Effect of free-stream inclination and buoyancy on flow past a square cylinder in large-scale heating regime

Abstract

The combined effects of free-stream inclination (α) and heating [ϵ=(Tw−T∞)/T∞] on aerodynamic and heat transfer parameters are studied at fixed Reynolds number (Re = 100), Prandtl number (Pr = 0.71), cylinder inclination (ϕ=0°), Froude number (Fr = 1.0), and Mach number (M = 0.1) in the large-scale heating regime. For this purpose, a non-Oberbeck–Boussinesq compressible model for thermally perfect gases incorporating volumetric straining as well as transport property variations under large-scale heating is employed. The free-stream inclination (α) is varied in the range [0°, 90°] while the over-heat ratio (ϵ) is varied in the range of [0, 1]. It is found that at small free-stream inclinations (α≤45°), increase in heating causes a significant increase in mean drag coefficient, while at large α (α>45°), heating has little effect on mean drag coefficient. The mean lift coefficient (CL) increases by increasing ϵ for any value of α except α = 0. At a fixed heating level, the variation of mean CL is very non-monotonic with lower values at α=45° and 90°. It is found that the increase in flow inclination from 0° to 90° reduces the sensitivity of Strouhal number (St) to heating. For ϵ≤0.6, mean Nusselt number exhibits a non-monotonic trend with increase in α and attains a maximum value at α ≅ 40°. However, for ϵ>0.6, heat transfer decreases with increase in α and is maximum for aligned flow (α=0°).