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The Rayleigh-Taylor instability (RTI) between a heavier Newtonian liquid and a lighter thixotropic liquid is studied in this paper by weakly compressible smoothed particles (WC-SPH). It is assumed that the thixotropic liquid obeys the Moore rheological model. First, the developed code is verified against available Newtonian RTI cases. Then, it is applied to thixotropic RTI cases to investigate the effects of the different non-dimensional parameters, including the thixotropic number (destruction-to-rebuild ratio), Reynolds number, Bond number, and Deborah number. It is shown that Bo is the most paramount non-dimensional parameter (i.e., it determines whether the two-phase boundary is stable or unstable), while Re , De , and thixotropic numbers have secondary influences on RTI. Based on the obtained results, the behavior of the thixotropic case is similar to the Newtonian high viscous counterpart at initial times; however, it is different at long times. It is demonstrated that the value of the thixotropic number determines when the transition between the short-time and long-time phenomena occurs. • The effects of thixotropy are investigated on single-mode and multi-mode RTIs by WC-SPH. • By increasing the thixotropic number, the spike position is more advanced. • The threshold for changing the behavior of the thixotropic RTI depends on the thixotropic number. • The impacts of thixotropic behavior appeared sooner for multi-mode RTI. [ABSTRACT FROM AUTHOR]

The study focuses on the flow characteristics with geometrical considerations utilizing electrical-conduct Non-Newtonian Fluid. The tubular concentric annulus is the geometry selected for the investigation. The electric-conductive Non-Newtonian Fluid is a character-wise two-constant Bingham model used in this study. The study also utilized geometry, the magnetohydrodynamic (MHD) effect, and the hall current. The employed system had the inner tube spinning and the outer tube stationary. Prandtl's assumptions of boundary layer principles are applied to solve the governing equations using the finite difference method for various fluid flow parameters, the Gauss-Elimination method to compute the results, and the MHD field and geometrical factors with hall current. This paper discusses fluid flow properties such as axial, radial, tangential velocities, and pressure distribution. Further, the mentioned above flow properties impact the heat transfer effect. This research details how flow parameters in the concentric tube flow process affect the development of heat transfer effects in the MHD field and hall current. [Display omitted] • The development of MHD flow and heat transport have been studied computationally. • The impact of Hall current and Magnetic effect on the flow field has been considered. • This work refers to the non-Newtonian fluid as a two-constant yield stress fluid model. • The heat transfer impact has been calculated using the fluid flow properties. • This work has been done using a variety of fluid and geometric factors. [ABSTRACT FROM AUTHOR]

This paper uses the Volume of Fluid (VOF) method to simulate a double Co-Flow microfluidic device that can produce double emulsions in both Newtonian (water) and non-Newtonian fluids. The simulation is 2D axisymmetric and involves three phases. A model is evaluated in this study to examine how the size and double emulsion's generation rate are impacted by factors such as phase velocity, viscosities, interfacial tension, and the rheological properties of non-Newtonian fluids. The model predicted the process of emulsification successfully in dripping and jetting regimes and predicted the impacts of phase velocity on the dimension and frequency of compound droplets. Increasing the flow rate of the inner phase causes the inner droplets to grow, while the outer droplet dimensions remain mostly unchanged. Vice versa, an increase in outer phase flow rate reduces compound droplet size. However, when the middle phase's flow rate is enhanced, the size of detached droplets in the inner and outer phases undergoes opposite changes, i.e., decreasing and increasing, respectively. The results showed that in non-Newtonian fluids, smaller droplets are formed compared to water, and the diameter of the double emulsions formed decreases with the rise in the viscosity at zero shear rate of the non-Newtonian fluid. • Double emulsion formation is studied in both Newtonian and non-Newtonian ambient fluids. • By adjusting phase flow rates in Newtonian and non-Newtonian fluids, the double emulsion characteristics can be readily tuned. • The results showed that in non-Newtonian fluids, smaller droplets are formed compared to Newtonian fluid. [ABSTRACT FROM AUTHOR]

As a pivotal prospective clean energy source, the secure and efficient extraction of natural gas hydrate has emerged as a forefront concern within the global oil drilling industry in recent years. In this study, a self-developed multiphase pump adapted to "gas-liquid-solid" three-phase mixing is used to extract natural gas hydrate slurries which have non-Newtonian characteristics. Prior research on pumps has primarily focused on water, introducing a significant disparity in handling slurries containing hydrates. This paper investigates the hydraulic performance and flow field variations of a multiphase pump using three different concentrations of Herschel-Bulkley non-Newtonian fluids that exhibit rheological properties similar to natural gas hydrate slurries. Additionally, a viscous Newtonian fluid with seawater as the liquid phase medium is studied for comparison. The results show that the shear-thinning properties of the non-Newtonian fluid improve the efficiency of the pump. However, excessive concentration negatively affects the hydraulic properties. The flow field characteristics such as apparent viscosity and turbulent kinetic energy are closely related to the pump structure and fluid properties. Compared with viscous Newtonian fluid, the non-Newtonian fluid's also have a greater effect on the distribution of gas-solid phases. [Display omitted] • Paper analyzes 'gas-liquid-solid' multiphase pump for transporting non-Newtonian fluids in gas hydrate exploitation, using experimental and numerical methods. • Non-Newtonian fluids enhance multiphase pump efficiency but concentrated ones may harm transportation efficiency. • Study compares internal flow in multiphase pump, analyzing viscosity, turbulent energy, and pressure during non-Newtonian and viscous Newtonian fluid transport. • Paper examines multiphase pump's hydraulic performance and internal flow with varying speeds during non-Newtonian fluid transport. [ABSTRACT FROM AUTHOR]

We consider the micro- and the macro-scale to investigate the motion of single grains in a dilute suspension under shear flow and Poiseuille flow to analyze effects like shear-wall migration and rolling of grains as observed in physical experiments. To be able to simulate the behavior of fresh concrete or mud flow, as realistically as possible, we are taking into account a non-Newtonian Bingham–Papanastasiou rheology for the carrier fluid. Due to a surface coupled approach, Smoothed Particle Hydrodynamics (SPH) gives the opportunity to consider both, the motion of a solid particle, by tracking its center of mass and also surface points, and the interaction and influence on the near field of the velocity field in the fluid phase. We show an independence of the motion of solid grains from the surrounding carrier fluid. While the macroscopic flow reaches a stationary flow field quite fast, the motion of the solid grains still oscillates between parts of the fluid that flow with different velocities and does not show a stable steady state. Providing a comparison between the motion in a Newtonian and a non-Newtonian fluid, we point out the differences and thus the importance of the choice of the material model for the carrier fluid in numerical simulations. • SPH simulations of suspensions with Newtonian or non-Newtonian carrier fluid. • Detailed analysis of the motion of solid grains in a suspension on different scales. • Focus on the analysis of the near velocity field at the surface of solid grains. [Display omitted] [ABSTRACT FROM AUTHOR]

The work at hand studies thin-film flow instabilities in a non-Newtonian second-grade fluid moving over a stretching sheet. The analysis considers the free surface evolution equation of the thin second-grade viscoelastic fluid model based on the long-wave approximation method. We undertook a linear stability analysis using a normal mode approach and obtained expressions for the linear time growth rate, linear phase speed, and critical wavenumber, which illustrates the linear stability structure of the flow system. Furthermore, the multi-scale analysis of the fluid's weakly non-linear stability characteristics reveals the presence of subcritical instability in the linear stability zone. The study shows that the varying flow parameters affect the threshold amplitude, which influences the stable and unstable zones in the subcritical region. The outcomes show a stabilizing effect spanning the range of non-dimensional parameters, such as the second-grade parameter ranging from 0 to 100 in values, the surface tension parameter ranging from 0 to 100 in values, and the modified Froude number from 0 to 100 in values. [ABSTRACT FROM AUTHOR]

In this article, we consider the boundary layer two-dimensional Carreau fluid flow induced by a heated inclined flat plate. The flow having variational viscosity of Carreau fluid is considered. The dependence of thermo-physical properties on temperature and concentration is also discussed. Using the Falkner-Skan solution, the governing equations are converted into a system of ordinary differential equations, which have been solved by RK-five integration scheme along with a shooting method. Solutions are calculated for fluid with thermo-physical properties of shear-thinning (viscosity decreases with increasing shear-rate) and thickening (viscosity increases with increasing shear-rate) effects. Physical interpretation and discussion are presented regarding the base flow, temperature and concentration profiles. Boundary layer thickness engages inversely with pressure gradient m , whereas temperature profile shows a significant increase for higher values of ε 1. [ABSTRACT FROM AUTHOR]

The causes of coating irregularities in high-speed slot-die coating of catalyst slurries for polymer electrolyte fuel cells (PEFCs) have not been determined. Accordingly, in this study, slot-die-coating experiments and computer simulations of two-phase gas–liquid flow were conducted to explore coating instability in the high-speed coating of PEFC catalyst slurries applied through slot-die coating. The results obtained from experiments and simulations were consistent. A thinner target layer and a faster coating, causing non-uniform coating. This is caused by movement of the gas–liquid interface on the upstream side and side of the die, which entraps the gas phase. Viscosity and surface tension are important, and a lower ethanol content in the solvent increases surface tension and lowers viscosity, improving coating stability. [Display omitted] • PEFC catalyst slurry coating uniformity studied through experiments and simulations. • Results were consistent across experiments and simulations. • Coating is non-uniform at high speed, low thickness, and high ethanol ratio. • The coating occurs in a region with weak non-Newtonian behavior. [ABSTRACT FROM AUTHOR]

The control mechanism of the pressure drop and bubble size has a guiding significance for selecting the micropump, the pressure resistance design, and the precise control of the microfluidics. In this study, single-phase flows and gas-non-Newtonian fluid two-phase flows are studied in a microchannel containing curved structures. Sodium carboxymethyl cellulose solutions are used as the non-Newtonian fluids; water and nitrogen are used as Newtonian fluid and gas phases, respectively. The pressure drop and the bubble length are measured. The influences of operating conditions are discussed. The non-Newtonian properties of the solutions are found to affect the parameters measured significantly. The experimental results are compared with the existing models, and the fanning friction factor is used to evaluate the pressure drop. The two-phase flow pressure drop can be predicted by the Lockhart-Martinelli method with a newly developed C-coefficient as a function of the fluid characteristic parameters and microchannel structure parameters. The new correlation for two-phase pressure drop prediction has an error within 18%, smaller than existing models. A new prediction method for the dimensionless bubble length containing the two-phase friction multiplier is also given with an error of 16%. [Display omitted] • A novel microchannel containing curved structures was studied experimentally. • Empirical models for predicting pressure drop and bubble length were developed and compared with existing models. • The prediction accuracy of the pressure drop was improved by considering structural and non-Newtonian fluid parameters. • The prediction accuracy of the bubble length was improved by considering the influence of pressure drop. [ABSTRACT FROM AUTHOR]

The hydrodynamics performance of a ring-style Hockmeyer© high-shear impeller (HSI) in an unbaffled tank with Newtonian and shear-thinning fluids at Reynolds numbers (Re) between 20 and 300 is addressed. Power measurements of this study were used to validate computational fluid dynamics simulations. Key hydrodynamic parameters for the HSIs performance, i.e., pumping and power numbers, and viscous dissipation are analyzed. The effect of the off-bottom clearance (C), working fluid height (Z) (in the range 0.18 ≤ C/T ≤ 0.38 and 0.8 ≤ Z/T ≤ 1, where T is the tank diameter), and fluid rheology, on these parameters were investigated. Results show that the examined C/T and Z/T ratios do not significantly affect the power number. The fluid rheology, C/T and Z/T had, on the contrary, a significant impact on the remaining hydrodynamic parameters. For 45 ≤ Re ≤ 300, the shear-thinning fluid showed better performance for dispersion processes, i.e., higher pumping number and viscous dissipation, and lower power number than the Newtonian fluid. [Display omitted] • Hydrodynamics induced by a high shear impeller is studied by CFD approach. • Newtonian and shear-thinning fluids are used as working fluids. • Shear-thinning fluid allows better hydrodynamic performance for dispersion processes. • Optimal operating conditions for pigment dispersion processes are reported. [ABSTRACT FROM AUTHOR]

Heat transfer is an important process in many engineering, industrial, residential, and commercial buildings. Thus, this study aims to analyse the effect of MHD and viscous dissipation on radiative heat transfer of Reiner–Philippoff fluid flow over a nonlinearly shrinking sheet. By adopting appropriate similarity transformations, the partial derivatives of multivariable differential equations are transformed into the similarity equations of a particular form. The resulting mathematical model is elucidated in MATLAB software using the bvp4c technique. To determine the impact of physical parameters supplied into the problem, the results are shown in the form of tables and graphs. The findings reveal that the heat transfer rate reduces as the Eckert number and radiation parameter are introduced in the operating fluid. However, increasing the magnetic parameter raises both the skin friction coefficient and the local Nusselt number, which impulsively improves the heat transfer performance. The suction effect has a noticeable influence on the Reiner–Philippoff fluid, since increasing the suction parameter's value is seen to enhance the skin friction coefficient and the heat transfer performance. The dual solutions are established, leading to the stability analysis that supports the first solution's validity. [ABSTRACT FROM AUTHOR]

Ionic field effect transistors provide flexible and fast control of electrokinetic transport in nanofluidics, but most research has focused on Newtonian fluids. In this study, we use the finite element method (FEM) in COMSOL Multiphysics to solve the electro-osmotic flow of power-law fluids in a nanochannel using the Poisson-Nernst-Planck (PNP) and Navier-Stokes (NS) equations. The changes in wall surface charge density, ion concentration, fluid velocity, axial potential, and ionic current in the nanochannel under different gate electrode voltages and power-law indices were studied. The results show that under the same gate electrode voltage, the change of the shear-thinning fluid is more obvious, and the difference between the shear-thickening fluid and the Newtonian fluid is relatively small. The shear-thinning fluid with a power-law index of 0.8 has a velocity about 10 times higher than the Newtonian fluid, and its ionic current is also much greater than the Newtonian fluid. [Display omitted] [ABSTRACT FROM AUTHOR]

Soft self-assembled systems with smart functions have been explored over the past decades for diverse applications. However, the toxicity of synthetic surfactant based self-assembled systems and their stability always remain a point of concern. There is always a great quest to find an alternative to overcome such shortcomings of self-assembled systems. Hence, in this context, we made an effort to engineer self-assembled lyotropic liquid crystals (LLCs) using different concentrations of the medicinal plant Glycyrrhiza glabra L. in the nonaqueous polar media of glycerol, ethylene glycol and formamide. These nonaqueous solvents with considerable polarity, high cohesive energy, dipole moment and hydrogen bonding ability, not only offer the perfect environment for self-assembly, but also provide longtime stability. Nematic lyotropic ordering is obtained for studied systems at different concentrations of Glycyrrhiza glabra L./ nonaqueous solvents as confirmed via polarising optical microscopy (POM) and X-ray diffraction (XRD) analysis. Electrostatic and hydrogen bonding interactions among polar solvents and amphiphilic Glycyrrhiza glabra L. molecules could be responsible for nematic ordering. FTIR spectroscopy is employed to confirm the hydrogen bonding in LLCs. The prepared LLCs are studied through static, dynamic rheology under the shear range 1–100 s-1 to explore their fluidic behaviour and establish correlation with structural parameters. The studied LLC systems from three solvents exhibit non-Newtonian shear thinning behaviour at all concentrations. The dynamic rheology tests indicate the elastic behaviour of all LLC systems. LLCs derived from glycerol exhibit soft-solid gel-like behaviour, while weak gel-type behaviour is observed for ethylene glycol and formamide-based LLCs. Considering the medicinal value of prepared LLCs, their antibacterial activity has been checked against the gram-positive bacteria Bacillus subtilis. LLC phases show strong antibacterial activity, about 2–3 times better than that of the standard drug streptomycin used for this study. [Display omitted] [ABSTRACT FROM AUTHOR]

• Impact dynamics of shear-thinning droplets on spherical particle surface is studied. • The droplet collision process can be divided into three phases. • The shear-thinning feature increases the energy dissipation during impact. • Evolutions of spread factor, film thickness and dynamic contact angle are revealed. • An empirical formula is proposed to predict maximum spread factor. Non-Newtonian droplet impact is common in nature and industry. The viscosity of non-Newtonian liquids changes with shear stress, leading to different impact behaviors compared to Newtonian liquids. This study prepared shear-thinning solutions by adding HPMC polymer into deionized water and investigated its impact dynamics on hydrophobic spherical surface. The evolution patterns of droplet spreading factor, film thickness, and dynamic contact angle are investigated under different impact conditions. The results show that addition of polymers increases the energy dissipation during impact and suppresses droplet rebound from spherical surface compared to Newtonian droplet with similar viscosity. The droplet-impacting process is distinguished into three phases: (I) initial deformation, (II) inertia-dominated, and (III) viscosity-dominated phases. The temporal evolution of film thickness in Phases I and II is fitted by simple equations. In addition, an empirical formula that integrates Weber and Reynold numbers is proposed to predict the maximum spreading factor of HPMC droplets. [Display omitted] [ABSTRACT FROM AUTHOR]

This work is focused on the transient heat transfer of non-Newtonian fluid in a coil-cooled stirred tank through experimental and numerical approaches. A modified lumped capacitance method was established for a more accurate definition of the time constant at a limited coolant flowrate. The modified method breaks down the time constant into two terms: the first term is based on the system heat transfer capability and the second one on the coolant heat transport capability. Limited by the assumption of an infinite cooling capability, the simple lumped capacitance method attributes all of the time constant solely to the first term. The significant difference between the two models results in fundamentally different derivations used to calculate the overall heat transfer coefficient. Theoretical analysis indicates that the modified method align harmoniously with its original form. The results manifest that: (1) Within the operating range of all tests, the second term contributes 26.5–12.9% to the total time constant as coolant flowrate increases, making it a significant factor that should not be overlooked. (2) The simple method underestimates the overall heat transfer capability by 15.4–29.2% compared to the modified one. It subsequently underestimates the coil external and internal convection coefficients by up to 12.8% and 70.6% in comparison to the modified model, respectively, compared to the modified model. (3) The CFD-predicted overall heat transfer coefficient, coil external convection coefficient, and coil internal convection coefficient deviate by a maximum of 15.2%, 7.2%, and 32.1% respectively compared to the experimental values obtained through the modified lumped capacitance method. By the way, the CFD-predicted coil internal convection coefficient closely aligns with the Nusselt correlation for straight tubes adjusted using C r = 1.2. (4) A thorough analysis of CFD results reveals complex dynamics in stirred tanks, such as viscosity distribution patterns and areas of limited mass and heat exchange between middle and bottom impellers. This deep understanding enables root cause analysis crucial for optimizing configurations or designing uniquely structured tanks. (5) The revised lumped capacitance method expands on its original version by transitioning from assuming infinite cooling to accounting for limited transient cooling capacity. This shift is more realistic and crucial for thermal management and process control. • Coil heat transfer coefficients of CMC solution in a stirred tank investigated. • Modified lumped capacitance method was proposed. • Modified time constant depends on both heat transfer capability and heat transport capability. • Coefficients are notably underestimated by simple method. • CFD predictions agree well with experiments and provide meaningful insights. [ABSTRACT FROM AUTHOR]

• An experimental methodology to measure a non-Newtonian fluid flow with free surface. • Photometric and ultrasonic systems providing similar amplitude of roll wave. • An absorbance photometric technique to measure the steep front of the roll wave with high precision. This work aims to measure forced steady roll waves evolving non-Newtonian fluid flow by using absorbance photometric technique. Instabilities on the free surface of the uniform flow were induced by controlled air pulses, generating roll waves under specific conditions of Froude number and disturbance frequency. A systematic procedure was presented to clarify a compromise between the aqueous concentrations of Carbopol (with adequate viscosity) and methylene blue dye (avoiding optical opacity), providing both sensitivity and resolution for absorbance measurements. Roll waves amplitudes were also measured using an ultrasonic sensor in order to compare the results with the absorbance photometric technique. Given a channel inclination, six scenarios defined by different flow rates were tested, which allowed us to observe the generation of roll waves as a succession of shocks. The measured profiles showed a better precision (maximum error of 0.11 mm against 1.37 mm, for pump rotation equal to 475 RPM) using the absorbance photometric technique compared to the ultrasonic system, respectively. [ABSTRACT FROM AUTHOR]

• Shear flows in vibrated granular materials were experimentally studied. • Viscosity transitions and non-Newtonian behaviors occur in granular shear flows. • Two non-Newtonian fluid models were used to compare with experimental results. • Viscosity–temperature relationship reveals granular gas-like behaviors. • These findings were explained based on the mechanism of viscosity generation. In a continuous fluid, the presence of a velocity gradient perpendicular to the flow creates shear stress and shear rate between adjacent layers. The fluid's viscosity can be constant, depending only on temperature (Newtonian fluid), or vary with shear rate (non-Newtonian fluid). However, the viscosity characteristics of shear flows in discrete media, such as vibrated granular materials, remain insufficiently understood. This study experimentally investigated shear flows in vibrated granular media, exploring the relationship between shear stress, shear rate, and the impact of vibration conditions and particle number on granular viscosity. The findings indicate that the viscosity of sheared granular material transitions between dilatant and pseudoplastic non-Newtonian states with increasing vibration strength, shifts from pseudoplastic non-Newtonian fluid to Newtonian fluid with increasing vibration frequency, and remains consistently pseudoplastic non-Newtonian with increasing particle number. Two continuous non-Newtonian fluid models were utilized for comparison with our experimental results. Additionally, ascending curves of granular viscosity against granular temperature reveal gas-like flow characteristics in the sheared granular material, albeit with an abnormal descending viscosity–temperature relationship. These are attributed to volume expansion and oblique collisions in the vibrated granular medium. This study uncovers distinct viscosity properties in a discrete medium under shear flows, markedly different from those in continuous fluids, and highlights potential new applications for granular materials. [Display omitted] [ABSTRACT FROM AUTHOR]

• MHD natural convection for cooling with non-Newtonian fluids is studied. • MRT-LBM is used for complex fluid dynamics and heat transfer simulations. • Shear-thinning fluids (n < 1) significantly enhance cooling performance. • RC configuration enhances cooling in the presence of magnetic field and radiation. • Key control parameters impacting flow and temperature patterns are identified. This study addresses magnetohydrodynamic (MHD) natural convection involving non-Newtonian fluids. Focusing on the annular region between concentric circular and square cylinders, the research examines the impact of a vertical magnetic field and thermal radiation. The Multiple Relaxation Time Lattice Boltzmann Method (MRT-LBM) is employed to simulate momentum and energy interactions in non-Newtonian fluid. Control parameters like Rayleigh number, Hartmann number, Radiation parameter, aspect ratio, square cylinder subdivision, and power-law index are systematically varied, while maintaining a constant Prandtl number. Using shear-thinning fluid (n < 1) significantly improves cooling, particularly in conjunction with radiation effect. Correlations for the mean Nusselt number are established, offering insights. Results emphasize the substantial influence of parameters like Ra, Rd, and AR. High values of the latter promote the flow intensity and heat evacuation. For n < 1, increasing Ra from 103 to 5 × 104 results in a substantial increase in the heat transfer rate reaching 65 %. For shear-thickening fluid, the heat transfer rate is reduced by 25.31 % at Ra = 5 × 104 when Ha is increased from 0 to 50 in the absence of radiation. In addition, radiation enhances the heat transfer rate by 71.41 % by incrementing Rd from 0 to 0.8 for Ha = 0. The most pronounced effect of the radiation parameter is observed in the cases of Newtonian and shear-thickening fluids. Conversely, Ha and n act by reduction effects on the outputs of the problem. The attenuating effect of the magnetic field is more pronounced in the case of shear-thinning fluids. The plot of mean Nusselt number vs. AR shows an hysteresis phenomenon due to the existence of multiple steady solutions in a range of this parameter. In the latter range of AR, heat transfer induced by multicellular flow is higher than that induced by bicellular one. Heat transfer is somewhat enhanced by the RC configuration, compared to SC one. [Display omitted] [ABSTRACT FROM AUTHOR]

• Three novel tube-tube premixers were designed and their macromixing were simulated. • Micromixing efficiency in RPBs with tube-tube premixers were experimentally studied. • Coupling mechanism of tube-tube premixers and RPBs was revealed. • Micromixing times of RPBs with tube-tube premixers ranged from 2 to 10 ms. Rotating packed beds (RPBs), as the typical chemical intensification devices, have been widely applied in liquid-phase fast reactions and precipitation processes. In this study, three novel tube-tube premixers were designed, and three-dimensional CFD models of the flow and mixing processes for non-Newtonian fluids in tube-tube premixers were established. Meanwhile, the micromixing efficiency in RPBs with different tube-tube premixers was experimentally investigated. The results show that TG-2 premixer exhibits the best premixing performance. The segregation index decreases as the rotational speed or flow rate increases, indicating the increase in micromixing efficiency. With the increase of CMC mass fraction, the segregation index initially decreases and then increases. Moreover, the micromixing efficiency of TG-0-RPB is the highest in aqueous solution, the micromixing efficiency of TG-4-RPB is the highest in 0.2 wt.% CMC system, and the micromixing efficiency of TG-2-RPB is the highest when the CMC concentrations is equal to or greater than 0.4 wt.%. The micromixing times of non-Newtonian fluid in RPBs range from 2 to 10 ms. [ABSTRACT FROM AUTHOR]

The finite difference schemes for equations depicting the fluid flow, heat and mass transfer of viscoelastic fluid in porous media based on fractional constitutive model are analyzed, when Soret and Dufour effects are taken into account. Different from the conventional fractional partial differential equations, the governing momentum equation of this system not only contains convection terms, but also a term: D t β 0 (∂ 2 u / ∂ y 2) , which are great challenges when we do the stability analysis. In addition, the temperature equation and concentration equation are coupled with each other, which increases the difficulty of numerical analysis. By using the energy method, the stability and convergence of the finite difference schemes employed for the governing equations are obtained. The accuracy of the scheme for momentum equation is O (τ + h x 2 + h y 2) , while the one for temperature and concentration equations is O (τ 2 + h x 2 + h y). Finally, numerical examples are presented to verify methods and demonstrate the analysis effectiveness. [ABSTRACT FROM AUTHOR]

The study of multiphase flows has earned much attention from researchers due to its numerous applications in mechanics and industry such as sewage management, synthetic fabrication, electricity generation, and medication processes. In the present work, we examined the Poiseuille flow of a couple stress fluid between parallel plates in presence of velocity and temperature slip boundary conditions. The effects of thermal conductivity and thermal radiations, variable viscosity, and non-uniform magnetic field on velocity and temperature fields in the existence of hafnium nanoparticles are also investigated. The temperature-dependent viscosity model, namely, Vogel's model is utilized. The non-linear system of equations is solved numerically by using the shooting technique due to its fast convergence and prosperity to initial approximation. It is examined that the velocity slip parameter speeds up the flow rate of fluid but decelerated the temperature field while the temperature slip parameter upsurges the temperature of the fluid. It is also investigated that the concentration of nanoparticles enhanced both the velocity and temperature of the fluid. Further, the comparison of Newtonian and non-Newtonian (Couple stress fluid) is expressed with the help of graphs. To check the validation of results, a comparison with previous literature is also presented. [ABSTRACT FROM AUTHOR]

In this study, we experimentally investigate the effects of metal foam porous rings on heat transfer, pressure drop, and the heat transfer performance ratio of two non-Newtonian fluids in a double-pipe heat exchanger. Enhancing the heat transfer rate is crucial for reducing the size and cost of heat exchangers. We considered various parameters in the experiment, including the power-law index (0.91 and 0.85), porous ring thickness (4, 6, and 8 mm), and the number of porous rings (2, 4, 6). The flow is a turbulent regime, with the Reynolds number ranging from 4000 to 10,000. The test setup includes a test section with a length of 1.6 m and a diameter ratio of 0.6. Open-cell copper metal foam rings with a porosity of 0.92 are placed in the annular pipe, while the internal surface of the inner pipe is subjected to constant heat flux. The results show that, for non-Newtonian Carboxy Methyl Cellulose fluids with concentrations of 0.1% and 0.2%, the average heat transfer coefficients at Reynolds number 4000 increase by 22.0% and 32.0%, respectively. With porous rings, these coefficients increase by 80.3% and 92.7%. Additionally, the average friction factor increases by 19.2% and 35.5% without porous rings and by 320% and 280% with porous rings, respectively. Furthermore, increasing the number of porous rings from 2 to 6 increases the Nusselt number by approximately 16.8% and 17.1%, respectively. The maximum friction factor is 400% higher when using a 0.2% concentration of non-Newtonian fluid. Finally, the performance of the two non-Newtonian fluids improved by approximately 28% and 36.4%, respectively, compared to the base fluid. • Nu number & friction factor of non-Newtonian fluids in double-pipe with porous ring. • Nusselt number increased by 22% & 32% without and by 80.3% & 92.7% with porous ring. • Friction factor increased by 19.2% & 35.5% without and 320% & 280% with porous ring. • Adding porous ring from 2 to 6 raised non-Newtonian fluid Nusselt by 17.1% & 15.7%. • Maximum friction factor was 400% when using CMC 0.2% fluid. [ABSTRACT FROM AUTHOR]

High-performance micromixers play a crucial role in diverse industrial applications. Utilizing chaotic advection as a well-established technique improves mixing efficiency due to the induction of strong secondary flows, acting at the microscopic level for homogenization. This study systematically compares the micromixing process of non-Newtonian fluids using different configurations of spiral micromixers, including Simple Spiral Micromixer (SSM), Rectangular Spiral Micromixer (RSM), Variable Radius Spiral Micromixer (VRSM), and Twisted Spiral Micromixer (TSM). The examination is performed by analyzing effective parameters, such as microchannel geometry, inlet configuration, microchannel aspect ratio, Reynolds number (30 < Re 〈110), and non-Newtonian fluid characteristics, i.e., flow index (0.05 < n < 1) and relaxation time (0.007 s < λ < 0.7 s). Non-Newtonian shear-thinning behavior is described by using the Carreau-Yasuda model. The results include velocity profiles, distributions of the mass fraction, overall assessment of micromixers' performance, mixing energy cost (MEC), the ratio of the Poiseuille number to mixing index (P 0 / MI), and figure of merit (FoM). It is revealed that the TSM micromixer exhibits superior mixing with MI > 84% at Re = 110 when n = 0.05 and 0.2128. The value of FoM strongly depends on n, for instance, FoM of the TSM micromixer is 0.00014 and 0.00004 for n = 0.05 and 0.8, respectively when Re = 50. It is revealed that the MEC is enhanced with n for all micromixers for a given Re , for instance, the MEC of RSM micromixer is about 0.05, 0.07, and 0.38 for n = 0.05, 0.5, and 0.8, respectively, when Re = 50. [ABSTRACT FROM AUTHOR]

This study presents droplet diameter distributions downstream of a Counterflow nozzle for atomization of water and four non-Newtonian liquids, with a Flow-Blurring nozzle used as a reference. The test liquids were aqueous solutions of sodium carboxymethylcellulose (0.5%, 1%, 1.5% and 2% by weight) and had zero shear viscosity values in the range 13.8 – 1280 mPas. Rheological measurements show significant shear-thinning behavior accompanied by viscoelasticity, as quantified by a characteristic time scale for capillary thinning, as well as increasing levels of storage and loss moduli with polymer concentration. Droplet diameters were measured using a Particle Digital Image Analysis technique combined with diffuse back-lit shadowgraphy. High-speed imaging suggests that at the higher weight concentrations, the near-field structure of the spray has a tree-like structure similar to that observed in effervescent atomization. Long filaments with droplets at their end are visible, attesting to the extensional stresses in the fluid. At lower concentrations, the spray emerges as a cloud of ligaments and droplets that rapidly disintegrate, accompanied by a gas core. Further downstream, beads-on-a-string structures are seen, corresponding to capillary instabilities. An unusual non-monotonic behavior of the Sauter Mean Diameter(SMD) is observed in the downstream direction, which may be the result of an experimental pitfall associated with the assumption of spherical geometry, along with the motion of beads-on-a-string structures from regions of high to low shear. The spatial variation of the SMD indicates that, compared to Newtonian liquids atomized using this nozzle geometry, secondary atomization plays a more dominant role in determining the far-field droplet diameter distribution. The SMD is expressed as a weak function of the ratio of viscoelastic relaxation time to the visco-capillary scale characterizing ligament thinning. • Visco-elastic fluids are atomized using a counterflow nozzle with flow blurring as a reference. • Shadowgraphic images show viscoelastic inhibition of droplet fission. • Droplets of mean diameter less than 75 μ m are produced for all polymer solutions studied. • Mean diameters are correlated using air–liquid mass flow ratio and time scales for visco-capillary and visco-elastic processes. [ABSTRACT FROM AUTHOR]

This work investigates the Ohmic heating, nonuniform heat generation, and Hall effects with Cattaneo-Christov model (CCM) on flow and heat transfer of power-low non-Newtonian fluids (NNFs) past stretching surface embedded in a porous medium. Runge-Kutta method is used to solve non-linear ODEs numerically using a shooting procedure. We study non-Newtonian fluids for power law values of 0.7 and 1.2, respectively. Innovation of this work lies in studying the effect of Hall currents in presence of buoyancy force and an irregular heat source on slip flow of NNFs moving through Darcy porous medium. Varying velocities, surface frictional forces, and Nusselt numbers are examined. Resulting entropy is also examined using computational flow problem investigation. Model-simulated results suggested that various factors play critical role in constructing thermal systems. It is asserted that Hall parameter, mixed convection parameter, Biot numbers, and thermal relaxation time improve heat transference rates by directly affecting fluid molecules temperature. [ABSTRACT FROM AUTHOR]

In the modern day science and medics, scholars are focusing on the behavioral study of non-Newtonian fluid and its relevance with ciliated motion in human body. This would offer advanced avenues of research to mitigate the risks of new and contagious diseases relating to various systems in human body. This manuscript focuses on the behaviour of metachronal wave in Prandtl fluid generated by ciliated movement through a horizontal tapering channel once magnetic field is applied to the fluid. The theoretical approach raises mathematical calculations and results obtained presented highly nonlinear system of PDEs. Latterly, ODEs are developed which accrue the accurate results by using scaling group of transformations. Second, approximation of long wavelength and low Reynold's number used to analyze the flow motion caused by metachronal waves. The emerging equations achieved are further solved numerically using the bvp4c method. Results are engendered through graphical attempt of velocity, temperature, pressure gradient, pressure rise and wall shear stress graphs in relation to various factors. It can be inferred that theoretical impact of velocity profile for magnetic parameter decreases near the walls of the ciliated channel while increases in the middle of channel. It concludes that magnetic field opposes the strength of the flow close to the walls. Another observation is the flow of temperature across the subject domain is accelerated by the Brinkman number. Thus, the flow of heat transfer may be increased by the fast metachronal wave and fixed initial temperature. While streamlines are also fabricated to exhibit the flow phenomenon of ciliary motion. [ABSTRACT FROM AUTHOR]

Current research on non-Newtonian fluids using Smoothed Particle Hydrodynamics (SPH) has primarily focused on dynamic behavior, with limited exploration into interactions between rigid bodies and non-Newtonian fluids. Leveraging the SPH method's effectiveness in addressing free surface flow challenges, a two-dimensional numerical model of a rigid body impacting non-Newtonian fluids based on the Herschel-Bulkley-Papanastasiou (HBP) constitutive model is developed within the SPH framework. The study integrates experimental and numerical findings from non-Newtonian dam break scenarios, comparing particle distribution and the evolution of the waterfront over time to ensure accurate representation of non-Newtonian fluid behavior. While ensuring the convergence of SPH results, the research simulates the impact of a wedge on the surface of non-Newtonian fluids. This comparison of the slamming load exerted by non-Newtonian fluids on the wedge serves to validate the accuracy of the numerical method. Furthermore, the study explores the effects of varying initial velocities and roll angles of wedges slamming into specific non-Newtonian fluids. It analyzes fluid jet phenomena and changes in slamming loads. • A Herschel-Bulkley-Papanastasiou (HBP) constitutive numerical model suitable for slamming was established by SPH method. • The accuracy and robustness of the numerical model were embodied by reasonable validations about non-Newtonian fluids. • The parameters of the non-Newtonian fluids exert significant effects on the jet shapes in the progress of wedge slamming. [ABSTRACT FROM AUTHOR]

Marine clay may experience stiffness degradation and catastrophic failure when subjected to complex ocean dynamic loadings. This can result in instability, destruction, or capsizing of offshore structures. In this study, marine clay was regarded as a non-Newtonian fluid with shear-thinning behaviour, and the mechanism of progressive stiffness degradation during cyclic loading was discussed from the perspective of fluid dynamics. A series of cyclic direct simple shear tests were conducted on undisturbed marine clay obtained from three offshore sites. Further, the stiffness degradation and flow characteristics under different plasticity index (I P) and cyclic stress ratio (CSR) conditions were investigated and quantified using the stiffness degradation index (δ) and average flow coefficient (κ), respectively. The results revealed that the decrease in δ with the increasing number of cycles (N) in a semi-log scale can be categorised into three modes: (1) "linear" (nonfailure), (2) "fast–linear–fast" (failure), and (3) "linear–stable" (failure). Consequently, a two-parameter model was proposed to predict the δ of failure marine clay from different sea areas with varying I P and CSR values. Moreover, with the increase in N , κ of the nonfailure marine clay increased gradually in a very limited range, thus exhibiting illiquidity characteristics; by contrast, κ of the failure marine clay exhibited a "slow linear–exponential–rapid linear" growth pattern, thus indicating a change in liquidity from weak to strong. Finally, a unified model linking the stiffness degradation and flow characteristics of marine clay under different types and conditions was proposed, where κ at the cyclic failure state (the failure criterion is a double-amplitude shear strain of 15%) was denoted as κ f. Evidently, all data points of κ / κ f ∼ δ were distributed in a narrow range, and a virtually negative exponential relationship was observed between κ/κ f and δ. • The stiffness degradation of marine clay was investigated based on a shear-thinning non-Newtonian fluid-based method. • A universal equation describing the correlation between δ and N / N f was presented and validated. • The average flow coefficient was introduced to characterise the fluidity evolving from weak to strong during cyclic loading. • A model for quantifying the stiffness degradation incorporating the normalised average flow coefficient was developed. [ABSTRACT FROM AUTHOR]

• Various industrial configurations were simulated and evaluated for optimal heat transfer efficiency. • Nano metal particles were employed in the simulation to enhance heat transfer efficiency. • The results show that the square geometry with a certain amount of nano metals performs better than other common industrial geometries. • The simulation results align well with other researchers' laboratory results in this field. Spiral tube heat exchangers represent a conventional type of exchanger that finds use in industries such as food, chemical reactors, ventilation, and heat recovery systems. The compact structure, high mass, and heat transfer coefficient of spiral tubes have made them popular in many industries as heat exchangers. This article delves into the investigation of the flow of non-Newtonian Nano fluid CuO-CMC within pipes that possess different cross-sections. In order to analyze the heat transfer of the non-Newtonian Nano fluid flow in the spiral channel, both the single-phase model and the ANSYS Fluent commercial software were employed for simulation. In the realm of numerical simulation, investigation has been conducted on the flow of non-Newtonian water-copper oxide Nano fluid through spiral tubes having three distinct cross-sections, namely circular, square, and oval. The study aimed to delve into the effects of varying volume fractions of nanoparticles, inlet velocities, and cross-sectional areas on several parameters, including but not limited to average Nusselt number, local Nusselt number, vorticity, bulk temperature, transferred heat, average friction coefficient, and local friction coefficient. Elevating Re has a greater impact on Nu than adding nanoparticles. Even with 4% nanoparticles, Nu is lower than pure water with Re of 5000. Incorporating nanoparticles enhances fluid's thermal characteristics but disrupts flow. [ABSTRACT FROM AUTHOR]

In this study, we present numerical and theoretical study of enthalpy and solar radiative heat transfer in a generalized Newtonian fluid flow induced by a flat plate. Our theoretical study depends on thermal diffusion coefficient, thermophoretic and viscous dissipation approach for modeling the steady boundary layer flow of heat and mass transfer over a flat surface. Impact of thermal diffusion coefficient with newly introduced enthalpy at heat and mass equations is considered. The boundary layer equations are transformed into system of ordinary differential equations by applying similarity variables and solved numerically by utilizing fifth-order Runge–Kutta integrator scheme with shooting technique. The physical results are explored by utilizing theoretical and numerical approaches. The numerical results acquired for different mechanisms are presented through tables and figures. The physical properties of the appearing parameters on the mean flow, temperature and concentration are presented through graphs and tables The comparative results are calculated for a limited case and good agreement is noted with previously published work. • Carreau fluid flow near a flat surface are investigated. • Viscosity at initial steady state is discussed. • Enthalpy and thermal diffusion coefficient are considered heat and mass equations. • Thermophoretic effect is considered mass equation. • Relationship between kinematic viscosity and intermolecular force is described. [ABSTRACT FROM AUTHOR]

[Display omitted] • The effect of coaxial mixer configuration on local and overall k L a was investigated. • Combination of the Rushton turbine and anchor impeller resulted in the highest k L a. • k L a increased with the anchor speed of up to 10 rpm. • Local k L a and gas holdup decreased from the bottom to the top of the vessel. • Uneven distribution of gas holdup resulted in variation of the local k L a. Aerated stirred tank bioreactors are one of the most commonly used systems in various processes such as biofermentation where ensuring adequate mass transfer rate is the sole purpose. In this study, the crucial role of the central impeller type (including Rushton turbine, pitched blade turbine, elephant ear impeller and their combinations) on the performance of an aerated bioreactor equipped with two central impellers and an anchor on the local and overall volumetric mass transfer coefficient was investigated at a variety of operating conditions such as non-Newtonian solution concentrations, and central and anchor impeller speeds. Carboxymethyl cellulose (CMC) solution was used as a power-law fluid. Through the use of electrical resistance tomography, simplified dynamic pressure method, and computational fluid dynamics, several aspects of the aerated coaxial mixer namely local and overall gas holdup and mass transfer were studied. The local mass transfer coefficients were measured using three dissolved oxygen sensors installed at three various heights of the bioreactor. The local gas holdup was also measured using tomography. The results showed the positive effect of the anchor impeller on the mass transfer coefficient up to 10 rpm for different coaxial mixing configurations with various impeller type combinations and CMC concentrations. Among different impeller types, the system with two Rushton turbines resulted in the highest volumetric mass transfer coefficient, which was attributed to the higher gas holdup provided by this configuration as well as the flow pattern generated by the coaxial mixer. Moreover, the local distribution of gas holdup and mass transfer coefficient demonstrated a reduction in both parameters from the bottom to the top of the bioreactor. [ABSTRACT FROM AUTHOR]

• Radial displacement of Newtonian-Non-Newtonian fluids in Hele-Shaw cell was studied. • Paraffin and carboxymethyl cellulose were Newtonian and Non-Newtonian fluids. • Tip-splitting and dendritic patterns were observed during the interfacial developments. • In contrast with literature, interfacial instability decreased in low concentration of CMC solution. • Low interfacial tension and high zero-shear viscosity were the main reasons for this contradiction. We report on experimental study of interfacial instability in immiscible Newtonian-Non-Newtonian radial displacement occurs in Hele-Shaw cell where liquid paraffin was injected to displace carboxymethyl cellulose (CMC) solution. For the benchmark system, tip-splitting pattern was observed. Results indicated that the maximum change in the shear rate and viscosity of CMC solution occurs in the very early stage of the displacement process. The comparison between Newtonian-Non-Newtonian and Newtonian-Newtonian interfacial development, showed higher number of fingers for Newtonian displacement, but wider and longer fingers for non-Newtonian system. Investigation of concentration effect indicated that the interfacial instability decreased in displacing of 0.5%wt CMC solution. In contrast with literature, the instability increased significantly for 1.5%wt CMC solution, and dendritic pattern emerged instead of tip-splitting. This was due to the significant reduction in interfacial tension and rise in viscose forces. Moreover, the results showed that increasing the initial injection radius led to increment in fingers number and reduction in velocity of the dominant fingertip. Additionally, increasing the injection flowrate resulted in fingering pattern change from tip-splitting to dendritic type. Finally, comparing the number of the observed fingers with literature, suggested that using average capillary number; Ca ≤ 10−3, Paterson's theory may be followed by the experimental results. [Display omitted] [ABSTRACT FROM AUTHOR]

[Display omitted] • The unique flow patterns of non-Newtonian fluid were observed and analyzed; • The influences of gas and liquid flow rate and flow pattern on the two-phase pressure drop were investigated; • A new two-phase friction multiplier correlation was developed to calculate the two-phase pressure drop. An experiment of gas-non-Newtonian fluid flow was performed in a horizontal square microchannel to investigate the two-phase pressure drop and flow pattern. The pressure drops were measured and the images of the flow pattern were captured. In the non-Newtonian fluid, the flow pattern and flow regime map were different from those in water. The non-Newtonian behavior of the liquid phase also significantly affected the two-phase pressure drop. The relationship between the two-phase pressure drop and the gas and fluid flow rates relied on the flow pattern. A new two-phase friction multiplier correlation considering the gas-liquid flow rate ratio and the rheological properties of the liquid phase was developed to calculate the two-phase pressure drop. The new correlation can predict the experimental pressure drop data within the root mean square percentage errors of 12% for the gas-non-Newtonian fluid two-phase flow and 17% for the gas-water two-phase flow. [ABSTRACT FROM AUTHOR]

Microfluidic devices have drawn many researchers in the various fields of area such as biomedical diagnostics, biological and chemical analysis. Among these applications, micromixing has a prominent impact on the efficiency and sensitivity of microfluidic devices. In this study, an induced-charge electroosmotic solver with the presence of Joule heating effects has been developed in the open-source code package, OpenFOAM, to investigate the rheological effects of non-Newtonian fluids in a trapezoidal micromixer. The mathematical model and the developed solver are validated with existing data in the literature and the effects of micromixer geometry, various applied DC electric potential, rheological effects of fluid and the heat transfer are studied to attain an efficient micromixer. Results show that the proposed micromixer offers the advantages of high mixing efficiency with a high flow rate in comparison to other investigated geometries. Newtonian, Shear-thinning, and shear thickening fluids are studied in this article and it is shown that in Newtonian fluid and shear-thinning fluid, the mixing efficiency is enhanced by amplifying the applied electric field which can be concluded that the effects of vortices have more impact on mixing efficiency in comparison to the flow rate. On the other hand, in shear thickening fluid, the mixing efficiency is decreased by amplifying the electric field, because the flow rate is enhanced which leads to the increment of fluid viscosity and decrement of the strength of vortices. Finally, to analyze the fluid temperature rising because of the presence of Joule heating, the heat transfer is studied to assure the health of cells in the proposed micromixer. [Display omitted] • The most efficient geometry of micromixer is achieved. • The rheological fluid behavior on vortex formation by conducting surface is investigated. • The mixing efficiency for various behavior indexes of non-Newtonian fluid is examined. • The effects of electric potential and behavior index on heat transfer are studied. [ABSTRACT FROM AUTHOR]

This study investigated heat transfer enhancement and pressure drop for forced convection in a parallel channel partially filled with porous blocks and non-Newtonian nanofluid. There are four porous types in the channel are inserted to partially fill the channelthat used non-Newtonian nanofluid. The effect of the Brownian motion term in forced convection on the flow is examined. CuO-Water has been considered as nanoparticles. Simulation is based on two energy equations for solid and fluid regions and Darcy model in the porous blocks and a single-phase model for mixture of nano particle and based fluid. Effects of parameters has been discussed such as index of power law, Reynolds number, thermal conductivity ratio and nano-particle volume fraction. The numerical analysis assumed that the channel is subjected to heat flux in one side. The results showed that Reynolds number increased led to an improvement in heat transfer for 300 to 400 and it can be improve the Nusselt number by 31% for power-law index 1.5 in compared with Newtonian fluid. Heat transfer coefficient is increased by 12.8% for the power low index 1.5 compared with Newtonian fluid with increasing nano particle. [Display omitted] • The path of the fluid in the channel partially filled with the four porous blocks. • Increasing Reynolds number in a significant with increasing Nusselt number. • By increasing Reynolds number, pressure drop tends towards a fixed value. • By Adding Nano-particles to the non-Newtonian fluid enhance the thermal behaviour. • Also, Nano-particles led to increase heat transfer and Nusselt number. [ABSTRACT FROM AUTHOR]

This paper presents a numerical investigation of power-law fluid flow past and through elliptical porous cylinder, considering heat transfer effects. The study covers a wide range of parameters, including Reynolds number, power-law index, cylinder aspect ratio and Darcy number. The wake pattern, streamline distribution, drag coefficient, pressure distribution, and Nusselt number are analyzed comprehensively for various cases. Within the investigated parameter range, four distinct vortices are observed: an external vortex separated from the cylinder, an external vortex attached to the cylinder, a boundary vortex partially inside and outside the cylinder, and an internal vortex entirely inside the cylinder. The occurrence of the external and separated vortex is limited to AR = 0.2 and = 10 − 3 , while the internal and boundary vortices are exclusively observed at AR = 2.0. Additionally, increasing the aspect ratio of the elliptical cylinder results in shorter vortices at a given Reynolds and Darcy number. For example, at Re = 40 and D a = 10 − 4 , vortex lengths decrease from 5 to 0.6 with increasing aspect ratio from 0.2 to 2. Furthermore, by decreasing aspect ratio, the drag coefficient generally increases and the Nusselt number decreases from 0.2 to 1, but this trend reverses as the aspect ratio rises from 1 to 2. • Four distinct vortices (external separated, external attached, boundary, and internal) are observed. • External separated vortex is limited to AR = 0.2 and D a = 10 − 3 . • Internal and boundary vortices are exclusively observed at AR = 2.0. • Drag coefficient is considerably affected by vortex type. • At high values of Da number (Da = 10−1, 10−2), as the power index increases, the Nusselt number increases. [ABSTRACT FROM AUTHOR]

The Tiwari-Das nanofluid model has a serious anomaly, while estimating the mass and energy transport rates. Due to the absence of clear correlations and the fact that desirable parameters fluctuate with the characteristics of nanofluids, make it unable for precise predictions. To overcome on this dispute the Tiwari-Das model is coupled with Buongiorno's theory in the current model. The Eyring-Powell fluid with suspended Zinc oxide (ZnO) and iron (F e 2 O 3) keeping different volume percentage of nanoparticles are used to create a fluid mixture. The flow originates due to stretching sheet. The flow is subjected to upright Lorentz forces, while binary chemical species are consider on the sheet surface and far field. Furthermore, the ratio, reaction diffusion and frictional dissipation are also considered. The dimensionless governing equations are reduced to first order employing shooting mechanism and solved computationally using RK-4 approach. The outcomes for frictional coefficient, energy and mass transfer rate of hybrid nanoparticles and chemical species are reviewed using various statistical charts. From the computational outcomes for drag coefficient, we can adjudged that the frictional coefficient diminished on escalating fluid primary parameter and magnetic number. Increased percentage of nanoparticles, also detract the frictional coefficient. The mechanism of slip for nanoparticles are encouraging for energy transfer. The enhancement of energy and mass is significant with diffusion ratio parameter N bt . The influence of Lewis number is diminishing function of mass transport rate. The effect of homogenous reaction is encouraging for mass transport, while the heterogeneous and Schmidt number are diminishing. [ABSTRACT FROM AUTHOR]

______________________________________________________________________________________________________ [Display omitted] One of the most common reported adverse events for intravenous (IV) infusions are infusion site reactions, ranging from redness and pain at the site of infusion to thrombophlebitis. The connection between drug infusion and what drives these adverse events is not well understood. To aid in understanding these phenomena, it is crucial to accurately characterize the evolving hemodynamic environment of the infusion site when developing new intravenous formulations, as too rapid dilution may cause precipitation in the vein, while too little dilution might contribute to phlebitis. In this study, a Large-Eddy Simulation (LES) turbulence modeling inside a Computational Fluid Dynamics (CFD) framework has been used to simulate the flow and mixing characteristics of an infusion entering the bloodstream. This work represents the first such study reporting transient flow fields for intravenous infusions using LES CFD simulations with a realistic non-Newtonian blood model. The output of the CFD model closely resembled the flow and mixing patterns generated in benchtop tests for infusions into a blood analogue and water as the venous fluid across a wide range of flow rates. These models were then investigated further to compare how changes to the fluid rheology model, needle orientation and needle position within the vein resulted in altered mixing regimes at different flow rates. [ABSTRACT FROM AUTHOR]

The flow behavior of non-Newtonian fluid and its effects on the thermohydraulic performance of fin-tube heat exchangers (FTHE) equipped with rectangular winglet pairs have been numerically investigated. Three-dimensional numerical simulations were carried out for a range of Reynolds numbers (50-200) using an aqueous solution of carboxymethylcellulose commonly known as non-Newtonian shear-thinning fluid as a working fluid. These winglets are arranged in a common flow-up and common flow-down configuration and mounted at various angles of attack. The present study examines the effect of attack angle, the orientation of the tubes, the shear-thinning behavior of the carboxymethylcellulose, and the Reynolds numbers on the thermohydraulic performance of the FTHE. The findings reveal that a decrease in the angle of attack up to a certain limit improves thermohydraulic performance by providing better fluid intermixing at the cost of a considerable pressure drop. With an increase in Reynolds numbers, the performance of the FTHE increases by enhancing the Nusslet number of fluid. Additionally, employing aqueous solutions of carboxymethylcellulose as a working fluid in the channel with winglet improves the average Nusselt number and the average quality factor by 124%–186% and 111%–133% respectively compared to the water. [ABSTRACT FROM AUTHOR]

• A first numerical study on gas-focused non-Newtonian micro-jets, described by power-law rheology. • New findings on stability, shape, and velocities of such jets. • A detailed analysis of fluid flow patterns in the nozzle and in the jet as a function of the power-law index. The present numerical study assesses the jet length, diameter and velocity of various non-Newtonian power-law fluids of a gas dynamic virtual nozzle. A related two-phase flow problem is formulated within the mixture framework and solved with the finite volume method and volume of fluid interface treatment in axisymmetry. The process parametric range allows the incompressible laminar flow assumption. A comprehensive jet characteristics analysis is carried out in a typical micro-nozzle configuration for a range of shear-thinning to shear-thickening fluids with power law indices 0.5 ≤ n < 1.5, gas mass flow rate of 10 mg/min and liquid volumetric flow rate of 43 µl/min, resulting in a gas Reynolds number of 130 with Reynolds and Weber numbers for a reference water jet being 90 and 10, respectively. It is observed that jets from shear-thinning fluids (0.5 ≤ n < 1.0) tend to be thicker, longer, and slower when compared with the shear-thickening fluids (1.0 < n ≤ 1.5). A dripping-jetting phase diagram of the nozzle is constructed by varying the power law index, gas and liquid flow rates in the range 0.9–1.1, 5–15 mg/min and 5–50 µl/min, respectively. It is observed that the area of stable jetting decreases with the increase of the power law index. The obtained novel information on the behaviour of non-Newtonian gas-focused micro-jets provides a possible new dimension for tailoring the serial crystallography sample delivery systems where the micro-jets carry dispersed crystals into an X-ray beam. [Display omitted] [ABSTRACT FROM AUTHOR]

This study presents a comprehensive continuum approach to modeling granular surface flows using the Incompressible Non-Newtonian Smoothed Particle Hydrodynamics (INNSPH) method. The model integrates an incompressible SPH method, where pressure is computed by solving a pressure-Poisson equation with a non-Newtonian rheology. Projection-based SPH has a strong and rigorous theoretical basis can lead to stable and accurate simulations. This paper aims to develop a projection-based SPH method for modeling complex granular flows. INNSPH method combines incompressible SPH and μ(I) rheology models to simulate non-Newtonian viscoplastic fluid behavior in granular flows. Surface deposition, and velocity and pressure fields are estimated using a rheology model. Validation is performed by comparing simulation results, including surface profiles and run-out distances with experimental data, showing good agreement. INNSPH method is then employed to model a 2D column collapse and a dam-break scenario on horizontal and inclined planes for sands and glass beads. The method captures three distinct final deposition morphologies; truncated cone, conic, and Mexican hat shapes in collapsing columns. INNSPH computational efficiency enables simulations of large-scale granular flows, and its open-source nature facilitates collaboration and further modifications by researchers. The method provides a good understanding of granular flow dynamics in various industrial applications including powder technology. [Display omitted] • (Incompressible non-Newtonian SPH) INNSPH models granular flows using μ(I) rheology. • INNSPH captures three deposit morphologies capable to simulate various behaviors. • INNSPH accurately illustrates pressure and velocity contour changes. • INNSPH results comply with experimental for surface profiles and run-out distances. [ABSTRACT FROM AUTHOR]

• The current study aims to enhance the double diffusive natural convection in an Ostwald-de Waele fluid filled in a hexagonal enclosures. • Non-uniform magnetic field is applied. • Two-dimensional mathematical model is developed for fluid flow under the impact of heat and mass transfer. • Finite element method is used to solve the problem under consideration. • The influence of flow on velocity, isotherms and iso -concentration field is examined by analyzing a broad variety of variables. The current study aims to enhance the double diffusive natural convection in an Ostwald-de Waele fluid filled in a hexagonal enclosures using non-uniform magnetic field embedded with circular obstacle. The upper wall has maximum temperature T h ∗ and concentration (C h ∗) whereas the lower wall is kept at minimum temperature T c ∗ and concentration C c ∗ . The parameters that play a significant role in the heat and mass transfer are evaluated, including Hartmann number, power law index, Rayleigh number and buoyancy ratio. In two-dimensions, the governing formulation is written as a set of balancing equations for velocities, pressures, energies and concentrations. The nonlinear governing PDEs are solved using numerical approach based on Finite Element Method (FEM). The discretization is performed using the stable finite element pair ℘ 2 / ℘ 1. Code validation and results are ensured by conducting a grid convergence and comparison test respectively. The influence of flow on velocity, isotherms and iso -concentration field is examined by analyzing a broad variety of variables such as power-law index 0.7 ≤ n ≤ 1.2 , Hartmann number 0 ≤ H a ≤ 50 , Rayleigh number 10 4 ≤ R a ≤ 10 6 , inclination angle 0 ° ≤ γ ≤ 90 ° and buoyancy ratio - 2 ≤ N ≤ 2. The findings are displayed graphically, including the flow, temperature and concentration fields. Heat and mass transfer rates are maximum for shear thinning fluids while for shear thickening fluids it reduces, whereas it is maximum for concentration dominated assistant flow and minimum for concentration dominant counter flow. The novel aspects of the research include its thorough examination of solar thermal power conversion and its inventive energy deficiency devices and a wide range of electrical design applications. [ABSTRACT FROM AUTHOR]

The study of blood flow through stenotic arteries is more important as the existence and progression of stenosis may lead to severe damage. The current study aims to analyze and understand the non-Newtonian nature of blood flow through the multi-stenosed artery of an elliptical cross-section. The Carreau fluid model accounts for the non-Newtonian nature of blood. The mathematical equations are transformed to dimensionless form, and assumptions of mild stenosis are employed to reduce the non-linearity of the mathematical model. The perturbation method via polynomial technique is utilized to solve the resulting equations by considering W e 2 as the perturbation parameter. The results of the velocity and wall shear stress are examined graphically. It is found that stenosis severity substantially impacts flow velocity in the narrower portion of the artery. The stenosis growth strongly affects the flow velocity and wall shear stress in the stenotic region. The non-Newtonian effects are found to dominate along the minor axis. This fact assures that the conduit's narrower cross-section strengthens the fluid's non-Newtonian behavior. It is observed that the non-Newtonian fluid has a smaller velocity than the Newtonian fluid. Moreover, non-Newtonian fluid has a different nature along the minor and major axes, but Newtonian fluid has the same behavior. [ABSTRACT FROM AUTHOR]