Stagnation Point Flow of A Non-Newtonian Fluid

Both Hiemenz flow and Homann flow are two classical problems in the field of fluid dynamics. In this project, both the flows are re-considered and the numerical solutions are obtained. Homann flow is studied with and without the presence of partial slip. These partial differential equations are reduced to ordinary differential equations using the similarity transformations. The obtained highly nonlinear ordinary differential equations with the relevant boundary conditions are solved using 4th order Runge-kutta method. The effects of flow parameters on the momentum boundary layer are studied in detail. It is observed that slip has significant effects on the velocity profiles

Computational Fluid Dynamics 2020

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

Application of bivariate spectral quasilinearization method to second grade fluid flow equations.

Masters Degree. University of KwaZulu-Natal, Pietermaritzburg.In this study, the steady flow of a second grade magnetohydrodynamic fluid in a porous channel is investigated. We further investigate the hydromagnetic flow of a second grade fluid over a stretching sheet. The partial differential equations that describe the flows are solved numerically using the bivariate spectral quasilinearization method. The method is extended to a system of non-similar partial differential equations that model the steady two dimensional flow of Falkner-Skan flow of an incompressible second grade nano fluid. The work is also concerned with heat and the mass transfer from the electrically conducting second grade magnetohydrodynamic fluid over a stretching sheet. The sensitivity of the flow characteristics with respect to the second grade fluid parameter, magnetic field parameter, thermal radiation parameter, and the chemical reaction parameter are investigated. The accuracy of the numerical method is determined using the residual error analysis

Convective heat and mass transfer in boundary layer flow through porous media saturated with nanofluids.

Doctor of Philosophy in Mathematics. University of KwaZulu-Natal, Pietermaritzburg 2016.The thesis is devoted to the study of flow, heat and mass transfer processes, and crossdiffusion effects in convective boundary layer flows through porous media saturated with nanofluids. Of particular interest is how nanofluids perform as heat transfer fluids compared to traditional fluids such as oil and water. Flow in different geometries and subject to various source terms is investigated. An important aspect of the study and understanding of transport processes is the solution of the highly non-linear coupled differential equations that model both the flow and the heat transportation. In the literature, various analytical and numerical methods are available for finding solutions to fluid flow equations. However, not all these methods give accurate solutions, are stable, or are computationally efficient. For these reasons, it is important to constantly devise numerical schemes that work more efficiently, including improving the performance of existing schemes, to achieve accuracy with less computational effort. In this thesis the systems of differential equations that describe the fluid flow and other transport processes were solved numerically using both established and recent numerical schemes such as the spectral relaxation method and the spectral quasilinearization method. These spectral methods have been used only in a limited number of studies. There is therefore the need to test and prove the accuracy and general application of the methods in a wider class of boundary value problems. The accuracy, convergence, and validity of the solutions obtained using spectral methods, have been established by careful comparison with solutions for limiting cases in the published literature, or by use of a different solution method. In terms of understanding the physically important variables that impact the flow, we have inter alia, investigated the significance of different fluid and physical parameters, and how changes in these parameters affect the skin friction coefficient, the heat and mass transfer rates and the fluid properties. Some system parameters of interest in this study include the nanoparticle volume fraction, the Hartmann number, thermal radiation, Brownian motion, the heat generation, the Soret and Dufour effects, and the Prandtl and Schmidt number. The dependency of the heat, mass transfer and skin friction coefficients on these parameters has been quantified and discussed. In this thesis, we show that nanofluids have a significant impact on heat and mass transfer processes compared with traditional heat transfer fluids

Inter- and intra- observer reliability of the offera method for assessing exposure risk of computer work-related to wmsds

The purpose of this study was to evaluate inter- and intra- observer reliability of the observers assessing office workers performing their jobs using the Office Ergonomic Risk Assessment (OFFERA) method. 44 Industrial Engineering students at UTHM participated in a training session on inter- and intra- observer reliability. The period interval between inter- and intra- observer training session was 1 week. Three different jobs were assessed by observer using the OFFERA method. Through the three different tasks, the average of inter- and intraobserver reliability ranged between good to very good agreement. Meanwhile, the level of agreement for the intra-observer (K=0.68-0.96) was higher than the inter-observer (K=0.62- 0.94). Items with the strongest agreement (K=0.96) were related to armrest, document holder and keyboard wrist rest. The OFFERA method has both good and very good agreement in terms of reliability. The observers stated that it was easy to evaluate the ergonomic risk at office using this simple tool

G-Jitter effect on heat and mass transfer of three-dimensional stagnation point nanofluid flow

The study of fluid motion in fluid mechanics is useful in many engineering applications. Fundamental studies based on physics law on fluid motion could be done by mathematical formulation. Effects based on thermal energy such as heat source and heat absorber with its transferring mode can also be formulated into a mathematical system. Due to this reason, a boundary layer nanofluid flow near a stagnation point region of a three-dimensional body is studied in this thesis. Here, nanofluid containing copper nanoparticles and hybrid nanofluid containing copper and alumina nanoparticles with water as a base fluid are considered. In addition, a microgravitational field environment known as g-jitter is also considered. The main purpose of this study is to investigate theoretically the effect of thermal radiation and heat generation on fluid characteristics, heat transfer behaviour, and concentration distribution of the fluid flow system. In this study, the mathematical models that govern the fluid flow consist of continuity, momentum, energy, and concentration equations. These nonlinear partial differential equations are initially reduced into a dimensionless system of equations using the similarity transformation technique. The resulting dimensionless governing systems are then solved numerically using the Keller-box method. The numerical values of the skin friction coefficients, Nusselt number, and Sherwood number as well as the velocity, temperature, and concentration profiles are obtained for various values of the curvature ratio, amplitude of modulation, frequency of oscillation, nanoparticle volume fraction, heat generation parameter and thermal radiation parameter. The results from the analysis in relation to the studied physical parameters are graphically displayed and validated by comparing them to those of previous studies. The current study shows that the curvature parameter had a significant effect on the skin friction coefficient where planar and axisymmetric stagnation point flow occurred in a specified range of this parameter. On the other hand, increasing the modulation's amplitude causes all the physical quantities to fluctuate. It is observed that, when a higher frequency of oscillation is induced, the physical quantities are seen to be reduced. The addition of a small amount of copper nanoparticle in the fluid results in enhancement of conductivity of the thermal, as demonstrated by the Nusselt number. However, a contradictory behaviour was noticed on Sherwood number as copper nanoparticle was considered in the fluid problem. The internal heat generation has caused the temperature profile to increase, while the heat flux to decrease. Also, thermal radiation is found to improve the rate of heat transfer. Moreover, the addition of other nanoparticles which are alumina, further increased the thermal characteristic of the fluid system

Teaching and Learning of Fluid Mechanics, Volume II

This book is devoted to the teaching and learning of fluid mechanics. Fluid mechanics occupies a privileged position in the sciences; it is taught in various science departments including physics, mathematics, mechanical, chemical and civil engineering and environmental sciences, each highlighting a different aspect or interpretation of the foundation and applications of fluids. While scholarship in fluid mechanics is vast, expanding into the areas of experimental, theoretical and computational fluid mechanics, there is little discussion among scientists about the different possible ways of teaching this subject. We think there is much to be learned, for teachers and students alike, from an interdisciplinary dialogue about fluids. This volume therefore highlights articles which have bearing on the pedagogical aspects of fluid mechanics at the undergraduate and graduate level

Numerical Simulation of Convective-Radiative Heat Transfer

This book presents numerical, experimental, and analytical analysis of convective and radiative heat transfer in various engineering and natural systems, including transport phenomena in heat exchangers and furnaces, cooling of electronic heat-generating elements, and thin-film flows in various technical systems. It is well known that such heat transfer mechanisms are dominant in the systems under consideration. Therefore, in-depth study of these regimes is vital for both the growth of industry and the preservation of natural resources. The authors included in this book present insightful and provocative studies on convective and radiative heat transfer using modern analytical techniques. This book will be very useful for academics, engineers, and advanced students

Droplet Impact and Solidification on Solid Surfaces in the Presence of Stagnation Air Flow

Droplet Impact and Solidification on Solid Surfaces in the Presence of Stagnation Air Flow. Morteza Mohammadi, Ph.D. Concordia University, 2016 Understanding the fundamentals of ice accretion on surfaces can help in proposing solutions to reduce or prevent ice accumulation on aircraft components and power lines. The main way in which ice forms on a surface is the solidification of supercooled droplets upon impacting on the surface. On an aircraft wing, ice accumulation can easily change the flow pattern, which could result in an increase in drag force. This research investigates the use of superhydrophobic coatings (surfaces with contact angles larger than 150) to counteract icing (anti-icing) as a result of their extremely low surface energy. The main goal of this study is to assess the performance of superhydrophobic surfaces in the presence of stagnation flow to mimic flight conditions (e.g. droplet impinging on the leading edge of an aircraft’s wing). A wide range of droplet impact velocities and stagnation flows in splashing and non-splashing regimes (at high and low Weber numbers) were carried out on surfaces with various wettabilities. The results were analyzed in order to highlight the advantages of using superhydrophobic coatings. Free stream air velocity were varied from 0 to 10 m/s with a temperature which was controlled from room temperature at 20 oC down to -30 oC. It was observed that while the presence of stagnation flow on hydrophilic (i.e. aluminum substrate) results in thin film formation for droplets with Weber numbers more than 220 upon impact in room temperature condition, instantaneous freezing at the maximum spreading diameter was observed in low temperature condition where air and substrate temperature was below the -20 oC. Same phenomenon was observed for hydrophobic substrate at aforementioned temperature. On the other hand, striking phenomenon was observed for superhydrophobic surface when stagnation air flow is present. Although it was expected droplet contact time to be increased by imposing stagnation air flow on an impacting droplet it was reduced as a function of droplet Weber number. This was referred to the presence of full slip condition rather than partial one where the spreading droplet moves on thin layer of air. Consequently, it promotes droplet ligament detachment through Kelvin-Helmholtz instability mechanism. While in low temperature condition above temperature of heterogeneous ice nucleation (i.e. -24 oC)1 supercooled water droplet contact time is reduced up to 30% to that of still air cases, droplet solidified diameter was increased up to 2 folds for air velocity up to 10 m/s compare to the still air condition at temperatures as low as -30 oC. These results were compared with a new predictive model of droplet impact behavior on the superhydrophobic substrate. New universal predictive model of droplet impact dynamics on the superhydrophobic surface was developed based on the concept of mass-spring model2 which was validated against experimental results. In the new model, viscosity effect was considered through adding a dashpot term in mass-spring model. In addition, the effect of stagnation flow was also integrated to the model through classical Homann flow approach.3 For non-isothermal condition, the effect of phase change (i.e. solidification) on droplet wetting dynamics was coupled to the model through classical nucleation theory. The universal model was compared against experimental results in room and low temperature conditions (i.e. supercooled condition) for model’s validation