Free convection and heat transfer characteristics in differentially heated finned cavities with inclination

Convection flow and heat transfer within differentially heated finned and non-finned cavities are numerically investigated at series of angle of inclination in this study. The present numerical results demonstrate that at the investigated Rayleigh number 1.84 x 10(9), for the non-finned cavity and at fully developed state, the flow is steady at Theta <= 25 degrees and it bifurcates with multimodal evolution when e increases beyond 30 degrees, where e denotes angle of inclination of the cavities. An examination of the spatial evolution of propagation of the travelling wave underneath the ceiling suggests that the corresponding flow is convectively unstable at large e, which, unlike the extensively studied e = 0 degrees scenario, self-sustains a cavity-wide perturbation. The present finned-cavity calcu-lations suggest that two flow regimes could be identified for the quasi-steady state. Regime I is featured with distinct plume-wraps-fin behaviour and it occurs at small e, while Regime II has no discernible plume-wraps-fin behaviour and it occurs at large e. It is further found that with tilting the cavity, the thermal stratification at the cavity centreline occurs over a narrower temperature range, whilst an increase in the velocity is clearly seen for both the non-finned and finned cavities. Flow rate across the cavity centreline is found to fluctuate in the quasi-steady state and its time averaged value dramatically improves with Theta. Heat transfer is estimated by integrating the local Nusselt number at the heated sidewall. The present work shows that immediately after the cavity is inclined, the Nusselt number is first increased. Further tilting the cavity will lead to a steady drop in the Nusselt number. It is demonstrated that the dependency of Nusselt number on e is similar for the non-finned and finned cavities with Nu of the finned cavity larger by approximately 5%.