Optimized heat transfer and drag reduction through corner modifications in square cylinders immersed in power-law fluids

This study numerically investigates fluid flow and heat transfer around a square cylinder with modified corner geometries, varying the corner radius ratio (CRR = r/d) from sharp (r/d = 0) to fully rounded corners (r/d = 0.5). Using computational fluid dynamics based on the finite volume method, the analysis is conducted for incompressible power-law non-Newtonian fluids with power-law indices (n = 0.6 to 1.4) and Reynolds numbers (Re = 5 to 40). The study focuses on how CRR influences heat transfer performance and flow behavior. Results show that increasing CRR significantly enhances heat transfer, as reflected in higher local and average Nusselt numbers (Nu). At Re = 40, the average Nusselt number (Nuavg) increases by 20%–26% when CRR changes from 0 to 0.5, demonstrating the thermal advantages of rounded geometries. Modified corners reduce recirculation lengths and delay flow separation, shifting the separation angle downstream and increasing the separation Reynolds number. These changes improve thermal mixing within the flow. Additionally, drag coefficients decrease by 7%–11% with increasing CRR, illustrating the dual benefits of drag reduction and heat transfer enhancement. Streamline, isotherms and vorticity contour plots provide detailed visualizations of boundary layer development and wake dynamics, revealing the role of CRR in disrupting flow structures and enhancing heat transport. This study highlights the potential of rounded geometries to optimize heat transfer and flow efficiency in systems using power-law non-Newtonian fluids, offering valuable insights for engineering applications.