Bingham Plastic Fluid Research Articles

Exploring the Dynamic Behavior of a Tapered Stenosed Artery: An Investigation into Its Unsteady Model

In this communication, blood flow is considered in a two-phase model of the tapered stenosed artery. Non-Newtonian and Newtonian models are considered in inner and outer regions, respectively. The transverse magnetic field is applied externally on the presumed pulsatile flow of blood to examine the nature of blood flow. It is anticipated that, in the inner region, blood follows the Jeffrey fluid model, and in the outer region, it follows the Bingham Plastic fluid model. The mathematical model of this system is formulated, a non-dimensionalization technique is used, and a numerical solution is obtained using the Finite difference method, one of the most suitable numerical methods for the formulated problem. The expressions for the primary/fundamental characteristics in determining the effect of blood flow are developed to explore the consequence of hematocrit, time component, tapering angle, and magnetic field. Scilab software is employed for mathematical simulations, revealing that flow characteristics within a stenosed artery undergo significant alterations, while the presence of a magnetic field aids in partially regulating the flow characteristics.

Empirical modeling and sensitivity analysis of pressure rise per wavelength and frictional forces for the peristaltic flow of Bingham plastic fluids: application of response surface methodology

The efficiency of mixed convection peristaltic flow can be investigated through pressure rise per wavelength (ΔPλ)\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$(\\Delta P_{{{\\uplambda }}} )$$\\end{document} and frictional forces (Fλ\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${F}_{\\uplambda }$$\\end{document}). The main aim of the present study is to discover the sensitivity analysis of non-Newtonian fluids using the Bingham plastic fluid model. In order to achieve this objective, we have empirically modeled the pressure rise per wavelength (ΔPλ)\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$(\\Delta {P}_{\\uplambda })$$\\end{document} and frictional forces (Fλ\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${F}_{\\uplambda }$$\\end{document}) as a function varying with leading parameters of problem. The flow problem is governed by three coupled nonlinear partial differential equations. They are reduced to nonlinear coupled ordinary differential equations by using the long wavelength and low Reynolds number approximations. They are solved numerically using MATLAB built-in routine bvp4c to analyze the sensitivity of pressure rise per wavelength (ΔPλ\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\Delta {P}_{\\uplambda }$$\\end{document}) and frictional forces (Fλ\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${F}_{\\uplambda }$$\\end{document}). We first derive the empirical model among each of responses ΔPλ\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\Delta {P}_{\\uplambda }$$\\end{document} and Fλ\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${F}_{\\uplambda }$$\\end{document} and physical parameters which govern the flow using response surface methodology. The goodness of fit of empirical model is decided on the basis of coefficient of determination (R2\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${R}^{2}$$\\end{document}) obtained from the analysis of variance (ANOVA). The coefficients of determination (R2\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${R}^{2}$$\\end{document}) are 99.78% both for ΔPλ\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\Delta {P}_{\\uplambda }$$\\end{document} andFλ\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${F}_{\\uplambda }$$\\end{document}. The higher values of R2\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${R}^{2}$$\\end{document} determine the goodness of fit of empirical model. No correlation has been developed to optimize ΔPλ\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\Delta {P}_{\\uplambda }$$\\end{document} and Fλ\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${F}_{\\uplambda }$$\\end{document} in peristaltic flow for Bingham plastic fluids using RSM. The results of sensitivity analysis revealed that ΔPλ\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\Delta {P}_{\\uplambda }$$\\end{document} and Fλ\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${F}_{\\uplambda }$$\\end{document} are most sensitive to flow rate (q) at all levels such as low (− 1), medium (0) and high (+ 1). The sensitivity of ΔPλ\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\Delta {P}_{\\uplambda }$$\\end{document} to Bingham number (Bn) shows a distinct behavior with varying levels of flow rate (q). At low level (− 1) of flow rate (q), the sensitivity is positive, and at high level (+ 1) of flow rate (q), the sensitivity becomes negative. Conversely, the sensitivity of Fλ\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${F}_{\\uplambda }$$\\end{document} to Bingham number (Bn) at low to high level of flow rate (q).

Effects of Electroosmosis Flow of Bingham Plastic Fluid Induced by a Curved Microtube

Effects of Electroosmosis Flow of Bingham Plastic Fluid Induced by a Curved Microtube

Bingham plastic fluids flow analysis in multimembranes fitted porous medium

A mathematical analysis is presented for the flow of a Bingham plastic fluid propelled by the multi-membranes pumping mechanism through porous media. Two successive membranes with different amplitude, diameter, and phase lag, are fitted at the upper wall of the channel, and the lower wall is stationary. Due to the simultaneous propagation of both membranes, the pressure is generated at the membrane's position, which helps in propelling the fluids in forward and backward directions depending upon the compression and expansion cycles of the membranes. The low Reynolds number assumption and lubrication theory are utilized to linearize the governing equations, which are further analytically derived, and then employing MATLAB codes to compute the illustrations for the interpretation of the results. The effects of key parameters like plug flow region, pore size and diameter of membranes on the velocity field, wall shear stress, pressure gradient, fanning friction factor, head loss and particle trajectories, are analysed in the microchannel. Results of the present model conclude that the geometrical properties of membranes, rheological properties of fluids and porosity of the medium significantly alter the flow and pumping characteristics which give valuable insights for the design of micro-valve less pumping actuators to be aimed at controlling microscale transport processes in various medical diagnoses and treatments.

Investigation of Pulsatile Behavior and Flow Characteristics in Stenosed Arteries: Analysis of Bingham Plastic Fluid Dynamics

Investigation of Pulsatile Behavior and Flow Characteristics in Stenosed Arteries: Analysis of Bingham Plastic Fluid Dynamics

Prediction of Foam Rheology Models Parameters Utilizing Machine Learning Tools.

Rheological models are usually used to predict foamed fluid viscosity; however, obtaining the model constants under various conditions is challenging. Hence, this paper investigated the effect of different variables on foam rheology, such as shear rate, temperature, pressure, surfactant types, gas phase, and salinity, using a high-pressure high-temperature foam rheometer. Power-law, Bingham plastic, and Casson fluid models fit the experimental data well. Therefore, the data were fed to different machine learning techniques to evaluate the rheological model constants with different features. In this study, seven different machine learning techniques have been applied to predict the rheological models' constants, including decision tree, random forest, XGBoost (XGB), adaptive gradient boosting, gradient boosting, support vector regression, and voting regression. We evaluated the performance of our machine learning models using the coefficient of determination (R2), cross-plots, root-mean-square error, and average absolute percentage error. Based on the prediction outcomes, the XGB model outperformed the other ML models. The XGB model exhibited remarkably low error rates, achieving a prediction accuracy of 95% under ideal conditions. Furthermore, our prediction results demonstrated that the Casson model accurately captured the rheological behavior of the foam. Additionally, we used Pearson's correlation coefficients to assess the significance of various properties in relation to the constants within the rheological models. It is evident that the XGB model makes predictions with nearly all features contributing significantly, while other machine learning techniques rely more heavily on specific features over others. The proposed methodology can minimize the experimental cost of measuring rheological parameters and serves as a quick assessment tool.

Enhanced Solubility and Bioavailability of Clotrimazole in Aqueous Solutions with Hydrophobized Hyperbranched Polyglycidol for Improved Antifungal Activity.

The poor solubility of clotrimazole in the aqueous medium and the uncontrolled removal of the drug-loaded suppository content limit its effectiveness in the treatment of vulvovaginal candidiasis. We present here the aqueous formulations of clotrimazole in the form of non-Newtonian structured fluids, i.e., Bingham plastic or pseudoplastic fluids constructed of hyperbranched polyglycidol, HbPGL, with a hydrophobized core with aryl groups such as phenyl or biphenyl. The amphiphilic constructs were obtained by the modification of linear units containing monohydroxyl groups with benzoyl chloride, phenyl isocyanate, and biphenyl isocyanate, while the terminal 1,2-diol groups in the shell were protected during the modification step, followed by their deprotection. The encapsulation of clotrimazole within internally hydrophobized HbPGLs using a solvent evaporation method followed by water addition resulted in structured fluids formation. Detailed Fourier-transform infrared spectroscopy (FTIR) and differential scanning calorimetry (DSC) analyses performed for aryl-HbPGLs with clotrimazole revealed the difference in drug compatibility among polymers. Clotrimazole in biphenyl-enriched HbPGL, unlike phenyl derivatives, was molecularly distributed in both the dry and the hydrated states, resulting in transparent formulations. The shear-thinning properties of the obtained fluid formulations make them injectable and thus suitable for the intravaginal application. Permeability tests performed with the usage of the Franz diffusion cell showed a 5-fold increase in the permeability constant of clotrimazole compared to drugs loaded in a commercially available disposable tablet and a 50-fold increase of permeability in comparison to the aqueous suspension of clotrimazole. Furthermore, the biphenyl-modified HbPGL-based drug liquid showed enhanced antifungal activity against both Candida albicans and Candida glabrata that was retained for up to 7 days, in contrast to the phenyl-HbPGL derivatives and the tablet. With their simple formulation, convenient clotrimazole/biphenyl-HbPGL formulation strategy, rheological properties, and enhanced antifungal properties, these systems are potential antifungal therapeutics for gynecological applications. This study points in the synthetic direction of improving the solubility of poorly water-soluble aryl-enriched pharmaceuticals.

Exact Solution of Tank Drainage for Bingham Fluid flow circular tube

Unsteady tank drainage of Bingham Plastic fluid whose flow of the fluid is due to gravity, is considered in this study. The separation of variables method is used to obtain the exact solution of the fluid. Due to very high yield stress of the fluid no slip condition is used to find out the velocity profile of the fluid. The primary objective of this work is to find the velocity profile, flow rate, shear stress, average velocity, time efflux, the relationship between the time (varying with the depth of a tank) and the time required for complete drainage from emerging partial differential equation. It has been observed that when the Bingham model parameters, flow region and pipe length increase, the time required to drain the fluid from the tank also increases. Furthermore, findings indicate that higher density and a larger pipe radius result in quicker drainage of Bingham plastic fluid from the circular tank.

Rheological characteristics of bauxite slurry with varying concentration, particle size distribution, and modal distribution for pipeline transportation

Some of the foremost parameters effecting the slurry rheology, preferably the slurry concentration, particle size distribution, and modal distributions, were studied in the current findings, figuring out the variation in shear stress and apparent viscosity using a rotational rheometer. The particle size considered for the test ranges from fine particle size of −75 µm to coarse particle size of +75–300 µm, separated at varied size fractions of +75–105, +105–150, +150–210, and +210–300 µm. The −75 µm bauxite slurry at 60 wt% has shown a maximum static settled concentration (Cw -max) under gravity after 48 h free settlement. This fine particle slurry at varying concentrations of Cw = 45–65% is discerned to behave like a Non-Newtonian Bingham plastic fluid at lower concentrations, unlike the other coarse fraction bauxite slurries at Cw = 55%, which exhibit shear thickening behavior. The present work carried out adds knowledge on the rheological behavior of bimodal, trimodal, and multimodal with four and five different size fraction bauxite slurries in finding the optimum mass concentration for a particle size fraction of (coarse):(fine), obtained in the ratio (25):(75), (25:25):(50), (25:25:10):(40), and (15:15:15:15):(40), respectively of the total 60 wt%. Certain parameters, like yield stress, consistency index (k), and flow behavior index (n), were estimated upon fitting the modal distributions to the Herschel Bulkley model to choose the best particle size distribution of the bauxite sample showing improved slurry stability, rheology, and flow characteristics.

Optimization of specific energy consumption in the high concentration slurry disposal pipelines for coal ash in thermal power plants

ABSTRACT In thermal power plants, the disposal of coal fly ash is one of the major challenges requiring energy input for its safe disposal, so optimization is needed to minimize the required energy input at maximum fly ash transportation. Present work is focussed on high concentration optimized transportation of ash slurry in thermal power plants using Computational Fluid Dynamics (CFD) which behaves as a Bingham plastic fluid, modeled using Herschel-Bulkley model. Specific Energy Consumption (SEC) is the measure of the energy required for the slurry transportation. Therefore, a parametric investigation to establish the effect of concentration of slurry (Cw), pipe diameter (D), no. of pipes (N), particle size (d) over SEC is conducted. Therefore, these operational parameters need to be carefully selected, as even a minor variation from the desired optimum values may result in huge SEC consumption thereby causing financial consequences. It is found in the current study that the SEC substantially depends on all of the above-mentioned parameters. Mathematical models for prediction of SEC based on the study are also developed for the future designers of such systems.

Non-Newtonian Fluid Film Lubrication of Asymmetric Rollers using Vogel Viscosity-Temperature Relationship

A theoretical analysis of asymmetric roller bearing system with cavitation that is hydro-dynamically lightly loaded and lubricated by a thin, in-compressible fluid is presented. The lubricant adheres to the non-Newtonian Bingham plastic fluid concept, in which the viscosity of the fluid should change depending on the mean film temperature. The continuity and momentum equations, which regulate fluid flow, are first solved analytically and then numerically using MATLAB. Through graphs and tables, some key bearing features are addressed and further explained. This leads to the conclusion that there is a discernible difference between Newtonian and non-Newtonian fluids in terms of pressure, temperature, load, and traction. The findings are good in line with the body of literature.

Introduction and implementation of fluid forces in a DEM code for simulating particle settlement in fluids

Simulations of a problem involving particles and fluid usually require coupling a discrete element method (DEM) with computational fluid dynamics (CFD) or smoothed particle hydrodynamics (SPH). The former suffers from the accuracy or even reliability problem induced by mesh size while the latter suffers from small size model and high computation time and cost. To overcome part of these problems, fluid forces have been formulated and directly implemented in a DEM code, resulting in a new model, named f-EDEM. Using this model, the settlement of particles in a fluid can be simulated by a single DEM code without the need of coupling with a CFD or SPH solver. In this study, the formulation and implementation of fluid forces into the DEM code are presented. The proposed f-EDEM model is first validated against an analytical solution. The applicability and ability of the f-EDEM model are examined by reproducing and predicting some laboratory results. The comparisons between the numerical, analytical and experimental results indicate that the f-EDEM model is successfully validated and has the required capacity for simulating the settlement of single and multiple particles in both Newtonian and some of non-Newtonian (Bingham plastic) fluids. The results also indicate that the time step recommended by most DEM manuals can be excessively small, resulting in a high computational cost. It is thus necessary to perform sensitivity analysis of time step to obtain an optimal numerical model, which ensures stable and reliable numerical result with the shortest time of computation.

Viscoplastic flow past a cylinder near a moving wall

The flow of kaolinite mixed with water at mass fractions ≤28.5% past a cylinder near a moving wall is numerically investigated. The fluid is a non-Newtonian yield stress one and modeled as a Bingham plastic fluid. Simulations are performed at Reynolds numbers of 100≤Re≤1000 and Bingham numbers of 6.3≤Bn≤1153.1, which correspond to generalized Reynolds numbers of 0.55≤Regen≤503.6. Effects of the wall with the gap ratio varied in the range of G/D=0.1 and G/D=9 on the flow structures and the drag and lift coefficients are analyzed. The flow regime spans from laminar steady without and with boundary layer separation (and with two static unyielded zones formed at the front and rear stagnation points) to unsteady with periodic shedding of vortices behind the cylinder (and almost no unyielded zones in the near field). At small gaps, i.e., G/D≤1, both the drag and lift coefficients increase rapidly as the gap is decreased. They also increase with decreasing Regen. At G/D=9, influence of the wall is negligible, three approximations of the drag coefficient as a function of Regen are proposed.

Effect of aspect ratio of enclosure on free convection from horizontal cylinders in Bingham plastic fluids

Effect of aspect ratio of enclosure on free convection from horizontal cylinders in Bingham plastic fluids

Numerical study on the flow of Bingham plastic fluids around an array of cylinders

Numerical study on the flow of Bingham plastic fluids around an array of cylinders

Lubrication of asymmetric rollers considering viscosity as function of mean temperature

A theoretical analysis of an asymmetric roller bearing system with cavitation that is hydro-dynamically lightly loaded and lubricated by a thin, incompressible fluid is presented. The lubricant adheres to the non-Newtonian Bingham plastic fluid concept, in which the viscosity of the fluid should change depending on the mean film temperature. The continuity and momentum equations, which regulate fluid flow, are first solved analytically and then numerically using MATLAB. Through graphs and tables, some key bearing features are addressed and further explained. This leads to the conclusion that there is a discernible difference between Newtonian and non-Newtonian fluids in terms of pressure, temperature, load, and traction. The findings are good in line with the body of literature.

A Bingham Plastic Fluid Solver for Turbulent Flow of Dense Muddy Sediment Mixtures

We have developed and tested a numerical model for turbulence resolving simulations of dense mud–water mixtures in oscillatory bottom boundary layers, based on a low Stokes number formulation of the two-phase equations. The resulting non-Boussinesq equation for the fluid momentum is coupled to a transport equation for the mud volumetric concentration, giving rise to a volume-averaged fluid velocity that is non-solenoidal, and the model was implemented as a new compressible flow solver. An oscillating pressure gradient force was implemented in the correction step of the standard semi-implicit method for pressure linked equations (SIMPLE), for consistency with the treatment of other volume forces (e.g., gravity). The flow solver was further coupled to a new library for Bingham plastic materials, in order to model the rheological properties of dense mud mixtures using empirically determined concentration-dependent yield stress and viscosity. We present three direct numerical simulation tests to validate the new MudMixtureFoam solver against previous numerical solutions and experimental data. The first considered steady flow of Bingham plastic fluid with uniform concentration around a sphere, with Bingham numbers ranging from 1 to 100 and Reynolds numbers ranging from 0.1 to 100. The second considered the development of turbulence in oscillatory bottom boundary layer flow, and showed the formation of an intermittently turbulent layer with peak velocity perturbations exceeding 10 percent of the freestream flow velocity and occurring at a distance from the bottom comparable to the Stokes boundary layer thickness. The third considered the effects of density stratification due to resuspended sediment on turbulence in oscillatory bottom boundary layer flow with a bulk Richardson number of 1×10−4 and a Stokes–Reynolds number of 1000, and showed the formation of a lutocline between 20 and 40 Stokes boundary layer depths. In all cases, the new solver produced excellent agreement with the previous results.

Development of Heavy-Weight Hematite-Based Geopolymers for Oil and Gas Well Cementing.

In the petroleum industry, ordinary Portland cement (OPC) is utilized for different cementing applications. Yet, there are some technical and environmental issues for the usage of OPC in well cementing. The technical problems include gas invasion while setting, instability at corrosive environments, cement failure while perforation and fracturing due to high stiffness and brittleness, and strength reduction and thermal instability at elevated temperatures. Moreover, OPC production consumes massive energy and generates high greenhouse gas emissions. This study introduced the first hematite-based class F fly ash geopolymer formulation that can be used in oil and gas well cementing. Different properties of the designed slurry and hardened samples such as rheology, thickening time, strength, and elastic and petrophysical properties were evaluated. Moreover, mixability and pumpability challenges of heavy-weight geopolymer slurries were investigated. Unlike most of the studies in the literature, this work used 4 M NaOH solution only as an activator that can reduce the overall cost. The results showed that increasing the hematite percentage significantly decreased the thickening time. The developed formulation fell within the recommended fluid loss ranges for some cementing applications without using a fluid loss control additive. A proposed mixture of retarder and superplasticizer was introduced to enhance the thickening time by almost 5 times. The compressive strength increased by 49% and the tensile strength was enhanced by 27.4% by increasing the curing time from 1 to 7 days. The improvement in both compressive and tensile strength with curing time indicated that the geopolymerization reaction continued for extended time but with a smaller rate. The developed slurry acted more like a power law fluid at low temperatures and more like a Bingham plastic fluid at high temperatures. The elastic properties of the developed geopolymer samples proved that they are more flexible than some cement systems.

Calculating the entropy generation of a Bingham plastic fluid flow due to a heated rotating disk

We present the numerical study of the flow on a heated rotating disk for Bingham plastic fluid. Thermo-physical properties and viscous dissipation are assumed with the influence of entropy generation. This kind of study has a significant attentiveness in the fields of applied engineering for their increased mathematical advantages. We analyzed the solutions of fluid flow and entropy phenomenon for the Bingham fluid. The similarity solution was firstly presented by von Kármán for Newtonian fluid, it is found to be beneficial for the Bingham plastic fluid by transforming the boundary layer partial differential equations into ordinary differential equations. Shooting method is used to crack the dimensionless ordinary differential equations. The Bingham model is momentous for unlimited high shear rates for this we suggest these numerical data provide accurate description of the Bingham fluid and entropy minimization near a rotating disk. The outcomes exhibits that the azimuthal velocity profiles upsurges for upward values of Bingham fluid, and the similar behavior for tangential radial velocity is perceived. The temperature curve is noted to be enhanced for higher magnitudes of Eckert number and thermal conduction parameter. The soret number and diffusivity coefficient creates increment in concentration curve. The entropy function in the flow system enhances for up surging the inputs of Bingham fluid coefficient and thermophoresis diffusion. The results are locally similar for various parameters. We have also included the comparison analysis with published works.

Core Variation of a Non-Newtonian Fluid in an Annular Cylinder

The objective of the paper is to investigate the variation of core thickness of a non-Newtonian fluid in an annular cylinder at the entrance region. It is derived numerically, with no prior assumptions on the form of the Velocity profile. The thickness of the core is examined at each cross section of annuli for various values of Bingham number and aspect ratio by applying mass balance equation. The effect of various parameters on the flow rate are obtained graphically. The examination incorporates Bingham plastic fluids, Casson and Herschel-Bulkley fluid. The administering equations are solved using an iterative procedure by converting non-linear algebraic equation, expressing the variation in pressure in terms of core thickness obtained using the mass balance equation and plug core velocities along the boundary layers. The core thickness is obtained numerically by solving this equation using an iterative procedure. MATLAB programming tool has been employed to get the graphical variation of core thickness for different values of aspect ratio. The comparisons have been made between the obtained results and the results of Casson and Herschel-Bulkley fluids. Also, we find excellent agreement between our numerical results and the results available in literature.