Turbulence Control in Plane Couette Flow by Spanwise Reflection Symmetry Breaking
We propose a new strategy shear flow turbulence control which can be realised by the following steps: (i) a specially designed, non-symmetric in spanwise direction seed velocity perturbations imposed at the boundaries of the flow; (ii) the configuration of the imposed perturbations ensures a gain of shear flow energy and the breaking of turbulence reflection symmetry - generates spanwise mean flow; (iii) the generated flow changes the self-sustaining dynamics and results in considerable reduction of the level of turbulence and its kinetic energy production. The generated spanwise mean flow is a result of an action of intrinsic nonlinear processes of forced turbulence and it is not directly introduced in the system - the activation of the intrinsic processes is the basic idea of the proposed strategy. A model, weak near-wall forcing was designed to impose in the flow the perturbations with required characteristics and the efficiency of the proposed scheme was demonstrated by direct numerical simulation using plane Couette flow as a representative example. The considerable reduction (up to 35%) of production of turbulent kinetic energy was obtained.
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