Numerical study on flow and heat transfer characteristics of square cylinder with lateral sides extension effect

The present study analyses the effect of triangular and circular extensions on lateral sides of square cylinder in a confined domain. Two-dimensional simulation has been carried out for laminar flow across a square cylinder with triangular and circular extensions for Reynolds number (Re) range 75-200. The momentum and energy equations are solved numerically by applying suitable boundary conditions using Ansys Fluent 18. The fluid flow and heat transfer characteristics of the square cylinder with extensions (at constant characteristics length) has been analysed by estimating and comparing the pressure drag, viscous drag, total drag, total pressure drop, Strouhal number, local and average Nusselt numbers. Different models with circular and triangular modifications are considered by modifying the lateral sides of a square cylinder by increasing the transversal height h without changing the characteristic length. Maximum decrease of 45% is observed in total drag coefficient when an ideal square cylinder is geometrically modified to form a cylinder with triangular extensions at h = 0.2 on the lateral side without affecting the characteristic length D at Re 200. Maximum decrease in pressure drop of around 42.8% is observed for square cylinder with triangular modifications with h = 0.2D. It is found that modified square cylinders have higher Strouhal number than an ideal square cylinder. An increase of 23.66% in Nu is observed for circular modification; h = 0.3D with respect to square cylinder at Re 200. Circular modification shows better heat transfer capabilities than triangular modification. Thus, the studies show enhancement in flow and heat transfer properties with lateral modifications.