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

作　　者：张子范[1] 何国威[1] 

机构地区：[1]中国科学院力学研究所非线性力学国家重点实验室,北京100080

出　　处：《力学学报》2004年第2期140-145,共6页Chinese Journal of Theoretical and Applied Mechanics

基　　金：国家重点基础研究发展规划(G1999032801;G2000077305);国家杰出青年科学基金(10325211)~~

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 closure approximation,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。In the PDF approach of turbulent reactive flows,the convection and reaction terms are closed but the molecular diffusuion term is unclosed.The currently existing models for the molecular diffusion are either empirical or introduced via external parameters,and it has been verified that 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 molecular diffusion.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 that the approach is able to predict the evolution of the variances,dissipation rates,conditional diffusion and PDFs in the diffusion process.

关 键 词：化学反应流 分子扩散 随机映射逼近 概率密度函数 刘维尔定律 

分 类 号：O643.12[理学—物理化学]