Role of curvature on heat flow visualization and irreversibilities during natural convection in enclosures

This article presents a detail analysis of heatlines and entropy generation during natural convection in various enclosures with curve (concave and convex) walls. The dimensions of enclosures are fixed in such a way that thedimensionless area of the cavity is one and the dimensionless length of the wall is one. Two heating strategies are considered such as (a) type 1: hot bottom wall, cold side walls in the presence of adiabatic top wall and (b)type 2: hot left, cold top and bottom walls in the presence of adiabatic right wall. Numerical simulations have been carried out for fluid with Prandtl number Pr = 0. 7 at different Rayleigh number (103 ≤ Ra ≤105). The distributions of isotherms, streamlines, heatlines and entropy generation due to heat transfer and fluid friction are compared for curved walled enclosures with those of square enclosure. The effect of Ra on the total entropy generation, average Bejan number and average Nusselt number is illustrated for considered enclosures involving both the heating strategies. The optimal configuration and optimal heating strategy is chosen based on the less entropy generation rate and higher heat transfer rate.