School for Science and Technology
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Browsing School for Science and Technology by browse.metadata.advisor "Makinde, Oluwole Daniel"
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- ItemModelling the impact of Magnetohydrodynamics (MHD) nanofluid flow on cooling of engineering systems(Stellenbosch : Stellenbosch University, 2021-12) Tshivhi, Khodani Sherrif; Makinde, Oluwole Daniel; Stellenbosch University. Faculty of Military Sciences. School of Science and Technology.ENGLISH ABSTRACT: The flow investigations regarding nonlinear materials are extremely important in the applied science and engineering areas to explore the properties of flow and heat transfer. Recent advancement in nanotechnology has provided a veritable platform for the emergence of a better ultrahigh-performance coolant known as nanofluid for many engineering and industrial technologies. In this study, we examine the influence of a magnetic field on the heat transfer enhancement of nanofluid coolants consisting of Cu-water, or Al2O3-water, or Fe3O4-water over slippery but convectively heated shrinking and stretching surfaces. The model is based on the theoretical concept of magnetohydrodynamics governing the equation of continuity, momentum, energy, and electromagnetism. Based on some realistic assumptions, the nonlinear model differential equations are obtained and numerically tackled using the shooting procedure with the Runge-Kutta-Fehlberg integration scheme. The existent of dual solutions in the specific range of shrinking surface parameters are found. Temporal stability analysis to small disturbances is performed on these dual solutions. It is detected that the upper branch solution is stable, substantially realistic with the smallest positive eigenvalues while the lower branch solution is unstable with the smallest negative eigenvalues. The influence of numerous emerging parameters on the momentum and thermal boundary layer profiles, skin friction, and Nusselt number are depicted graphically and quantitatively discussed.
- ItemTheoretical study of variable viscosity nanofluids flow in microchannels(Stellenbosch : Stellenbosch University, 2020-12) Monaledi, Ramotjaki; Makinde, Oluwole Daniel; Stellenbosch University. Faculty of Science. Dept. of Mathematical Sciences. Division Mathematics.ENGLISH ABSTRACT: The study of fluid flow and heat transfer through a microchannel is an important research area due to its wide applications in engineering and industrial processes. Some practical applications include problems dealing with cooling, lubrication of porous bearings, petroleum technology, ground water hydrology, drainage and purification processes. A nanofluid is the suspension of nanoparticles in a base fluid. Nanofluids are capable of heat transfer enhancement due to their high thermal conductivity. For practical applications of nanofluids, research in nanofluids convection is significant. Due to their enhanced properties, nanofluids can be used in the deficiency of technical and biomedical applications such as nanofluid coolant in electronics cooling, vehicle cooling and transformer cooling. This study considered the detailed analysis of both single and two-phase Couette and Poiseuille flow behaviour and heat transfer using this innovative fluid as working fluid through a microchannel. Useful results for the velocity, temperature, nanoparticles concentration profiles, skin friction and Nusselt number were obtained and discussed quantitatively. The effects of important governing flow parameters on the entire flow structure were examined. In this thesis, a more realistic modified Buongiorno’s nanofluid model is proposed and utilized to examine the impact of nanoparticles’ injection and distribution on inherent irreversibility in a microchannel Poiseuille flow of nanofluid with variable properties. The governing nonlinear differential equations are obtained and tackled numerically using the shooting method coupled with the Runge-Kutta-Fehlberg integration scheme. Graphical results showing the effects of the pertinent parameters on the nanofluid velocity, temperature, nanoparticles concentration, skin friction, Nusselt number, Sherwood number, entropy generation rate and Bejan number are presented and discussed quantitatively.