Large-eddy simulations of control of a separated flow over a 2D bump by means of pulsed jets

Abstract

A numerical study of active flow control of a separated converging-diverging channel flow is presented. Several geometrical and operating parameters of the continuous and pulsed jets are investigated using large-eddy simulations (LES), which are highly resolved in the actuation region. The LES without control is validated with a direct numerical simulation of the same flow. Configurations with both counter-rotating and co-rotating jets are tested. The main statistical results are in general agreement with the literature. Thanks to the unsteady highly resolved simulation, both temporal and spatial organizations of the generated vortices are investigated. An optimal frequency associated with the convective time as well as an optimal duty cycle are obtained, leading to a control efficiency comparable to the cases with continuous jets and the same operating velocity and, consequently, to a significant saving in mass flow rate.

Keywords:

• turbulence
• active control
• pulsed jets

Acknowledgements

This work was supported by CISIT (International Campus on Safety and Inter-modality in Transport) and WALLTURB (A European synergy for the assessment of wall turbulence), which is funded by the EC under the sixth framework program (CONTRACT: AST4-CT-2005-516008). The DNS was performed through two successive DEISA Extreme Computing Initiatives (DEISA is a Distributed European Infrastructure for Supercomputing Applications). The other calculations were performed with the computing facilities of Lille University (CRI) and GENCI (French National Computing Facilities).