EI、Scopus 收录
中文核心期刊

化学反应流中分子扩散的二点封闭MCA模型

A MCA model for molecular diffusion in turbulent reactive flows

  • 摘要: 在化学反应流的概率密度函数(PDF)方法中,对流项和化学反应项都是封闭的,但分子扩散项必须模拟. 现有的分子扩散模型都是唯象的,需要引入外加参数,并难以通过一些基本物理过程的检验. 本文发展了随机映射逼近(mapping closureapproximation, MCA)方法, 解析地从控制方程导出一个封闭的分子扩散模型.该方法考虑两点联合概率密度函数方程,引入空间特征尺度,因此解决了以往映射封闭方法中分子扩散速率无法确定的问题. 数值模拟表明该方法能用于预测标量扩散的速度,以及概率密度函数和条件平均扩散等统计量.

     

    Abstract: In the PDF approach of turbulent reactive flows, the convection and reaction terms are closedbut the molecular diffusuion term is unclosed. The currently existing models for the moleculardiffusion are either empirical or introduced via external parameters, and it has been verifiedthat they are not valid for such physical processes as the diffusion process. In this paper,a stochastically mapping approximation approach is developed to model the effect of moleculardiffusion. A length scale is introduced by a two-point joint probability density function,to account for the evolutions of the conditional diffusion. Numerical simulation shows thatthe approach is able to predict the evolution of the variances, dissipation rates, conditionaldiffusion and PDFs in the diffusion process.

     

/

返回文章
返回