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Seminar: Fluid Mechanics

Modifications on a flow separated from a sharp edge by the use of fluidic or plasma actuators

Speaker: Patricia Sujar-Garrido
Organization: Ecole Centrale de Lyon, France
Time: 2018-10-19 10:30
Place: Teknikringen 8

Abstract

Here, active control attempts to reduce flow separation drawbacks using plasma or fluidic devices. The flow developing downstream of a 2D step exhibits a complex behaviour that includes the development of several periodic motions. The study focused on the effects produced by plasma actuation on the mean reattachment point, on the shear layer, and the Reynolds stresses. Different locations of the actuators and an extended parametric study of the discharge intend to determine an optimal forcing. However, the minimum reattaching position is achieved by forcing the flow at the shear layer mode; but pressure fluctuations are maximized for an actuation at half the shear layer mode. These results highlight the importance of understanding the whole flow dynamics and the actuation interactions, even for a two-dimensional configuration. At the moment, the 3D turbulent wake behind a trailer model is modified via high-frequency forcing. The comprehension of the physical phenomena relating the individual dynamics of the different zones of the non-controlled wake (shear layers and backflow), their mutual interactions, and the modifications produced by the fluidic actuation is still under examination. From the results, two aspects are highlighted for enhancing active flow control. Firstly, the understanding of the natural flow dynamic permits to select the best location and timing of actuation. Secondly, to comprehend the actuator itself and the resulting perturbation is important to estimate possible interactions with the natural flow.