湍动剪切微米尺度粒子凝并TEMOM模型研究

THE STUDY ON MICRO-SCALE PARTICLE COAGULATION DUE TO TURBULENT SHEAR MECHANISM USING TEMOM MODEL

湍动流场中剪切凝并是导致微纳米尺度颗粒系统非稳定性的主要机理.耦合相应的湍流计算模型,Smoluchowski平均场理论可以有效地解决该颗粒系统的时空演化问题.把泰勒展开矩方法(TEMOM)应用于微纳米尺度颗粒剪切碰撞问题,重点研究湍动剪切条件下,Smoluchowski方程在矩方法框架内的封闭问题,并进一步分析计算精度与展开阶数的关系.结果表明,所提部分四阶泰勒展开矩方法模型能以较高精度对微纳米尺度湍动剪切凝并问题进行理论分析,且证实微纳米尺度颗粒系统在湍动剪切凝并机理控制下存在拟自保持分布状态特性.

The coagulation due to turbulent shear is the main mechanism leading to the instability of micro- and nanoparticle-laden multiphase flows.The Smoluchowski mean-filed theory is considered to be a good selection for solving this problem since it can be coupled to some turbulent models.In this study,the Taylor-expansion method of moments（TEMOM） is first applied in micro- and nanoparticle coagulation due to turbulent shear mechanism in which the closure of Smoluchowski equation as well as the relationship between the numerical accuracy and the order of Taylor series expansion are emphatically investigated.The result show the partial 4-order Taylor expansion method of moments can be applied to analyze the problem involving micro- and nanoparticle turbulent shear coagulation with high accuracy,and the pseudo self-preserving size distribution is found in micro- and nanoparticle-laden multiphase systems dominated by turbulent shear mechanism.