Shear Rate Relationship Research Articles

Effect of Silica Flour and Potasium Chloride as Additives in the Rhelogical Properties of High Temperature High Pressure Gas Well Cement Slurry

This study explores the effects of silica flour and potassium chloride on the rheological properties of high temperature and pressure gas wells. Seven different materials were used as additives which includes: fresh water, dyckerhoff, silica flour, antifoam, extender, fluid loss, dispersant, retarder, anti-settling agent, gas control agent, dry viscosifier, potassium chloride and accelerator. Four recipes were prepared using these additives in different mixtures. Recipe four has all the additives including silica flour and potassium chloride. A series of flow tests was performed using an advanced shear-stress/shear strain controlled rheometer. Rheological properties of cement slurries were calculated from the resulting flow curves using the Bingham plastic model and the Herschel–Bulkley’s model. Changes in shear stress–shear rate relationships, yield stress, plastic viscosity, and shear thinning/thickening behavior were found to be related to temperature and the type and dosage of supplementary cementitious material. The four recipes were applied in 10 cases.Among the four different recipes tested for all the 10 cases, Recipe 4 has the best regression values for both temperature vs transit time and pressure vs transit time this can be attributed to the presence of silica flour and potassium chloride.

Effect of whey and soy proteins fortification on the textural and rheological properties of value-added yogurts

The objective of this study was to develop whey and soy proteins fortified value-added yogurts based on their textural and rheological properties to meet a high demand to increase protein content of conventional yogurts for many health benefits. Seven yogurts (control, 1, 3 and 5% of whey/soy proteins) were developed by fortifying with whey and soy proteins. The protein fortified yogurts were compared with control (without protein fortification) for their textural and rheological properties. The dynamic viscosity of yogurts was determined, and the shear stress-shear rate relationship was modeled using a power law equation to determine the apparent viscosity and flow behavior of yogurts. There was a significant effect of protein fortification on the textural and rheological properties of yogurts (p < 0.05). The textural properties and viscosities of 1-5% soy protein fortified samples were close or better to control. Textural and rheological properties of the yogurts indicated that up to 5% soy protein could be incorporated for the quality yogurts. whereas only 1-3% whey fortification of yogurt was possible because 5% whey protein created aggregates and syneresis of yogurts. Power law modeling could predict the shear stress and shear rate relationship and apparent viscosity of all yogurts with an accuracy of 80-99% depending on level of protein fortification and protein type. Dynamic viscosity and apparent viscosity of all yogurts decreased with shear rate. Power law (n < 1) showed that all yogurt samples were shear thinning products. The desired viscosity could be obtained using an optimum protein fortification. The study indicated that soy protein could be used as an alternative to whey protein for the improved protein fortified yogurt production.

Flow past a porous plate of non-Newtonian fluids with implicit shear stress shear rate relationships

One of the simplest problems in the classical Navier–Stokes theory that illustrates the development of boundary layers is the asymptotic suction problem (Schlichting (1960)). This problem has been studied within the context of many different non-Newtonian fluid models and in this note we consider it within the context of a new class of constitutive relations that has been put into place. Depending on the values of the parameters, this class of constitutive relations includes models for both shear thinning and shear thickening fluids, and truly implicit shear stress shear rate relationships. For any set of the material parameters we are able to find exact solutions to the governing equations, study their stability, show that suction has a stabilizing effect, and delineate the development of boundary layers.

The rheological assumptions of classical EHL: What went wrong?

Abstract The field of elastohydrodynamic lubrication (EHL) now has two very different approaches to the problem. For the first approach, two assumptions regarding the pressure, temperature and shear dependence of viscosity have been essential to the way that classical EHL developed over the last forty years. 1. The liquid in the inlet zone responds in Newtonian fashion. 2. The shear stress versus shear rate relationship of the liquid has the same form as the average shear stress versus average shear rate obtained from a traction curve. The new, quantitative, approach employs viscosities measured in instruments which do not rely upon these assumptions. There has been a rapid succession of advances in understanding of film forming and friction under the new approach.

THE SCIENTIFIC AND PRACTICAL PRINCIPLES OF CREATING PRODUCTS WITH INCREASED PROTEIN CONTENT

Abstract: The studies show that there is an increased interest in the market for the production of protein-fortified products due to the clearly observed trend of general decline in the protein intake by the population. The purpose of this work is to develop the new types of dairy products with increased protein content using the principle of products gradation for protein content, and to assess their functional and textural characteristics. The applied methods included an assessment of the rheological and textural characteristics, an optical microscopy, and the characteristic of color parameters of the products developed. It has been shown that the protein performs various functions in dairy products, such as changes in structural properties of the dairy products, reduction of fat level, and fortification of the products with the rich source of the branched-chain essential amino acids. The assessment of the textural properties of the developed products, which includes the measurements of the viscosity versus shear rate relationship, of the functional and technological properties of foam (fold and stability), and of the texture parameters (hardness and adhesion), has showed the acceptability of the developed technological solutions. The inclusion of the desired level of protein into the dairy products has not significantly affected their textural characteristics. An analysis of the viscosity-shear rate relationship has demonstrated the similar trends in the rheological properties for all the products studied. The texture of the new products was analyzed instrumentally pointing to their similarity with the commercial versions of the products containing half as much of the complete protein. The results of the study indicate the similar values of the color attributes of the developed products. The studies of the biological value of the new products has showed an increased content of the essential amino acids to an average of up to 76.9%, 80%, and 80.7% in cream, drinks, and desserts, respectively, as compared to their commercial counterparts. The amount of leucine, which is an amino acid that plays a fundamental role in the muscle protein synthesis, increased up to 61.9%, as compared to the commercial variants. This study can lay the foundation for the further development of a wide range of the structured food products with increased protein content.

The rheology of cementitious suspensions: A closer look at experimental parameters and property determination using common rheological models

This paper investigates the influence of gap between parallel plates, surface texture of the bottom plate, and mixing intensity on the yield stress and plastic viscosity of cementitious suspensions extracted using the Bingham model. Special emphasis is paid toward understanding the effects of shear rate range and different rheological models on the flow parameters. It is shown that the use of a wider shear rate range (0.1–100/s), can be beneficial in obtaining a reasonable portion of the stress plateau in the shear stress–shear rate relationship, which facilitates a model-less, yet accurate extraction of yield stress. The Bingham model that considers only the linear region (i.e. ∼5–100/s) overestimates the yield stress as indicated by the stress asymptote while the Herschel–Bulkley (H–B) equation applied in the 0.1–100/s shear rate range underestimates the yield stress. Further lowering the evaluated shear rate range (i.e. 0.005–100/s) does substantially improve the H–B prediction of yield stress.

Effect of Supplementary Cementitious Materials on Rheology of Oil Well Cement Slurries

Abstract This study explores the effects of supplementary cementitious materials (SCMs) on the rheological properties of oil well cement slurries. Four different mineral admixtures including metakaolin (MK), silica fume (SF), rice husk ash (RHA), and class F fly ash (FA) were used as partial replacement for API class G oil well cement. A new generation polycarboxylate-based high-range water reducing admixture was used to improve the fluidity of slurries. A series of flow tests was performed using an advanced shear-stress/shear strain controlled rheometer at three different temperatures, namely 23, 45, and 60°C. Rheological properties of cement slurries were calculated from the resulting flow curves using the Bingham plastic model and the Herschel–Bulkley’s model. Changes in shear stress–shear rate relationships, yield stress, plastic viscosity, and shear thinning/thickening behavior were found to be related to temperature and the type and dosage of supplementary cementitious material. Among the four different mineral admixtures tested, low calcium fly ash was found to achieve most suitable yield stress and plastic viscosity values.

Rheological behavior of coir‐fiber‐filled polypropylene composites at constant shear stress

The rheological behavior of coir‐fiber‐filled polypropylene (PP) composite has been studied at constant shear stress. The shear stress versus shear rate relationship for the composite follows power law model of viscous flow. Unlike similar studies in the literature, the viscosity is treated as a stress‐independent parameter, which increases with the increase of fiber loading; but decreases with the rise of temperature. The SEM reveals that the fibers are loosely bound to the polymer matrix and the outer surface of the composite is rough and irregular, making it susceptible to high friction with the wall of the flow channel. With analogy to nth order chemical reaction, new formula has been derived for the activation energy of viscous flow, which is found to increase with the increase in the fiber content. The die‐swell ratio decreases with the increase of fiber loading, but increases with the rise of temperature. The elastics parameters of the composite such as the recoverable shear strain, the first normal stress difference, and the elastic strain induced by the stored energy in the capillary reservoir have been estimated based on the die‐swell data. POLYM. COMPOS., 36:51–61, 2015. © 2014 Society of Plastics Engineers

Rheological Characteristics and Debris Flow Simulation of Waste Materials

휴 폐광산지역은 복합지질재해지역으로 집중호우에 의해 토사재해와 산성광산배수를 발생시킨다. 본 연구는 폐석적치장 전반에 걸쳐 토사재해가 관측된 임기광산에 대해 지반공학적 유변학적 시험을 수행하고 얻어진 시험결과를 토대로 1-D 토석류 수치해석을 수행함으로써 토석류의 확산성을 조사하였다. 모래와 자갈로 구성된 광산폐석 시료의 유변학적 특성을 조사하기 위해 베인관입형 레오미터(Vane-penetrated rheometer)를 사용하였으며, 전단응력 제어를 통한 전단응력(<TEX>${\tau}$</TEX>)-전단속도(<TEX>${\dot{\gamma}}$</TEX>)와 점도(<TEX>${\eta}$</TEX>)-전단속도(<TEX>${\dot{\gamma}}$</TEX>) 간의 상관관계를 얻었다. 또한 광산폐석 시료에 대해 잘 알려진 유변학적 모델들(Bingham, Herschel-Bulkley, Power-law, bilinear 및 Papanastasiou 모델)을 적용함으로써 수치해석에 필요한 유변학적 매개변수(항복응력과 소성점도)를 결정하였다. 실험결과에 따르면, 체적농도에 무관하게 전형적인 전단담화(shear thinning) 거동이 관측되었으며, 함수비가 증가할수록 Bingham 유체처럼 거동하는 것으로 나타났다. 또한 사용된 모든 유변학적 모델들은 파괴 후 거동에 적합한 모델들로 밝혀졌다. 토석류 흐름특성을 조사하기 위해 실험결과를 토대로 토석류 크기(5 m, 10 m 및 15 m)와 항복응력(100 Pa, 200 Pa, 300 Pa 및 500 Pa)을 선정하여 1-D BING을 통해 수치해석을 수행하였다. 그 결과, 토석류 이동거리와 이동속도는 항복응력의 크기에 반비례한 것으로 나타났으며, 토석류 항복응력이 500 Pa 이하인 경우 대부분의 토사는 계곡부까지 흘러갈 수 있는 것으로 나타났다. 따라서 집중호우 기간에 산악지역에 방치된 광산폐석은 토사재해에 취약하고 2차적으로 인근 수계로 유입되어 환경적 문제를 야기시킬 수 있는 것으로 나타났다. Abandoned mines often cause environmental problems, such as alteration of landscape, metal contamination, and landslides due to a heavy rainfall. Geotechnical and rheological tests were performed on waste materials corrected from Imgi waste rock dump, located in Busan Metropolitan City. Debris flow mobility was examined with the help of 1-D BING model which was often simulated in both subaerial and subaqueous environments. To determine flow curve, we used a vane-penetrated rheometer. The shear stress (<TEX>${\tau}$</TEX>)-shear rate (<TEX>${\dot{\gamma}}$</TEX>) and viscosity(<TEX>${\eta}$</TEX>)-shear rate (<TEX>${\dot{\gamma}}$</TEX>) relationships were plotted using a shear stress control mode. Well-known rheological models, such as Bingham, bilinear, Herschel-Bulkley, Power-law, and Papanastasiou concepts, were compared to the rheological data. From the test results, we found that the tested waste materials exhibited a typical shear shinning behavior in <TEX>${\tau}$</TEX>-<TEX>${\dot{\gamma}}$</TEX> and and <TEX>${\eta}$</TEX>-<TEX>${\dot{\gamma}}$</TEX> plots, but the Bingham behavior is often observed when the water contents increased. The test results show that experimental data are in good agreement with rheological models in the post-failure stage during shearing. Based on the rheological properties (i.e., Bingham yield stress and viscosity as a function of the volumetric concentration of sediment) of waste materials, initial flowing shape (5 m, 10 m, and 15 m) and yield stress (100 Pa, 200 Pa, 300 Pa, and 500 Pa) were input to simulate the debris flow motion. As a result, the runout distance and front velocity of debris flow are in inverse propositional to yield stress. In particular, when the yield stress is less than 500 Pa, most of failed masses can flow into the stream, resulting in a water contamination.

On-line blood viscosity monitoring in vivo with a central venous catheter, using electrical impedance technique

Blood viscosity is an important determinant of microvascular hemodynamics and also reflects systemic inflammation. Viscosity of blood strongly depends on the shear rate and can be characterized by a two parameter power-law model. Other major determinants of blood viscosity are hematocrit, level of inflammatory proteins and temperature. In-vitro studies have shown that these major parameters are related to the electrical impedance of blood. A special central venous catheter was developed to measure electrical impedance of blood in-vivo in the right atrium. Considering that blood viscosity plays an important role in cerebral blood flow, we investigated the feasibility to monitor blood viscosity by electrical bioimpedance in 10 patients during the first 3 days after successful resuscitation from a cardiac arrest. The blood viscosity–shear rate relationship was obtained from arterial blood samples analyzed using a standard viscosity meter. Non-linear regression analysis resulted in the following equation to estimate in-vivo blood viscosity (Viscosityimp) from plasma resistance (Rp), intracellular resistance (Ri) and blood temperature (T) as obtained from right atrium impedance measurements:Viscosityimp=(−15.574+15.576RpT)SR (−.138RpT−.290Ri). This model explains 89.2% (R2=.892) of the blood viscosity–shear rate relationship. The explained variance was similar for the non-linear regression model estimating blood viscosity from its major determinants hematocrit and the level of fibrinogen and C-reactive protein (R2=.884). Bland–Altman analysis showed a bias between the in-vitro viscosity measurement and the in-vivo impedance model of .04mPas at a shear rate of 5.5s−1 with limits of agreement between −1.69mPas and 1.78mPas. In conclusion, this study demonstrates the proof of principle to monitor blood viscosity continuously in the human right atrium by a dedicated central venous catheter equipped with an impedance measuring device. No safety problems occurred and there was good agreement with in-vitro measurements of blood viscosity.

Processing the vane shear flow data from Couette analogy

A new procedure is described to convert the vane torque and rotational velocity data into shear stress vs shear rate relationships. The basis of the procedure consists in considering locally the sheared material as a Bingham fluid and computing a characteristic shear rate from Couette analogy. The approach is first applied to experimental vane data of Newtonian fluid, then used to process vane experimental data of non-Newtonian and yield stress materials. Results, which are favourably compared with torsional flow, show that the approach correctly predicts the rheological behaviour of the materials investigated.

Investigation of interfacial slip in immiscible polymer blends

In this study, we investigated an interfacial slip phenomenon occurring in immiscible polymer blends. We chose a binary polymer blend in which the interaction parameter, χ, between the component polymers is high, and thus the interface is thin and entanglement is weak. It was observed that the negative viscosity deviation (NVD) of the blends is large, which might be attributable to interfacial slippage between the interfaces. It was also observed that incorporation of a compatibilizer in the blends significantly reduced the NVD, via suppression of interfacial slip due to increased interfacial strength. We carried out a specially designed experiment to verify that interfacial slip is indeed responsible for the NVD. We prepared several blend samples having different phase sizes ranging from 50 ∼ 5 μm, and evaluated the shear stress vs. shear rate relationships of the samples using a capillary rheometer. We observed that the viscosities of the samples decreased as the phase sizes decreased, which is strong evidence of the occurrence of interfacial slip.

Shear Thinning Behavior of Concentrated Latex Dispersions

AbstractSummary: Measured viscosity vs. shear rate relationships were analyzed for a wide variety of carboxylated latexes reported in the literature using the theoretical model proposed by one of the authors. The theory contains three main parameters: cm, ko and δ, which are the maximum volume fraction, a particle interaction parameter closely related to the secondary electroviscous effect, and the thickness of the stabilizing surface layer, respectively. It is assumed that sheared dispersions always approach close packing for high volume fractions, i.e. cm = 0.74, and that the shear thinning is entirely due to the energy dissipation associated with hydrodynamic and colloidal particle interactions, which at low shear rates is larger than at high ones (for simple shear flows). The experimental data include those by Laun who measured the viscosity of concentrated latex dispersions over nine order of magnitude of shear rate ranging from 10−3 to 106 s−1, and Chu et al., who prepared several monodisperse latexes and measured the viscosity of individual as well as trimodal blends of these three latexes as a function of shear rate. The viscosity of carboxylated latex is also influenced by surface “hair”, which appears to be closely related to the amount and type of functional monomers, and degree of dissociation of carboxylic acid groups on the latex surface.

Comparisons of modified effective medium theory with experimental data on shear thinning of concentrated latex dispersions

Measured viscosity vs shear rate relationships were analyzed for a wide variety of carboxylated latexes reported in the literature using a modified effective-medium theory proposed by one of the authors. The theory contains three main parameters, cm, ko, and δ, which are the maximum volume fraction, a particle interaction parameter, closely related to the secondary electroviscous effect, and the thickness of the stabilizing surface layer, respectively. It is assumed that sheared dispersions always approach close packing for high volume fractions, i.e., cm=0.74 (for monodisperse suspensions). In general, ko increases with the magnitude of the secondary electroviscous effect and its value varies typically between 2.46 and 4.0 for low Péclet numbers, Pe, and approaches 1.7 for very high Pe. For dispersions of highly charged particles at low electrolyte concentrations, the electroviscous effects become especially significant and experiments show that the viscosity can increase by more than three orders of magnitude when the electrolyte concentration is reduced from 10−1 to 10−3 M, an effect predicted by the modified effective medium theory. The viscosity of carboxylated latex is also influenced by a “hairy” surface layer, the thickness, δ, of which appears to be closely related to the amount and type of functional monomers, and the degree of dissociation of carboxylic acid groups on the latex surface. The theory also explains the shear thinning behavior of blends of latexes with different size.

Processing the Vane Shear Flow Data from Couette Analogy

Abstract A new procedure is described to convert the vane torque and rotational velocity data into shear stress vs shear rate relationships. The basis of the procedure consists in considering locally the sheared material as a Bingham fluid and computing a characteristic shear rate from Couette analogy. The approach is first applied to experimental vane data of Newtonian fluid, then used to process vane experimental data of non-Newtonian and yield stress materials. Results, which are favourably compared with torsional flow, show that the approach correctly predicts the rheological behaviour of the materials investigated.

A Comparison of Simple Rheological Parameters and Simulation Data for Zymomonas mobilis Fermentation Broths with High Substrate Loading in a 3-L Bioreactor

Traditionally, as much as 80% or more of an ethanol fermentation broth is water that must be removed. This mixture is not only costly to separate but also produces a large aqueous stream that must then be disposed of or recycled. Integrative approaches to water reduction include increasing the biomass concentration during fermentation. In this paper, experimental results are presented for the rheological behavior of high-solids enzymatic cellulose hydrolysis and ethanol fermentation for biomass conversion using Solka Floc as the model feedstock. The experimental determination of the viscosity, shear stress, and shear rate relationships of the 10 to 20% slurry concentrations with constant enzyme concentrations are performed with a variable speed rotational viscometer (2.0 to 200 rpm) at 40 degrees C. The viscosities of enzymatic suspension observed were in range of 0.0418 to 0.0144, 0.233 to 0.0348, and 0.292 to 0.0447 Pa s for shear rates up to 100 reciprocal seconds at 10, 15, and 20% initial solids (w/v), respectively. Computational fluid dynamics analysis of bioreactor mixing demonstrates the change in bioreactor mixing with increasing biomass concentration. The portion-loading method is shown to be effective for processing high-solids slurries.

Rheological characterisation of food thickeners marketed in Australia in various media for the management of dysphagia. II. Milk as a dispersing medium

The shear stress–shear rate relationship of six food thickeners from guar gum, modified starch and xanthan gum in homogenised and pasteurised full cream (HPFC), skim milk (SKIM) and ultra-high temperature or ultra-heat treated full cream (UHT) was investigated at 20 °C. For all the thickened fluids, shear stress increased as the rate of shear increased from 1 to 100 s −1. An increase in solids content increased the viscosity, density and yield stress. The type of milk significantly influenced ( p < 0.05) the density of the fluids and SKIM milk could yield the densest fluids. Irrespective of the type of milk, the guar gum-based thickened fluids (Guarcol TM and Supercol TM) were the most viscous, and they exhibited the highest yield stress. Among the three types of milk, the most viscous thickened fluids or thickened fluids with the highest yield stress were obtained when SKIM was the dispersing medium. The Herschel–Bulkley models were found to be the most suitable rheological models for the shear stress–shear rate data. The regression parameters obtained are valuable in calculating the weights of the thickener and dispersing medium for clinical uses.

Rheological characterization and wall slip of polymethylvinylsiloxane and high density polyethylene

The rheological behavior and wall slip phenomena in the shear flow of a commercial polymethylvinylsiloxane (PMVS) and a high density polyethylene (HDPE) were studied by using a rotary rheometer with parallel plates fixtures. The damping function obtained from the stress relaxation experiment was compared with the prediction results of Doi-Edwards theory with the independent alignment approximation (IAA) and that of Marrucci et al model. Wall slip phenomena in the steady shear flow for PMVS and HDPE were studied by checking the gap dependence of the shear-stress and shear-rate relation. The results show that when strain grows, the discrepancy between the experiment and theory increases probably in that single reptation considered is not enough for polydisperse systems. As the strain applied in stress relaxation increases, more than one peak stress values are obtained, suggesting that strain localization or stratified strain may occur inside the samples. In the shear stress range from 100 to 5 000 Pa, anomalous slip behavior can be observed for PMVS, while no obvious slip for HDPE.

Viscosity–Shear Rate Relationship during the Thixoforming of HP9/4/30 Steel

Thixoforming involves shaping metal components in the semi-solid state. Work on the thixoforming of high temperature materials, such as steel, is still at its initial stage; this is mainly due to the high processing temperatures involved and the potential for oxidation. For thixoforming to be possible, it is preferable for an alloy to have an appreciable melting range and before forming the microstructure must ideally consist of solid metal spheroids in a liquid matrix. This paper discusses the thixoforming load versus displacement curves of HP9/4/30 steel semi-solid slugs under compression. The data from the corresponding load-displacement curves is converted into viscosity against shear rate adopting Stefan’s equation for flow between two parallel planes. The viscosity at processing conditions, i.e. at processing temperatures in the range of 1470 to 1480°C and zero to two minutes soak times, showed a rapid decrease initially, which corresponds to a rapid breakdown in the structure, followed by a steady decrease to a near constant value with increasing rate. The work shows pseudoplasticity (or shear-thinning) behaviour of the HP9/4/30 semi-solid slurries. This data would be required for modeling the die fill with these slurries.

On the derivation of the symmetric and asymmetric Hele–Shaw flow equations for viscous and viscoplastic fluids using the viscometric fluidity function

In viscometric flows, the viscometric fluidity function is used to define the shear rate as a function of the shear stress. This relationship is unique even if the viscosity function is constant or has a plateau. As far as a viscoplastic fluid is concerned, the viscometric function is zero when the magnitude of the shear stress is below the yield stress and is positive when the fluid has yielded. Using this fluidity function and integration by parts, it is quite simple to integrate the equations of motion defining a Hele–Shaw flow in viscous and viscoplastic fluids for both symmetric and asymmetric flow conditions. From this, the average velocity field is derived in a manner which is superior to those based on the viscosity–shear rate relationship, especially since such a relation is not invertible in all cases.