Numerical investigation of a jet-and-vortex-actuator without and with cross-flow boundary layer

In this study we consider an active flow control actuator which was first investigated experimentally by Lachowicz et al. (1999a,b) and called "Jet and Vortex Actuator" (JaVA). The Fluent (R) CFD software package has been used because of its ability to employ user-defined functions for specification of the unsteady boundary conditions and a sliding mesh interface for discretization of the moving parts of the JaVA. Three cases are presented, one without cross flow and two with a cross-flow boundary layer. The difference in the latter two is that the actuator arrangement with respect to the cross flow is reversed from one case to the other. The results for the first case prove that the available experimental results can be reproduced in a computational study and that the numerical simulation provides additional information because it covers the unsteady details as well. The other two cases show that the actuator increases the wall-normal velocity gradient by a redistribution of momentum within the boundary layer, especially when the wide gap of the actuator is behind the small gap and the moving actuator plate. (C) 2011 Elsevier Inc. All rights reserved.