Mixed Convection from Tandem Semi-Circular Cylinders Arranged in a Vertical Channel

Semi-circular cylinders provide better space economy than circular and other non-circular cylinders. The cylinders are frequently used in a tandem arrangement in heat transfer equipment. The present study aims to obtain the flow and heat transfer characteristics for the tandem arrangement of semi-circular cylinders. The cylinders are placed in a vertical channel with a blockage (β) of 0.2. The upward flow under the reverse gravity is considered here. The influence of various parameters such as Reynolds number (Re), Prandtl number (Pr), Richardson number (Ri), and spacing between cylinders (YC) is observed. The governing parameters are varied in a range of 1 ≤ YC ≤ 6, 1 ≤ Re ≤ 50, 0.7 ≤ Pr ≤ 50, and 0 ≤ Ri ≤ 2. The numerical results are obtained by solving governing equations using FVM (Finite volume method). The velocity field, thermal field, drag coefficient (CD), pressure coefficient (Cp), and average Nusselt number (Nuavg) are presented. The increase in Re and Pr has enhanced the Nuavg and CD, whereas Ri and YC have shown complex dependency. The obtained results show that the mutual interaction of upstream and downstream cylinders has vanished for YC > 4. The upstream and downstream cylinders have shown different behavior at identical operating conditions. The drag coefficient for the upstream cylinder varies with YC for 1 ≤ Re ≤ 10, whereas for 10 ≤ Re ≤ 50, it shows negligible change except for the case of Pr = 0.7 and Ri = 2. The drag on the downstream cylinder increases monotonically with an increase in YC. The average Nusselt number for both cylinders increased with an increase in YC except for the downstream cylinder at Re = 1 and Pr = 0.7. Overall, the complex interplay of governing parameters has been observed in the flow and thermal characteristics.