Flow past two finite-length wall-mounted cylinders in tandem arrangement at Re = 200

Abstract

To investigate the characteristics of flow over two finite-length cylinders in tandem arrangement, numerical simulations were performed using CFD technique for spacing ratios (S = D/d, where d is the diameter of the cylinders and D is the separation gap between the cylinders) between 0.5 and 12 at a Reynolds number of 200. The height-to-diameter ratio (h/d, where h is the height of the cylinders) was fixed at 8. This study primarily focuses on the effects of S and the free ends on the vortical structure behind the cylinders. The S has a significant effect on the Strouhal number and on the lift and drag coefficients of cylinders. The results show extremely different vortex streets at different cylinder heights. With an increase in S, the average drag coefficient of the downstream cylinder increases, whereas that of the upstream cylinder first decreases and then increases. Additionally, as S changes between 4.5 and 5, the average drag coefficient of the two cylinders changes suddenly. The effects of S on Strouhal number and the lift coefficient ex-hibit a complex behavior.