Abstract
A numerical investigation of entropy generation, heat and mass transfer is performed on steady double diffusive natural convection of water-based Al(2)O(3) nanofluid within a wavy-walled cavity with a center heater under the influence of an uniform vertical magnetic field. The top horizontal wavy wall, left and right vertical walls of the enclosure are kept at low temperature and concentration of Tc and cc whereas central part of the bottom horizontal wall is maintained at high temperature and concentration of Th and ch and the remaining part is kept adiabatic where temperature and concentration gradient are taken as zero. The Bi-CGStab method and Tri-diagonal algorithm are used to solve the governing equations. The study has been performed for several relevant parameters such as Rayleigh number ( 103 ≤ Ra ≤ 105 ), Hartmann number ( 0 ≤ Ha ≤ 60 ), buoyancy ratio number ( - 2 ≤ N ≤ 2 ), volume fraction of nanoparticles ( 0.0 ≤ ϕ ≤ 0.2 ) and different undulation number of the upper wavy wall (n). The Prandtl number and Lewis number are kept fixed at Pr = 6.2 and Le = 2 . The effect of these parameters are revealed in terms of streamlines, isotherms, isoconcentrations, entropy generation, average Nusselt number and Sherwood number. Results indicate that heat and mass transfer rate augment as Rayleigh number and volume fraction of nanoparticles increase and are found to drop with the increase in Hartmann number and buoyancy ratio.