可压剪切层线性稳定性特征直接数值模拟

基于伪随机数生成技术促白噪声扰动，以高精度迎风／对称紧致混合差分算法求解二维／三维非定常可压Navier－Stokes方程，揭示了可压自由剪切层初始剪切过程中扰动的线性演化特征，以及该过程对扰动波数和方向的内在选择性，验证了所用算法的有效性，表明线性理论同数值模拟相结合是可压剪切层研究的合理途径之一。

DIRECT SIMULATION OF THE LINEAR INSTABILITIES IN COMPRESSIBLE SHEAR LAYERS

The linear instabilities in compressible shear layers areinvestigated by solving the two-and three-dimensional time-dependent compressible Navier-Stokes equations.A high-accuracy upwind-symmetric compact difference hybrid algorithm is used.A pseudo-random number generation technique is employed to simulate the white noise disturbance.Based on numerically solving the three-dimensional viscous disturbance equations by using a new method named as SCD-MNR,some results related to linear stability analysis are first given.Both two-and three-dimensional waves are considered.Compressibility effect can increase the most unstable wave angles besides that damps the growth rates of unstable waves.Numerical results confirm the prediction of linear theory that during the initial evolution of the compressible shear layer unstable waves are linear,and that in this course the wave number and angle of the most unstable disturbance are selective.The algorithm used here appears to be effective.It is a reasonable means for the study on compressible shear layers that linear theory combines with numerical simulation.