STUDY OF NATURAL AND MIXED CONVECTION FLOW OF A NANOFLUID

Abstract

Investigating problems with nanofluids is the major aim of this thesis. Numerical studies were conducted to examine natural convection in a two-dimensional enclosure using the spectral collocation method. Various dynamic viscosity and thermal conductivity formulae were used to build various nanofluid models. A larger Nusselt number is observed when thermal conductivity is high and the viscosity is low at all Rayleigh numbers. The Nusselt number is sensitive to the aspect ratio at low Rayleigh numbers. The two-dimensional single and double lid-driven cavities problems were solved by in- vestigating the Navier-Stokes equations. Two cases of mixed nanofluid convection with various boundary conditions were examined in single and double lid cavities. Two viscosity models, the Brinkman (1952) and Pak and Cho (1998) models, are used to calculate the vis- cosity of nanofluids. The results of a numerical investigation were studied and discussed in order to show how the presence of nanoparticles and viscosity models affect flow and heat transfer behaviour. With the small Richardson number Ri = .0001 − .000001, new results have been discovered. When particle concentration increases, it is clear that the Pak and Cho model reduces corner eddies significantly more than the Brinkman model. Investigations were conducted on the two-dimensional problem of nanofluid flow over a flat surface with a hump. By assuming that the impact of Brownian diffusion is negligible, numerical solutions were found using the triple deck theory. The Brinkman (1952) and Pak and Cho (1998) models are used to evaluate the viscosity of nanofluids. Nanofluid helps to delay separation, and the Pak and Cho model showed a considerably longer delay than the Brinkman.