The scenario of two-dimensional instabilities of the cylinder wake under EHD forcing: A linear stability analysis

L GONZALEZ; J D'ADAMO; A GRONSKIS; G ARTANA

Hawaii

Conferencia; 41 st AIAA Fluid Dynamics Conference; 2011

American Instritue of Aeronautics and Astronautics

We propose to study the stability properties of a wake air flow forced by electrohydrodynamic (EHD) actuators, dielectric barrier discharge (DBD) type. EHD actuators can add momentum to the flow around an object in regions close to the wall. As the forcing frequencies, characteristic of DBD, are much higher than the natural shedding frequency of the flow (kHz vs. Hz), we consider in this work the forcing actuation as stationary. The actuators are disposed symmetrically near the boundary layer separation point. We study the flow around a cylinder modied by EHD actuators experimentally by means of particle image velocimetry (PIV) measures and also computationally by solving the generalized eigenvalue problem obtained from linearized Navier-Stokes equations. In the numerical part, the presence of the EHD actuators has been implemented as a boundary condition on the cylinder surface. The base flow obtained computationally using this boundary condition has been compared with the experimental one in order to match the control parameters from both methodologies. Once the base  flow agreement has been veried, the Hopf bifurcation produced when the flow starts the vortex shedding has been studied by dierent methods: on onehand, when the base flow is obtained from experimental snapshots the evolution of the amplitude velocity oscillations is used, on the other hand when the base flow is computationally obtained a global linearized eigenvalue problem is solved for the instability study. Finally, the critical parameters have been compared.