Displacement amplitude scaling of a two-dimensional synthetic jet

A two-dimensional synthetic jet is studied numerically by solving the incompressible, unsteady, Reynolds-averaged, Navier-Stokes equations and using a k-epsilon turbulence model. Rather than a resonant cavity, the synthetic jet is supplied by a fully developed channel flow. Results for two exit geometries, a sharp exit and a rounded exit, and several dimensionless stroke lengths are compared. This study focuses on the effect of the displacement amplitude (stroke length) on the power required to form the jet, the net momentum flux downstream of the exit, the formation threshold, and the spatial development of the synthetic jet. It is shown that the channel flow development length, the self-similar region, and the region from which the jet draws fluid all scale on the stroke length. It is also demonstrated that the power required to form the jet increases with stroke length as does the resultant momentum flux. Finally, the power required to form a synthetic jet is significantly smaller for a rounded exit compared to a sharp-edged exit. (C) 2005 American Institute of Physics.