Vortex shedding suppression in mixed convective flow past a square cylinder subjected to large-scale heating using a non-Boussinesq model

Abstract

In the present work, numerical simulations are performed to investigate the vortex shedding suppression phenomenon for mixed convective flows past a square cylinder in the large-scale heating regime. A full compressible flow model with variable transport and thermo-physical properties is employed to capture large-scale heating effects. The Reynolds number, Prandtl number, and Mach number are kept constant at Re = 100, Pr = 0.71, and M = 0.1, while the cylinder inclination (ϕ), free-stream inclination (α), and over-heat ratio (ϵ) are varied in the range [0, 45°], [0, 90°], and [0, 2], respectively. The governing equations are solved numerically using the particle velocity upwind (PVU-M+) scheme. The buoyancy parameter which governs the vortex shedding suppression process in the non-Boussinesq model is identified as RiNB=ϵFr222+ϵ, where Fr is the Froude number. Using the Stuart-Landau model, the neutral curves separating the steady and unsteady flow regimes are generated in the ϵ–ϕ and ϵ–α parametric spaces. The neutral curves show qualitatively similar characteristics as observed for Boussinesq models. The relative contribution of various large-scale heating effects in suppression of vortex shedding is also highlighted. This reveals that buoyancy effects followed by variations in transport properties play a major role in suppression of vortex shedding. The findings are also applicable to a range of low Re (O(100)) as supported by data obtained at Re = 130 for ϕ = 40°. The mechanism of vortex shedding suppression has been analyzed and extended for the large-scale heating scenarios.