Numerical study of natural convection of nanofluids in an inclined flat bottom flask using finite-volume approach.

Abstract

In this work, we study numerically the natural convection of nanofluids (NF) in an inclined flat bottom flask; it is one of laboratory flasks used in organic chemistry synthesis. The main reason of this study is to enhance the thermal properties of the reaction medium inside the flat bottom flask and to ameliorate the rate of chemical reactions using nanofluids. The flat bottom wall is maintained at a constant high temperature Th. While the top, left and right walls of the cavity are maintained at a low temperature TL. The NF comprises Cu and Al2O3 nanoparticles (NP) suspended in pure water. The governing equations are solved numerically using the finite-volume approach and formulated using the Boussinesq approximation. In this simulation we examined the effects of the NP volume fraction (φ) from 0% to 5%, the Rayleigh number from 103 to 106, the various inclination angles of enclosure (γ=0°,5°,10°, 15°) and the NF type (Cu and Al2O3) on the flow streamlines, isotherm distribution and Nusselt number. The obtained results show that the addition of Cu and Al2O3 NP increases the mean Nusselt number which enhances the heat transfer in the flat bottom flask and causes significant changes in the flow pattern. In addition, the mean Nusselt number is increase with increasing the Rayleigh number and the volume fraction and the best results have obtained from the Cu nanofluide. Also, as the inclination angle increases the mean Nusselt number decreases and the highest value of Nusselt number was obtained for a vertical enclosure (γ=0°). The obtained streamlines are mostly symmetric and their values are generally increase by increasing the Rayleigh number and volume fractions of NPs. Besides, the obtained isotherms are generally follow the geometry of the flat bottom flask.