Flow control around a circular cylinder with swinging thin plates

Flow around a 2D circular cylinder with attached swinging thin splitter plates is numerically investigated. The ratio of the plates' length to the cylinder diameter is 1 (L/D = 1) where L is the Plates' length and D is the cylinder diameter. The plates are attached at 55 degrees (trigonometric angle) downstream and are forced to oscillate at different ratios of the natural vortex shedding frequencies with magnitudes of FR = 0.75, 1, 1.25, 1.5 and 2. The oscillation amplitude "alpha" as the other main variable ranges from 10 to 18 degrees. Two-dimensional simulations are carried out at the Reynolds number 100, and then extended to higher Reynolds number of 200. The results show that in certain configurations, an in-phase vortex-shedding pattern is dominant and the oscillatory nature of the lift force completely vanishes. Different flow patterns are observed and classified as well. The effects of the splitter plates' oscillation on the lift and drag forces, flow patterns and vortex shedding frequencies are also discussed to develop a link between different flow patterns and the acting lift force on the cylinder. (C) 2018 Elsevier Ltd. All rights reserved.