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Addition of a vortex generator (VG) to the heated surface creates longitudinal vortices in the flow; however, it induces drag. Surface modification of the VG may play a role in the thermal performance of the system. Therefore, flow and thermal behavior are studied for a secondary surface (SS) attached to the primary surface of a rectangular VG, which is placed inside a rectangular channel using air at Re = 5000. The VG with the SS is compared with a conventional rectangular VG having volume constant. With the addition of SS, the flow behind the VG greatly shears the produced primary vortex (P), which results in stretching. Stretching increases the angular momentum of the vortex with the decrease in the span of the produced vortices. The interaction between the co-rotating vortices P and high pressure side horse-shoe vortex (Hp) shows that the higher strain field induced by the vortex P shears away the vortex Hp. The vortex P developed under the influence of SS induces a higher degree of tilting toward the heated surface with low propagation speed. Finally, the dynamic decomposition of the vortices in the channel reveals that the vortex P appears to be dominant.

A numerical analysis is performed to elucidate the forced convective fluid flow and heat transfer characteristics past a blunt-headed cylinder. Simulations are carried out employing air (Pr = 0.71) as an operating fluid in a Reynolds numbers range 40≤Re≤200. The curvature ratio is varied from 0 to 0.5. The flow and heat transport features are elucidated in detail for different curvature ratios. Important flow parameters such as boundary layer thickness, vortex strength, wake width, drag, lift, skin friction coefficient, pressure coefficient, Strouhal number, and recirculation length are computed. Also, a primary stability analysis has been carried out using the Landau equation, whereas secondary stability analysis has been done implementing dynamic mode decomposition (DMD) to compute the critical Reynolds number at each curvature ratio. Calculating local and time-averaged values of Nusselt numbers, heat transfer characteristics are studied. An entropy generation analysis is done to investigate the effects of corner modification on the efficacy of thermofluid transport characteristics.

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