Dynamics of Unsteady Turbulent Plane Jets Relevant to Synthetic Jet Control

Incompressible Direct Numerical Simulation (DNS) of a planar pulsed jet for Strouhal (0.05, 0.3, and 0.6) and Reynolds (3000 and 10000) numbers are used to understand the effect of inlet conditions in the development of vortical structures, their interactions among themselves and with turbulence, that are produced by the pulsations. This study is motivated by our interest in the dynamics of synthetic jets. With low St, the formed turbulent shear layer tends to roll into a vortex pair with higher circulation, this enhances the global flux of momentum and mass. When turbulence intensity on the inlet flow is increased, no pairing is observed. Low-frequency pulsations generate vortex pairing farther to the inlet with a very weak steady-like jet flow. Further details will be discussed.