Numerical investigation of flow around hairy flaps cylinder using FSI Capabilities

Flow around a cylinder has been extensively studied due to its practical importance in engineering; much attention has been devoted to drag reduction and vortex shedding suppression using active and passive control devices. A strong motivation for studying such practical problems come from the fact that large amplitude of lift fluctuation and alternate vortex shedding are generally design concerns for engineers. Several numerical and experimental studies have been devoted for studying flow around a cylinder with a flexible plate attached to its centerline. This investigation has been known to be one of the most successful ways of controlling vortex shedding. Other active device for vortex shedding cycle reduction in order to minimize sound pressure is a cylinder equipped with hairy flaps. Experimental studies of air around a cylinder equipped with hairy flaps show that hairy flaps can reduce the wake deficit by modifying the shedding cycle behind the cylinder. For the modelisation and simulation of such a coupling problem, fluid structure capabilities need to be performed. Fluid structure coupling problems can be solved using different solvers; a monolithic solver and a partitioned process. Monolithic process is a fully implicit method preserving energy at the fluid structure interface. However its implementation is more complex when specific methods are required for both fluid and structure solvers. When efficient fluid and structure software packages are available, a partitioned procedure can be used in order to couple the two codes. The present work is devoted to simulation of fluid structure interaction problems and flow around thin flexible hairy flaps, using a partitioned procedure. One of the main problems encountered in the simulation is the automatic remeshing when the flaps come into contact and the fluid mesh between the flaps undergoes high mesh distortion. . In this paper, numerical simulation has been performed and Strouhal number for two different Reynolds number Re=1.46 104 and 1.89 104 have been investigated. For both Reynolds number experimental data is available. For comparison with flow around a plain cylinder, numerical simulation were also performed and Strouhal number compared to experimental value