Abstract
Direct numerical simulations of flow induced by a zero-net-mass-flux jet (ZNMFJ) actuator are performed in order to investigate the effects of the Reynolds number and Strouhal number on the formation of jet flow above the orifice. It is found that the ZNMF jets are realized when a vortex pair formed during the blowing period at the orifice advects away from the orifice, in such a way that the pair will not be sucked into the cavity during the suction period. This condition can be described with U_j (U_j/f)/v>1000,where U_j is the mean velocity at the orifice, f the frequency of the membrane, and v the kinematic viscosity.
