Control of vortex shedding from a circular cylinder surrounded by eight rotating wake-control cylinders at Re=100. (August 2019)

• Record Type: Journal Article
• Authors: Assi, G.R.S.; Orselli, R.M.; Silva-Ortega, M.
• Is Part Of: Journal of fluids and structures. Volume 89(2019)
• Page Start: 13
• Page End: 24
• Publication Date: 2019-08
• Subjects: Vortex shedding -- Wake control -- Rotating cylinders -- Drag reduction; Fluid-structure interaction -- Periodicals; Fluid mechanics -- Periodicals; Structural dynamics -- Periodicals; Structural analysis (Engineering) -- Periodicals; 620.106
• DOI: 10.1016/j.jfluidstructs.2019.03.003
• Languages: English
• ISSNs: 0889-9746

Abstract

Abstract: The present work investigates the suppression of vortex shedding of a circular cylinder of diameter D surrounded by a polar array 8 rotating wake-control cylinders of a considerably smaller diameter d ∕ D = 0 . 05 . A numerical approach was employed to simulate the laminar flow at a Reynolds number of 100. The governing equations were discretised by the finite volume method for a two-dimensional computational domain. The main varying parameter was the rotation speed of the control cylinders, measured as a fraction of the incoming flow speed. A controlled wake (one without alternating vortices) was achieved when the tangential velocity at the surface of the control cylinders was greater than 3 times the free stream velocity. A significant reduction of the overall drag coefficient and mitigation of the unsteady hydrodynamic forces acting on the system were observed as rotation was increased. Given enough rotation, a negative mean drag (thrust) was achieved. The power spent to rotate the 8 control cylinders appeared to be higher than the power-loss associated with the mean drag of a bare cylinder. While still working with an active, open-loop control system, this investigation supports the development of a closed-loop wake-control device for offshore applications.