Modification of energetic modes for transitional flow control

We introduce a mechanism of using collocated serpentine shaped plasma actuators for controlling the flow via an input electrical signal to either advance or delay transition by amplification or annihilation of energetic modes of turbulent structures. A wall resolved implicit large eddy simulation is conducted to examine the process of turbulent flow control due to this mechanism. Collocation allows for selective superposition of different energetic modes, which can either subtract or add energy to the baseline flow resulting in turbulent streak manipulation. Unlike most flow control methods that use either a localized large amplitude forcing or a low amplitude distributed forcing, this mechanism uses a localized low amplitude forcing to cause reduction in skin friction of more than 53% across the plate. This is achieved by manipulating strength as well as the spacing between the low-speed turbulent streaks, which are ubiquitous in a turbulent flow field. Reduction in skin friction drag can result in decreasing fuel consumption and in turn reducing pollution.