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Abstract The intricate dynamics of mixed convective thermic and species transport in a power-law flowing fluid through a continuously stretched surface are investigated. The uniqueness of this study lies in the consideration of fluid variable thermic conductivity and viscosity, which introduces a higher degree of realism into the analysis. The transformation of similarity is used to transform the fundamental governing equations, and after that, the set of equations is processed numerically utilizing a non-similarity local approach. Furthermore, the effects of Soret and Dufour represent the cross-diffusion phenomena, accounting for the energy exchange with the surroundings. These factors collectively influence the stretching surface’s gradient velocity, affecting the thermal and species concentration rates. The findings offer a comprehensive understanding of these complex interactions, paving the way for optimizing thermic and species transport processes in various industrial applications. This study, therefore, holds significant potential for enhancing efficiency and performance in relevant industrial sectors. The main terms are the combinations of Dufour and Soret numbers that significantly impact the flow rate profile and mass transfer field. The coupled study of the nonlinear velocity, energy distribution and chemical mixture variance made the study more impactful in practicality. Skin friction variation shows limited impact with variations in the Soret number. The enhanced thermal gradient results in improved non-similarity parameters, yet it demonstrates a decrease with an increase in variable thermal diffusivity. There is a decrease in the temperature gradient as the buoyancy term reduces, while an increase is observed with changes in the Prandtl number. Similarly, the Nusselt number experiences a comparable impact due to changes in the Soret number.

This paper presents a complete investigation into the phenomenon of dual convection flow within a bulging enclosure along with non-Newtonian power-law fluids and employs the Galerkin finite element method for simulation. The main objective is to study the heat and mass transfer and entropy generation within the enclosure. Various factors, such as the Rayleigh number, power law coefficient, Lewis number, and effects of magnetic inclination are evaluated for their influence on flow dynamics and heat distribution. The study also investigates the relationship between these parameters and entropy generation, providing insights into the irreversible processes within the system. A comparative analysis of averaged Nusselt and Sherwood coefficients reveals distinct thermal and fluidic behaviours across varying power-law indices, emphasizing differences between shear thickening, shear thinning, and Newtonian fluid behaviours. The findings provide valuable insights into non-Newtonian power-law fluids in complex flows, enhancing our understanding of flow and heat transfer in bulging enclosures.

This study examines the molecules motion influences and thermal attributes in power-law non-Newtonian dissipative fluids' magnetohydrodynamic behavior, Joule heating, electromigration, and Cattaneo-Christov effects. Effects of Hall on both flow velocity and temperature, as well as the heat transport are considered. The investigation looks at heat transference that occurs when there is a slippage consequence, how the temperature influences the viscosity of the fluid, and how the potential parameters influence the exponential non-Newtonian flow of fluid via an extensible sheet. Runge-Kutta-Fehlberg's approach, which is based on the shooting procedure, was used to develop computational solutions for nonlinear ordinary differential equations. When exposed to a deformation that is generated by expansion, pressure, or agitation, a dilatant fluid is characterized by a phenomenon in which its viscosity rises and may harden. This phenomenon is referred to as the dilatation phenomenon. High shearing rates provide the impression that it is stable. When expanded, subjected to pressure, or agitated, dilatant fluids become more viscous and transform into solids. Both the non-equilibrium that occurs within the fluid and the reduction of the irreversibility processes that occur within it are caused by the acquired charges that are a result of Hall effect of fluid molecules.

This study deals with the effect of Lorentz force on forced convection flow of electrically conducting magneto-hydrodynamic, (MHD) power law fluid through the annular sector duct by using finite volume method. In existence literature, hydro-thermal flow of MHD power law fluid within an annular sector duct has not been reported. The effect of Lorentz force on hydro-thermal power law fluid flow makes it very much novel in its own right. Here the main objective is to explore the effect of Lorentz force on hydro-thermal flow characteristics. The influence of uniform magnetic field is taken parallel to the radial direction. The effects of Hartman parameter, H a and power law index, n , corresponding to Lorentz force and power law fluid respectively, on the quantities of interest such as velocity and temperature profiles, friction factor and average Nusselt number N u are discussed for different geometric configuration parameters' values of the annular sector duct. Computer code is developed and validated by comparing the results of limiting cases with the available literature. It has been observed that N u increases with the increase in H a . This trend is prevalent in both pseudo-plastic and dilatant fluids. The impact of H a is pronounced in the later case. [ABSTRACT FROM AUTHOR]

This study examines the molecules motion influences and thermal attributes in power-law non-Newtonian dissipative fluids' magnetohydrodynamic behavior, Joule heating, electromigration, and Cattaneo-Christov effects. Effects of Hall on both flow velocity and temperature, as well as the heat transport are considered. The investigation looks at heat transference that occurs when there is a slippage consequence, how the temperature influences the viscosity of the fluid, and how the potential parameters influence the exponential non-Newtonian flow of fluid via an extensible sheet. Runge-Kutta-Fehlberg's approach, which is based on the shooting procedure, was used to develop computational solutions for nonlinear ordinary differential equations. When exposed to a deformation that is generated by expansion, pressure, or agitation, a dilatant fluid is characterized by a phenomenon in which its viscosity rises and may harden. This phenomenon is referred to as the dilatation phenomenon. High shearing rates provide the impression that it is stable. When expanded, subjected to pressure, or agitated, dilatant fluids become more viscous and transform into solids. Both the non-equilibrium that occurs within the fluid and the reduction of the irreversibility processes that occur within it are caused by the acquired charges that are a result of Hall effect of fluid molecules. [ABSTRACT FROM AUTHOR]

This paper presents a complete investigation into the phenomenon of dual convection flow within a bulging enclosure along with non-Newtonian power-law fluids and employs the Galerkin finite element method for simulation. The main objective is to study the heat and mass transfer and entropy generation within the enclosure. Various factors, such as the Rayleigh number, power law coefficient, Lewis number, and effects of magnetic inclination are evaluated for their influence on flow dynamics and heat distribution. The study also investigates the relationship between these parameters and entropy generation, providing insights into the irreversible processes within the system. A comparative analysis of averaged Nusselt and Sherwood coefficients reveals distinct thermal and fluidic behaviours across varying powerlaw indices, emphasizing differences between shear thickening, shear thinning, and Newtonian fluid behaviours. The findings provide valuable insights into non-Newtonian power-law fluids in complex flows, enhancing our understanding of flow and heat transfer in bulging enclosures. [ABSTRACT FROM AUTHOR]

The present study investigates heat transfer characteristics of power law fluid flow and energy transfer in a crown cavity with adjustment of the heated cylinder. The flow distribution is generated by the response of the heated cylinder. Additionally, the enclosure is partially adiabatic and the influence of cold interfaces is also taken. This whole setup generates a partial differential system in its mathematical translation. The numerical simulation is performed for the mathematical formulation by adopting the Galerkin Finite element method. The obtained results are analyzed against pertinent parameters of interest and presented via line graphs and contour maps for better explanation. The findings indicate that the K.E (energy motion) and Nu (Nusselt number) are higher for shear thinning While K.E energy motion) and Nu (Nusselt number) are higher is minimum for shear thickening.

The prime motive of this disquisition is to scrutinize simultaneous aspects of external forcing mechanism and internal volumetric forces on non-Newtonian liquid filled in square enclosure. Inertially driven upper lid is assumed by providing constant magnitude of slip velocity whereas thermal equilibrium is disturbed by assuming uniform temperature at lower boundary and by keeping rest of walls as cold. To enhance thermal diffusion transport with in the flow domain cold as well as adiabatic temperature situation is provided. In view of velocity constraints all the extremities at no-slip except the upper wall which is moving with ULid. Formulation is attained in dimensional form initially and afterwards variables are used to convert constructed differential system into dimensionless representation. A numerical solution of leading formulation is sought through Galerkin finite element discretization. Momentum and temperature equations are interpolated by quadratic polynomials whereas pressure distribution is approximated by linear interpolating function. Domain discretized version is evaluated in view of triangular and rectangular elements. Newton’s scheme is employed to resolve the non-linearly discretized system and a matrix factorization based non-linear solver renowned as PARADISO is used. Validation of results is ascertained by forming agreement with existing studies. In addition, grid independence test is also performed to show credibility of performed computations. Stream lines and isothermal contours patterns are portrayed to evaluate variation in flow distributions. Kinetic energy and local heat flux for uniform and non-uniform heating situations are also divulged in graphical and tabular formats. Increase in Reynold number produces decrease in kinetic energy of fluid. Enhancement in Grashof number causes enrichment of thermal buoyancy forces due to which Nusselt number uplifts. Clock wise rotations increase against upsurge in magnitude of Reynold number which is evidenced form stream lines. Squeezing of secondary vortex against Prandtl number arises due to dominance of viscous forces.

The prime motive of this disquisition is to scrutinize simultaneous aspects of external forcing mechanism and internal volumetric forces on non-Newtonian liquid filled in square enclosure. Inertially driven upper lid is assumed by providing constant magnitude of slip velocity whereas thermal equilibrium is disturbed by assuming uniform temperature at lower boundary and by keeping rest of walls as cold. To enhance thermal diffusion transport with in the flow domain cold as well as adiabatic temperature situation is provided. In view of velocity constraints all the extremities at no-slip except the upper wall which is moving with U Lid . Formulation is attained in dimensional form initially and afterwards variables are used to convert constructed differential system into dimensionless representation. A numerical solution of leading formulation is sought through Galerkin finite element discretization. Momentum and temperature equations are interpolated by quadratic polynomials whereas pressure distribution is approximated by linear interpolating function. Domain discretized version is evaluated in view of triangular and rectangular elements. Newton's scheme is employed to resolve the non-linearly discretized system and a matrix factorization based non-linear solver renowned as PARADISO is used. Validation of results is ascertained by forming agreement with existing studies. In addition, grid independence test is also performed to show credibility of performed computations. Stream lines and isothermal contours patterns are portrayed to evaluate variation in flow distributions. Kinetic energy and local heat flux for uniform and non-uniform heating situations are also divulged in graphical and tabular formats. Increase in Reynold number produces decrease in kinetic energy of fluid. Enhancement in Grashof number causes enrichment of thermal buoyancy forces due to which Nusselt number uplifts. Clock wise rotations increase against upsurge in magnitude of Reynold number which is evidenced form stream lines. Squeezing of secondary vortex against Prandtl number arises due to dominance of viscous forces. [ABSTRACT FROM AUTHOR]

Performance features of a thermoelectric system mounted in a chaotic channel with non-Newtonian power law fluid are numerically explored with finite element method. The analysis is performed for different values of Re number of the hot and cold fluid streams (250⩽Re⩽1000), power law indices (0.75⩽n⩽1.25) and solid volume fraction of alumina (0⩽ϕ⩽4%) in water. It is observed that the fluid type with different power law indices significantly affected the electric potential variations and power generation of the thermoelectric system. Impacts of Re number on the power generation enhancement amount depends upon the power law index. The power rises by about 123.78%, 94.13% and 52.30% at the highest Re for different power law index combinations of (0.75,0.75), (0.75,12.5) and (1.25,1.25), respectively. Thermoelectric power reduces by about 39.71% for shear thinning fluids in both channels while it rises by about 43.48% for shear thickening fluids in chaotic channels. The potential of using nanofluids is more when both channels contain shear thinning fluids. Nanofluids rise the power of thermoelectric system by about 31%, 29% and 28% for the case when the hot side fluid is shear thinning, Newtonian and shear thickening fluid types while the cold side chaotic channel is shear thinning. When constant and varying interface temperature configurations are compared, there is at most 3% variations in the generated power while the trends in the curves for varying parameters are similar. The computational cost of constant interface temperature and computations only in the thermoelectric domains are much cheaper as compared to high fidelity coupled computational fluid dynamics simulations. The temperature field in the whole computational domain is approximated by using POD based approach with nine modes. A polynomial type regression model is used for POD-modal coefficients while fast and accurate results for interface temperatures are obtained.

The accurate calculation of the three-phase flow pressure distribution of oil, gas and water is of great significance for oil well production test, wellbore analysis and dynamic analysis. It is an important basis for on-site production design and gas well monitoring. In order to study the variation law of pressure drop of oil, gas and water three-phase flow with different viscosity in vertical pipe and establish a new prediction and calculation method of pressure drop of three-phase flow. Based on the multiphase flow Laboratory of PetroChina gas lift test base, the simulation experiment of oil, gas and water three-phase flow under different viscosity oil phase in vertical rising pipeline was carried out. Under the condition of fixed oil-water ratio, the oil-gas-water three-phase flow test was carried out by adjusting different oil-phase viscosity, gas-liquid ratio and gas-liquid flow, and the influence of oil-phase viscosity on the pressure drop of oil-gas-water three-phase pipe flow was studied. CFD software was used to simulate the three-phase flow of oil, gas and water with reference to the test conditions to determine the gas-liquid two-phase distribution under different viscosity conditions. Through CFD software simulation, it is determined that the oil-water two-phase can be regarded as a single non-Newtonian fluid mixed phase after full mixing. Based on the results of CFD model and considering the influence of viscosity on friction coefficient, a new calculation. New pressure calculation method was reestablished based on the new calculation method of friction coefficient. Comparing the test data with the calculation results, it is found that the error range of the pressure drop calculation model is within 15%, which meets the actual needs of the project, indicating that the pressure drop model is practical. [ABSTRACT FROM AUTHOR]

The Mooney wall slip correction procedure is sometimes mandatory in the rheological characterization via capillary viscometry of certain complex fluids that have the tendency of slipping at solid walls. Besides making the measurement more complex, the Mooney procedure may give rise to measurement error amplification due to an imprecise knowledge of the capillary radius, even if the uncertainty is of the order of 0.01 mm. This error amplification may be so large that the result becomes grossly inaccurate, and in the worst case the procedure may even not produce a physically acceptable result. In this work a MATLAB‐based software that can help researchers determine the maximum allowable inaccuracy on the capillary diameter that can yield feasible data for fluids characterization is devised. For best results, though, the user should know in advance the constitutive characteristics of the unknown fluid in an approximate sense. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Petrochemical Universities / Shiyou Huagong Gaodeng Xuexiao Xuebao is the property of Journal Editorial Department Of Liaoning Shihua University and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Performance features of a thermoelectric system mounted in a chaotic channel with non-Newtonian power law fluid are numerically explored with finite element method. The analysis is performed for different values of Re number of the hot and cold fluid streams (250 ⩽ Re ⩽ 1000), power law indices (0.75 ⩽ n ⩽ 1.25) and solid volume fraction of alumina (0 ⩽ ϕ ⩽ 4 %) in water. It is observed that the fluid type with different power law indices significantly affected the electric potential variations and power generation of the thermoelectric system. Impacts of Re number on the power generation enhancement amount depends upon the power law index. The power rises by about 123.78 % , 94.13 % and 52.30 % at the highest Re for different power law index combinations of (0.75,0.75), (0.75,12.5) and (1.25,1.25), respectively. Thermoelectric power reduces by about 39.71 % for shear thinning fluids in both channels while it rises by about 43.48 % for shear thickening fluids in chaotic channels. The potential of using nanofluids is more when both channels contain shear thinning fluids. Nanofluids rise the power of thermoelectric system by about 31 % , 29 % and 28 % for the case when the hot side fluid is shear thinning, Newtonian and shear thickening fluid types while the cold side chaotic channel is shear thinning. When constant and varying interface temperature configurations are compared, there is at most 3 % variations in the generated power while the trends in the curves for varying parameters are similar. The computational cost of constant interface temperature and computations only in the thermoelectric domains are much cheaper as compared to high fidelity coupled computational fluid dynamics simulations. The temperature field in the whole computational domain is approximated by using POD based approach with nine modes. A polynomial type regression model is used for POD-modal coefficients while fast and accurate results for interface temperatures are obtained. [ABSTRACT FROM AUTHOR]

This paper presents an approximate analytical solution capable of analyzing the velocity, temperature and concentration distribution in the poiseuille flow of an arrheniusly reactive power law fluid incorporated within parallel plates. The equations governing the phenomenon are solved analytically using regular perturbation method and direct integration, to show the influence of the parameter involved on the system. The effect of change in parameters such as the power law index, the pressure gradient coefficient, the viscous heating parameter, the Arrhenius chemical reaction rate and the Frank-Kamenetskii number are presented graphically and discussed. The result obtained revealed that the power law index, the pressure gradient coefficient, the viscous heating parameter, the Frank-Kamenetskii number and the Arrhenius chemical reaction rate enhanced the fluid flow, average temperature and species concentration. [ABSTRACT FROM AUTHOR]

In this work, we analyze the characteristics of periodic flows in non-isothermal viscous fluid over a heated block in the presence of thermal plates at Reynolds number (Re=100). The unsteady, incompressible Navier–Stokes (NS) equations with suitable initial and boundary data in 2D are executed by the finite element technique using a highly refined hybrid mesh. The temporal discretization is performed by an implicit stable backward differencing in time and a stable choice of finite elements from the finite element library for spatial discretization. The discrete nonlinear system arising from this discretization is linearized by Newton’s method and then solved through a direct linear solver PARDISO. For this forced convective study, the range of dimensionless parameters, namely, the Prandtl number (Pr) and power law index (n), are varied from 1 to 10 and 0.6 to 1.4 with a low Grashof number varying as (1≤Gr≤10) to produce a forced convection regime, respectively. For the authentication, we have compared our results with the literature at a similar configuration. After simulation, the results accomplished in the velocity profile, pressure, isotherm contours, drag and lift coefficients (trajectory motion), average Nusselt number (Nuavg), etc. are considered. For convergence of solution at low shear rate (n1), it converges to a single value. Furthermore, the drag (CD) and lift (CL) coefficients are more pronounced for shear-thinning cases (n1).

This study considered numerical applications of smoothed particle hydrodynamics (SPH) to non‐Newtonian flow in filled or partially filled conveying elements of twin‐screw extruders (TSEs). The algorithms were validated by using a plane Poiseuille flow. Two geometrical configurations with different gap were investigated. A large sound speed was used to prevent particles penetrating the wall boundary of the complex geometry. The velocity field and flow rate of Newtonian flow and non‐Newtonian flow (power law) in filled model and partially filled model were analyzed. The distribution of particles in partially filled conveying element in one rotation is introduced. The rheological properties of material take important effect on the flow in fully filled and partially filled cases. For the fully filled cases, the screw–barrel clearance takes important effect on the flow due to the leakage flow reducing the flow rate. For the partially filled case, the clearance affects the non‐Newtonian flow by changing the rheological properties of the fluid. The effect of clearance on Newtonian flow is very limited due to no back pressure in the partially filled case. This work prepared a groundwork for the accurate analysis of real extrusion by SPH. [ABSTRACT FROM AUTHOR]

The key goal of the study under concern is to test the effects of Brownian movement and thermophoresis dispersion on MHD Casson nanofluid limit layer stream over a nonlinear slanted permeable extending surface, with the impact of convective limits and warm radiation with synthetic response. Nonlinear ODEs are gotten from overseeing nonlinear PDEs by utilizing good comparability changes. The amounts related with building angles, for example, skin grating, Nusselt number and Sherwood number alongside different effects of material factors on the speed, temperature, and focus, are explained and explained with outlines. The numerical consequences of the current investigation are acquired through the Runge-Kutta Fehlberg strategy alongside shooting procedure and in a constraining sense are diminished to the distributed outcomes for a precision reason. [ABSTRACT FROM AUTHOR]

Non-Newtonian fluid rheology representing the properties of pseudoplastic and dilatant materials has received overwhelming attention due to extensive applications in industrial and technological sectors like in metallurgical processes, shock absorbing materials, smart structures, and devices with adaptive stiffness, damping, emulsions, suspensions and so forth. Thus, in current communication characteristics of power law fluid elucidating attributes of pseudoplastic and dilatant materials in channel driven cavity is addressed. Finite element method (FEM) is implemented to interpret rheological features of power law fluid by varying flow controlling parameters. Discretization of domain at coarse level is performed by using stable first and second order polynomial (P2−P1) shape functions. Square shaped cylinder is placed at (1, 1.5) above the cavity. Hydrodynamics forces like pressure difference drag and lift variations are measured at outer surface of cylinder. The impact of primitive parameters like power law index (n) and Reynold number on velocity, pressure and viscosity for shear thinning and thickening cases is adorned. It is deduced that pressure difference increased against the variation in power law index. In similar way the impact of drag and lift forces mounts by increasing power law index. Reynold number has delineating impact on drag and lift forces near the obstacle. It is also seen that pressure shows optimized non-linear behavior near the obstacle and becomes linear along the downstream as expected in channel flow. It is divulged that pressure drops more rapidly for increasing magnitude of Reynold number. Velocity of fluid increases when power law fluid flow is behaving as shear thinning fluid in comparison to shear thickening case.

Here we numerically analyse the effects of viscous dissipation and Joule heating on forced convection heat transfer rate of electrically conducting magnetohydrodynamic, (MHD) power law fluid flow through annular duct. Mathematical model is formulated for constant properties power law fluid with steady, incompressible and laminar fully developed flow assumptions. Heat transfer results are determined by taking constant heat flux with peripheral wall temperature "known as H 1 thermal boundary condition" at the solid walls of the channel. It has been observed that the effect of viscous dissipation reduces due to enhance damping magnetic field effect by increasing the value of Hartman number, Ha, especially in the case of shear thickening fluids. [ABSTRACT FROM AUTHOR]

In this paper, we study the stationary incompressible power law fluid flow in a thin porous medium. The media under consideration is a bounded perforated 3D domain confined between two parallel plates, where the distance between the plates is very small. The perforation consists in an array solid cylinders, which connect the plates in perpendicular direction, distributed periodically with diameters of small size compared to the period. For a specific choice of the thickness of the domain, we found that the homogenization of the power law Stokes system results a lower-dimensional nonlinear Brinkman type law. [ABSTRACT FROM AUTHOR]

In this paper, effects of stationary contraction on mixing and transport of a non-Newtonian fluid in the small intestine are analyzed theoretically. A semi-analytical method is developed to solve the governing equations of fluids flow in the intestine using lubrication theory. Results indicate that the stationary contraction helps in conferring two functions – (1) shearing of the contents, and (2) bidirectional transport over a short distance. The flow resulting from contraction is symmetric and occurs in both the directions; however, they do not lead to a net flow rate in one direction. The amount of shearing developed during such flows is reflective of their mixing ability. The effort of such peristalsis is largely determined by the flow behavior index; where energy requirements of developing similar shearing forces are higher for dilatants and lower for pseudoplastics. Flow is sensitive to frequency of contraction, luminal occlusion and wavelength of the contraction. [ABSTRACT FROM AUTHOR]

Effect of finite ion size on the transport of a neutral solute across the porous wall of a nanotube is presented in this study. Modified Poisson–Boltzmann equation without the Debye–Huckel approximation is used to determine the potential distribution within the tube. Power law fluid is selected for the study, as its rheology resembles closely to the real-life physiological fluids. The flow within the tube is actuated by the combined effects of pressure and electroosmotic forces. Steady-state solute balance equation is solved by the similarity technique in order to track the solute transport across the tube. The effects of ionic radius, ionic concentration, and flow behavioral index on the length-averaged Sherwood number, permeate flux, and permeate concentration are analyzed. This study will be extremely helpful in predicting the transport characteristics of a neutral solute in real physiological systems and also to fine-tune the performance of microfluidic devices having porous wall. [ABSTRACT FROM AUTHOR]

The present study deals with an unsteady laminar free convection inside the annuli confined between an outer square enclosure and an inner circular cylinder. The annuli are filled with non-Newtonian power law fluids. The inner cylinder is located at three positions along the vertical center line. The unsteadiness arising due to bifurcation of flow from steady state is also reported in this study. The flow characteristics were found to be steady in nature in case of shear thickening fluid. However, most of the cases in the shear thinning fluid regime are found to be unsteady in nature with periodic and non-periodic fluctuations. The bifurcation of the flow from steady to unsteady state is mainly governed by the location of the cylinder as well as the characteristics of non-Newtonian fluid. The Bernard cells arising due to very high convective flow at Ra = 107 are also observed in the flow fields. [ABSTRACT FROM AUTHOR]

The present study deals with an unsteady laminar free convection inside the annuli confined between an outer square enclosure and an inner circular cylinder. The annuli are filled with non-Newtonian power law fluids. The inner cylinder is located at three positions along the vertical center line. The unsteadiness arising due to bifurcation of flow from steady state is also reported in this study. The flow characteristics were found to be steady in nature in case of shear thickening fluid. However, most of the cases in the shear thinning fluid regime are found to be unsteady in nature with periodic and non-periodic fluctuations. The bifurcation of the flow from steady to unsteady state is mainly governed by the location of the cylinder as well as the characteristics of non-Newtonian fluid. The Bernard cells arising due to very high convective flow at Ra = 107 are also observed in the flow fields. [ABSTRACT FROM AUTHOR]

Buoyancy-driven flows were investigated inside an enclosure with an inner cylinder embedded within it. The square enclosure contains the power law fluids. The effects are reported for the position of the cylinder along the horizontal and diagonal directions on the flow and thermal characteristics based on a rigorous unsteady numerical analysis. The cylinder was placed at several locations along the diagonal near the top-left corner, the center, and near the bottom right corner. The cylinder was also placed along the horizontal centerline near the right wall. This paper reports the effects of shear thickening and thinning fluids on the heat transfer mechanism in the enclosure. The thermal characteristics were more pronounced when the cylinder was near the bottom right corner than when near the top left corner and at the center. Pseudoplastic and dilatant fluids can be used in applications requiring increased and decreased heat transfer rates, respectively. [ABSTRACT FROM AUTHOR]

The problem of free convective steady boundary layer flows over a solid horizontal flat plate nested in a porous medium filled with a nanofluid containing gyrotactic microorganisms is considered. The exponent of the temperature, the nanoparticle volume fraction and the density of motile microorganisms are introduced to make the quantities dimensionless. The impacts of the considered exponent and bioconvection parameters on the dimensionless temperature, velocity, nanoparticle concentration and density of motile microorganisms along with Nusselt, Sherwood and motile microorganism numbers are tabulated and shown graphically. For a regular fluid and also for the isothermal case, the results are compared with the existing data and excellent compatibility is found. [ABSTRACT FROM AUTHOR]

Cuttings settle down freely in the drilling fluid due to the density difference when drilling fluid circulation is stopped. Further study of cuttings settling movement helps to predict the risks in hole cleaning. In this paper, cuttings settling experiments are carried out in PAM solution whose rheological property is in accordance with power law model. Three axis diameters of cuttings are obtained by CT scan. Based on experimental data regression, a new prediction model of the settling velocity in the power law fluid is obtained. The absolute average error between the new prediction model and the experiments data is 8.46%. The simulation results show the settling velocity of the cuttings in the power law fluid greatly deviates from in the Newtonian fluid under the same assumption, which indicates cuttings shape and rheological property of drilling fluid have a great influence on settling velocity. Unlabelled Image • Triaxial diameter of cuttings is regarded as the equivalent diameter of cuttings. • 432 tests involve single cutting and multiple cuttings settlement are conducted. • An explicit model for cuttings settling velocity in the power law fluid is obtained. [ABSTRACT FROM AUTHOR]

The forced convection of non-Newtonian nanofluid for a backward-facing flow system was analyzed under the combined use of magnetic field and double rotating cylinders by using finite element method. The power law nanofluid type was used with different solid volume fractions of alumina at 20 nm in diameter. The effects of the Re number (100≤Re≤300), rotational Re number (−2500≤Rew≤3000), Ha number (0≤Ha≤50), and magnetic field inclination (0≤γ≤90) on the convective heat transfer and flow features were numerically assessed. The non-Newtonian fluid power law index was taken between 0.8 and 1.2 while particle volume fractions up to 4% were considered. The presence of the rotating double cylinders made the flow field complicated where multiple recirculation regions were established near the step region. The impacts of the first (closer to the step) and second cylinders on the heat transfer behavior were different depending upon the direction of rotation. As the first cylinder rotated in the clockwise direction, the enhancement in the average heat transfer of 20% was achieved while it deteriorated by approximately 2% for counter-clockwise directional rotation. However, for the second cylinder, both the rotational direction resulted in heat transfer augmentation while the amounts were 14% and 18% at the highest speeds. Large vortices on the upper and lower channel walls behind the step were suppressed with magnetic field effects. The average Nu number generally increased with the higher strengths of the magnetic field and inclination. Up to 30% increment with strength was obtained while this amount was 44% with vertical orientation. Significant impacts of power law fluid index on the local and average Nu number were seen for an index of n = 1.2 as compared to the fluid with n = 0.8 and n = 1 while an average Nu number of 2.75 times was obtained for the flow system for fluid with n = 1.2 as compared to case for fluid with the n value of 0.8. Further improvements in the local and average heat transfer were achieved with using nanoparticles while at the highest particle amount, the enhancements of the average Nu number were 34%, 36% and 36.6% for the fluid with n values of 0.8, 1 and 1.2, respectively.

In this article, the effects of a Casson Nanofluid boundary layer flow, over an inclined extending surface with Soret and Dufour, is scrutinized. The model used in this study is based on the Buongiorno model of the thermal efficiencies of the fluid flows in the presence of Brownian motion and thermophoresis properties. The non-linear problem for Casson Nanofluid flow over an inclined channel is modeled to gain knowledge on the heat and mass exchange phenomenon, by considering important flow parameters of the intensified boundary layer. The governing non-linear partial differential equations are changed to non-linear ordinary differential equations and are afterward illustrated numerically by the Keller-Box scheme. A comparison of the established results, if the incorporated effects are lacking, is performed with the available outcomes of Khan and Pop [1] and recognized in a nice settlement. Numerical and graphical results are also presented in tables and graphs.

Copyright of Special Oil & Gas Reservoirs is the property of Special Oil & Gas Reservoirs Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

• Semi-analytical model for predicting rise velocity of Taylor bubble in power law fluid. • Numerical simulation for Taylor bubble rise in a power law fluid using VOF method. • Effect of n and K on dynamics of Taylor bubble. • Influence of surface tension on the shape of bubble tail only. • Pronounced effect of n on shape and speed of the bubble. An attempt has been made to explore the dynamics of Taylor bubbles rising through circular tubes filled with stagnant power law fluids using CFD and a semi-analytical technique. While the freeware OpenFOAM was used for CFD simulation, the semi-analytical model was developed considering viscous film drainage around the axisymmetric bubble and was closed using a single tuning coefficient from experimental data. Bubble rise velocity derived from both the techniques exhibit good agreement with experiments. Though the velocity field around a bubble rising through a power law fluid does not show any remarkable difference with that observed for bubbles through Newtonian liquids, the rise velocity is noted to depend strongly on both K and n of the power law relationship. Nevertheless, the influence of n is much greater as is evident from the change of nose shape with its variation. Effect of such variation in nose shape is also reflected in the predicted rise velocity. However, as observed in case of Newtonian fluids, for a given n and K, the rise velocity of Taylor bubble asymptotically reaches a constant value as the bubble volume is increased. It is also seen that surface tension does not have any significant effect on the nose shape and rise velocity while it modifies the tail shape. Finally, it has been noted that the increase in rise velocity with tube diameter depicts a non linear trend for non-Newtonian fluids while it is linear for their Newtonian counterpart. [ABSTRACT FROM AUTHOR]

Numerical simulation of mixed convection heat transfer in a lid-driven triangular cavity filled with power law nanofluid and with an opening was performed under the effect of an inclined magnetic field. The left vertical wall of the cavity moves in + y-direction, and the bottom wall of the cavity is partially heated. Galerkin weighted residual finite element method was used to solve the governing equations. Influence of Richardson number, Hartmann number, inclination angle, opening ratio and nanoparticle volume fraction on the fluid flow and heat transfer is examined for various power law indices. It was observed that average heat transfer deteriorates as the value of Richardson number and Hartmann number enhances. At the lowest value of Richardson number, the discrepancy between the average heat transfer corresponding to different power law indices is higher. The inclination angle of the magnetic field where the minimum of the average Nusselt number is seen depends on the fluid type. Average heat transfer number is the highest for the highest value of the opening ratio. The average Nusselt number enhances with solid particle volume fraction, and there are slight variations in the reduction in the average Nusselt number when base fluid and nanofluid are considered for various power law indices. [ABSTRACT FROM AUTHOR]

Mixed convection heat and mass transfer along a vertical plate embedded in a power-law fluid saturated Darcy porous medium with chemical reaction and radiation effects is studied. The governing partial differential equations are transformed into ordinary differential equations using similarity transformations and then solved numerically using shooting method. A parametric study of the physical parameters involved in the problem is conducted and a representative set of numerical results is illustrated graphically.

Highlights • Analytical solution of the periodic Graetz problem in elliptical duct is presented. • Elliptical ducts reduce the thermal length needed for the amplitude attenuation. • A Correlation giving the thermal length is obtained. • The case of non-Newtonian Cu-water nanofluid flow is investigated. • Using nanofluids and elliptical ducts enhance the heat transfer and up to 80%. Abstract In this study, an analytical solution was obtained for a laminar forced convection of non-Newtonian nanofluid flowing inside an elliptical duct, with inlet temperature varying periodically with the time. The solution was obtained using the Generalized Integral Transform Technique (GITT). The thermal behavior of Cu-water non-Newtonian nanofluid, described by the power-law model was investigated. Also, an accurate correlation was established to estimate the thermal length required to achieve 99% of the amplitude attenuation. The results show a significant effect of aspect ratio β / α and fluid behavior index on the temperature amplitude reduction. For instance, an elliptical duct with β / α = 0.25 reduces the thermal length L th more than 50% compared with circular duct. Adding nanoparticles until 5% increases the heat transfer coefficient up to 27% for the cylindrical tube. Besides, the heat transfer coefficient is improved over 42% relatively to the cylindrical configuration by reducing the aspect ratio to 0.25. Therefore, adding 5% of nanoparticles both using an elliptical duct with β / α = 0.25, improves the mean heat transfer coefficient around 83% compared to the flow of water base fluid inside a cylindrical duct. [ABSTRACT FROM AUTHOR]

In the first part of this paper a universal fluid velocity based algorithm for simulating hydraulic fracture with leak-off was created for a penny-shaped crack. The power-law rheological model of fluid was assumed and the final scheme was capable of tackling both the viscosity and toughness dominated regimes of crack propagation. The obtained solutions were shown to achieve a high level of accuracy. In this paper simple, accurate, semi-analytical approximations of the solution are provided for the zero leak-off case, for a wide range of values of the material toughness and parameters defining the fluid rheology. A comparison with other results available in the literature is undertaken. [ABSTRACT FROM AUTHOR]

In the first part of this paper, a universal fluid velocity based algorithm for simulating hydraulic fracture with leak-off, previously demonstrated for the PKN and KGD models, is extended to obtain solutions for a penny-shaped crack. The numerical scheme is capable of dealing with both the viscosity and toughness dominated regimes, with the fracture being driven by a power-law fluid. The computational approach utilizes two dependent variables; the fracture aperture and the reduced fluid velocity. The latter allows for the application of a local condition of the Stefan type (the speed equation) to trace the fracture front. The obtained numerical solutions are carefully tested using various methods, and are shown to achieve a high level of accuracy. [ABSTRACT FROM AUTHOR]

In this paper time-dependent, 2-D, axisymmetric flow and heat transfer of a viscous incompressible fluid impinging orthogonally on a disc is examined. The disc is lubricated with a thin layer of power-law fluid of variable thickness. It is assumed that surface temperature of the disc is time-dependent. Continuity of velocity and shear stress at the interface layer between the fluid and the lubricant has been imposed to obtain the solution of the governing partial differential equations. The set of partial differential equations is reduced into ordinary differential equations by suitable transformations and are solved numerically by using Keller-Box method. Solutions are presented in the form of graphs and tables in order to examine the influence of pertinent parameters on the flow and heat transfer characteristics. An increase in lubrication results in the reduction of surface shear stress and consequently viscous boundary layer becomes thin. However, the thermal boundary layer thickness increases by increasing lubrication. It is further observed that surface shear stress and heat transfer rate at the wall enhance due to unsteadiness. The results for the steady case are deduced from the present solutions and are found in good agreement with the existing results in the literature. [ABSTRACT FROM AUTHOR]

The rheological characteristics of the oil film on the rod-seal interface in the sealing zone have a major influence on the behavior of reciprocating seals. Because of the addition of polymers, the viscosity and temperature properties of hydraulic oil have improved and the fluid presents non-Newtonian characteristics. To investigate the influence of these characteristics on seal behavior, a soft elastohydrodynamic lubrication (EHL) numerical model is introduced to simulate a step seal under a mixed lubrication condition. A modified Reynolds equation is derived for calculating the fluid film pressure distribution more accurately. The equation is based on the power law fluid model and Jakobsson-Floberg-Olsson (JFO) cavitation theory. Results are presented to gain insight into the effect of non-Newtonian fluid characteristics on seal behavior, and the simulated results are compared to those of a Newtonian fluid to reveal the seal mechanism. The influence of operating parameters and the seal surface root mean square (RMS) roughness on sealing performance under different power law indexes is also investigated and discussed. [ABSTRACT FROM AUTHOR]