Values Of Shear Rate Research Articles

Synthesis and Analyses of Hair Conditioner with Natural Essence from <i>Picea Pungens Glauca</i> Leaves

The main purpose of this study is to synthesize hair conditioners using natural essence sources and determine the fluid properties of hair conditioners. The essence obtained from Picea pungens glauca (Blue Spruce Pine) leaves using Soxhlet extraction via ethanol was used to formulate a hair conditioner. Picea pungens, native to North America, are resistant to wind and air pollution and are grown in many regions. It has a strong flavor due to the terpenes in the leaf extracts. Here, we formulated a hair conditioner with these extracts, and then the physical and chemical features of the conditioners were examined. Characterization studies were done by viscometer, gas chromatography, gas chromatography-mass spectrometry, Fourier transform infrared spectroscopy, and ultraviolet-visible spectroscopy. On the other hand, the shear rate and viscosity values were used to determine whether the synthesized creams were Newtonian or non-Newtonian. The conditioners were determined to be Newtonian fluids based on the results obtained.

Understanding the flow behavior around marine biofilms

In vitro platforms capable of mimicking the hydrodynamic conditions prevailing in natural aquatic environments have been previously validated and used to predict the fouling behavior on different surfaces. Computational Fluid Dynamics (CFD) has been used to predict the shear forces occurring in these platforms. In general, these predictions are made for the initial stages of biofilm formation, where the amount of biofilm does not affect the flow behavior, enabling the estimation of the shear forces that initial adhering organisms have to withstand. In this work, we go a step further in understanding the flow behavior when a mature biofilm is present in such platforms to better understand the shear rate distribution affecting marine biofilms. Using 3D images obtained by Optical Coherence Tomography, a mesh was produced and used in CFD simulations. Biofilms of two different marine cyanobacteria were developed in agitated microtiter plates incubated at two different shaking frequencies for 7 weeks. The biofilm-flow interactions were characterized in terms of the velocity field and shear rate distribution. Results show that global hydrodynamics imposed by the different shaking frequencies affect biofilm architecture and also that this architecture affects local hydrodynamics, causing a large heterogeneity in the shear rate field. Biofilm cells located in the streamers of the biofilm are subjected to much higher shear values than those located on the bottom of the streamers and this dispersion in shear rate values increases at lower bulk fluid velocities. This heterogeneity in the shear force field may be a contributing factor for the heterogeneous behavior in metabolic activity, growth status, gene expression pattern, and antibiotic resistance often associated with nutrient availability within the biofilm.

Kinematics-Based Design Method and Experimental Validation of Internal Meshing Screw for High-Viscosity Fluid Mixing

The challenge of mixing high-viscosity materials is a common issue encountered in the manufacturing process of food materials. The advantages of the internal meshing screw mixer have led to its adoption in various manufacturing processes, but it has yet to be implemented in the food industry. The paper presents a design method for an internal meshing screw mixer based on kinematic principles. The mixer features a helical chamber created by alternating volumes formed by the stator and rotor, establishing an extension-dominated environment for mixing high-viscosity fluids. A kinematic model based on the internal cycloid principle was established, providing trajectories and equations for key points on the rotor, simulating both its rotation and revolution processes, and revealing the velocity variations at different points on the rotor. Based on the kinematic analysis results, a stator and rotor design method was developed according to relevant functional divisions. To achieve the desired motion effects, transmission and support devices were designed, and the relationship between the transmission device and the internal cycloid surface of the fixed rotor was established. The mixer’s application and mixing effectiveness in the food industry were validated using corn syrup and flour. Experimental results showed that the extensional mixer described in the paper effectively mixed high-viscosity fluids while also efficiently blending fine powders. Slurry viscosity was tested with a rheometer at different speeds with an eccentric rotor mixer. Results showed that viscosity decreased with increasing shear rate, with a more pronounced decrease at higher shear rates. The apparent viscosity trend remained consistent at different speeds, although variations were observed at lower shear rates, especially concerning speed. The non-Newtonian fluid index exhibited minimal variations at different speeds, while the consistency coefficient showed significant fluctuations. The mixing uniformity index of the slurry was used to evaluate the mixing uniformity and dispersion uniformity of this extensional mixer. At different rotational speeds, the density of the slurry changes little. The uniformity index of mixing decreases gradually with the increase of rotational speed, reaching its maximum at 15 r/min. The overall trend of the uniformity index decreases with increasing rotational speed, indicating a decrease in density uniformity. A peak appears at 45 r/min, possibly due to the maximum values of elongation rate and shear rate at this speed. As the rotational speed increases, the residence time of the material in the mixer decreases, which may be the main reason for the decrease in mixing uniformity. These findings provide valuable insights into the design and utilization of extension-dominated screw mixers within the food industry, laying a solid foundation for future research and practical applications in this field.

Development of zinc nitrate hexahydrate salt (ZNH)/ethylene glycol (EG) binary composite deep eutectic electrolytes

In this study, zinc nitrate hexahydrated (ZNH)/ethylene glycol (EG) binary composite deep eutectic solvent (DES) were developed by a combination of hydrogen bond acceptor (HBA) (i.e.ZNH) and hydrogen bond donor (HBD) (i.e. EG) at various molar ratios (1:3, 1:4, 1:5 and 1:6) using heating method. The electrochemical and physicochemical properties DES were analyzed using Ionic conductivity (σ), refractive index, density, viscosity, thermogravimetric (TGA), Fourier transform infrared spectroscopy (FTIR), cyclic voltammetry (CV), and electrochemical impedance (EIS). The results revealed that DES 1:6 exhibited the lowest viscosity values of 579, 381, 119, 110, and 58 mPa s at shear rate values of 20, 30, 60, 100, and 200 (s−1) respectively. Similarly, the lowest values of density (1.392 g/cm3) and lowest values refractive index (1.441) and highest value of σ (7.51 mS/cm) were obtained. The cyclic voltammetry (CV) result also presented a wider range value of electrochemical potential window (EPW) (i.e. 1.06 V) showing the reversibility of electrochemical electrolytes due to the delocalization of charged ions that creates a bigger void volume inside the solution. Hence, these findings show that DES with the molar ratio of 1:6 can be a potential solvent for different electrochemical storage applications.

Design and experimental study on rheological behavior and sealing performance of shear sensitive fluids to control lost circulation during drilling

Loss circulation is considered as a time-consuming, costly, and challenging issue while drilling or cementing jobs, which ought to be treated and resolved promptly. The choice of a treatment that quickly plugs the loss zone and helps to restore the circulation is critical. Cross-linkable polymer gels play a significant role in mitigating drilling fluid loss, but controlling the gelation time and pumpability are the main challenges of these gels. This research aims to evaluate a novel smart fluid that has high flexibility in design. The shear sensitive fluid (SSF) is an oil-based fluid containing a polymer, gelation agents, and multi-crosslinkers. After passing through the drilling bit, the SSF is crosslinked with time to produce a high strength gel. The designed shear sensitive fluid is one of the possible solutions for severe loss circulation.The overall purpose of this research was to scrutinize the gelation behavior and SSF performance as a smart lost circulation treatment, which was followed in two sections including experimental analysis and empirical modeling. The effect of various factors including the type of crosslinker, shear rate, emulsifier concentration, temperature, shear history, salinity, etc. on the performance of the formed gels was studied. Furthermore, the maximum sealing pressure of formed gels in the highly permeable porous medium and fractured core as well as the probability of formation damage was evaluated.In order to determine the correlations required to predict the ultimate gelation time of SSF, the response surface methodology was utilized according to the central composite design. The considerable values of correlation coefficients (R2 = 0.91) prove the validity of estimated models for the fit enough responses with the experimental data. For the designed SSFs, depending on the operating conditions, the appropriate gelation time can be adjusted by emulsifier concentration and shear rate values. Also, the minimum gelation time and the highest crosslinking rate occur approximately at the shear rate of 45,000 1/s. At high shear rates, the effect of temperature on the functionality of the formed gels decreases, which is due to the high rate of crosslinking. Based on dynamic sealing pressure tests, the SSFs have a high potential in mitigation of lost circulation during drilling. The maximum sealing pressure was measured above 1000 psi in highly permeable porous medium and up to 600 psi in fractured core, which indicate the high strength of the formed gels against drilling fluid pressure. The designed SSFs could be easily removed from reservoir by 15 vol% hydrochloric acid, indicating the non-damaging properties of the formed gels.

A comparative study of altered hemodynamics in iliac vein compression syndrome.

Introduction: Iliac vein compression syndrome (IVCS) is present in over 20% of the population and is associated with left leg pain, swelling, and thrombosis. IVCS symptoms are thought to be induced by altered pelvic hemodynamics, however, there currently exists a knowledge gap on the hemodynamic differences between IVCS and healthy patients. To elucidate those differences, we carried out a patient-specific, computational modeling comparative study. Methods: Computed tomography and ultrasound velocity and area data were used to build and validate computational models for a cohort of IVCS (N = 4, Subject group) and control (N = 4, Control group) patients. Flow, cross-sectional area, and shear rate were compared between the right common iliac vein (RCIV) and left common iliac vein (LCIV) for each group and between the Subject and Control groups for the same vessel. Results: For the IVCS patients, LCIV mean shear rate was higher than RCIV mean shear rate (550 ± 103s-1 vs. 113 ± 48s-1, p = 0.0009). Furthermore, LCIV mean shear rate was higher in the Subject group than in the Control group (550 ± 103s-1 vs. 75 ± 37s-1, p = 0.0001). Lastly, the LCIV/RCIV shear rate ratio was 4.6 times greater in the Subject group than in the Control group (6.56 ± 0.9 vs. 1.43 ± 0.6, p = 0.00008). Discussion: Our analyses revealed that IVCS patients have elevated shear rates which may explain a higher thrombosis risk and suggest that their thrombus initiation process may share aspects of arterial thrombosis. We have identified hemodynamic metrics that revealed profound differences between IVCS patients and Controls, and between RCIV and LCIV in the IVCS patients. Based on these metrics, we propose that non-invasive measurement of shear rate may aid with stratification of patients with moderate compression in which treatment is highly variable. More investigation is needed to assess the prognostic value of shear rate and shear rate ratio as clinical metrics and to understand the mechanisms of thrombus formation in IVCS patients.

Rheological Characterization of Gofio and Aloe Vera Blended Juice

Considering that gofio (Gf) and aloe vera juice (AVJ) have very good nutritional qualities, their combination is proposed because it is indicated as an easy and fast source of basic bio-elements. The texture of a food must be accepted by customers. This means that the rheological characteristics of the product must be known and controlled. Therefore, the influence of Gf concentration on the rheological behavior of Gf/AVJ suspensions must be determined. With continuous shear experiments, the purely viscous response of a material can be obtained. AVJ and Gf/AVJ suspensions showed shear-thinning behavior. The ability of Gf particles and aggregates to distort the flow field was quantified determining the intrinsic viscosity η of the suspensions at several shear rates using Krieger–Dougherty equation. The results indicated that the shape and size of Gf aggregates is not affected by the mechanical action due to shear. The power law (Ostwald–de Waele) model fitted the experimental steady viscosity versus shear rate values (steady viscosity curves). The flow index was less than 1, which corresponded to shear-thinning behavior. It was obtained that the flow index of AVJ maintained unaltered despite the presence of Gf particles. However, the viscosity value increased with the increasing amount of Gf as it was expected. The viscoelastic behavior of the microstructure at rest of the AVJ and Gf/AVJ suspensions was studied using oscillatory shear tests. First, linear viscoelastic response was confirmed in the relatively low amplitude shear region γ0<0.001 using an amplitude sweep shear test. After that, frequency sweep shear tests were conducted in the region where Gf/AVJ suspensions showed linear viscoelastic behavior. Varying the frequency, the response of the microstructure at rest of the suspensions when the mechanical action lasts from short to long time interval can be characterized. Jeffreys mechanical model was used for the analysis of the LVE response of Gf/AVJ suspensions. Using small amplitude oscillatory shear (SAOS) tests, it was obtained that Gf/AVJ suspensions are viscoelastic liquids that change their texture from chewy to creamy when the Gf concentration increases.

Study on the Function of Conveying, Kneading Block and Reversing Elements on the Mixing Efficiency and Dispersion Effect inside the Barrel of an Extruder with Numerical Simulation.

In order to better understand the extrusion process mechanism of plant protein inside a barrel, the parameter changes and flow characteristics of fluids under conveying, kneading block and reversing elements were investigated with numerical simulation. The results showed that the shear rate increased obviously with the increase in pitch; the shear rate value of the reversing element was larger, while that of the kneading block was the opposite. The screw combinations of conveying, kneading blocks and reversing elements all have a certain degree of mixing effect on the particles, and the reduction in pitch can effectively increase the mixing effect of the particles. The conveying element can provide a relatively constant acceleration for the particles, due to the pumping capability and pressure buildup as the pitch increases. The kneading block and the reversing element can increase the leakage flow between the discs and backflow, resulting in an extension of the residence time distribution that facilitates fluid interaction in the barrel and improves the dispersion of the particles. The restraint by the reversing element on the particles is obviously weaker than that of the kneading block and shows a higher particle mixing degree. Overall, the influence of different elements on the flow condition, mixing degree and residence time is significantly different, which improves the process controllability and provides references for potential applications to meet multiple demands.

READY-TO-EAT CHICKPEA PURÉE POWDER BY DRUM DRYING; PHYSICOCHEMICAL AND RHEOLOGICAL PROPERTIES OF POWDER PRODUCT

This study aims to convert raw chickpea (Cicer arietinum L.) into dried chickpea puree powder form using a drum dryer having a high rehydration ratio and for ready-to-use consumption form maintaining its healthy properties. The effects of the drying conditions on the physical, chemical, and rheological properties of chickpea puree powders were investigated. Before drying, raw chickpeas were soaked in water at 25°C for 12 hours and boiled at 100°C for 55 minutes. In the drying process, saturated steam pressures (2, 3, and 4 bar) and drum rotation speeds (2.0, 3.0, 4.0, and 5.0 rpm) were chosen as process variables. The most appropriate process conditions were determined as 3 bar of steam pressure and 2 rpm of drum rotation speed targeting the maximum protein content (30.35±0.18%), maximum rehydration ratio (515±0.01%), and as low as possible browning index (BI)(59.28±4.90) values. It was determined that chickpea puree had the appropriate rheological characteristics when the shear stress and shear rate values for chickpea puree powders with various dry matter contents (%25, %26, %27.5, %30) produced under suitable process parameters were examined.

Binary glycerol-based deep eutectic solvents containing zinc nitrate hexahydrate salt for rechargeable zinc air batteries applications with enhanced properties

Deep eutectic solvents (DESs) have attracted interest due to their unique and favorable electrochemical characteristics. This study reported a novel binary glycerol-zinc salt deep eutectic solvents were prepared with a combination of hydrogen bond donor (glycerol (Gly)) and hydrogen bond acceptor (Zinc nitrate hexahydrate (ZNH)) at different molar ratios of 1:2, 1:3, 1:4, 1:5, and 1:6. The various physicochemical properties including viscosity, refractivity index, conductivity, thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FTIR), cyclic voltammetry (CV) and electrochemical impedance (EIS) were measured. The results showed that among the various combinations tested, DES 1:2 resulted in a low viscosity value of 690, 500, 310, 220, and 160 mPa (mPa s) at shear rate (S−1) values of 20, 30, 60, 100, and 200 respectively. Moreover, DES 1:2 resulted in more electrochemically stable solvents with a lower refractive index value of 1.446, and a higher conductivity (σ) of 4.41 mS/cm. The findings found disclose the features, nature and of properties of prepared DESs as a potential solvents for different electrochemical storage applications.

CONTROL OF THE SHEAR STRAIN IN THE HOMOGENIZATION ZONE OF THE DISK EXTRUDER

A simple method for determining the quality of a polymer melt is very important in production. A method that provides simplicity and quick use, making it valuable for optimizing extrusion processes.
 This work describes how the mixing effect can be improved by changing the velocity fields and thereby changing the shear strain values. The shear strain has been calculated for all four channels of the homogenization zone of a disk extruder. It was found that changing the disk rotation frequency allows changing mean value of the channel shear strain rate from 3324 to 4966 with constant performance for the entire homogenization zone. The impact of the different channels on the mixing effect was evaluated, with the first, second, third, and fourth channels contributing 21%, 57%, 15%, and 7% respectively to the overall homogenization zone's effectiveness of mixing. Additionally, it was found that the second channel experiences the highest shear strain values. In the case of the third channel, although the shear rate values are relatively high, the short residence time of the melt element results in comparatively smaller shear strain values. The average shear strain values remain constant for a given disk speed. It is indicated that it is possible to assess the quality of mixing by the amount of energy supplied, which simplifies the process of determining the quality of the melt, as well as its regulation.

Microscopic activated dynamics theory of the shear rheology and stress overshoot in ultradense glass-forming fluids and colloidal suspensions

We formulate a particle and force level, activated dynamics-based statistical mechanical theory for the continuous startup nonlinear shear rheology of ultradense glass-forming hard sphere fluids and colloidal suspensions in the context of the elastically collective nonlinear Langevin equation approach and a generalized Maxwell model constitutive equation. Activated structural relaxation is described as a coupled local-nonlocal event involving caging and longer range collective elasticity which controls the characteristic stress relaxation time. Theoretical predictions for the deformation-induced enhancement of mobility, the onset of relaxation acceleration at remarkably low values of stress, strain, or shear rate, apparent power law thinning of the steady-state structural relaxation time and viscosity, a nonvanishing activation barrier in the shear thinning regime, an apparent Herschel–Buckley form of the shear rate dependence of the steady-state shear stress, exponential growth of different measures of a yield or flow stress with packing fraction, and reduced fragility and dynamic heterogeneity under deformation were previously shown to be in good agreement with experiments. The central new question we address here is the defining feature of the transient response—the stress overshoot. In contrast to the steady-state flow regime, understanding the transient response requires an explicit treatment of the coupled nonequilibrium evolution of structure, elastic modulus, and stress relaxation time. We formulate a new quantitative model for this aspect in a physically motivated and computationally tractable manner. Theoretical predictions for the stress overshoot are shown to be in good agreement with experimental observations in the metastable ultradense regime of hard sphere colloidal suspensions as a function of shear rate and packing fraction, and accounting for deformation-assisted activated motion appears to be crucial for both the transient and steady-state responses.

Rheological Test of Flowability and Diffusion Behavior of Carbon Fibre Reinforced Polyamide

Various materials have been produced to be used as feeder material in 3D printing application to obtain the level of mechanical properties and physical properties of a product. Before to its usage as a 3D printing feed material, polyamide-reinforced carbon fibre composites were investigated for flowability and diffusion behaviour. Using a heated nozzle to transform polymer filament into a semi-liquid that is extruded to create a structure layer-by-layer, the primary issue to prevent is delamination. For the success of this study, there are 2 main methods, namely to study the physical properties of carbon fibre reinforced polyamide composites against the composition of 20 wt.% carbon fibre and to study the temperature and rheological load on the rheological properties. Rheological test analysis found that the material flowability of 20 wt.% CF/PA at temperature parameters 210 °C, 230 °C and 250 °C against rheological loads (40, 60, 80) N recorded a range of viscosity values between 48.80 Pa.s to 97.88 Pa.s and shear rate value range between 19700 s<sup>-1</sup> to 20270 s<sup>-1</sup>. Parameter optimization analysis using Taguchi method found that the largest factor contributing to the viscosity of CF/PA composite feed material was the addition of load applied. Moreover, the microstructural results of CF/PA composites show that smoother surfaces and good polymer structural bonding occur at an extrusion temperature of 250 °C. As a result, the rheology-derived flow rate may be used to tackle the problem of delamination and layer separation in 3D printing.

Investigation of Polymer Flood Performance in Light Oil Reservoir: Laboratory Case Study

The use of polymer solutions in the application of chemical EOR injection technology has a role in increasing oil recovery efforts by improving oil mobility in porous media. The addition of the polymer solution is expected to increase the viscosity value of the displacement fluid so that it can form a “piston-like” effect to increase the volumetric sweep efficiency of the light oil reservoir. The polymer used in this study was HPAM using 3 concentrations, namely 500 ppm, 1000 ppm, and 1500 ppm conducted at a temperature of 70 °C. The rheology test of the polymer included concentration vs temperature and shear rate vs viscosity. Thermal stability testing of polymer for 7, 14, 30, 60, and 90 days at 70 °C was done to determine the stability of the polymer solution. Filtration testing was conducted with the criteria of FR 1.2. The static adsorption test has been done with the standard limit of adsorption value 400 µg / gr. Polymer injectivity test using 3 variations of injection rates and coreflooding test were conducted to determine the reduction of Sor in reservoirs due to polymer displacement. From the polymer testing stage, it was found that HPAM polymers at 3 concentrations were compatible with the injection. This is indicated with the clear solution for 3 concentrations at room temperature and 70 °C. The rheology test results showed that the polymer solution with 3 concentrations was decreased in viscosity with the addition of the shear rate value. In the thermal stability test, the viscosity value of the HPAM with 500 ppm was relatively constant. The value of the FR for HPAM 500 ppm is 1.1, HPAM 1000 ppm is 1.07 and HPAM 1500 ppm is 1.03. The results of the static adsorption test showed the lowest HPAM value of 500 ppm was 156 µg/gr. In the injectivity test results, the resistance residual factor (RRF) values at injection rates of 0.3, 0.6, and 1 cc/min were 0.8, 1.04, and 1.12. The RRF value was close to 1, indicating that after injection of 500 ppm of HPAM tended to not experience plugging. Polymer flooding shows the oil recovery factor (RF) of water injection is 39% OOIP, and RF after polymer injection with 0.35 PV with flush water is 13.5% OOIP or 22% Sor. Knowing the behavior of HPAM polymer with various concentrations to be used for chemical EOR injection, it could provide advantages for future implementation in the light oil reservoir in Indonesia.

Role of Goldenberry (Fruits with Husk) Extract in Ameliorating the Architecture and Osmotic Fragility of Red Blood Cells in Obese Rats.

Goldenberry (GB) is a promising fruit that can be a constituent in many possible nourishments. No notifications were obtained regarding the impact of exposure to goldenberry extract in the viewpoint of blood rheological properties as well as erythrocyte osmotic fragility of red blood cells (RBCs) in obese rats. A substantial reduction in plasma triglyceride, total cholesterol, and LDL, with a considerable increment in HDL levels relative to the obese group (p ≤ 0.05), was observed in rats receiving low and high doses of GB, accompanied by restoration of SOD activity and GSH levels. Rheological parameters of rats' blood have been studied over a wide range of shear rates (225-1875 s-1). A significant decrease in blood viscosity in rats who received low and high doses of GB extract was compatible with every shear rate compared to the control group. The shear stress values of the obese rats reduced appreciably (p ≤ 0.05) in all values of shear rate (from 75 to 500 s-1) proportional to the control group, while in the groups that received low and high doses of GB extract, shear stress was restored to the control values. Finally, administration of GB extract significantly decreased yield stress and indices of whole blood aggregation, with an extremely substantial increment in flow rate, in rats given low or high doses of GB compared to obese ones. The result also showed a decrease in both the average raised osmotic fragility and the hemolysis rate in rats after supplementation with low and high doses of GB extract.

The study of edible vegetable oils rheological properties

The study of technological media rheological properties in the food industry is of primary importance for innovative food products development. This kind of research results can be recommended for reconstructing the suspensions, solutions, and mixtures properties and behavior. The objects of testing are the following types of edible vegetable oils: sunflower, mustard, linseed, camelina, rapeseed, milk thistle. The aim is to determine the rheological properties of the studied oils and to find out their dependence on temperature. Tests at shear rates γ = 100 ÷ 1000 s-1 in the temperature range of 20 - 120°C were carried out in this work. The viscosity was determined with the Brookfield DV-II + PRO viscometer. The data analysis showed that the dynamic coefficient for the studied samples of oils changed insignificantly in the range of the shear rate values γ = 600 ÷ 800 s-1. This can be explained by the structure strengthening due to the formation of additional intermolecular bonds. The nature of the rheological curves was established. The data obtained are recommended for use in the implementation of methods of hydromechanical and thermal processes intensification in the studied oils obtaining.

Investigation of the Changes in Rheological Properties of Purple Basil Sherbet Samples Concentrated by Ohmic Heating at Different Voltage Gradient

Purple basil is widely used medicinally and aromatically due to its essential oil properties, and it is a plant that stands out with its antibacterial, antimutagenic and antioxidant properties. It has been determined that purple basil has positive effects on health such as appetizing, insomnia, sputum, diuretical and antispasmodic. Purple basil contains high concentrations of anthocyanins and with these properties it stands out as a potential new source of stable red pigments for the food industry. In recent years, it has been seen that purple basil has been processed into different products such as tea and sherbet in order to benefit from its functional properties. With the processing of purple basil into different products, it is seen that the consumption of basil and basil products has increased by consumers. In this study, purple basil sherbet samples were concentrated at different voltage gradient values (14, 17 and 20 V/cm) under atmospheric conditions with ohmic heating up to 25% soluble solid content (SSC) and the changes in their rheological properties during the concentration process was investigated. The changes in the rheological properties of the purple basil samples were determined in the range of 1-148 s-1 shear rate values and measurement temperature was 25°C. The compatibility of different rheological models (Newton, Power-Law and Herschel-Bulkley) to the experimental data was statistically evaluated to determine the flow behavior index of the purple basil sherbet samples. It has been determined that the shear stress values increased as the shear rate values increased in all the process conditions. Similarly, at the same shear rate values, it was determined that the shear stress values increased as the SSC values increased. It has been determined that the best suitable rheological model was Herschel-Bulkley Model for all purple basil sherbet concentrates. It is thought that the results obtained will provide important data to the food and machinery industry for the installation of pilot and industrial scale ohmic heating systems.

Three-dimensional simulation of lateral migration of fiber in a laminar channel flow

The lateral migration of a neutrally buoyant fiber in a three-dimensional (3D) channel flow bounded by four walls is numerically studied using a generalized immersed boundary-lattice Boltzmann method. The slender fiber is modeled as an elastic Kirchhoff rod to well reproduce its bending and twisting behaviors. Our simulations first examined the lateral migration of a flexible fiber released at six typical positions. The results show that the fiber accumulate at an isosurface of a specific shear rate value regardless of its initial lateral position. Thus, it would be more physical to characterize fiber accumulation behavior by the accumulation shear rate (γα*) rather than the accumulation position. The fiber basically migrates laterally along the shear rate gradient when there is a discrepancy between the local and the accumulation (target) shear rates. For a fiber of medium flexibility, varying its initial position does not change its γα*, while it could impact its orbits and tumbling plane. Compared to planar Poiseuille flows, more complex fiber orbits with out-of-plane deformations are observable in channel flows, and the fiber could adjust its tumbling plane to adapt to the surrounding shear rate gradient during its lateral migration. Our simulation results further confirm that the tumbling rate of the fiber increases with the increasing local shear rate. The impact of the effective flexibility of the fiber (Λeff) on its lateral migration is also explored by considering a broad range of effective flexibility (Λeff). The results show that the Λeff relates to the γα* non-monotonically, and five monotone intervals are captured. The results would enrich our understanding of fiber accumulation behavior in 3D wall-bounded flows and may also shed light on how we can sort fibers/filaments in microfluidic devices.

A Novel ZnO Nanoparticles Enhanced Surfactant Based Viscoelastic Fluid Systems for Fracturing under High Temperature and High Shear Rate Conditions: Synthesis, Rheometric Analysis, and Fluid Model Derivation.

Surfactant-based viscoelastic (SBVE) fluids are innovative nonpolymeric non-newtonian fluid compositions that have recently gained much attention from the oil industry. SBVE can replace traditional polymeric fracturing fluid composition by mitigating problems arising during and after hydraulic fracturing operations are performed. In this study, SBVE fluid systems which are entangled with worm-like micellar solutions of cationic surfactant: cetrimonium bromide or CTAB and counterion inorganic sodium nitrate salt are synthesized. The salt reagent concentration is optimized by comparing the rheological characteristics of different concentration fluids at 25 °C. The study aims to mitigate the primary issue concerning these SBVE fluids: significant drop in viscosity at high temperature and high shear rate (HTHS) conditions. Hence, the authors synthesized a modified viscoelastic fluid system using ZnO nanoparticle (NPs) additives with a hypothesis of getting fluids with improved rheology. The rheology of optimum fluids of both categories: with (0.6 M NaNO3 concentration fluid) and without (0.8 M NaNO3 concentration fluid) ZnO NPs additives were compared for a range of shear rates from 1 to 500 Sec−1 at different temperatures from 25 °C to 75 °C to visualize modifications in viscosity values after the addition of NPs additives. The rheology in terms of viscosity was higher for the fluid with 1% dispersed ZnO NPs additives at all temperatures for the entire range of shear rate values. Additionally, rheological correlation function models were derived for the synthesized fluids using statistical analysis methods. Subsequently, Herschel–Bulkley models were developed for optimum fluids depending on rheological correlation models. In the last section of the study, the pressure-drop estimation method is described using given group equations for laminar flow in a pipe depending on Herschel–Bulkley-model parameters have been identified for optimum fluids are consistency, flow index and yield stress values.

ESTUDIO NUMÉRICO DE LUBRICACIÓN VISCOELASTOHIDRODINÁMICA EN PRÓTESIS DE RODILLA CON FLUIDO NO NEWTONIANO

In this work, a computational model of thin film lubrication applied to a knee prosthesis was designed in order to make a comparison between three constitutive models, i.e. a power law, the Carreau-Yasuda model and the Cross model. The equivalent model of the knee prosthesis was modeled as a rigid cylinder on a deformable plane. The mechanical behavior of the deformable component representing the tibial base was assumed as a viscoelastic Standard Linear Solid(SLS). The governing equations were solved simultaneously with the determination of a free-moving boundary by implementing it in COMSOL Multiphysics software. The results obtained showed that the Cross model presents the highest shear rate value, the lowest film thickness and the dynamic viscosity with less variation along the lubrication channel, reaching a minimum viscosity value of 0.02 Pa.s. The Carreau-Yasuda model presents the highest value of friction coefficient, being 21.5 % higher than for the Power Law model and 3.67 % higher than the Cross model.