展向行波电磁力控制下的槽道湍流雷诺应力

为研究槽道湍流的电磁力减阻控制问题,采用直接数值模拟(DNS)方法对槽道湍流的展向行波电磁力控制问题进行数值研究.讨论了由展向行波诱导的诱导流场对槽道湍流流场的调制过程,分析了控制前后雷诺应力离散点分布、平均雷诺应力分布以及雷诺应力波谱分布的规律.研究表明,在合适参数条件控制下,展向行波电磁力的控制不仅使近壁条带结构基本消失,形成加宽的低速条带,而且能使控制后的流场中涡结构几乎消失,而仅剩下由展向行波电磁力诱导产生的带状负涡结构,同时展向行波电磁力在一定程度上抑制了湍流的脉动,减小了雷诺应力,最终使壁面阻力下降.

Reynolds stress in the turbulent channel flow controlled byspanwise travelling wave Lorentz forc

The flow control and drag reduction in a turbulent channel flow by using a spanwise travelling wave Lorentz force are investigated numerically via the direct numerical simulation (DNS). The evolution of the streaks and the vortex structures adjoining the wall in the turbulent channel flow controlled by Lorentz force are described. Moreover, normal fluctuation velocity, streamwise fluctuation velocity distribution, the average Reynolds stress distribution and the spectra analysis of Reynolds stress are also discussed simultaneously. The results show that, under the action of the distributed Lorentz force with proper control parameters, only well-organized strip-shaped streamwise vortexes are observed in the near-wall region of the turbulent channel flow, and the others vortexes are almost disappeared, which is the same as the streaks in the near-wall region. Besides the Reynolds stress in the controlled channel flow was inhibited sharply by the spanwise travelling wave Lorentz force which leads to the reduction of skin-friction drag. The mechanism of turbulence drag reduction controlled by using a spanwise travelling wave Lorentz force is further clarified.