Comparing steady and unsteady rectangular jets issuing into a crossflow

The foundational differences of steady and unsteady jets issued into a laminar boundary layer crossflow are considered. Jets have been used widely for flow control applications, due to their ability enhance mixing mitigate separation, but it is unclear what role jet steadiness plays in effectiveness. Here we compare experimentally (synthetic) rectangular flat-plate with varying orifice pitch skew. coherent streamwise vortices produced by were shown be much stronger than those jets, despite producing similar patterns. These rooted how vorticity generated the orifice, through either Stokes (unsteady) or Blasius (steady). Exploring time- phase-averaged transport equation reveals that time-varying term reason enhanced vortical structure. When considering metrics, find greater added momentum when compared momentum-matched jet. Both penetration characteristics.