非保守系统中的对称不稳定I弱粘性的强迫作用

Symmetric Instability in Nonconservative Systems Part I: Forcing Effect of Weak Viscosity

对非保守系统中的对称不稳定问题进行了深入的研究，第一部分讨论弱粘性的强迫作用。研究结果表明，在取一级近似时，弱粘性的首要作用是衰减波长较长的波，对波长较短扰动的衰减作用要小一些。在Ｐｒ～Ｏ（１）的条件下，波动的衰减率σ１对Ｐｒａｎｄｔｌ数的依赖性较小。在取二级近似时，弱粘性的主要作用则是衰减短波。因此，在中尺度对称不稳定中，粘性的作用主要是衰减长波及短波，从而确保发展的扰动具有中尺度量级。

The problems of symmetric instability in nonconservative systems have been comprehensively studied Here is its part I which mainly deals with the forcing effect of weak viscosity It is found that the first effect of weak viscosity is decaying the waves whose wavelengthes are longer under O(ε) approximation Its decaying effect is smaller for those disturbances whose wavelengthes are shorter The decaying rate is less dependent on Prandtl number on condition that the order of Pr is one The main effect of weak viscosity is decaying the waves whose wavelengthes are shorter under O(ε 2) approximation Consequently, its main effect is to make the scale developing symmetric disturbances to be placed in mesoscale spectrum