Numerical study of flow characteristics behind a stationary circular cylinder with a flapping plate

Abstract

The laminar flow over a stationary circular cylinder with a flapping plate is simulated in this study to investigate the flow characteristics by using our recently developed boundary condition-enforced immersed boundary-lattice Boltzmann method [Wu and Shu, J. Comput. Phys.228, 1963 (2009); Wu et al. Int. J. Numer. Methods Fluids62, 327 (2010); Wu and Shu, Comm. Comp. Phys.7, 793 (2010)]. The purpose of this work is to study the flow control behind a bluff body by an alternative way different from the rotationally oscillating motion. The idea is in fact from the tadpole locomotion, where the bluff head-body is modeled by a circular cylinder, and the thin tail is simplified by a rigid plate with flapping motion. In this work, only the laminar flow is considered and thus the Reynolds number is chosen as 100. Similar to the case of rotationally oscillating cylinder, the flow wake behind the cylinder and flapping plate is strongly affected by the flapping amplitude and frequency of plate. On the other hand, because of the existence of flapping plate, the length of plate can also modify the flow structures. Due to flapping motion of plate, some typical flow patterns and drag reduction are found, and two different vortex interaction modes, known as constructive interaction and destructive interaction, are observed. © 2011 American Institute of Physics.