Entropy generation study due to MHD double-diffusive convection in the rectangular cavity with built-in rectangular blockage
Sudhanshu Kumar, Krunal M. Gangawane
Abstract
In the present work, the influence of the aspect ratio of the rectangular cavity (length > width) and the built-in rectangular blockage (length > width) on the local and global entropy generation (EG) characteristics due to double-diffusive convection and external magnetic field have been explored. Particularly, the effect of the pertinent parameters, such as the aspect ratio of the cavity (AR=2−4) and blockage (ar=2−4), Lewis number (Le=2−10), Rayleigh number (103≤Ra≤105), Hartmann number (0≤Ha≤100), and buoyancy ratios (−2≤N≤2) on the EG characteristics have been explored. The working fluid is considered to be a liquid metal-sodium–potassium alloy (Pr = 0.054). Lattice Boltzmann method numerical scheme is employed to solve the double-diffusive natural convection phenomenon. The increase in Ra induces an enhancement in the localized EG terms, whereas the augmentation in Ha diminishes the local total EG (STotal) for a given Ra. The dominance of thermal and species transport irreversibility (Beavg>0.5) in the cavity was noticed for AR=2,N=2. Conversely, for AR = 4, the significance of flow friction irreversibility within the cavity was observed (Beavg≤0.5). The results of the work are also summarized in terms of simpler empirical correlations of SFF,SC, and ST, which might be useful for possible engineering design purposes.