Compressible and viscous flow over a heated cylinder with varying thermal effects: Aerodynamics and heat transfer

This study numerically investigates the effects of the surface-to-free-stream temperature ratio on aerodynamics and heat transfer in compressible flow over a two-dimensional heated circular cylinder. Wall-resolved simulations with fully compressible Navier–Stokes equations are performed at Reynolds number, Re, ranging from 20 to 150 and free-stream Mach number, M∞, of 0.2 and 0.4, which are both defined based on the free-stream values and cylinder diameter. The effects of temperature ratio, TR, between the cylinder surface and free-stream are investigated at neutral (1.0), low (1.1), moderate (1.5), and high (3.0) TR that cover the Boussinesq (neutral and low TR) and non-Boussinesq (moderate and high TR) regimes. The rigid cylinder is represented using a second-order robust ghost cell immersed boundary method. This study extends previous literature by exploring higher TR effects on steady and unsteady aerodynamics, vortex shedding, flow separation, and heat transfer. An increase in TR stabilizes the flow and can completely suppress vortex shedding. Although at low TR, the time-averaged local Nusselt number distribution at the cylinder surface is sensitive to M∞ due to the aerodynamic heating, at higher TR, it becomes insensitive to M∞. The effects of fluid transport coefficient model choice are also examined using constant and temperature-dependent (power-law) coefficients. Both models provide similar results for aerodynamics in the Boussinesq regime; however, the constant fluid transport coefficient model fails to capture the underlying flow physics in the non-Boussinesq regime. The temperature-dependent transport coefficient model is essential even within the Boussinesq regime for accurate heat transfer predictions and analysis.