Mesoscopic simulation of double-diffusive natural convection and entropy generation of Bingham fluid in an open cavity

Abstract

In this paper, double-diffusive natural convection, studying Soret and Dufour effects and viscous dissipation in an open cavity filled with Bingham fluid has been simulated by Finite Difference Lattice Boltzmann Method (FDLBM). In addition, entropy generations through fluid friction, heat transfer, and mass transfer has been studied. The problem has been solved by applying the regularized Papanastasiou model. However, the Bingham model without regularizations for some cases have been studied to demonstrate the accuracy of the applied regularization. This study has been conducted for certain pertinent parameters of Rayleigh number (Ra=103, 104 and 105), Bingham number (Bn), Lewis number (Le=2.5, 5 and 10), Dufour parameter (Df=0, 1, and 5), Soret parameter (Sr=0, 1, and 5), Eckert number (Ec=0, 0.001, and 0.01), and the Buoyancy ratio (N=−1, 0.1, 1). Results indicate that the increase in Rayleigh number enhances heat and mass transfer for various Bingham numbers. The rise of Bingham number reduces heat and mass transfer. In addition, the increase in Bingham number enlarges the unyielded zones. The increase in the Lewis number augments mass transfer in different Rayleigh and Bingham numbers, although the enhancement of Lewis number causes heat transfer to drop marginally. The rise of Dufour parameter increases heat transfer gradually. The increase in Soret parameter enhances mass transfer for different Bingham and Rayleigh numbers. The addition of Soret parameter, Dufour parameter and Lewis number do not affect the unyielded zone considerably. The augmentation of the buoyancy ratio number enhances heat and mass transfer at Ra=104 and 105. The rise of buoyancy ratio number alters the unyielded section significantly. The increase in Eckert number influences heat and mass transfer marginally. The augmentation of Rayleigh number enhances different entropy generations and reduces the average Bejan number. The increase in the Bingham number provokes various irreversibilities to drop significantly. The rise of Soret and Dufour parameters enhances the entropy generations due to heat transfer and fluid friction. The rise of Eckert number alters various entropy generations, but the alteration does not follow a specific manner in different studied parameters.