Analysis of thermal buoyancy effect on flow patterns behind a heated square cylinder for low Prandtl number fluids

The aim of this research is to numerically simulate and investigate the effect of thermal buoyancy on the flow field passing over a horizontal square cylinder. The upper surface of the cylinder is considered to be at constant temperature, and the remaining surfaces are insulated. The problem variables are Reynolds number (Re), Prandtl number (Pr), and Richardson number (Ri). A home-made solver based on the finite volume method is used to numerically solve the governing equations. In this method, the governing equations are discretized with a symmetry-preserving method with fourth-order accuracy. The validity of the present solver is investigated by comparing the results with available experimental and numerical data. The investigated range for Reynolds, Prandtl, and Richardson numbers is 100–150, 0.1–0.7, and 0–0.7, respectively. The results showed new flow patterns at low Prandtl numbers, including symmetric steady flow with 4 vortices and asymmetric steady flow. In addition, it was found that changing the flow pattern has a significant effect on the cylinder drag coefficient.