bluuebunny/crossref_metadata_2025_split huggingface dataset:
Simulation of Lubricated Squeezing Flow of a Herschel-Bulkley Fluid Under Constant Force
Authors: Ak M. Mehmet , Gunasekaran Sundaram 
Published: May 2019

AbstractLubricated squeezing flow (LSF) of a Herschel-Bulkley fluid between parallel disks under constant force was theoretically analyzed. An analytical expression for the fluid thickness as a function of time was obtained in terms of a hypergeometric function. The fluid thickness profiles in LSF were simulated for a range of each of the model parameters (n, K, τo). The solution obtained in this study reduces to the corresponding analytical equations previously derived for LSF of Newtonian and power-law fluids. The simulations for Herschel-Bulkley fluid were compared with the response of Newtonian and power-law fluids. The dependence of the limiting fluid thickness (i.e. H(t)/H0 at 180 s) on model parameters is presented.
Using the Microsoft Excel ‘Solver’ Tool to Perform Non-Linear Curve Fitting, Using a Range of Non-Newtonian Flow Curves as Examples.
Authors: Roberts G.P. , Barnes H.A. , Mackie C. 
Published: May 2019

Abstract
The Microsoft Excel ‘Solver’ tool is a very simple but powerful procedure, even in the hands of the mathematically disadvantaged. It has very good application for quickly fitting experimental flow-curve data to non-Newtonian flow models with any number of parameters, and can cope with data from a number of sources. Examples are given for a range of industrially important examples ranging from standard non-Newtonian liquids, through detergent solutions to gels, pastes, and filled polymer melts, often measured on different viscometers.
The Lodge Rubberlike Liquid Behavior for Cheese in Large Amplitude Oscillatory Shear
Authors: Wang Y.-C. , Gunasekaran S. , Giacomin A. J. 
Published: May 2019

Abstract
The viscoelasticity of reduced-fat Cheddar and Mozzarella cheeses was characterized in small (parallel disk rheometer, go = 0.01) and large (sliding plate rheometer, 0.2< go <7) amplitude oscillatory shear at 40 and 60˚C. We deduced the linear relaxation spectrum from the small strain measurements. At large strain amplitudes, we found sinusoidal stress responses whose amplitudes are well below those predicted from the linear relaxation spectrum, and yet remarkably linear with strain amplitude. We call this the large strain linear regime. We discovered that the Lodge rubberlike liquid can quantitatively explain the large strain linear regime if we scale down the relaxation moduli in the linear spectrum by a constant. This large strain linear regime persists to much higher strain amplitudes for Cheddar (go £ 4) than for Mozzarella (go £ 1). This is perhaps due to oriented structure of the protein matrix in the Mozzarella cheese.
Vane Rheometry with a Large, Finite Gap
Authors: Baravian Christophe , Lalante Audrey , Parker Alan 
Published: May 2019

Abstract
The vane geometry with a large gap is used to determine the Newtonian, non-Newtonian and viscoelastic properties of complex fluids. We show that when this geometry is carefully characterized, it can be used for precise rheometry. A novel effective cylinder approximation is used to obtain the shear rate and shear stress factors. The effective radius is found to be close to the height of the triangle formed by joining the tips of adjacent blades. This result differs significantly from that of previous work. Flow visualization has been used to confirm that the stream lines bend towards the centre between the blades. These factors can be used to determine the flow curves of non-Newtonian liquids, using Krieger’s power law expansion. The standard procedure for using the vane to determine the yield stress is also carefully investigated and alternative procedures are suggested.
A Numerical Model of Yield Stress Fluid Dynamics in a Mixing Vessel
Authors: Marouche M. , Anne-Archard D. , Boisson H. C. 
Published: May 2019

Abstract
A numerical study is conducted on the behaviour of yield stress fluids in a mixing vessel equipped with anchor agitator in laminar regime. It is shown that extending a standard Carreau model of shear thinning fluid is a suitable practice. Validations versus Couette flow analytical solution are satisfactory. Main features of local hydrodynamics and global power consumption are described for a 2D flow. Significant changes in the flow pattern are observed for low inertia and high yield stress and the results are considered as guidelines for further laboratory experiments.
On the Use of an Internal Mixer For the Rheological Characterizattion of Maize Starch
Authors: Brouillet-Fourmann Stéphanie , Carrot Christian , Mignard Nathalie , Prochazka Frédéric 
Published: May 2019

Abstract
The rheological behaviour of hydrated maize starch is investigated by means of a Haake internal mixer equipped with a sealed chamber. Results were obtained at temperatures between 89 and 115°C with water content between 25 and 30%. Through a proper calibration torque measurements and rotation speeds are converted to shear stress and shear rate data and this leads to the plot of a flow curve in the 10 - 1000 s-1 range. The data are compared with results of capillary rheometer and show that the mixer enables a reproducible plastification of the maize starch. The viscosity of the maize starch in the high shear rate range can be described by an apparent power law taking into account the moisture and temperature effects. On a larger range of shear rate, a Carreau law is preferred but the dependence on the temperature can only be described with shift factors that require a moisture dependent activation energy. Finally, this later discrepancy can be avoided by using a reference temperature to fulfil the iso-free volume condition by taking a constant temperature difference towards the glass transition of the samples. The glass transition is calculated by the Couschman and Karasz equation.
Linear Viscoelastic Behavior of Bentonite-Water Suspensions
Authors: Bekkour Karim , Kherfellah Nadia 
Published: May 2019

Abstract
Bentonite are extensively used materials in a wide range of applications. Creep and oscillatory shear experiments in the linear viscoelastic domain were carried out on bentonite-water suspensions at different solid fractions. It was found that bentonite dispersions exhibit important viscoelastic behavior which could be represented by the generalized Kelvin-Voigt mechanical model. It is well known that an exhaustive study of colloidal dispersions may require the determination of its viscoelastic properties over a wide frequency scale. Unfortunately, due to microstructure changes, the experiments are limited in time. In order to avoid such limitation, oscillatory data were deduced from creep curves - without actually vibrating the clay dispersions - because a periodic experiment at frequency ω is qualitatively equivalent to a creep test at time 1/ω. That is, it was possible to complete the dynamic response in the low-frequency range using data obtained from the transient response in creep.
The Effect of Yellowing Inhibitor Total Charge on The Rheology of Paper Coating
Authors: El-Sadi Haifa , Esmail Nabil 
Published: May 2019

AbstractNew compounds, called inhibitors, provide anti-yellowing effect for mechanical pulps and papers, when added to the coating formulation. The rheology of coating mixtures, which contain clay, ground calcium carbonate, starch, latex, inhibitors and other minor additives, affects to a certain extent the final quality of the coated paper. The purpose of this work is to investigate the effect of the total weight charge of inhibitors, when present between coating color ingredients, on the thixotropy and visco-elasticity of the mixture and other rheological properties. We also study the degree of interaction between inhibitor and coating ingredients using Transmission Electron Microscope (TEM) and water retention measurements.For the industrially preferred inhibitor system of low RS/UVA ratio and high total charge the coating formulation will have a significant increase in the general value of viscosity and a clear and profound shear-thinning behavior. Under the desired conditions of higher total charge the coating formulation acquires significant thixotropic behavior. A higher level of energy is required to coat such formulation. The elastic modulus increases with frequency. This rise in the elastic modulus reveals the increasing interaction between particles in the coating formulation. The total charge does not affect the resistance of a coating color to the applied stress. The coating color with low total charge has the strongest water holding capability decreasing with increasing total charge.
Apparent Viscosity and First Normal Stress of Starch Dispersions: Role of Continuous and Dispersed Phases, and Prediction with the Goddard-Miller Model
Authors: Genovese Diego B. , Rao M. A. 
Published: May 2019

Abstract
Apparent viscosity, ηa, and first normal stress coefficient, ψ1, of six different concentrations of cross-linked waxy maize (CWM), 3.5-5 % w/w, and tapioca, 2.8-4 % w/w, starch dispersions (SDs) showed power law relationships with shear rate, ̇γ , and increased with starch concentration. In both ηa and ψ1, volume fraction of the granules, ϕ, played a more important role than the amylose content of the continuous phase. Slope of ηa - ̇γ curves increased mildly with starch concentration, while slope of ψ1 - ̇γ curves was almost the same for CWM at all concentrations and 4 % tapioca SDs. Values of ηa and ψ1 predicted from dynamic rheological and apparent viscosity data based on the Goddard-Miller model were in reasonable agreement with experimental values.
Radiation Scattering by Dilute Polymer Solutions in Shear Flow: An Example of Mesoscale Modeling and Brownian Dynamics Simulation
Authors: Cifre J.G. Hernández , de la Torre J. García 
Published: May 2019

Abstract
The intention of the paper is to illustrate the ability of the Brownian dynamics simulation technique applied to mesoscale polymer models in order to reproduce light scattering experiments of dilute polymer solution under flow. After suitable parameterization of a real polymeric system, polystyrene solved in a oligostyrene/toluene mixture at 299 K (good solvent conditions), a bead-spring model of the polymer chain is built and used to generate molecular trajectories on a computer. Such trajectories will capture the deformational and orientational processes experienced by the real polymer chain under flow. Then, from the set of molecular conformations generated, several polymer properties as well as typical scattering patterns can be reproduced quite accurately. FENE springs were used and excluded volume and non-preaveraging hydrodynamic interaction were taken into account in order to build a chain model as realistic as needed.
Direct Simulation of Fluid Transport at Solid Interfaces with a Multiscale Lattice-Boltzmann Finite-Volume Method
Authors: Rotondi R. , Succi S. , Bella G. 
Published: May 2019

Abstract
It is shown that the combined use of a mesoscopic lattice Boltzmann solver with finite-volume techniques, both enriched with local-refinement (multiscale) capabilities, permits to describe transport phenomena at fluid-solid interfaces to a degree of detail which may help dispensing with empirical correlations.
Creeping Sphere-Plane Squeeze Flow to Determine the Zero-Shear-Rate viscosity of HDPE Melts
Authors: Cua Edwin C. , Shaw Montgomery T. 
Published: May 2019

Abstract
A creeping squeeze flow apparatus [1 - 2] was modified with a Fizeau interferometer optical motion transducer and equipped with a high-temperature, high-vacuum enclosure. Long-term squeeze flow experiments were done on a broad-MW, 1 melt-flow index commercial HDPE at 190˚C, with runs covering about a week. Over this period, no thermal degradation of the polymer was observed, and the geometry of the apparatus was stable. Low-shear-rate viscosities were measured within the maximum shear rates from 1.7 × 10−5 to 7.6 × 10−5 1/s (stress ~ 1.7 to 8 Pa), resulting in an two-decade expansion in the experimental window for this difficult-to-characterize HDPE resin with long relaxation times.
Phenomenological Modelling of Non-Monotonous Shear Viscosity Functions
Authors: David J. , Filip P. 
Published: May 2019

AbstractThe aim of this paper is to present a new phenomenological rheological model suitable for the description of a wide class of viscoelastic fluids. Classical phenomenological models predict the relation shear viscosity vs. shear rate (or shear stress) for shear-thinning (or thickening) materials exhibiting smooth monotonous passage from the first - upper (lower) - Newtonian plateau to the second - lower (upper) - one. However, present state of non-Newtonian materials used in practice (ranging from aqueous surfactant solutions, bituminous materials, associative polymers, polymer thickeners, lacquers and gels, to some special disperse systems, etc.) evokes the need to describe this - for many materials non-monotonous - relation in the corresponding way, i.e. through the sufficiently simple phenomenological model with a moderate number of parameters. A six-parameter model enabling description of not only monotonous but also non-monotonous course of shear viscosity function against shear rate (stress) is proposed including physical characterisation of the parameters. This model describes not only extreme points (maximum or minimum) but also a possible appearance of intermediate Newtonian plateau or its indication. The meaning and influence of the individual six parameters is documented on the experimental data published in the literature. There is a good agreement of the model proposed with many different experimental data representing different rheological behaviour. The applicability of this model for a wide class of viscoelastic materials is its principal advantage over the hitherto published phenomenological models.
Extensional Viscosity of Coating Colors and its Relation With Jet Coating Performance
Authors: Arzate A. , Ascanio G. , Carreau P.J. , Tanguy P.A. 
Published: May 2019

Abstract
An orifice flowmeter was used to measure the extensional viscosity of several non-pigmented fluids and paper coating colors containing calcium carbonate as pigment in the context of a jet coating application. The orifice flowmeter was first calibrated in terms of a dimensionless Euler number versus Reynolds number curve with Newtonian fluids. The calibration curve was then used to determine the apparent extensional viscosity of coating colors. In the strain rate range investigated, all the fluids were found to exhibit strain-thinning and the Trouton ratio of the coating colors was in the range 5 to 20. Jet coating tests were also carried out in order to evaluate the effect of the extensional viscosity on the jet performance. The extensional viscosity was shown to be a key parameter determining the configuration of the downstream meniscus in the web contact region.
Rheological Studies of Interferon Creams
Authors: Zumalacárregui Lourdes , Vázquez Miguel , Estévez Tania , Aguilera Ana , Hardy Eugenio 
Published: May 2019

Abstract
The determination of flow curves and the apparent viscosity curves at 28°C of creams containing human leukocyte alpha interferon as active principle is presented in this paper. These creams are used for the treatment of papiloma virus and herpes simplex. It is demonstrated that their behaviour corresponds to a thixotropic fluid. The Herschel-Bulkley model parameters are presented and discussed as an indicator of the grade of thixotropy. Apparent viscosity plotted as a function of shear rate and storage time allows defining the time period in which the samples recover their initial structure. Additionally it was concluded that for determining the quality of the product, the acceptance limit of the viscosity should be specified for a given shear rate.
Capillary Break-up Rheometry of Low-Viscosity Elastic Fluids
Authors: Rodd Lucy E. , Scott Timothy P. , Cooper-White Justin J. , McKinley Gareth H. 
Published: May 2019

Abstract
We investigate the dynamics of the capillary thinning and break-up process for low viscosity elastic fluids such as dilute polymer solutions. Standard measurements of the evolution of the midpoint diameter of the necking fluid filament are augmented by high speed digital video images of the break up dynamics. We show that the successful operation of a capillary thinning device is governed by three important time scales (which characterize the relative importance of inertial, viscous and elastic processes), and also by two important length scales (which specify the initial sample size and the total stretch imposed on the sample). By optimizing the ranges of these geometric parameters, we are able to measure characteristic time scales for tensile stress growth as small as 1 millisecond for a number of model dilute and semi-dilute solutions of polyethylene oxide (PEO) in water and glycerol. If the final aspect ratio of the sample is too small, or the total axial stretch is too great, measurements are limited, respectively, by inertial oscillations of the liquid bridge or by the development of the well-known beads-on-a-string morphology which disrupt the formation of a uniform necking filament. By considering the magnitudes of the natural time scales associated with viscous flow, elastic stress growth and inertial oscillations it is possible to construct an “operability diagram” characterizing successful operation of a capillary breakup extensional rheometer. For Newtonian fluids, viscosities greater than approximately 70 mPas are required; however for dilute solutions of high molecular weight polymer, the minimum viscosity is substantially lower due to the additional elastic stresses arising from molecular extension. For PEO of molecular weight 2 · 106 g/mol, it is possible to measure relaxation times of order 1 ms in dilute polymer solutions with zero-shear-rate viscosities on the order of 2 – 10 mPas.
Temperature Calibration of Rotational Rheometers with Electrically Heated Tools and Hood Oven
Authors: Schweizer Thomas 
Published: May 2019

Abstract
The calibration of the temperature control unit of a rotational rheometer with a hood oven is shown. The calibration technique shown for a Paar-Physica rheometer can be adapted to any rheometer with hood oven (indirect heating). The temperature of the bottom fixed plate and the air bearing suspended cone or plate are measured independently. By keeping the amount of venting gas constant, the set temperature of the hood oven is adjusted to reach a minimum gradient across the measuring gap. The calibration procedure is optimized to keep the oven as close as possible to the measuring position.
A Model for Velocity Profile in Turbulent Boundary Layer with Drag Reducing Surfactants
Authors: Krope A. , Krope J. , Lipus L.C. 
Published: May 2019

Abstract
A new model for mean velocity profile of turbulent water flow with added drag-reducing surfactants is presented in this paper. The general problem of drag due to frictional resistance is reviewed and drag reduction by the addition of polymers or surfactants is introduced. The model bases on modified Prandtl's mixing length hypothesis and includes three parameters, which depend on additives and can be evaluated by numerical simulation from experimental datasets. The advantage of the model in comparison with previously reported models is that it gives uniform curve for whole pipe section and can be determined for a new surfactant with less necessary measurements. The use of the model is demonstrated for surfactant Habon-G as an example.
Zone Method for Representing Relaxation Characteristics of Viscoelastic Materials
Authors: Koenigsberg William , Selverian John H. 
Published: May 2019

Abstract
Exponential integral functions were fitted to relaxation data obtained from tensile and shear loading of an asphalt-sand mixture at different temperatures. This approach yields a better fit to the experimental data than the traditional Prony series and provides physical insight into essential characteristics of the relaxation processes that govern the asphalt-sand mixture. We expect that using this model beyond the time range covered by the experimental data would result in a significantly better representation of the material behavior than would extrapolation of the Prony series fit.
Effect of Electric Fields on the Rheological Properties of the Isotropic Phase of phic/p-Xylene Solutions
Authors: Menna Todd J. , Filisko Frank E. , Lynch Rachel A. 
Published: May 2019

Abstract
The effect of high ac electric fields upon a liquid crystalline polymer solution, poly(n-hexyl isocyanate) in p-xylene, is examined. The results show that the solutions exhibit an increase in rheological properties proportional to the strength of the field at concentrations well below those exhibiting liquid crystalline behavior. The effects of frequency and field strength are examined as a means to explain this previously unreported phenomenon.
Influence of an Ultrasonic Treatment on the Structure and Flow Behaviour of Oxide Ceramic Masses
Authors: Götz Joachim , Rewesa Lars , Walch Michael , Geißler Adam 
Published: May 2019

Abstract
Oxide ceramic masses are used for catalysts and catalyst carriers. For a reliable processing hydrocolloids (e. g. cellulose) are usually added in order to decelerate demixing phenomena. Oxide ceramic masses react to simple shearing with hardening (peptisation: increase of the shear stress with the shear deformation) [1]. The present study analyses, if an ultrasonic treatment has also an impact on the structure, the shelf-life (in the green state), the correlated flow behaviour of oxide ceramic masses and presumably (not tested) the mechanical properties in the hardened, sintered state. The idea of using ultrasonic treatment is to change the microstructure (see below) and, therefore, to minimise or even give up the standard addition of stabilizers to minimize demixing in aqueous oxide ceramic suspensions. Besides the additional costs of an extra process unit, stabilisers cause often deteriorated mechanical properties (porosity, crack behaviour) of the ceramics in the hardened state after the sintering. Therefore, pump experiments (apparent viscosity), oscillatory (G´ and G´´) and steady shear experiments (h), particle-size analysis (particle-size distribution, agglomerate strength), light microscopy, decanting experiments and pH-determinations have been performed. The obtained results show, that the hardening of the apparent viscosity (derived from the flow) during pump experiments with simultaneous ultrasonic treatment in a flow cell is combined with an increase of the fine fraction, the formation of enlarged, but smoother agglomerates, the change of the pH-value and the evolution of a three-dimensional network (gelling). All these processes increase both the amount of bound/immobilised (chemically or physically bound by or onto the solid-surfaces) and of retained water (interior of agglomerates and/or the pores of the flowand ultrasonic-induced network). This means that the volume fraction of the rheologically "free" water decreases and simultaneously the effective solid volume fraction increases. With respect to the concept of the rheologically effective solid fraction this is combined with an increasing viscosity. At the same time the tendency of demixing decreases significantly. Thus, by an appropriate combination of shear flow and ultrasonic treatment, the aqueous oxide ceramic suspensions are stabilised and a reliable processing of the initially problematic solid/fluid mixtures can be realised without stabilisers (eluding their negative consequences with respect to the quality of the sintered state).