On the modelling of the particle dynamics in electro-hydrodynamic flow-fields: I. Comparison of Eulerian and Lagrangian modelling approach
On the modelling of the particle dynamics in electro-hydrodynamic flow-fields: I. Comparison of Eulerian and Lagrangian modelling approach
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DOI：
10.1016/j.powtec.2003.08.009
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发表时间：
2003-10
影响因子：
5.2
通讯作者：
H. Schmid;L. Vogel
中科院分区：
文献类型：
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作者：
H. Schmid;L. Vogel
电流体动力学两相流在各种应用中遇到，例如电增强涂覆、静电沉淀或调色剂应用。在所有情况下，湍流场、强电场、电晕放电和颗粒运动之间存在复杂的相互作用。本文首先对所有主要现象的可能建模方法进行了概述和分类。之后，手稿侧重于粒子动力学的建模：拉格朗日，连续随机游走模型与欧拉方法进行了比较，用于一些测试用例。这项研究主要集中在细颗粒上，即在拉格朗日方法中直径大约小于100 μm，在欧拉模型中直径小于10 μm。结果表明，局部湍流扩散系数可以推导出基于流场计算的比例常数相同的拉格朗日随机游走模型。在这种情况下，即使对于非均匀湍流，两种模型也同样描述湍流弥散。对于叠加的粒子漂移速度，Csanady引入的模型方程给出了合理的协议。最后，它表明，建模的充电动力学是一个非常关键的点，欧拉建模。这是证明静电降水的例子，拉格朗日和欧拉模型之间的良好协议是实现只有当当地的粒子充电动力学占。即使拉格朗日粒子跟踪仍然是上级的电流体动力学颗粒流的物理建模方面，它表明，欧拉方法可能会导致合理的结果，大大减少数值工作。
Electro-hydrodynamic two-phase flows are encountered in various applications, e.g. electrically enhanced coating, electrostatic precipitation or toner application. In all cases there is a complex interaction between a turbulent flow field, a strong electric field, a corona discharge and the particle motion. This paper starts with an overview and classification of possible modelling approaches for all major phenomena. Afterwards the manuscript focuses on the modelling of particle dynamics: A Lagrangian, continuous random walk model is compared with an Eulerian approach for a number of test cases. The study is mostly focused on fine particles, i.e. roughly smaller than 100 μm in diameter for the Lagrangian approach and smaller than about 10 μm in the case of Eulerian modelling. It is shown that a local turbulent dispersion coefficient may be derived based on flow field calculations with a constant of proportionality identical to the Lagrangian random walk model. In this case the turbulent dispersion is equally described by both models even for inhomogeneous turbulence. For a superimposed particle drift velocity a model equation introduced by Csanady gives a reasonable agreement. Finally it is shown that modelling of the charging kinetics is a very crucial point in Eulerian modelling. This is demonstrated for the example of electrostatic precipitation where good agreement between Lagrangian and Eulerian modelling is achieved only if local particle charging kinetics is accounted for. Even though Lagrangian particle tracking is still superior in terms of physical modelling of electro-hydrodynamic particulate flows, it is shown that an Eulerian approach may lead to reasonable results with substantially reduced numerical effort.