Influence of external magnetic field inclination on three-dimensional buoyancy-driven convection in an open trapezoidal cavity filled with CNT-Water nanofluid

Abstract

A three-dimensional numerical analysis of the effects of an external magnetic field inclination on natural convection flow inside an open trapezoidal cavity filled with Carbon Nanotube (CNT)-nanofluid has been carried out using finite volume method. In this investigation, the inclined wall is maintained at isothermal hot temperature while cold nanofluid enters into the enclosure from its right open boundary and all other walls are assumed to be perfect thermal insulators. Analysis has been conducted in a wide range of governing parameters such as Rayleigh number (103 ≤ Ra ≤ 105), volumetric fraction (0 ≤ φ ≤ 0.05) of the nanofluid, inclination angle of the external magnetic force (0° ≤ α ≤ 90°) and the Hartmann number (0 ≤ Ha ≤ 100). Main efforts have been focused on the effects of these parameters on the fluid flow and heat transfer inside the cavity. The obtained results indicate that key parameters have substantial effects on the flow and heat transfer characteristics. It has been found that an increase of Ha with high values of Rayleigh number is accompanied by a reduction in the heat transfer rate, while an increase of solid volume fraction resulted in heat transfer enhancement regardless of the inclination angle of the magnetic field. The maximum heat transfer rate took place for α = 60°, φ = 0.05, Ha = 25 and Ra = 105.