Entropy generation for mixed convection in a square cavity containing a rotating circular cylinder using a local radial basis function method

摘要

The entropy generation for steady mixed convection due to a concentric isothermal rotating circular cylinder within a square enclosure is numerically investigated using a local radial basis function interpolation method. The top and bottom walls of the enclosure are adiabatic while the left and right walls have lower constant temperature, and the rotating concentric circular cylinder with high constant temperature hence induces the mixed convection. Air is considered as the working fluid and Prandtl number is fixed at 0.71. With the restriction of Taylor instability for viscous fluid flow, the Reynolds number should be below 60 and ranges from 1 to 50 for present work. Numerical results are obtained for various irre-versibility distribution ratios (10~(-3) ≤ Φ ≤ 10~(-1)) and Richardson numbers (0.1 ≤ Ri ≤ 20). The variation of total entropy generation and average Bejan number with different parameters are discussed and analyzed in detail. The numerical results indicate that the total entropy generation increases with the irre-versibility distribution ratio, Reynolds number and Richardson number generally. The average Bejan number decreases with the irreversibility distribution ratio and Richardson number generally while it almost keeps constant for Ri ≤ 1 and it decreases with Reynolds number remarkably for Ri ≥ 10 since the sufficient increase of entropy generation due to fluid friction corresponding to the obvious change of flow patterns. The maximum value of local entropy generation due to heat transfer and fluid friction is found around the wall of the rotating cylinder.