Dynamics of newtonian fluids and nanofluids in various geometries

Abstract

In this thesis, the boundary-layer flows of Newtonian fluids in different geometries newlineprimarily, a horizontal surface and a vertical surface. To account for the imperfections arising in realistic scenarios, we have considered a horizontal surface with undulations and a vertical surface with a non-uniform temperature distribution. Additionally, it is wellknown that to meet the cooling rate requirements in the industry, the thermal performance of ordinary heat transfer fluids is not suitable. The concept of insertion of nanometresized metallic particles in the fluid leads to an increase in the thermal conductivity of the newlineordinary base liquids. Therefore, to fully comprehend the affect of these nanoparticles on the onset of convection and fluid motions and to assess how the enhanced thermophysical newlineproperties may affect the heat transfer is another key objective of this research. newlineA Comparative Study of Thermo-convective Flows of a Newtonian Fluid over Three newlineHorizontal Undulated Surfaces in a Porous Medium In the first problem of this thesis, elaborated in Chapter 5, a comparison has been presented between the results of three thermoconvective flows of a Newtonian fluid over uniformly heated, undulated horizontal surfaces in a porous medium against the background of the results of a flat plate. The undulations are assumed to have sinusoidal, sawtooth, and triangular waveforms. At large surface amplitudes, secondary flow is observed in the cases newlineof sinusoidal and triangular waveforms, but not in the cases of a sawtooth surface and a newlineflat plate. The variation of the mean Nusselt number and mean skin friction with surface newlineamplitude and the Rayleigh number indicate that heat transfer and viscous friction at the boundary increase with individual and collective increases in the values of the amplitude and the Rayleigh number. The heat transfer and skin friction by the flat surface are much less than that of all three undulated surfaces.