平面可压基频涡卷非线性演化行为数值研究
NUMERICAL INVESTIGATION OF THE NONLINEAR EVOLUTION OF THE PLANE COMPRESSIBLE PRIMARY VORTEX
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摘要: 采用高精度迎风／对称紧致混合差分算法，对可压自由剪切层转捩区中的几种典型展向 大尺度涡作用型态进行了直接数值模拟．通过施加给定来流条件下的线性最不稳定动性基频扰 动及其亚谐扰动，以被动守恒标量技术给出了基频涡卷的饱和、撕裂、融合以及三涡对并等细 节结构．分析显示，亚谐扰动相差是促生基频涡卷不同非线性演化过程的重要因素之一，可对 扰动能量的发展变化，以及剪切层厚度和混合效率产生直接影响．计算结果同实验流动显示图 像十分相似，表明了主导线性扰动的非线性耦合效应与一些实际涡作用行为间的内在联系．
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关键词:
- 可压剪切层 /
- 涡卷对并 /
- 线性扰动 /
- 紧致格式 /
- Navier-Stokes方程
Abstract: Several prototype flows typical of the spanwise large-scale rolluop interactions are investigated through using the direct numerical simulation method. These phenomena have been captured experimentally in the transition region of the free shear layer for a long time. A highaccuracy upwind/symmetric compact difference hybrid method is developed and is used to solve the two-dimenmsional compressible Navier-Stokes equations. A fifth-order upwind compact scheme is employed to discretize the convective flux terms with the help of the Sieger-Warming flux- splitting technique, while a sixth-order symmetric compact scheme obtained by Collatz is selected to discretize the transport flux terms. The three-stage third-order explicit Runge-Kutta algorithm found by Wray is introduced for time-marching. The temporally-developing compressible shear layer is disturbed by the most-unstable viscous wave and its subharmonic modes obtained numerically by linear stability analysis. The fine-scale struCtures... -
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