大涡旋的分类和模式理论的封闭*

本文依据前文1]大小涡旋分开考虑的湍流模式,对局部产生的湍流大涡旋引进了新的几率分布,由此引入了一种新的平均过程和平均值.通过这种平均,我们就可以把局部产生的湍流大涡旋和外来的湍流大涡旋进行严格的区分.然后,再引进适当的辅助条件和根据外来干扰的实际情况确定了外来大涡旋的耗散尺度l_N,使得湍流脉动二阶矩的方程组封闭,同时对前文1]中的一些扩散系数进行了适当的修改.最后,得到了一个封闭的、能够数值求解的方程组.

The Separation of Large Vortexes and the Closed Equations of Turbulence Model

This paper presents a new kind of everage for the loeally-generated large vortexes so that the physieal quantities of the locally-generated large vortexes and the external large vortexes canberigorously separated from the equal ions for the large vortexes proposed in a previous paper1] To the equations for the two kinds of large vortexes,some auxiliary relations are introduced,and the value,of the length-scale l_N of energy dissipation of the external large vortexes may he determined according to the actual circumstances of the disturbance of external sources.Thus the resulting equations of the second moments of turbulent velocity fluctuations for the two kinds of large vortexes can be made closed.Meanwhile,the corresponding coefficients of diffusion in the previous paper1] are improved,Finally,a closed set of numerically-solvable equations of turbulence model are obtained.