FDLBM simulation of entropy generation in double diffusive natural convection of power-law fluids in an enclosure with Soret and Dufour effects

© 2015 Elsevier Ltd. All rights reserved. In this paper, double-diffusive natural convection with Soret and Dufour effects in a square cavity filled with non-Newtonian power-law fluid has been simulated by Finite Difference Lattice Boltzmann Method (FDLBM) while entropy generations through fluid friction, heat transfer, and mass transfer are analyzed. This study has been conducted for certain pertinent parameters of Rayleigh number (Ra = 10⁴ and 10⁵), power-law index (n = 0.6-1.4), Lewis number (Le = 2.5 and 5), Dufour parameter (Df = 0-1), Soret parameter (Sr = 0-1) and the buoyancy ratio (N = -1, 0.1, 1). Results indicate that the augmentation of the power-law index causes heat and mass transfer to drop. Entropy generation due to fluid friction, heat and mass transfer rises with increase in Rayleigh number. Augmentation of Lewis number enhances entropy generation due to mass transfer. At N = 0.1 and 1, growth of power-law index causes different types of entropy generation to drop. The rise of buoyancy ratio from N = -1 to 1 augments the total irreversibility. The Dufour parameter provokes heat and mass transfer to rise while results in the enhancement of the total irreversibility. The Soret parameter augments mass transfer, but it does not affect heat transfer and total entropy generation considerably.