Bimodal control of three-dimensional wakes

Philippe Poncet (1)

1 LMAP - Laboratoire de Mathématiques et de leurs Applications [Pau]

This paper investigates control strategies for drag reduction of three-dimensional wake generated by a circular cylinder at Reynolds number Re = 300, such flows presenting mode B instabilities whose main feature is streamwise finger-shaped eddies. The control is performed thanks to a field of tangential velocities on the cylinder. One first focuses on two-dimensional velocity fiels (spanwise invariant), using both a clustering genetic algorithm (see [7]) and Newton algorithm in Fourier space with five Fourier modes. Besically the same field comes out, whatever the control technique used. A square-root regression of the drag reduction versus amplitude of the control leads to the formulation of an efficiency criterion. One then considers a class of spanwise harmonic perturbation of this quasi-optimal profile, leading to a two paramater optimization problem, involving amplitude and wavelength of the perturbation. A cartography of the efficiency with respect to these two parameters is finally obtained, showing regions of interest.

Domaines: Optimisation et contrôle [math.OC]; Modélisation et simulation; Mécanique des fluides [physics.class-ph]

Philippe Poncet. Bimodal control of three-dimensional wakes. ERCOFTAC Workshop DLES-6, 2005, Poitiers, France. ⟨hal-02011183v2⟩