INVESTIGADORES
ARTANA Guillermo Osvaldo
congresos y reuniones científicas
Título:
Forcing the shear layer of a backward-facing step flow using DBD plasma actuator
Autor/es:
J. L. AIDER; T DURIEZ; J E WESFREID; G ARTANA
Lugar:
Long Beach, California, USA
Reunión:
Conferencia; 63rd Annual Meeting of the APS Division of Fluid Dynamics; 2010
Institución organizadora:
AIP
Resumen:
The Kelvin-Helmholtz convective instability is the key mechanism in a backward
facing step (BFS) flow. The natural flow selects the most amplified mode below
the cutoff wavenumber. We introduce time-dependant perturbations inside the
shear layer using a DBD plasma actuator. The perturbation is a pulsed low
velocity spanwise jet, parallel to the mean flow. It is introduced inside the
boundary layer, just upstream separation. Using time-resolved visualizations we
show that forcing with a given frequency can have a dramatic effect on the
spectral content of the flow and its global properties. The modification of the
BFS flow depends strongly on the value of the frequency with respect to the
natural frequency. Using 4Hz Particle Image Velocimetry (PIV) we study the
evolution of time-averaged properties such as the recirculation length or the
shear layer thickness. Recording the forcing perturbation signal together with
the PIV acquisition signal we achieve phase-average reconstruction based on the
forcing frequency. The phase-averaged time series give access to the wavelength,
phase velocity and the spatial distribution of the vortex shedding. It also
allows us to build the stability diagram of the shear layer