Dilatant Fluids Research Articles

Analysis of power-law natural conjugate heat transfer under the effect of magnetic field and heat absorption/production based on the first and second laws of thermodynamics for the entropy via lattice Boltzmann method

The amount of entropy generated during the conjugate heat transfer of a non-Newtonian fluid regarding to natural convection within a two-dimensional cavity under the influence of a magnetic field and heat absorption/production has been appraised. The lattice Boltzmann method (LBM) method is developed to perform numerical simulations. Moreover, the first and second laws of thermodynamics are simulated via LBM for the entropy investigation. The influence of variables such as wall shape and aspect ratio of chamber, thermal conductivity ratio, fluid type, Hartmann number, heat absorption/production coefficient and type of magnetic field are analyzed. The lower the power-law index, the more effective the magnetic field applied. The mean Nusselt number for pseudoplastic fluid is about 52% and for dilatant fluid about 18% decreases to the highest value with enhancement of the Hartmann number. By changing the shape of the wall, the amount of current vigor, heat transfer and entropy produced can be significantly affected. In such a way that by designing the wall diagonally, the amount of heat transfer up to about 11% and the power of flow up to about 32% more than other cases. The effect of increasing the strength of the magnetic field decreases with increasing the chamber aspect ratio, and in this case the lowest heat transfer rate is seen, however the Bejan number increases.

Investigation of non-Newtonian power-law free convection affected by a magnetic field in an inclined quarter-circle chamber containing the lozenge-shaped obstacle via MRT-LBM of first and second laws of thermodynamics

Investigating the effect of the strength, type and angle of the magnetic field applied on the amount of entropy generation caused by the heat transfer of non-Newtonian fluid under the inflyence of heat production/absorption is the aim of the available study. The simulation has been done by writing the FORTRAN code using Multi relaxation time lattice Boltzmann method. Qualitative and quantitative comparison of the present work with preceding valid researches confirmed the accurateness of the outcomes. The magnetic field influence can be controlled by the angle of rotation of the chamber, and this impact decreases with power-law index enhancement. In general, application of a non-uniform magnetic field increases the mean Nusselt number by about 10% and leads to an increase in flow strength. The outcomes reveal that the impact of the angle of inclination chamber, type and direction of magnetic field application for dilatant fluid is insignificant. Increasing the coefficient of the heat absorption/production lessens the mean Nusselt number but increases the impact of the magnetic field. Enhancement of the barrier temperature and decreasing index of power-law results in an increment in the share of entropy generated by the magnetic field.

Simulation of forced convective power law fluid by using Darcy–Brinkman–Forchheimer flow model field

This study investigates the fully developed heat transfer of steady, incompressible and laminar flow of power law fluid saturated porous medium through the rectangular duct by utilizing Darcy–Brinkman–Forchheimer flow model field. Hydrodynamic flow of power law-based fluid within a rectangular duct with porosity has not been reported in the literature. The consideration of Darcy–Brinkman–Forchheimer flow model makes it very much novel in its own right. The main objective of the present study is to explore the modified Darcy parameter on flow and heat transfer characteristics. Numerical results are obtained for different values of Darcy parameter, Da, inertia coefficient, Fr and power law model, n. We note the significant impact of inertial force on flow and heat transfer in the case of dilatant fluid; however, inertial force term can be ignored in the case of pseudo-plastic fluid due to its lower effect. Furthermore, with the decrease in aspect ratio, the effect of the inertial force can be reduced. It is also noted that, axial velocity significantly enhances with Darcy parameter Da. This behavior of the axial velocity is found to be similar for higher inertia coefficient Fr as well.

Dynamics of the Rabinowitsch fluid in a reduced form of elliptic duct using finite volume method

The investigation of Computational Fluid Dynamics (CFD) focuses on the mechanical properties of a Rabinowitsch fluid model that was constructed with the help of a stenosed elliptic conduit using the well-known Finite Volume Method (FVM). If you are interested in studying physiology or biomedicine, you will find that the Rabinowitsch fluid model in peristalsis is very helpful. This is because it is used to move blood around the heart and lungs, as well as in sanitary fluid transport systems, the transfer of corrosive fluids and innovative pharmaceutical delivery systems. By using the Cartesian coordinates, it is feasible to get the elliptic domain for this duct model. Additionally, the equation of an ellipse is used in the boundary conditions for this duct in order to maintain the elliptic cross-section for this duct in its current state. The Partial Differential Equations (PDEs) for the velocity profile may be determined as soon as the issue is recast in a form that does not need any dimensions to be specified. With the assistance of boundary conditions that are provided, these PDEs are solved over elliptical cross-sections, and after that, numerical solutions are obtained for them. A dilatant fluid represents state [Formula: see text], a Newtonian fluid represents state [Formula: see text] and a pseudoplastic fluid represents state [Formula: see text] in this model, making it significant. The desired model is computed numerically. FVM is used to study the results at a low Reynolds number (around [Formula: see text]. The goal is to theoritically analyze the transmission of heat and fluid resistance to the flow. The CFD findings with experimental data are compared to confirm the model predictions. A CFD model based on the FVM and experimental data from a flow cell is used to study how fluid moves through the ducts. This study focuses on the pressure, velocity and temperature fields of a fluid moving through a stenosed duct.

Analytical solutions of PDEs by unique polynomials for peristaltic flow of heated Rabinowitsch fluid through an elliptic duct

In this research, we have considered the convective heat transfer analysis on peristaltic flow of Rabinowitsch fluid through an elliptical cross section duct. The Pseudoplastic and Dilatant characteristics of non-Newtonian fluid flow are analyzed in detail. The Rabinowitsch fluid model shows Pseudoplastic fluid nature for sigma > 0 and Dilatant fluid behaviour for sigma < 0. The governing equations are transformed to dimensionless form after substituting pertinent parameters and by applying the long wavelength approximation. The non-dimensional momentum and energy equations are solved analytically to obtain the exact velocity and exact temperature solutions of the flow. A novel polynomial of order six having ten constants is introduced first time in this study to solve the energy equation exactly for Rabinowitsch fluid flow through an elliptic domain. The analytically acquired solutions are studied graphically for the effective analysis of the flow. The flow is found to diminish quickly in the surrounding conduit boundary for Dilatant fluid as compared to the Pseudoplastic fluid. The temperature depicted the opposite nature for Pseudoplastic and Dilatant fluids. The flow is examined to plot the streamlines for both Pseudoplastic and Dilatant fluids by rising the flow rate.

Insight Into the Dynamics of the Rabinowitsch Fluid Through an Elliptic Duct: Peristalsis Analysis

The current research is concerned with the mechanical characteristics of a Rabinowitsch fluid model that has been developedviaan elliptic duct. If we study physiology or biomedicine, we will find that the Rabinowitsch fluid model in peristalsis is very useful because it is used to move blood around in the heart, lungs, sanitary fluid transport systems, transfer of corrosive fluids, and innovative pharmaceutical delivery systems. It is possible to get the elliptic domain for this duct model by using Cartesian coordinates, and in the boundary conditions for this duct, the equation of an ellipse is used to keep the elliptic cross-section for this duct in place. A mathematical model for an incompressible fluid is being created, and the mathematical issue is then transformed into its dimensionless form by using suitable transformations, including long-wavelength approximation. As soon as the problem is put into a dimensionless form, the partial differential equations for the velocity profile can be found. These partial differential equations are solved across elliptical cross-sections with the help of boundary conditions that are given, and accurate mathematical solutions are then found for them. This model is important because it shows three different types of flow: a dilatant fluid forγ&lt;0, a Newtonian fluid forγ=0, and a pseudoplastic fluid forγ&gt;0. The prime objective of our work is to obtain a novel solution to this problem as well. In the last section, we see and read about how the formulas for flow characteristics were made.

Non-Newtonian power-law fluids with variable magnetic field and slip conditions

The purpose of this paper is to study the effect of heat transfer and flow of non-Newtonian power-law fluids towards a stretching sheet in the appearance of transverse magnetic field with slip boundary conditions. Suitable similarity transformations are used to change the non-linear partial differential equations to ordinary differential equations. For the numerical solution Maple software by applying built-in command dsolve with numeric is utilized. It is noticed from the obtained results that an increase in the magnetic parameter results in a decrease in the dimensionless velocity profile and in the stream function while the temperature profile increases for the Newtonian, dilatant, and pseudo-plastic fluids. Increasing the velocity slip parameter, a reducing behavior can be seen in the stream function and in the velocity profile while temperature profile is enhancing. Moreover, with increasing thermal slip, a decrease occurs in the dimensionless temperature. The variations in the velocity and temperature profiles under dimensionless parameters are significant for n = 0.8 (pseudo-plastic fluid) rather than for n = 1 (Newtonian fluid) and n = 1.02 (dilatant fluid).

Numerical analysis of thermophoresis of charged colloidal particles in non-Newtonian concentrated electrolyte solutions.

Thermophoresis of colloidal particles in aqueous media is more frequently applied in biomedical analysis with processed fluids as biofluids. In this work, a numerical analysis of the thermophoresis of charged colloidal particles in non-Newtonian concentrated electrolyte solutions is presented. In a particle-fixed reference frame, the flow field of non-Newtonian fluids has been governed by the Cauchy momentum equation and the continuity equation, with the dynamic viscosity following the power-law fluid model. The numerical simulations reveal that the shear-thinning effect of pseudoplastic fluids is advantageous to the thermophoresis, and the shear-thickening effect of dilatant fluids slows down the thermophoresis. Both the shear-thinning and shear-thickening effects of non-Newtonian fluids on a thermodiffusion coefficient are pronounced for the case when the thickness of electric double layer (EDL) surrounding a particle is moderate or thin. Finally, the reciprocal of the dynamic velocity at the particle surface is calculated to approximately estimate the thermophoretic behavior of a charged particle with moderate or thin EDL thickness.

Mathematical model of convective heat transfer for peristaltic flow of Rabinowitsch fluid in a wavy rectangular duct with entropy generation

This research article unfolds a novel mathematical model that interprets the ‘peristaltic flow of Heated Rabinowitsch fluid’ inside a wavy rectangular duct. The fluid flow characteristics are thoroughly examined for Pseudo-plastic in addition to Dilatant nature, (i.e. α > 0 for pseudo-plastic nature and α < 0 for dilatant nature respectively). Peristaltic flow inside a wavy rectangular duct is widely being studied due to immense number of biomedical and engineering applications. We have derived the dimensionless nonlinear partial differential equations in coupled form after applying certain relevant dimensionless quantities, the lubrication technique of low Reynolds number and long wavelength estimations (i.e., ). The dimensionless energy equation is solved by dividing it into two additional equations and after employing suitable procedures, an exact temperature profile solution is computed. The present study has been developed by using hit and trial method to solve the single partial differential equation having two dependent variables in form of extra stress tensors. The solution of temperature profile provides a detailed solution method to exactly solve such complex partial differential equations. For both dilatant and Pseudo-plastic fluids, effective physical parameters are used to depict velocity distribution, pressure gradient and pressure rise, convection and entropy phenomena. When compared with Pseudo-plastic fluid, the Dilatant nature of fluid has a high convection rate. Finally, the phenomenon of entrapment is examined through streamlines that provide a flow visualization inside the wavy sinusoidal duct. Peristaltic pumps are being used for transportation of many fluids like toxic chemicals in nuclear industry, food processing, heart-lung machines, roller and finger pumps and transportation of slurries etc. These usage of these pumps leads to an upgraded mechanical efficiency and lower cost for transportation purposes.

Electrokinetic energy conversion of power-law fluids in a slit nanochannel beyond Debye-Hückel linearization

Electrokinetic energy conversion of power-law fluids is analyzed in a slit nanochannel. Electrical potential distribution is considered without Debye-Hückel linear approximation. The general analytical expressions of flow velocity and streaming potential are obtained for arbitrary power-law behavior indexes. Due to the strongly nonlinear constitutive relation of power-law fluids, the energy conversion efficiency is analyzed numerically. Results show that the electrokinetic energy conversion efficiency can be underestimated for the same physics parameters, when the Debye-Hückel linear approximation is applied. The conversion efficiency of pseudoplastic fluids is larger than that of dilatant and Newtonian fluids. The maximum in conversion efficiency of pseudoplastic fluids (n = 0.8) is about 5% and it is more than 78% than that of dilatant fluids (n = 1.2). Finally, the optimal flow parameters exist and such optimal values can be used to design an energy converter with high conversion efficiency.

Hydrodynamics of electro-capillarity propelled non-Newtonian droplets through micro-confinements.

In this article, we theoretically explore the dynamics of droplet motion and its evolution during electro-capillarity propelled actuation within microfluidic systems. The study covers a wide gamut of fluids, wherein we investigate the dynamics of both pseudoplastic and dilatant fluid droplets. It is observed that change in the fluid rheology of the non-Newtonian fluids leads to significant morphing of the droplet dynamics during the actuation and propulsion event when compared to the Newtonian counterparts. We validate the theory using experimental reports on similar systems employing Newtonian droplets. The influence of governing parameters such as the actuation voltage and its transients, dielectric layer thickness on the electrodes and electrode spacing is probed. We also explore the influence of the interfacial properties of the system, such as channel wall friction, droplet wettability, and capillary friction, and establish that the fluid rheology, in conjunction with the interfacial features regulate the electro-actuation and propulsion of the droplets. We further provide theoretical estimates on the optimal design of the electro-actuation system in terms of a proposed electro-interfacial tension parameter. The findings may hold significance towards design and development of microfluidics with electro-actuation systems.Graphical Supplementary InformationThe online version contains supplementary material available at 10.1140/epje/s10189-022-00196-0.

LBM simulation of non-Newtonian fluid seepage based on fractional-derivative constitutive model

This paper proposes a truncated fractional-derivative constitutive model to consider the non-locality of non-Newtonian fluids. The single relaxation time lattice Boltzmann method (SRT-LBM) is used to simulate seepage of non-Newtonian fluid. The results are verified by analytical solutions while the flow characteristics of non-Newtonian fluids are explored. In the case of laminar flow, the steady-state velocity distribution of shear-thinning and shear-thickening fluids after 105 - time steps are compared with the analytical distribution, and the results show an agreement within 2%. For non-Newtonian index simulation, the thicker the fluid, the larger the velocity and the more volatility, implying the more complex flow characteristics for shear-thickening fluid. Additionally, small fractional indexes correspond to large computational errors in regions away from the boundary. Flow characteristics research shows that the seepage of power-law fluid in fractured media exhibits non-Darcy phenomenon. As the fractional index decreases (i.e., fluid becomes thicker), the obstruction of the medium increases, resulting in a reduction in the medium's permeability. The shear stress of non-Newtonian fluids can be memorized by the mean section velocity distribution, and the memory capacity of different fluids can be captured by the fractional index. Furthermore, the fractional-derivative critical Reynolds number is introduced to clarify the applicable conditions of non-Newtonian flow equations, which increase with diameter and initial kinematic viscosity. The fractional-derivative critical Reynolds number of dilatant fluids is larger than pseudoplastic fluids, due to the memory properties of the fluid as well as the physical characteristics.

CFD analysis of Effect of journal bearing lubricated with non-Newtonian fluid

The present paper deals with the CFD analysis of hydrodynamic bearing lubricated with a non-Newtonian fluid and the non-Newtonian behaviour of lubricant is represented by a power-law. Bearing parameters such as fluid film pressure and load-carrying capacity are determined by varying the power-law index (n) in terms of its viscosity from 0.8 to 1.2 under steady-state conditions through the CFX 17.2 software module and the flow model opted as Laminar based on Reynolds number calculation as per the geometry developed for the simulation. The relationship between the pressure and load-carrying capacity are also obtained for different relative clearance, revolution per minute and L/D ratio. Fluid film pressure profile was drawn by varying input parameters at different power-law index for understanding the performance of HDB under different regimes i.e. dilatant, Newtonian and pseudoplastic fluids. Plots were also created between Pressure, load carrying capacity and power law index to study the performance of HDB. This has been observed that the bearings lubricated with dilatant fluid (n >1) have higher pressure and load carrying capacity as compared to those lubricated with pseudoplastic fluid (n < 1). Occurrences of cavitation were also seen at lower angle with increases in power law index for 0.0006 relative clearance but increases at 0.0008.

Dynamics of mixed convection and Hall current in radiative power-law velocity slip flow of non-Newtonian fluid

The present research letter aims to highlight the incompressible, laminar, two-dimensional electrical convoying flow of power-law material subject to the exponentially stretched sheet. Power-law velocity slip conditions are accounted. Hall current, radiative heat flux, transverse magnetic field, and dissipation effects are considered in the mathematical modeling. Radiative heat flux is defined in the presence of Rosseland’s diffusion model. Heat and mass transfer rates are discussed. The governing nonlinear derivation satisfying the flow is altered into nonlinear ordinary ones by the implementation of similarity quantities. The obtained nonlinear ordinary ones system is tackled numerically through the bvp4c technique. The resultant outcomes are calculated for various variables in tabular form and graphical demonstration for perfect consideration of the thermo-physical quantities. The considered model is discussed for two important fluids i.e. pseudo-plastic fluid (n = 0.7) and dilatant fluid (n = 1.3), and its primary and secondary velocities, concentration, and temperature fields are analyzed for emerging variables. The derived results are verified with limiting literatures by Shamshuddin et al. [4] and Saleem and El-Aziz [6] and found a 99.99 percent good agreement for the Newtonian case. Sherwood number, skin friction coefficient, and Nusselt number are computed for various emerging parameters.

Effect of Silica Fume on the Rheological Properties of Cement Paste with Ultra-Low Water Binder Ratio

The effect of silica fume on the rheological properties of a cement–silica fume–high range water reducer–water mixture with ultra-low water binder ratio (CSHWM) was studied. The results indicate that the W/B ratio and silica fume content have different effects on the rheological parameters, including the yield stress, plastic viscosity, and hysteresis loop area. The shear-thickening influence of CSHWM decreased with the increased silica fume content. When the silica fume content increased from 0% to 35%, the mixture with W/B ratio of 0.19 and 0.23 changed from a dilatant fluid to a Newtonian fluid, and then to a pseudoplastic fluid. When the silica fume content was less than 15%, the yield stress was close to 0. With the increase of silica fume content, the yield stress increased rapidly. The plastic viscosity and hysteresis loop area decreased slightly with the addition of a small amount of silica fume, but increased significantly with the continuous increase of silica fume. Compared with the Bingham and modified Bingham models, the Herschel–Buckley model is more applicable for this CSHWM.

Insights into carbon dioxide hydrate formation, fluid type, and agglomeration in the system with or without tween-80

In this work, the flow of carbon dioxide (CO2) hydrate slurry is systematically investigated by analyzing its rheological behavior, apparent viscosity, and crystal shape. The results show that blocking is easy to occur in the pure water system, while no blockage is observed from the system containing Tween-80. Besides, we confirm that the hydrate slurry formed in the pure water system is a dilatant fluid with shear-thickening behavior. However, that obtained from the system containing Tween-80 are pseudoplastic fluids with shear-thinning behavior. The time development of hydrate slurry flow in the system with or without Tween-80 showed that the shear-thinning behavior is a key factor in preventing the hydrate slurry from blockage. In addition, in the presence of Tween-80, hydrates will form on the surface of the bubble. These hydrates are easily dispersed on top of the liquid phase and will not adhere to the top wall of the pipeline. However, in pure water, a dense adhesive layer is observed on the top of the pipeline, which will reduce the flow area in the pipeline, increasing the flow resistance. Overall, the main role of Tween-80 in preventing hydrates from aggregation includes two aspects, (1) changing the type of fluid from dilatant to pseudoplastic; (2) providing bubbles for hydrate formation. The addition of defoamer(BK601) will reduce the Tween-80′s effects in preventing hydrates by reducing shear-thinning behavior and the amount of bubbles.

Large eddy simulation of turbulent flow of pseudoplastic and dilatant fluids: turbulence characteristics

Large eddy simulation of turbulent flow of pseudoplastic and dilatant fluids: turbulence characteristics

Large eddy simulation of turbulent flow of pseudoplastic and dilatant fluids: rheological and hydrodynamic behaviour

Large eddy simulation of turbulent flow of pseudoplastic and dilatant fluids: rheological and hydrodynamic behaviour

Численное исследование влияния неизотермичности на характеристики течения степенной жидкости в трубе с резким расширением

In this paper, a steady laminar non-isothermal flow of a power-law fluid in an axisymmetric sudden pipe expansion is numerically simulated. The rheological behavior of the fluid is described by the modified Ostwald-de Waele law; the apparent viscosity is an exponential function of temperature. The equations are written in terms of dimensionless stream function - vortex - temperature. No-slip conditions and zero temperature are used on the solid wall. At the inlet boundary, the velocity and temperature profiles correspond to a one-dimensional steady non-isothermal flow of the considered fluid. “Soft” boundary conditions are assigned at the outlet boundary. The formulated problem is solved using the finite-difference method. The structure of the flow through a sudden pipe expansion is shown to include one- and two-dimensional flow zones with a recirculation region occurring in the inner corner vicinity. The variation in the two-dimensional flow zone length is analyzed with respect to a power-law index and dimensionless criteria of the problem. Distributions of the velocity, temperature, and apparent viscosity are presented at various Peclet and Reynolds numbers for dilatant and pseudoplastic fluids.

Origin of the effects of optical spectrum and flow behaviour in determining the quality of dry fig, jujube, pomegranate, date palm and concentrated grape vinegars

In this study, we focused on physical characterization and quality control of dry fig, jujube, pomegranate, date palm and concentrated grape vinegars using UV spectroscopy method and rheology technique. The optical spectra and flow behaviour of the vinegars were analysed in detail in the selected specific wavelength, shear rate and frequency ranges, respectively. It was determined that the peak values seen in the UV spectra of the vinegars were caused by the organic acid and phenolic compound concentration. The peak values in the UV spectra of the vinegars wavelength range of 190 nm to 240 nm and 250 nm to 300 nm were caused by the organic acid and phenolic compound concentration, respectively. In this context, it was predicted that concentrated grape vinegar, which has the highest absorbance value, has higher organic acid content and more antibacterial/antioxidant properties compared to the others. It is thought that the optical energy gaps of vinegars are related to the organic acid concentration and the release time. Flow properties of the vinegars were non-Newtonian thickening fluids (dilatant fluids) and compatible with the Power law model. The stable flow of the vinegars in the high shear rate region was interpreted as having a successful production process and being of good quality.