed the useful microflora of the dried samples. It has been revealed that microorganisms undergoing convective and sublimation (freeze drying are subjected to the smallest destructive effect. We found that microorganisms are less destroyed by convective and freeze drying. The microbial titer in these samples is at least 1(105CFU/g. While drying by the method of infrared irradiation, this titer is lower by a factor of ten

Modeling the kinetics nonenzymatic browning reactions and rheological behavior in the termal process of fruit juices and pulps

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Damian Manayay

2010-06-01

Full Text Available In the manufacture of fruit juices and pulps, is of paramount importance to refer to non-enzymatic browning and rheological behavior. The non-enzymatic browning is a phenomenon of darkening of a purely chemical (Braverman, 1980, is characterized by the presence of brown polymers called melanoidins, generated by the Maillard reaction or condensation of melanoidins, the caramelization and degradation of acid ascorbic, while the rheological behavior is define as the proportion deformation of the material when exposed to shear stress (σ caused by a rheometer (Muller, 1978; Ibarz, 2005. Modeling studies of colour formation and definition of rheological behavior, considered in this review, aimed at the conclusion of the existence of a zero kinetic and first order respectively, and the most influential factors with the reactions are mainly Maillard, temperature, amino acids presence, water activity and pH, while the rheological behavior is affected by temperature, solid concentration and particles size that make up the suspension in the specific case of the pulps.

Dark matter as a non-linear effect of gravitation

International Nuclear Information System (INIS)

Maia, M.D.; Capistrano, A.J.S.

2006-01-01

The rotation curves of stars in disk galaxies are calculated with the Newtonian law of motion applied to a scalar potential derived from the geodesic equation, only, under the slow motion condition, the so-called Nearly Newtonian Gravity (NNG). A nearly Newtonian gravitational potential, Φ NN = -1/2 c 2 (1+g 44 ), is obtained, characterized by an exact solution of Einsteins equations, with the non-linear effects present in the component g 44 . This gravitational field lies somewhere between General Relativity and Newtonian Gravity. Therefore, Einsteins equations and the equivalence principle are preserved, but the general covariance is broken. The resulting curves are remarkably close to the observed rotation curves in spiral galaxies, suggesting that a substantial component of dark matter may be explained by the non-linearity of Einsteins equations. (author)

Rheology of oleo gels based on sorbitan and glyceryl mono stearates and vegetable oils for lubricating applications

Energy Technology Data Exchange (ETDEWEB)

Sanchez, R.; Franco, J. M.; Delgado, M. A.; Valencia, C.; Gallegos, C.

2011-07-01

Oleo gels based on sorbitan and glyceryl mono stearates and different types of vegetable oils, potentially applicable as biodegradable alternatives to traditional lubricating greases, have been studied. In particular, the rheological behavior, by means of small-amplitude oscillatory shear (SAOS) measurements, and some lubrication performance-related properties (mechanical stability and tribological response) have been evaluated in this work. SAOS response and mechanical stability of these oleo gels are significantly influenced by the type and concentration of the organogelator and the vegetable oil used in the formulations. Glyceryl monostearate (GMS) generally produces stronger gels than sorbitan monostearate (SMS). The use of low-viscosity oils, such as rapeseed and soybean oils, yields gels with significantly higher values of the linear viscoelastic functions than oleo gels prepared with high-viscosity oils, i.e. castor oil. The rheological behavior of SMS-based oleo gels also depends on the cooling rate applied during the gelification process. On the other hand, the oleo gels studied present low values of the friction coefficient obtained in a tribological contact, although only some GMS/castor oil-based oleo gels exhibit a suitable mechanical stability. (Author) 28 refs.

Application of Technology of Hydrodynamic Cavitation Processing High-Viscosity Oils for the Purpose of Improving the Rheological Characteristics of Oils

Science.gov (United States)

Zemenkov, Y. D.; Zemenkova, M. Y.; Vengerov, A. A.; Brand, A. E.

2016-10-01

There is investigated the technology of hydrodynamic cavitational processing viscous and high-viscosity oils and the possibility of its application in the pipeline transport system for the purpose of increasing of rheological properties of the transported oils, including dynamic viscosity shear stress in the article. It is considered the possibility of application of the combined hydrodynamic cavitational processing with addition of depressor additive for identification of effect of a synergism. It is developed the laboratory bench and they are presented results of modeling and laboratory researches. It is developed the hardware and technological scheme of application of the developed equipment at industrial objects of pipeline transport.

Time in Newtonian physics and special relativity

International Nuclear Information System (INIS)

Kichenassamy, S.

1980-01-01

The Newtonian point of view is presented as is the relativist one over time: concepts of guide-marks, clocks and setting to time. One of the consequences of Einstein's theory, the dilation of durations, is developed in particular [fr

Estudo do efeito da temperatura nas propriedades reológicas da polpa de butiá (Butia eriospatha / Study of temperature effect on rheological parameters of the butia pulp (Butia eriospatha

Directory of Open Access Journals (Sweden)

Maurício Rigo

2010-04-01

Full Text Available O objetivo deste trabalho foi estudar o efeito da temperatura no comportamento reológico da polpa de butiá, na forma integral, e a influência da geometria de medida na determinação do comportamento reológico da polpa de butiá. O reômetro utilizado foi da marca Haake Rotovisco, modelo RV-20, com cilindros concêntricos ou placas paralelas. Os dados experimentais dos reogramas para a polpa de butiá foram bem ajustados pelos modelos de Herschell-Bulkley, Casson e Ostwald-de-Waelle. O melhor ajuste se deu pelo modelo de Herschell-Bulkley. Para polpa de butiá, a viscosidade diminui com aumento da temperatura. Os índices de comportamentos obtidos dos dados experimentais foram menores do que um para todas as temperaturas investigadas, o que caracteriza comportamento pseudoplástico da polpa. O sistema de medida de placas paralelas se mostrou inadequado para o estudo do comportamento reológico de polpa de butiá. Portanto é necessária a padronização do sistema de medida empregado para determinação da análise reológica. O modelo de Arrhenius descreve o efeito da temperatura sobre a viscosidade aparente da polpa de butiá.AbstractRheological parameters of Butia (Butia eriospatha pulp were determined at different temperatures (10-60°C using a concentric cylinder Haake Rotovisco rheometer, model RV-20, with concentric cylinders and parallel plate. Butia pulp was found to exhibit non-Newtonian, pseudoplastic behavior at all temperatures investigated and the rheological parameters were adequately described by the Herschel-Bulkley, Ostwald-de-Waelle and Casson models. Yield stress, flow behavior index, and consistency coefficient were significantly affected by temperature. The apparent viscosity calculated through the Herschel-Bulkley model decreased with an increase in temperature. The Arrhenius model gave a good description of temperature effect on apparent viscosity of the pulp. The measurement system of parallel plate was inadequate to

Non-linear Shear and Uniaxial Extensional Rheology of Polyether-Ester-Sulfonate Copolymer Ionomer Melts

DEFF Research Database (Denmark)

Shabbir, Aamir; Huang, Qian; P. Baeza, Guilhem

2017-01-01

We present unique nonlinear shear and extensional rheology data of unentan-gled amorphous polyester ionomers based on polyethers and sulphonated phthalates with sodium/ lithium counterions. Previous linear viscoelastic (LVE) measurements1 showed significant elasticity in these ionomers due...

Effect of various supplementary cementitious materials on rheological properties of self-consolidating concrete

OpenAIRE

Saleh Ahari, Reza; Erdem, Tahir Kemal; Ramyar, Kambiz

2015-01-01

In design of self-consolidating concrete (SCC) for a given application, the mixture's rheological parameters should be adjusted to achieve a given profile of yield stress and plastic viscosity. Supplementary cementitious materials (SCM) can be useful for this adjustment in addition to their other advantages. In this study, the rheological properties of 57 SCC mixtures with various SCM were investigated for a constant slump flow value. For this aim, various amounts of silica fume (SF), metakao...

Dynamics of Newtonian annular jets

International Nuclear Information System (INIS)

Paul, D.D.

1978-12-01

The main objectives of this investigation are to identify the significant parameters affecting the dynamics of Newtonian annular jets, and to develop theoretical models for jet break-up and collapse. This study has been motivated by recent developments in laser-fusion reactor designs; one proposed cavity design involves the use of an annular lithium jet to protect the cavity wall from the pellet debris emanating from the microexplosion

Relation between structure and properties of modified starches. Application to the formulation of non-polluting drilling fluids; Relation structure/proprietes d'amidons modifies. Application a la formulation de fluides de forage non polluants

Energy Technology Data Exchange (ETDEWEB)

Dubois, I

1999-12-06

Starch is a polymeric carbohydrate derivative with anhydro-glucose units and is extracted from the tissues of certain plants. In its native form, starch granule is non soluble in cold water and therefore most applications need a cooking period in the presence of an excess of water. The cooking treatment is therefore associated with large changes in viscosity. Overall, starch suspensions properties are strongly influenced by starch botanical origins, shearing and heating conditions under which they are prepared. Their properties can be modulated though chemical modifications depending on their uses in the petroleum industry. This study focuses on the relations between structure and physico-chemical, rheological and filtration properties of modified starches. These starches are originated from native potato, i. e. hydroxy-propyl and/or crosslinked starches above or below the gelatinization temperature. The samples were characterised in terms of swelling capacity, average granule size distribution and molecular weight. Microscopic methods were used to investigate starch structure. Relations were established between the rheological properties and the physico-chemical parameters. These properties are governed by the deformability and rigidity parameters as a function of the concentration. The best samples were then chosen and were submitted to the high temperature (140 deg. C - 160 deg. C), high shearing (16000 tr/ mn) and salinity (CaCl{sub 2}, 1M). The physico-chemical and rheological studies showed that the starch system which is crosslinked below the gelatinization temperature is more resistant that the samples crosslinked above the gelatinization temperature. Then, a drilling fluid formulation was investigated. The filtration results evidenced an increase of the cake permeability in the presence of starch particles but the good stability of these samples permits their uses for high temperature. Thus, non crosslinked / crosslinked starch mixtures were investigated

Effect of non-Newtonian characteristics of blood on magnetic particle capture in occluded blood vessel

Science.gov (United States)

Bose, Sayan; Banerjee, Moloy

2015-01-01

Magnetic nanoparticles drug carriers continue to attract considerable interest for drug targeting in the treatment of cancer and other pathological conditions. Magnetic carrier particles with surface-bound drug molecules are injected into the vascular system upstream from the desired target site, and are captured at the target site via a local applied magnetic field. Herein, a numerical investigation of steady magnetic drug targeting (MDT) using functionalized magnetic micro-spheres in partly occluded blood vessel having a 90° bent is presented considering the effects of non-Newtonian characteristics of blood. An Eulerian-Lagrangian technique is adopted to resolve the hemodynamic flow and the motion of the magnetic particles in the flow using ANSYS FLUENT. An implantable infinitely long cylindrical current carrying conductor is used to create the requisite magnetic field. Targeted transport of the magnetic particles in a partly occluded vessel differs distinctly from the same in a regular unblocked vessel. Parametric investigation is conducted and the influence of the insert configuration and its position from the central plane of the artery (zoffset), particle size (dp) and its magnetic property (χ) and the magnitude of current (I) on the "capture efficiency" (CE) is reported. Analysis shows that there exists an optimum regime of operating parameters for which deposition of the drug carrying magnetic particles in a target zone on the partly occluded vessel wall can be maximized. The results provide useful design bases for in vitro set up for the investigation of MDT in stenosed blood vessels.

Parameterized post-Newtonian cosmology

International Nuclear Information System (INIS)

Sanghai, Viraj A A; Clifton, Timothy

2017-01-01

Einstein’s theory of gravity has been extensively tested on solar system scales, and for isolated astrophysical systems, using the perturbative framework known as the parameterized post-Newtonian (PPN) formalism. This framework is designed for use in the weak-field and slow-motion limit of gravity, and can be used to constrain a large class of metric theories of gravity with data collected from the aforementioned systems. Given the potential of future surveys to probe cosmological scales to high precision, it is a topic of much contemporary interest to construct a similar framework to link Einstein’s theory of gravity and its alternatives to observations on cosmological scales. Our approach to this problem is to adapt and extend the existing PPN formalism for use in cosmology. We derive a set of equations that use the same parameters to consistently model both weak fields and cosmology. This allows us to parameterize a large class of modified theories of gravity and dark energy models on cosmological scales, using just four functions of time. These four functions can be directly linked to the background expansion of the universe, first-order cosmological perturbations, and the weak-field limit of the theory. They also reduce to the standard PPN parameters on solar system scales. We illustrate how dark energy models and scalar-tensor and vector-tensor theories of gravity fit into this framework, which we refer to as ‘parameterized post-Newtonian cosmology’ (PPNC). (paper)

Parameterized post-Newtonian cosmology

Science.gov (United States)

Sanghai, Viraj A. A.; Clifton, Timothy

2017-03-01

Einstein’s theory of gravity has been extensively tested on solar system scales, and for isolated astrophysical systems, using the perturbative framework known as the parameterized post-Newtonian (PPN) formalism. This framework is designed for use in the weak-field and slow-motion limit of gravity, and can be used to constrain a large class of metric theories of gravity with data collected from the aforementioned systems. Given the potential of future surveys to probe cosmological scales to high precision, it is a topic of much contemporary interest to construct a similar framework to link Einstein’s theory of gravity and its alternatives to observations on cosmological scales. Our approach to this problem is to adapt and extend the existing PPN formalism for use in cosmology. We derive a set of equations that use the same parameters to consistently model both weak fields and cosmology. This allows us to parameterize a large class of modified theories of gravity and dark energy models on cosmological scales, using just four functions of time. These four functions can be directly linked to the background expansion of the universe, first-order cosmological perturbations, and the weak-field limit of the theory. They also reduce to the standard PPN parameters on solar system scales. We illustrate how dark energy models and scalar-tensor and vector-tensor theories of gravity fit into this framework, which we refer to as ‘parameterized post-Newtonian cosmology’ (PPNC).

Variational formulation for the Newtonian cosmology

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