Common Rheological Models Research Articles

Assesment of rheological properties of drilling fluids based on rotational viscometry data

The model of interpretation of rotational viscometry data is described using a strict solution of the Couette flow equation and considering the information resulting from the experiments. Using the example of common rheological models of drilling muds, the influence of the radii ratio and rheological properties on the accuracy of their estimation was studied using the dependence of the Newtonian fluid shear rate gradient. Comparative results of the rheological properties assessment for drilling muds in industrial conditions are given. Keywords: bi-viscous fluid; Couette flow; maximum likelihood principle; rheologically stationary models.

Effect of Rheological Properties of Polymer Solution on Polymer Flooding Characteristics.

Polymer flooding is an appropriate enhanced oil recovery (EOR) process that can increase macroscopic sweep efficiency. We examined two polymeric superpushers at different salinities (10,000 and 42,000 ppm of NaCl and 18,000 ppm of CaCl2) and temperatures (30 to 75 °C) as polymer-flooding agents for the EOR process. Rheological and thixotropic tests were attempted to find shear viscosity change when the polymer solutions were introduced under different salinity and temperatures, followed by describing the rheological behavior with the two most common rheological models used for polymer solutions, and then a quadratic model with Design-Expert to detect the effective parameters. Core flooding tests were conducted afterward to determine the final proposed fluid. An increase in the concentration of monovalent ions and the addition of divalent ions adversely affected both types of polymers used, which was similar to the effects of a temperature increase. The Flopaam 3630S at 1000 ppm has more stability under harsh conditions and enables 22% and 38% oil recovery in carbonate and sandstone core rocks, respectively. Consequently, Flopaam 3630S can be the perfect polymer agent for different chemical flooding procedures in high-salinity oil reservoirs.

Реологічні моделі біологічних клітин

The most important experimental methods of studying the mechanical properties of cells, as well as the most common rheological models, among which the discrete models of the micro/nanostructure of the cell and continuous models that allow calculating the modulus of elasticity and viscosity of the cell in normal and pathological conditions are discussed. A review of continuous models is given with an indication of their features and differences. A new continuum model of the cell as a multi-layer shell filled with a viscoelastic fluid is proposed. Equations of the model and their solutions for cases of isotonic, isometric and dynamic experiments are obtained. Peculiarities of the mechanical behavior of the models depending on the identified parameters are investigated. A comparison with the data of experimental measurements is given. It is shown that the proposed multi-layer model allows evaluation of separate contribution of the mechanical properties of the cytoskeleton, membrane, adsorbed substances and the hydrated shell, which is important for clinical diagnosis of diseases by measuring the mechanical parameters of cells.

Viscosity reduction in polymer nanocomposites: Insights from dynamic neutron and X‐ray scattering

AbstractThe addition of nanoparticles to a polymer matrix can in certain cases induce a reduction in viscosity, with respect to the pure matrix, in the resulting composites. This counterintuitive phenomenon cannot be explained using the most common rheological models. For this reason, it has been chosen as a good example in this paper to demonstrate the value and methods of dynamic X‐ray and neutron scattering techniques for the investigation of polymer nanocomposites. An overview of the main results on this topic is presented together with an introduction to the basic concepts relating to X‐ray photon correlation spectroscopy, neutron backscattering, and neutron spin echo measurements.

Rheological characteristics of muskmelon (cantaloupe) pulp

The rheological characteristics of musk melon (cantaloupe) pulp was evaluated with a view to determine its flow behaviour, yield stress and applicability of common rheological models. The experimental data on rheological behaviour were analyzed on the basis of four models viz., Ostwald, Casson, Bingham and Herschel-Bulkley (H-B). However, Herschel-Bulkley model showed best fit. Consistency index (K) was found to decrease with increase in temperature. The yield stress value determined by three methods showed in the range of 3.6 to 4.1 Pa. Yield stress calculated from stress-strain plot showed the maximum value. Overall the rheological behaviour of musk melon pulp followed the pseudo plastic with yield stress.

Effect ­­­­­of ultrasonic irradiation treatment on rheological behaviour of extra heavy crude oil: A solution method for transportation improvement

AbstractThe highly viscous property of heavy oil often causes problems in its transportation in pipelines. Mixing heavy oil with light oil as well as ultrasound treatment are viable solutions to this problem. In this study, extra heavy crude oil samples were first diluted with 0, 0.05, 0.1, and 0.15 mL/mL (0, 5, 10, and 15 vol%) of a light crude oil; then the mixture was irradiated by ultrasonic waves for 0, 5, 10, 15, and 20 min; finally the viscous shear functions of all mixtures was measured at different values of shear rate at different temperature levels. The results revealed that the minimum viscosity of the diluted extra heavy crude oil samples was obtained at 10 min of ultrasonic irradiation. Moreover, the viscosity reduction rate in relation to temperature decreases as temperature increases. In other words, the maximum viscosity reduction rate occurred at 0.05 mL/mL (5 vol%) of light crude oil. Using the experimental data, the parameters of common rheological models were obtained and a new modified Power Law model was presented to calculate the effect of shear rate and temperature simultaneously.

Comparison of rheological models for jet grout cement mixtures with various stabilizers

The use of jet grouting technique for ground improvement has become very popular approach for civil engineering projects. Despite the availability of large number research related to development of this technique, the rheological models of grout flow have still become in concern for jet grout applications. Thus, an investigation on the performances of the most common rheological models (Bingham, Modified Bingham, Casson, Herschel-Bulkley, Robertson-Stiff, De Kee) for prediction of flow behavior in terms of the shear stresses due to the cement grout mixtures incorporating with the stabilizers of clay, sand, lime, bottom ash in various proportions (0–100%) has been addressed in this article for jet grouting. For this purpose, a thorough comparison of the rheological models has been performed using the flow curves of the shear stress-shear rate data collected from previous study. On the basis of the comparisons, the performances have been presented in a ranking scheme that represents the favorable models within the low to high ranking. It is found from the performances that all rheological models, except the Casson, at most of the stabilizer inclusions have been adequately fitted to the shear stress-shear rate data, resulting in the lower errors (MAE, RMSE) and the strong correlations (R>0.8) with a significant evidence (p<0.05). It is proposed from the ranking scheme that the Robertson-Stiff model and derived formulas in this study are most acceptable (high ranking), the De Kee model is moderate acceptable (moderate ranking), the Herschel-Bulkley and Modified Bingham models are less to moderate acceptable (low to moderate ranking), the Bingham model is least acceptable (low ranking), and the Casson model is unacceptable. Applicability of the ranking performances is relatively promising for jet grouting when compared with the measured shear stress-shear rate data.

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.

Rheological properties of salep powder-milk mixture.

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.

A generalized hydraulic calculation model for non-newtonian fluid pipe flow and its application evaluation

A generalized hydraulic model that is independent of the rheological model is presented for non-Newtonian fluids flow in pipes. The generalized model was developed without assuming that the generalized flow index (n’) remains constant over all shear rates. Based on the pipe flow control equation, the explicit equations between the wall shear stress and volumetric flow of all common rheological models flowing in pipe were obtained, such as the Casson model, HerschelBulkley model and the Robertson-Stiff model, and they all can be solved numerically to obtain the accurate wall shear rate and shear stress. We give the theoretic calculation method of n’ for all time-independent non-Newtonian fluids. This method is applicable to all common rheological models without the assumption that n’ is constant. Moreover, we derived the general expression of generalized Reynolds number and then gave a utility pressure loss calculation model. A set of measured hydraulic data were utilized to evaluate this model. The results show that it can precisely calculate pipe flow parameters for all types of different non-Newtonian fluid. The proposed model will lay a foundation for the application and more extensive use of complex but more precise rheological models in engineering.

Wetting and rheological characteristics of hydrophobic organic pigments in water in the presence of non-ionic surfactants

Wettability and rheological characteristics of highly hydrophobic organic pigments were determined in the absence and presence of surfactants. Two widely used pigments, carbon black (CB) and copper phthalocyanine blue (CuPc), were selected as model pigments. As wetting and dispersing agents, a range of non-ionic nonylphenol ethoxylated (NPE) surfactants with varying hydrophilic chain length was used in the tests. Wetting properties of the pigment powders were investigated by the contact angle measurements based on capillary rise method. Rheology experiments were carried out by a controlled shear stress rheometer. Rheological properties of pigment suspensions were determined by applying common rheological models to shear stress (τ) versus shear rate (γ) plots. The experimental results demonstrated that, highly ethoxylated surfactants were more efficient than less ethoxylated surfactants in reducing contact angle of pigment powders. Finally, it was inferred that CB and CuPc suspensions behaved virtually as Bingham plastic and shear thickening (dilatant) type suspensions, respectively.

A new utility calculation model for axial flow of non‐Newtonian fluid in concentric annuli

A new utility approach that is independent of the rheological model is presented for the flow of non‐Newtonian fluids in concentric annulus. The novel model was developed without assuming that the generalised flow index remains constant over all shear rate ranges. Based on the slot model, the flow rate expressions for all common rheological models flowing in annuli were obtained, such as the Herschel–Bulkley model, the Robertson–Stiff model, and the Four‐parameter model, and they all can be solved numerically to obtain accurate wall shear rate and shear stress. Following Metzner and Reed's study, we defined a generalised flow index for non‐Newtonian fluid flow in annuli. Through a theoretical analysis, we also defined a new effective diameter for non‐Newtonian fluid flow in annuli, which accounts for the effects both of annulus geometry and fluid rheology but which is different from that was proposed by Reed and Pilehvari. Through the generalised effective diameter we linked non‐Newtonian annular flow with Newtonian pipe flow. A general annular Reynolds number expression was derived from this method for conditions under which the generalised flow index is variable. A theoretical calculation method for the generalised flow index and a uniform pressure loss calculation model for non‐Newtonian flow in concentric annuli were developed, which are applicable to all time‐independent non‐Newtonian fluid. The predictions of this model have been compared with an extensive set of data from the literature. The comparisons of different fluids in different size annuli show very good agreement over the entire range of flow types.

Comparative Study of Different Form of Asphalt Mixture Viscoelastic Rheological Model

In this paper, based on the essential attribute of the asphalt mixture, the characteristics of the asphalt mixture creep deformation were analyzed. With the comparison of the theoretical and experimental results, the advantages and disadvantages of the common rheological models used as the reaction of asphalt mixture creep characteristics were studied. The characteristics of of the asphalt mixture deformation have been analyzed. For the accurate response of nonlinear viscous elasticity model of asphalt mixtures must be a reasonable combination of the characterization of deformation characteristics of various components, this paper reveals the rheological deformation of asphalt mixture of components and parts of correspondence with the proper models. Finally, the experimental data were given to verify the correctness of the proposed model.

Rheological and Textural Characteristics of Date Paste

The rheological properties of two commercial date pastes were investigated in the temperature range of 20–70°C. From typical flow behavior curves, it was observed that date pastes exhibited pseudoplastic behavior. The shear stress-shear rate data were fitted using six common rheological models. The Casson model best described the experimental data at all temperatures. The Arrhenius model described successfully the temperature dependence of apparent viscosity of date pastes (R2 > 0.99) with an Ea value in the range of 25,392.6–25,485.7 kJ/kmol. The textural attributes measured were: hardness, springiness, gumminess, cohesiveness, chewiness, and adhesiveness for the texture profile analysis test, and firmness, adhesive force, mean load, and total positive area for the Ottawa test. There was a significant difference in textural attributes between two varieties of date paste studied. Texture profile analysis results showed that all parameters obtained for black date pastes were higher than golden date pastes except for springiness and cohesiveness. However, the Ottawa results showed that golden date pastes were firmer and less adhesive than black date pastes.

Numerical analysis of a cylinder moving through rate-dependent undrained soil

Geo-hazard assessment of the potential damage to a pipeline caused by a submarine landslide requires a quantitative model to evaluate the impact forces on the pipeline. In contrast with typical geotechnical problems, the strain rate within the fast moving, flow-like submarine landslide is typically far higher, which will lead to enhancement of the soil strength and therefore result in larger impact forces. Generally, there are two possible predictive frameworks for strain-rate dependence: a fluid dynamics framework and a geotechnical framework. By comparison of common rheological models adopted in these two different approaches, a unified additive power-law model, a normalised form of the Herschel–Bulkley model from fluid mechanics, is explored in this paper. This model has been used in conjunction with a large deformation finite element approach to investigate the undrained limiting loads on a cylinder moving steadily through inertia-less soft rate-dependent material, in order to quantify the strain-rate effects. The flow mechanism and the effects of the shear-thinning index and Oldroyd number on the shear zones are explored. The calculated resistance factors are compared with the drag coefficients obtained from computational fluid dynamics analysis. The average rate of strain experienced by the soil flowing past the cylinder is estimated for a given flow velocity and an expression in the form of a conventional bearing capacity equation, but with shear strength linked directly to the normalised flow velocity, is proposed to predict the magnitude of the viscous force exerted by the debris flow.

A balanced foreland–hinterland deformation model for the Southern Variscan belt of Sardinia, Italy

AbstractDeformation related to orogenic collision has been investigated along a complete crustal section exposed throughout the Sardinian Variscides, Italy. The dynamics of grain‐scale deformation processes and palaeo‐differential stress have been examined within three major shear zones (Rosas Shear Zone—RSZ, Baccu Locci Shear Zone—BLSZ and Giuncana Badesi Shear Zone—GBSZ) developed at progressively deeper structural levels from the foreland to the inner zone during the D1 phase of shortening associated with Barrovian‐type metamorphism. Microstructural analysis reveals that the overall strain in quartz‐feldspathic and calc‐mylonites results from a combination of and, possibly, competition between several deformation mechanisms. At the sub‐greenschist level (RSZ), operating mechanisms are pressure‐solution associated with grain boundary sliding. Dislocation creep is the dominant process at the greenschist level (BLSZ), although pressure‐solution is still effective in zones of strain concentration. In the lower crust (GBSZ), deformation occurred in the range of 600–620°C and 0.7–0.9 GPa by a combination of dislocation creep and high‐T diffusional processes. Differential stresses inferred from quartz grain‐size and calcite twin piezometers decrease with increasing depth, as predicted by most common rheological models. Despite this general trend, the stress profile across each shear zone suggests a pronounced stress gradient towards the zone of maximum deformation, leading to an increase of strain‐rate up to two orders of magnitude. The results of this regional study demonstrate that both stress and strain within orogenic wedges are localized rather than distributed, allowing the crust to deform coherently at different structural levels. Copyright © 2010 John Wiley &amp; Sons, Ltd.

Rheological Properties of Chocolate Drink from Cupuassu

Flow behavior of chocolate drinks from Cupuassu (Theobroma grandiflorum, Sterculiaceae) from instantised and normal formulation, and enriched with calcium, were studied. Flow behavior was described using common rheological models (Newton, Power Law, and Bingham plastic). Experimental results, obtained at 25 oC and 40oC, fitted mostly the Ostwald and Bingham models, with R2 ? 0.997. The Newtonian model has 0.886 ? R2 ? 0.991. At 25 oC, as expected, viscosity of samples was higher and pseudoplasticity increased (n values were lower than 1). The spray-dryer process lead to differences of rheology of the ``chocolate'' milk drinks. The addition of microcrystalline cellulose plus calcium leads to a lower viscosity.

Flow properties of cellulose and carboxymethyl cellulose from orange peel

Cellulose was extracted with 10% NaOH at 35 °C for 22 h from defatted, protein, pectin and hemicellulose free, delignified orange peel. The combined effects of temperature and concentration on the viscosity of orange peel cellulose solutions were examined for a temperature range 20–60 °C and a concentration range 1–10 kg/m 3. Twenty-eight different models describing the combined effects of temperature and concentration on the viscosity were derived. Models were fitted to the experimental data and the model parameters were determined by nonlinear regression analysis. The orange peel cellulose was converted carboxymethyl cellulose (CMC) by etherification. The rheological properties of CMC from orange peel cellulose were determined using a rotational viscometer at five temperatures (10, 20, 30, 40 and 50 °C) and six concentrations (10, 15, 20, 25, 30, 35 kg/m 3), and it was found that CMC solutions exhibited pseudoplastic behaviour. Among the common rheological models, the power law model fits well the shear rate and shear stress data. The consistency index increased with concentration and decrease with temperature. The apparent viscosity was measured, at constant spindle speed, as a function of shearing time. It was found that the CMC solutions were described by the Weltman model and found to exhibit thixotropic behaviour.

Steady state flow behaviours of extruded blend of rice flour and soy protein concentrate

Rheological properties in terms of steady state flow behaviours of extruded dispersions (rice flour/soy protein concentrate blend), were investigated using dynamic rheometry. The effects of concentration (2%, 5%, 7%, 9% and 11%) and temperature (25–70 °C) on the rheological parameters (yield stress, flow behaviour index) of the non-expanded pellet blend (12.5% protein) were determined using common rheological models. Steady-shear viscosities in a range of shear rate from 0 to 500 s −1 were observed as a function of concentration and temperature. From typical curves showing the dependence of shear stress on shear rate, it could be observed that all suspensions exhibited a non-Newtonian and pseudoplastic behaviour. The model that best fitted the experimental data at all temperatures and concentrations was the Herschel–Bulkley model.

Rheological properties of cupuassu and cocoa fats

Cocoa butter is an important ingredient in chocolate formulation as it dictates the main properties (texture, sensation in the mouth, and gloss). In the food industry, the texture of fat-containing products strongly depends on the macroscopic properties of the fat network formed within the finished product. Cupuassu ( Theobroma grandiflorum , Sterculiaceae) is an Amazonian native fruit and the seeds can be used to derive a cocoa butter like product. In general, these fats are similar to those of cocoa, although they are different in some physical properties. The objective of this study was to analyze several properties of the cupuassu fat and cocoa butter (crystal formation at 25 ° C, rheological properties, and fatty acid composition) and mixtures between the two fats (rheological properties), in order to understand the behavior of these fats for their use in chocolate products. Fat flow was described using common rheological models ( Newton , Power Law, Casson and Bingham plastic).