Numerical analysis of effects of fins and conductive walls on heat transfer in side heated cavities — Onset of three-dimensional phenomena in natural convection

In the present study, we analyse individual and combined effects of conductive horizontal walls fins on natural convection air in side heated cavities (SHC). The flow heat transfer are studied for Rayleigh numbers range 104−109: Direct Numerical Simulation (DNS) is conducted lower Large Eddy (LES) higher (>108). Thermally destabilize yielding an earlier transition to turbulence expedite decay boundary layer thickness with increase number. preheating/precooling along reduces actual at vertical walls. Above fin, instabilities only marginally enhanced adiabatic walls, whereas plumes erupt from fin. This localized Rayleigh-Bénard-like effect triggers 3D entire field yields a steeper slope Nusselt-Rayleigh diagram. presence fin increases integral by 18% 21% We show that 2D simulations similar smooth cases (i.e., without fin), but differ 4% 13% respectively. local characteristics even deviates up 50%, therefore simplification should be avoided.