Statistical characteristics of wall turbulence with a passive scalar
Statistical characteristics of wall turbulence with a passive scalar
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DOI：
10.1017/s0022112088002654
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发表时间：
1988-11
影响因子：
3.7
通讯作者：
Y. Nagano;M. Tagawa
中科院分区：
文献类型：
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作者：
Y. Nagano;M. Tagawa
测量和分析了各种类型的速度矩和一阶至四阶标量涨落。首先，使用累积量和 Hermite 多项式开发三维联合概率密度函数 (p.d.f.) 的正交级数展开式。这个pdf。发现可以为湍流动量和标量传递的统计特征（包括三重积）提供令人满意的预测。接下来，采用条件采样和平均技术来研究动量和标量相干湍流传递过程的统计特性。条件 p.d.f.s 是针对各种速度矩和直至三阶的标量而开发的。结果表明，当前的 p.d.f.s 可以预测相干运动在壁湍流剪切流动力学以及湍流标量传输的相关过程中的详细作用。特别是，本理论首次证明了雷诺应力分量和标量通量的湍流扩散过程中相干运动的重要性。
Various types of moments of velocity and scalar fluctuations of the first to the fourth order have been measured and analysed. First, an orthogonal series expansion for the three-dimensional joint probability density function (p.d.f.) is developed using the cumulants and Hermite polynomials. This p.d.f. is found to provide satisfactory predictions for the statistical characteristics, including triple products, of turbulent momentum and scalar transfer. Next, the conditional sampling and averaging technique is employed to investigate the statistical characteristics of coherent turbulent transfer processes of momentum and scalar. Conditional p.d.f.s are developed for various moments of velocity and scalar up to the third order. It is shown that the present p.d.f.s can predict the detailed role of coherent motions in the dynamics of wall turbulent shear flows and in the relevant process of scalar transport by turbulence. In particular, the importance of coherent motions in the turbulent diffusion process of Reynolds-stress components and scalar fluxes is demonstrated for the first time by the present theory.