Abstract
Purpose This study aims to analyze entropy generation and magnetohydrodynamic (MHD) natural convection of hybrid nanofluid in a square cavity, with a heated elliptical block placed at the center, in presence of a periodic-variable magnetic field. Design/methodology/approach In this paper, simulations were performed with a FORTRAN home code. The numerical methodology used to solve Navier-Stokes, energy and entropy generation equations with corresponding boundary conditions, is essentially based on the finite volume method and full multigrid acceleration. Findings The cavity is filled with Ag-Tio(2)/Water hybrid nanofluid. The main objective of this investigation is to predict the effects of body's size (6 cases), type of applied magnetic field (variable or uniform), the non-dimensional period number of the variable magnetic field (VMF) (0.2 <= ? <= 0.8), the inclination angle of the VMF (0 <= chi <= 90), Rayleigh number (5 x 103 <= Ra >= 105) and Hartmann number (5 <= Ha >= 100) on thermal performance, heat transfer rate, entropy generation and flow patterns. Originality/value To the authors' best knowledge, this paper is the first numerical investigation deals with the entropy generation and natural convection of hybrid nanofluid in a two-dimensional cavity, with specific thermal boundary conditions, containing an elliptical block under periodic-variable magnetic field. Different combinations between flow-governing parameters were made to find optimal thermal performance.