Three-dimensional evolution of structure and acoustic wave generation in a compressible plane wake
Three-dimensional evolution of structure and acoustic wave generation in a compressible plane wake
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可压缩平面尾流中结构的三维演化和声波产生
DOI：
10.1016/j.fluiddyn.2003.10.003
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发表时间：
2004
影响因子：
1.5
通讯作者：
H. Maekawa
中科院分区：
文献类型：
--
作者：
Daisuke Watanabe;H. Maekawa
数值求解可压缩Navier-Stokes方程，研究了可压缩平面尾迹向湍流转捩的三维结构。空间导数采用高阶紧致差分格式，时间推进采用四阶龙格-库塔格式。垂向采用Navier-Stokes特征边界条件，流向和展向采用周期边界条件。利用线性稳定性理论，采用映射傅立叶方法求解粘性可压缩方程组，得到不稳定扰动。三维结构的尾流研究的随机扰动和不稳定模式的组合，迫使通过时间演变的平面尾流。一对斜向不稳定模态的强迫在鞍形区域产生流向/垂直反向旋转涡。随着流向/垂直涡流在外部发展，它们的自感应导致尾流中形成倾斜的编织状结构。斜向不稳定模态的作用也是引起展向滚柱断裂的原因。平面尾流的声波是在尾流中出现大致二维的卷起结构并旋转时产生的。尾流的三维演化降低了近场声压。
The compressible Navier–Stokes equations are numerically solved to study three-dimensional structures of a compressible plane wake undergoing transition to turbulence. High-order compact finite difference schemes are used for spatial derivatives and a fourth-order Runge–Kutta scheme is employed for time advancement. Navier–Stokes characteristic boundary conditions are used in the vertical direction and periodic boundary conditions in the streamwise and spanwise directions. Unstable disturbances are obtained from linear stability theory using a mapped Fourier method for the viscous compressible equations. Three-dimensional structures of the wake are studied by means of temporally evolving plane wakes forced with random disturbances and a combination of unstable modes. Forcing with a pair of oblique unstable modes yields streamwise/vertical counter-rotating vortices in the saddle region. As the streamwise/vertical vortices evolve outside, their self-induction causes inclined braidlike structures to form in the wake. The effect of the oblique unstable modes is also to cause the spanwise roller breakdown. Acoustic waves of the plane wake are generated when roughly two-dimensional rollup structures appear and rotate in the wake. The three-dimensional evolution of the wake reduces the near-field sound pressure.