Flow and heat transfer characteristics over a square cylinder with corner modifications

In the present study, the effect of corner modifications on fluid flow and heat transfer characteristics across a square cylinder has been analyzed numerically in an effort to improve thermohydraulic parameters. Two-dimensional simulations have been carried out for laminar flow across a square cylinder with sharp, round, chamfered and recessed corners for Reynolds number range 55-200. Corner variations have been made for dimension c/D = 0.125, where c and D indicate corner size and cylinder diameter respectively. When compared with the sharp-cornered cylinder, the results illustrated that corner modifications lead to significant drag reduction, however, the penalty in terms of Strouhal number increment is comparatively low. Deflected flow from upstream modified corners promotes flow separation from downstream corners in contrast to the sharp-cornered cylinder results in narrow wake width with intense fluid circulations, farther vortex shedding location and consequently reduced pressure drag as well as improved heat transfer coefficients. Recirculating fluid inside the upstream corner cut of recessed corners additionally contributes towards drag increment as compared to other corner configurations. Results also indicate that upstream corners modifications are more influential in amelioration of thermohydraulic characteristics as compared to downstream corners. Moreover, a new correlation for the average Nusselt number has been developed as a function of Reynolds number.