Optimal control of circular cylinder wakes using long control horizons
نویسندگان
چکیده
The classical problem of suppressing vortex shedding in the wake of a circular cylinder by using body rotation is revisited in an adjoint-based optimal control framework. The cylinder’s unsteady and fully unconstrained rotation rate is optimized at Reynolds numbers between 75 and 200 and over horizons that are longer than in previous studies, where they are typically of the order of a vortex shedding period or shorter. In the best configuration, the drag is reduced by 19%, the vortex shedding is effectively suppressed, and this low drag state is maintained with minimal cylinder rotation after transients. Unlike open-loop control, the optimal control is shown to maintain a specific phase relationship between the actuation and the shedding in order to stabilize the wake. A comparison is also given between the performance of optimizations for different Reynolds numbers, cost functions, and horizon lengths. It is shown that the long horizons used are necessary in order to stabilize the vortex shedding efficiently. C 2015 AIP Publishing LLC. [http://dx.doi.org/10.1063/1.4928896]
منابع مشابه
A Rotary Control of the Circular Cylinder Wake: an Analytic Approach
In this paper, we establish some quantity relationships between the dynamics of circular cylinder wakes and the rotation speed of the cylinder. It has been shown analytically that rotating the cylinder can regularize the flow behavior, and delay the transition from steady flow to turbulent flow. The work needed to overcome the drag exerted on the cylinder is provided.
متن کاملNumerical investigation on the effects of six control rods arranged in equilateral triangular configurations on fluid flow and forced convection heat transfer from a circular cylinder
The present work deals with heat transfer characteristics as well as fluid flow patterns in laminar flow regime for a circular cylinder with six control rods arranged in equilateral triangular geometries. The computations have been carried out by a finite volume approach using the overset grid method. The unsteady flow at Re= 200 and Pr= 0.7 and 7.0 was examined. The effect of the control rods ...
متن کاملVisualization study on suppression of vortex shedding from a cylinder
A narrow strip has been introduced as a control element to suppress vortex shedding from a cylinder. The strip is set parallel to the cylinder axis, and the key parameter of control in this study is the strip position, which is determined by the angle of attack of the strip and the distance between the strip and the cylinder axis. A circular cylinder and a square cylinder were tested respective...
متن کاملHigh-Order Methods for the Numerical Simulation of Vortical and Turbulent Flows Control of three-dimensional wakes using evolution strategies
We investigate three-dimensional cylinder wakes of incompressible fully developed flows at Re = 300, resulting from control induced by tangential motions of the cylinder surface. The motion of the cylinder surface, in two dimensions, is optimized using evolution strategies, resulting in significant drag reduction and drastic modification of the wake as compared to the uncontrolled flow. The qua...
متن کامل