Mixed convection heat transfer from a circular cylinder submerged in wake

This work numerically investigates the effects of Richardson number Ri (= 0 2.0) on the flow and heat transfer topologies of a circular cylinder submerged in the wake of another cylinder at a Reynolds number Re = 100. Three spacing ratios L/D = 1.2, 3.0, and 5.0 are selected, where L is the center-to-center distance between the two cylinders and D is the cylinder diameter. The upstream cylinder is maintained at zero heat flux while the downstream cylinder is heated and maintained at a constant temperature. The results of flow structures, shedding frequencies, fluid forces, and heat transfer are presented and delineated. The results reveal that, although the upstream cylinder is not self-heated, its temperature can reach upto 85% of the downstream cylinder temperature due to the reverse flow generated in the gap between the cylinders. At a sufficiently high Ri, the wake is characterized by a P + S (pair and single) vortex street with the P vortices becoming hotter than S vortices. When Ri is increased, downwash and upwash flows are generated before and after the heated cylinder, enhancing the heat transfer from the cylinder. The Ri effect is exclusively imparted on aerodynamic parameters including fluid forces, Strouhal numbers, Nusselt numbers, and Reynolds stresses.