Numerical simulation of buoyant convection of nanofluids in a vertical cylindrical annular enclosure

Abstract

Buoyancy-driven convection in an annular enclosure formed by two vertical, newlineconcentric cylinders is an important and ideal physical configuration of many newlinepractical applications. The poor thermal conductivity of conventional fluids newlinepaved the way for development of a new class of heat transfer fluids known as newlinenanofluids. This is engineered by dispersing nanoparticles in traditional heat newlinetransfer fluids and has helped in overcoming the drawbacks existing in traditional newlinefluids. Nanofluids appear to have the potential to significantly increase newlinethe heat transfer rates in a variety of applications. Hence, this thesis numerically newlineinvestigates the buoyant convective flow and associated thermal processes newlineof various nanofluids/hybrid nanofluids in a differently heated annular geometry newlinewith insulated horizontal boundaries. By considering a finite thickness in newlinethe inner wall of annulus, the effect of conduction in solid region and convection newlinein fluid region, known as conjugate heat transfer has been numerically newlineinvestigated. The influence of sinusoidal thermal profile on natural convective newlineflow of different hybrid nanofluids has also been studied numerically. Further, newlinenumerical simulations of natural convection of different nanofluids with heat newlinesources and sinks of different lengths mounted at various locations of inner and newlineouter walls of the annulus has been analyzed. In addition, the impact of porous newlinemedium on buoyancy-driven convection of nanofluids has also been investigated. newlineFinally, the size, thickness and location effects of a conductive baffle on newlinebuoyant convective heat transfer of nanofluids in an annulus has been analyzed. newlineThe model equations governing the physical process of the problems investigated newlinein the thesis are numerically solved using an implicit finite difference newlinemethod. The numerical simulations for various parameters are presented in the newlineform of streamline and isotherm contours, local and average Nusselt numbers.