Analysis of entropy generation on mixed convection in square enclosures for various horizontal or vertical moving wall(s)

Entropy generation during the mixed convection process have been studied in a square enclosure for various moving horizontal (cases 1a–1d) or vertical wall(s) (cases 2a–2c) where the bottom wall of the cavity is isothermally hot, side walls are cold, and the top wall is adiabatic. Simulations have been performed for Prandtl number Pr = 0.026 and 7.2, Reynolds number Re = 10 − 100, and Grashof number Gr = 103 − 105. Results show that, in the case of the horizontally moving wall(s) (cases 1a–1d), the overall heat transfer rate Nub¯ and total entropy generation (Stotal) are identical for cases 1a–1d and the cup-mixing temperature (θcup) is high for case 1b at Pr = 0.026, Re = 100, and Gr = 105. Similarly, in the case of the vertically moving wall(s) (cases 2a–2c), Nub¯ and Stotal are identical for cases 2a–2c with the maximum θcup occurring for the case 2a. At Pr = 7.2, Gr = 105, and Re = 10, case 1a and case 1c are preferable for horizontally moving wall(s) and either of case 2a–2c is preferable for vertically moving wall(s). At Pr = 7.2, Gr = 105, and Re = 100, case 1d may be preferable for the horizontally moving wall(s) and case 2a may be preferable for the vertically moving wall(s).