24 research outputs found

    Heat and mass transfer analysis of nonlinear mixed convective hybrid nanofluid flow with multiple slip boundary conditions

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    The current study focuses on the 3D nonlinear mixed convective boundary layer flow of micropolar hybrid nanofluid in the presence microorganism and multiple slip conditions across the slendering surface. The concentration and energy equations are developed in the occurrence of activation energy and joule heating effect. The aim of this research is to consider the Carbon nanotubes (CNTs) which are favored materials in the manufacture of electrochemical devices because of their mechanical and chemical stability, good thermal and electrical conductivities, physiochemical consistency, and featherweight. By keeping such extraordinary properties of carbon nanotubes in mind, we investigate the flow of hybrid nanofluid having MWCNT (multi-wall carbon nanotubes) and SWCNT (single-wall carbon nanotubes). Using an appropriate similarity variable, the flow model (PDEs) are converted into nonlinear ordinary differential equations. The bvp4c approach is utilized to tackle the coupled differential equations. The impact of emerging parameter on temperature distribution, velocity field, concentration distribution, and microorganism field are presented graphically. It is noted the stronger values of wall thickness parameter and Hartmann number produces retardation effect, as a result fluid velocity declines for both SWCNT (single-wall carbon nanotubes) and MWCNT (multi-wall carbon nanotubes) hybrid nanofluid. Furthermore, the transport rate of heat and mass improves by the higher values of for φ2 both simple and hybrid nanofluid.</p

    Bioconvection Effects on Non-Newtonian Chemically Reacting Williamson Nanofluid Flow Due to Stretched Sheet With Heat and Mass Transfer

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    The aim of this paper is to scrutinize the mixed convective flow of Williamson nanofluid in the presence of stretched surface with various physical effects. The impact of Brownian motion and thermophoresis is the part of this investigation. In addition, the features of thermal radiations is considered in energy equation for motivation of problem. Theory of the microorganism is used to stable the model. Mathematical modelling is carried out. Appropriate similarity functions are used to transform the couple of governing PDEs into set of ODEs. Wolfram MATHEMATICA is engaged to solve transformed equations numerically with the help of shooting scheme. The influence of emerging flow parameters like magnetic, thermophoresis, porosity, PĂ©clet and Lewis number on the velocity, temperature, volumetric concentration and density of microorganism distribution are presented in tables and graphs

    Numerical studies of nanofluid boundary layer flows using spectral methods.

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    Doctoral Degree. University of KwaZulu-Natal, PietermaritzburgThis thesis is focused on numerical studies of heat and mass transport processes that occur in nanofluid boundary layer flows. We investigate heat and mass transfer mechanisms in the flow of a micropolar nanofluid above a stretching sheet, the squeezed nanofluid flow between two parallel plates and the impact of activation energy and binary chemical reaction on nanofluid flow past a rotating disk. We present an analysis of entropy generation in nanofluid flow past a rotating disk and nanofluid flow past a stretching surface under the influence of an inclined magnetic field. This study aims to numerically determine to a high degree of accuracy, how nanoparticles can be utilized to alter heat and transport properties of base fluids in order to enhance or achieve desirable properties for thermal systems. The heat and mass transfer processes that feature in nanofluid boundary layer flow are described by complex nonlinear transport equations which are difficult to solve. Because of the complex nature of the constitutive equations describing the flow of nanofluids, finding analytic solutions has often proved intractable. In this study, the model equations are solved using the spectral quasilinearization method. This method is relatively recent and has not been adequately utilized by researchers in solving related problems. The accuracy and reliability of the method are tested through convergence error and residual error analyses. The accuracy is further tested through a comparison of results for limiting cases with those in the literature. The results confirm the spectral quasilinearization method as being accurate, efficient, rapidly convergent and suited for solving boundary value problems. In addition, among other findings, we show that nanofluid concentration enhances heat and mass transfer rates while the magnetic field reduces the velocity distribution. The fluid flows considered in this study have significant applications in science, engineering and technology. The findings will contribute to expanding the existing knowledge on nanofluid flow

    Steady forced convection flow and heat transfer in a nanofluid with passive control model

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    The study of convective heat transfer and fluid flow has important engineering and industrial applications, for instance in the cooling of engine vehicles. Fluid such as water is commonly used as a heat transfer fluid because of its high heat capacity. Nevertheless, the limitation of water and the low thermal conductivity of other conventional heat transfer fluids could affect the efficiency of heat exchange. Therefore, a type of fluid with suspension of solid particles into base fluid, namely nanofluid was considered due to the property of nanofluid that enhances heat transfer. Mathematical models of nanofluid normally include a boundary condition that assumed nanoparticle volume fraction at the surface is constant. This boundary condition however might not be able to describe adequately the condition of nanofluid volume fraction at the boundary. Hence, a different boundary condition that considers nanoparticle mass flux at the boundary to be zero and adjusted accordingly is applied in this thesis. Recently, the use of micropolar fluid as a base fluid to nanofluid was applied in many studies. The local influence of intrinsic motion and microstructure of the fluid elements that are essential to this model of fluid can be advantageous as it can appropriately describe the types of fluid such as polymeric suspension and animal blood. Motivated by these reasons, numerical analysis of nanofluid and micropolar nanofluid flow with zero nanoparticle mass flux along with three different effects and geometries for each problem were deliberated in this thesis. The effects are viscous dissipation, Soret and Dufour, and chemical reaction, and the geometry that was investigated are moving plate, stretching plate, and wedge. In order to reduce the governing equations, series of transformation variables are used to transform the dimensional governing equations into dimensionless differential equations. The non-dimensional equations in ordinary differential equations were then solved numerically using Runge-Kutta Fehlberg. The results obtained were then compared with the limiting cases from previous study. This is done to determine the accuracy of the results published. Several parameters were examined in this thesis, namely Eckert number, Soret number, Dufour number, magnetic field, Brownian motion, thermophoresis, Lewis number, and Prandtl number. The results of reduced Nusselt number, skin friction coefficient, velocity profile, angular velocity profile, temperature profile, and concentration profile for each parameter were presented in tables and graph. It was found that the temperature and concentration profile shown a consistent result when there is an effect of viscous dissipation and chemical reaction. Temperature profile increases when thermophoresis parameter increases. In thermophoresis, the particle from the heated region is transferred to the cold region. Thus, this causes the nanofluid temperature to be increasing due to huge number of nanoparticles shifted from the hot region, which enhance the fluid temperature. Concentration profile was found to increase then decrease for both of the problems when the thermophoresis parameter and Brownian motion parameter increase. However, in the presence of Soret and Dufour, the temperature profile was found to increase when Brownian motion parameter increases, and concentration decreases then increases when the thermophoresis parameter increases. In comparison to the previous study, the difference is the temperature profile increases following an increase of Brownian motion parameter and concentration profile increase when thermophoresis increases

    Recent Trends in Coatings and Thin Film–Modeling and Application

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    Over the past four decades, there has been increased attention given to the research of fluid mechanics due to its wide application in industry and phycology. Major advances in the modeling of key topics such Newtonian and non-Newtonian fluids and thin film flows have been made and finally published in the Special Issue of coatings. This is an attempt to edit the Special Issue into a book. Although this book is not a formal textbook, it will definitely be useful for university teachers, research students, industrial researchers and in overcoming the difficulties occurring in the said topic, while dealing with the nonlinear governing equations. For such types of equations, it is often more difficult to find an analytical solution or even a numerical one. This book has successfully handled this challenging job with the latest techniques. In addition, the findings of the simulation are logically realistic and meet the standard of sufficient scientific value

    Computational Fluid Dynamics 2020

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    This book presents a collection of works published in a recent Special Issue (SI) entitled “Computational Fluid Dynamics”. These works address the development and validation of existent numerical solvers for fluid flow problems and their related applications. They present complex nonlinear, non-Newtonian fluid flow problems that are (in some cases) coupled with heat transfer, phase change, nanofluidic, and magnetohydrodynamics (MHD) phenomena. The applications are wide and range from aerodynamic drag and pressure waves to geometrical blade modification on aerodynamics characteristics of high-pressure gas turbines, hydromagnetic flow arising in porous regions, optimal design of isothermal sloshing vessels to evaluation of (hybrid) nanofluid properties, their control using MHD, and their effect on different modes of heat transfer. Recent advances in numerical, theoretical, and experimental methodologies, as well as new physics, new methodological developments, and their limitations are presented within the current book. Among others, in the presented works, special attention is paid to validating and improving the accuracy of the presented methodologies. This book brings together a collection of inter/multidisciplinary works on many engineering applications in a coherent manner

    Current Perspective on the Study of Liquid-Fluid Interfaces: From Fundamentals to Innovative Applications

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    Fluid interfaces are promising candidates for confining different types of materials - e.g., polymers, surfactants, colloids, and even small molecules - and for designing new functional materials with reduced dimensionality. The development of such materials requires a deepening of the Physico-chemical bases underlying the formation of layers at fluid interfaces, as well as on the characterization of their structures and properties. This is of particular importance because the constraints associated with the assembly of materials at the interface lead to the emergence of equilibrium and dynamics features in the interfacial systems, which are far from those conventionally found in the traditional materials. This Special Issue is devoted to studies on fundamental and applied aspects of fluid interfaces, trying to provide a comprehensive perspective on the current status of the research field

    Structural, Magnetic, Dielectric, Electrical, Optical and Thermal Properties of Nanocrystalline Materials: Synthesis, Characterization and Application

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    This book is a collection of the research articles and review article, published in special issue "Structural, Magnetic, Dielectric, Electrical, Optical and Thermal Properties of Nanocrystalline Materials: Synthesis, Characterization and Application"

    Advances in Heat and Mass Transfer in Micro/Nano Systems

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    The miniaturization of components in mechanical and electronic equipment has been the driving force for the fast development of micro/nanosystems. Heat and mass transfer are crucial processes in such systems, and they have attracted great interest in recent years. Tremendous effort, in terms of theoretical analyses, experimental measurements, numerical simulation, and practical applications, has been devoted to improve our understanding of complex heat and mass transfer processes and behaviors in such micro/nanosystems. This Special Issue is dedicated to showcasing recent advances in heat and mass transfer in micro- and nanosystems, with particular focus on the development of new models and theories, the employment of new experimental techniques, the adoption of new computational methods, and the design of novel micro/nanodevices. Thirteen articles have been published after peer-review evaluations, and these articles cover a wide spectrum of active research in the frontiers of micro/nanosystems
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