Three-dimensional investigation of the effects of external magnetic field inclination on laminar natural convection heat transfer in CNT–water nanofluid filled cavity

A finite volume-based three-dimensional numerical analysis is conducted to investigate the effects of the angle of inclination of an external magnetic force on the natural convection inside a cubical cavity filled with a carbon nano-tube (CNT)-water nanofluid. The governing equations are solved using vorticity-vector potential formalism. The vertical walls are differentially heated and the horizontal walls are assumed to be adiabatic. The effects of the Rayleigh number (103 ≤ Ra ≤ 105), volumetric fraction (0 ≤ φ ≤ 0.05) of the CNT particles, angle of inclination of the external magnetic force (0° ≤ α ≤ 90°), and the Hartmann number (0 ≤ H a ≤ 100) are investigated. The results of a fluid flow using a single-phase model are illustrated based on the particle trajectories, velocity vectors, isosurfaces of temperature, and the Nusselt number. The heat transfer is shown to intensify with the increasing percentage of CNT particles and a larger Rayleigh number. The repelling effect of the magnetic force inhibits the heat transfer by 50% when Ha is increased from 50 to 100.