non-Newtonian Power-law Fluid Research Articles

Numerical simulations for a non-Newtonian Power Law Fluids in oscillating lid-driven square cavity

Numerical simulations for a non-Newtonian Power Law Fluids in oscillating lid-driven square cavity

Investigation of entropy generation in power law fluid-filled bulging enclosures: effects of flow and heat transfer

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.

Fluid-structure interaction induced mixed convection characteristics in a lid-driven square cavity with non-Newtonian power law fluids

The present study aims to numerically explore Fluid-Structure Interaction (FSI) induced mixed convection characteristics in a square cavity filled with a non-Newtonian power-law fluid. The side walls of the cavity under consideration are subjected to constant low temperature having motion in opposite directions while the insulated top wall and the bottom hot wall are kept stationary. A flexible fin is mounted on the bottom wall that essentially serves as a passive flow modulator. To solve the transient flow, thermal, and stress fields, the FSI problem is presented in an arbitrary Lagrangian-Eulerian framework employing the Galerkin finite element method. Different non-Newtonian fluids are represented by the power-law index (n) varied within the range, of 0.6 ≤ n≤ 1.4. Besides, the dynamic as well as mixed convection condition of the flow is analyzed by variation of Reynolds number (100 ≤ Re ≤ 300) and Richardson number (0.1 ≤ Ri ≤ 10.0) respectively. System characteristics have been evaluated in terms of streamline and isotherm contours, spatial and time-averaged Nusselt number as well as Normalized Nusselt number in regard to the “No Fin” case. The outcome of the present study reveals that the efficacy of a flexible fin for a given system depends on both the system dynamic condition (Re) and the mixed convection regime (Ri). The presence of a flexible fin has been found to have positive impact on heat transfer performance for both the shear-thinning and shear-thickening fluids for higher values of Re and Ri. However, for lower values of Re, the inclusion of a flexible fin has been found to adversely affect the heat transfer performance for shear-thickening fluids. Moreover, the thermal field exhibits periodic oscillation properties at Ri = 10, which can be attributed to the induced motion of the flexible fin. This phenomenon has been further elucidated through Power Spectrum Analysis. Results obtained in the present study might provide valuable insights into FSI-induced mixed convection with non-Newtonian fluids having versatile industrial applications such as solar thermal collectors with strategically positioned passive flexible flow modulators.

Lattice boltzmann simulation of power-law fluids flow around a forced-oscillation circular cylinder

Direct numerical simulations of power-law non-Newtonian fluids flow around a circular cylinder are performed by lattice Boltzmann method coupled with immersed moving boundary scheme. Obvious differences in macroscopic hydrodynamics and wake vortex dynamics between shear-thinning and shear-thickening fluids are resolved. Results show that shear-thickening effect increased drag coefficient but decreased lift coefficient, and delayed separation of boundary layer leading to lower vortex shedding frequency. The position with lowest viscosity on surface of cylinder in shear-thinning fluid is closer to leading edge stagnation point than the position in shear-thickening fluid. Wake vortex appears from surface of cylinder in shear-thinning fluid, however appears after some distance away from rear end of cylinder in Newtonian and shear-thickening fluid through dynamic mode decomposition. Vortex shedding modes in shear-thinning and shear-thickening fluids are very different at high oscillation amplitudes and transited from Chaos to 2S mode (two single vortexes with opposite directions but same energy shed) or P + S mode (a pair of vortexes with opposite rotation direction shed on one side of the cylinder and a single vortex shed on the other side) when increasing power-law index.

Hall current effect on molecules motion in viscous non-Newtonian power law fluid with Joule heating and fluxing model of Cattaneo-Christov

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.

Double-diffusive convection of non-newtonian power-law fluids in an inclined porous layer

This paper presents a numerical study of Double-Diffusive convection within an inclined porous medium saturated by a non-Newtonian fluid. The power-law model is utilized for modelling the behavior of the flow in the porous layer. The given statement implies that the long side of the cavity experience thermal and solutal flux rates, whereas the other walls are impermeable and thermally isolated. The issue is characterized by a set of tightly linked non-linear differential equations, termed governing equations, encompassing the mass conservation equation (known as the continuity equation), the momentum equation, the energy equation, and the species equation. The relevant factors that govern the problem being investigated are the Rayleigh number, R_T, the power-law index, n, the angle of inclination, Φ, the cavity aspect ratio, A, the Lewis number, Le, the normalized porosity, ξ, and the buoyancy ratio, N, two types of cavity configuration have been studied: inclined cavity (i.e. Φ≠0°), then we have studied the case of a vertical cavity (i.e. Φ=90°) where the buoyancy forces induced by the thermal and solutal effects are opposing each other and of equal intensity (N=-1). A semi-analytical solution, valid for an infinite layer (A>>1), is derived on the basis of the parallel flow approximation, A numerical approach utilizing the finite differences method was utilized to resolve the governing equations within the porous medium. It is demonstrated that both the inclination of the layer, Φ, and the power-law index, n, have a strong influence on the strength of the intensity of flow, Ψ_0, the heat transfer rate, Nu, and the mass transfer rate, Sh, within the enclosure. A good agreement is found between the predictions of the parallel flow approximation and the numerical results obtained by solving the full governing equations.

Hysteresis and Bistability Bifurcation Induced by Combined Fluid Shear Thickening and Double-Diffusive Convection in Shallow Porous Enclosures Filled with Non-Newtonian Power-Law Fluids

Hysteresis and Bistability Bifurcation Induced by Combined Fluid Shear Thickening and Double-Diffusive Convection in Shallow Porous Enclosures Filled with Non-Newtonian Power-Law Fluids

Mixing mechanism of power-law non-Newtonian fluids in resonant acoustic mixing

Resonant acoustic mixing (RAM) is a widely applied technology that utilizes low-frequency vertical harmonic vibration for fluid transfer and mixing. However, the current research on the mixing mechanism of RAM technology primarily focuses on the initial mixing stages, neglecting the subsequent turbulent transition. This lack of understanding hinders the further improvement of RAM technology. This paper aims to investigate the mixing mechanism of power-law non-Newtonian fluids (NNF) in RAM using the phase field model and the spectral analysis. The study focuses on understanding the facilitating effect of turbulent transition in mixing and explores the influence of the power-law index and the excitation parameter on the mixing characteristics. The results indicate that the flow field experiences Faraday instability due to the intense perturbation during transient mixing. This leads to the fluid mixing through the development of large-scale vortex to small-scale vortex. During this process, the frequency components of the flow field are distributed around the working frequency, demonstrating transient and broad frequency characteristics. The steady state then dissipates energy through the viscous dissipation of small-scale vortices and ultimately relies on the single-frequency components such as submultiples and multiples excited by the nonlinear effect to complete the mixing. The mixing effects of NNF and Newtonian fluids (NF) are essentially the same, but they consume energy in different ways. The mixing uniformity and mixing efficiency of NNF increase with increasing vibration acceleration and decrease with increasing vibration frequency. These findings provide new insights into the RAM mechanism of power-law NNF.

Comparative predictions of turbulent non-isothermal flow of a viscoplastic fluid with yield stress

RANS simulation of turbulent non-isothermal flow in a pipe by transition of Newtonian fluid into a viscoplastic non-Newtonian fluid is carried out. Carrier phase turbulence was modeled using two-equation isotropic k‒ε˜ – model and Reynolds stress transport model. Results of calculations of Newtonian and non-Newtonian power-law fluids were compared with data of DNS calculations of other authors. Comparisons with data from other works for isothermal Schwedoff-Bingham fluid were performed in this work using k‒ε˜ – model. Satisfactory agreement was obtained with data from other studies for the axial averaged velocity and turbulent kinetic energy radial profiles (the difference is up to 15 %). Reynolds stress transport model showed significant anisotropy between streamwise and transverse velocity fluctuations (up to several times) and good agreement with DNS results of other authors. Averaged and pulsation profiles express the indicated transformation of the non-isothermal turbulent flow.

Numerical simulation of thermosolutal natural convection of power-law non-Newtonian fluids in a parallelogram with sensitivity analysis by response surface methodology

Thermosolutal natural convection originates in a fluid when the density changes due to the presence of two distinct components with varying rates of diffusion. This convection is driven by buoyancy resulting from concurrent temperature and concentration gradients. This study focuses on the thermosolutal free convection flow within a parallelogrammic enclosure. The functioning fluid under consideration is non-Newtonian and formulated by the viscosity model (power-law). The top and bottom walls of the chamber are adiabatic and are assumed to be impermeable. The temperature and concentration on the left side are maintained at a high level, while the conditions on the right side are cold and low. The controlling parameters for the present case include Rayleigh number Lewis number (Le = 5, 10), Prandtl number (Pr = 6.2), buoyancy ratio (N = 0.8, −0.8) along with power-law index (n = 0.6, 1, 1.4). The results obtained from this numerical study are validated with existing results and indicate the correctness of the code. The output of the study is shown in terms of velocity and temperature profiles, streamlines, isotherms, and iso-concentrations, the average rate of heat and mass transmission in terms of the average Nusselt number () and the average Sherwood number (). The correlation equation derived from the RSM approach demonstrates the relationship between the output responses and the input parameters. It concludes that n negatively affects both heat and mass transfer, while Ra affects positively. The findings of this study could be helpful for understanding of thermosolutal natural convection behavior of non-Newtonian (power-law) fluid in an enclosure and therefore accelerate the industrial application of such fluid in the relevant field, such as HVAC (heating, ventilation, and air conditioning) system.

Pore-scale hydrodynamics of non-Newtonian power-law fluids across a partially blocked porous medium in a confined channel

Transport of non-Newtonian fluids in porous media is pervasive in many natural and industrial applications. However, capturing the rheological behaviors of fluids by direct experimental techniques is challenging at the pore-scale. This paper outlines the pore-scale hydrodynamic interactions of non-Newtonian power-law fluids across a partially blocked porous medium in the laminar flow regime by computational fluid dynamics. The porous medium consists of an array of uniformly arranged square pillars. We explore the complex interplay of power-law rheology and Reynolds number on the microscopic flow field at the pore-scale. We capture the momentum transfer at the permeable interface between the porous and non-porous regions through stream-wise and span-wise velocity components and average volumetric flow rates at each pore-throat. Our results unveil a significant augmentation in stream-wise momentum by shear-thinning behavior and a diminution in momentum by shear-thickening behavior of the fluid through the porous medium. Further, the flow-leakage at the top interface purely depends on the combined effects of Reynolds number and power-law index. The channel pressure drop between the windward and leeward faces of the porous medium increases with the power-law index at low Reynolds number, while it decreases at high Reynolds number. Moreover, we provide a simple numerical framework to comprehend how the power-law behavior of the fluid dynamically regulates the flow field at the pore-scale.

Wall-modeled large-eddy simulation of turbulent non-Newtonian power-law fluid flows

For high-fidelity predictions of turbulent flows in complex practical engineering problems, the Wall-Modeled (WM) Large-Eddy Simulation (LES) has aroused great interest. In the present study, we prove that the conventional Wall-Stress Models (WSMs) developed for WMLES of Newtonian fluids fail to predict the shear-thinning-induced drag reduction in power-law fluids. Therefore, we propose novel algebraic, integrated, and Ordinary-Differential-Equation (ODE) WSMs, for the first time, for WMLES of power-law Non-Newtonian (NN) fluids and assess their performance against reference Wall-Resolved (WR) LES solutions. In addition, the effects of the key model parameters, including the WSM type, sampling height, sampling cell, and axial grid resolution are explored, and it is revealed that turbulent NN flow predictions have a much higher sensitivity to the choice of WSM, compared to their Newtonian counterparts. It is manifested that, in contrast to WRLES, accurate modeling of the mean apparent and subgrid-scale NN viscosities in the Non-Newtonian ODE (NNODE) model can improve the predictions considerably. Therefore, closures with lower uncertainties on coarse WMLES grids are sought for these terms. Finally, the best performance for the present test cases is obtained via the integrated NN WSM, sampling at the lower edge of the log layer within the third off-the-wall grid cell. Nevertheless, the new NNODE WSM can have an advantage in the presence of non-equilibrium effects in more complex problems.

Pipe Flow of Suspensions of Cellulose Nanocrystals

The pipeline flow behavior of suspensions of cellulose nanocrystals (CNCs) was investigated over the CNC concentration range of 0.24 to 3.65 wt% in different diameter pipelines. The CNC suspensions were Newtonian below the CNC concentration of 1 wt%. At higher concentrations, the CNC suspensions were non-Newtonian power-law fluids. For Newtonian CNC suspensions, the experimental friction factor–Reynolds number data were obtained only in the turbulent regime, and the data followed the Blasius equation closely. For power-law CNC suspensions, the experimental data of friction factor–Reynolds number covered both laminar and turbulent regimes. The experimental data followed the friction factor–Reynolds number relationships for power-law fluids reasonably well.

A numerical study of gas focused non-Newtonian micro-jets

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.

Unsteady 3D MHD Boundary Layer Stream for Non-Newtonian Power-Law Fluid Near Stagnation Point of Moving Surfaces

An unsteady three-dimensional MHD boundary layer is a fluid flow region near a surface where magnetic fields are present and interact with the fluid flow, causing it to become unsteady. This type of flow is commonly found in various astrophysical and technological applications, such as in plasmas and fusion reactors. The 3D nature of the flow introduces additional complexities to the flow dynamics, making the study and modeling of unsteady MHD boundary layers a challenging and active area of research. The unsteady boundary layer flow of fluid over a moving stagnation surface is theoretically examined in the current work with the impression of a magnetic field. The exact outcomes of the governing equations for the flow domain are obtained by utilizing the shooting phenomena. The specified analytical outcomes are also obtained for some cases. Detailed discussions of the parameters involved are confirmed both physically and graphically. Numerical results for both profiles are presented graphically. The study and modeling of unsteady 3D MHD boundary layers is imperative for a thorough understanding of various physical phenomena, improving the performance of technological systems, and advancing our knowledge of fluid dynamics.

Dimensionless Analysis of Non-Newtonian Power-Law Fluid Hammer

Dimensionless Analysis of Non-Newtonian Power-Law Fluid Hammer

Close-contact melting of phase change materials with a non-Newtonian power-law fluid liquid phase—Modeling and analysis

Close-contact melting of phase change materials with a non-Newtonian power-law fluid liquid phase—Modeling and analysis

Effect of an ascendant magnetic field on Rayleigh–Bénard convection for non-Newtonian power-law fluids in a horizontal rectangular cavity submitted to vertical temperature gradient

Effect of an ascendant magnetic field on Rayleigh–Bénard convection for non-Newtonian power-law fluids in a horizontal rectangular cavity submitted to vertical temperature gradient

Optimizing energy generation in power-law nanofluid flow through curved arteries with gold nanoparticles

The investigation of blood flow into curved arteries is fascinating and essential to prevent the advancement of vascular disease. Motivated by electro-kinetic manipulation, gold nanoparticles, and their size applications, a mathematical model is developed to explain blood flow, entropy generation, and electro-kinetic energy conversion (EKEC) efficiency in curved arterial flow. To make this study more realistic, a patient-specific overlapped stenosis condition and non-Newtonian (power-law fluid) blood flow model have been considered. The effects of a magnetic field, external heating, and chemical reactions are also included. The Stone’s strongly implicit scheme has been considered to solve the system of non-linear partial differential equations (PDE’s) in the” MATLAB” software. In this numerical investigation, an error tolerance of has been considered for every iteration step under Stone’s scheme. The significance of various physical parameters, such as nanoparticle volume fraction (m), their size (dp), magnetic field intensity (M), inverse Debye length (), flow behavior index (Sc), heat source (H), and chemical reaction parameter (ξ) on the blood flow velocity, temperature, concentration, EKEC efficiency, and entropy generation have been explained graphically. This study also developed stream function contours to describe flow trapping patterns. The findings of this study conclude that the blood flow EKEC efficiency reduces with the presence of nanoparticles and stenosis in the artery. In addition, both flow velocity and entropy enhance by adopting large-size nanoparticles instead of small diametric nanoparticles. Clinical researchers and biologists may use the results of this computational study to forecast endothelial cell damage and plaque deposition in curved arteries with WSS profiles, by which the severity of these conditions can be reduced.

Similar construction method for non-Newtonian power-law fluid seepage models with elastic outer boundary conditions

Similar construction method for non-Newtonian power-law fluid seepage models with elastic outer boundary conditions