湍流各向同性回归过程的非线性模化

Nonlinear Modelling of Turbulence Return-to-Isotropy Process

本文通过对不同湍流结构衰减过程的研究,发展了一个成功描述“馅饼”湍流和“雪茄”湍流衰变的压力一应变相关项中的慢速项的模式。根据湍流模式应满足的可实现性条件,本文对各向同性回归过程模式进行了分析,得到了模式系数所必须满足的一个具有普遍意义的重要等式。本模式满足了可实现性条件。通过计算本文验证了模式的瞬时行为,并与各向同性回归过程的实验数据进行了比较,结果表明本文模式成功地捕捉到了各向同性回归过程所表现的非线性趋势和湍流结构。与其它典型线性和非线性模式的计算结果相比,本文模式的预测能力有很大的提高。

According to the realizibility consition the present work developes a nonlinear turbulence model which is capable of describing the nonlinear behaviour of the return-to-isotropy process satisfactorily. The analysis of the new model shows that it, based on general formulation, has one less free coefficient than conventional ones. The modes coefficient is determined on the structure of the decaying turbulence. The well-known 'Pancake' and 'Cigar' turbulence phenomenon can now be successfully captured.