DOI: 10.1615/TSFP8
TURBULENCE CONTROL BY INDUCED SPANWISE REFLECTION SYMMETRY BREAKING
要約
We propose a new strategy of shear flow turbulence control which is realized by the imposition in the plane Couette flow of a specially designed, non-symmetric in spanwise direction seed velocity perturbations by a near wall volume forcing. The configuration of the imposed perturbations ensures a gain of shear flow energy and the breaking of turbulence spanwise reflection symmetry − generates spanwise mean flow. The latter changes the self-sustained dynamics of turbulence and results in considerable reduction of its level and kinetic energy production. It has to emphasized that the generated spanwise mean flow is a result of the intrinsic, nonlinear processes in the forced turbulence and not directly introduced in the system. A model, near-wall weak forcing is designed to impose in the flow the perturbations with required statistics and characteristics. The efficiency of the proposed scheme has been demonstrated by direct numerical simulation (DNS) using the plane Couette flow as a representative example. However, the strategy can be naturally applied to channel and boundary layer flows. The results are promising: the reduction of level of turbulence about 35% was obtained. Of course, the considered forcing is volume and hypothetical one. Nevertheless, it helps to gain a knowledge about the design of the seed velocity field that is necessary to impose in the flow to achieve a substantial reduction of the turbulent kinetic energy.