A numerical study on the drag reduction and wake regime control of the tandem circular cylinders using splitter plates

The present study focuses on the control of an unsteady vortex flow regime and flow-induced forces on the tandem circular cylinder using the splitter plate-based technique at a Reynolds number (Re) of 100. The in-house developed flexible forcing immersed boundary lattice Boltzmann method (FFIBLBM) solver is employed for these two-dimensional numerical simulations. Three distinct tandem cylinder spacing is considered: small spacing (G/ D = 2.0), medium spacing (G/D = 3.5), and large spacing (G/D = 5.0), where G is the center-to-center distance between the cylinders having diameter D. For each spacing, the effectiveness of two different configurations of splitter plates are examined: splitter plate attached to the upstream cylinder (TC-SPU) only and splitter plate attached to the downstream cylinder (TC-SPD) only. The arrangement and length of the splitter plate have a significant effect on the suppression of vortex shedding and reduction of flow-induced force on the cylinders. The result shows that the TC-SPD is beneficial for small spacing, yielding a drag reduction of 0.58 % and 0.05 % for the upstream and downstream cylinders. At the same time, both the TC-SPU and TC-SPD configurations are useful for suppressing the flow unsteadiness for medium spacing. However, the drag reduction in TC-SPD is more. In this case, the drag of the upstream and downstream cylinders is reduced by 1.4 % and 247 %, respectively. At large spacing, the TC-SPU arrangement is suitable for the suppression of vortex shedding from both cylinders. The corresponding drag reduction for the upstream and downstream cylinders is 13.7 % and 89.2 %, respectively.