A comparison of two-fluid model, dense discrete particle model and CFD-DEM method for modeling impinging gas-solid flows
A comparison of two-fluid model, dense discrete particle model and CFD-DEM method for modeling impinging gas-solid flows
复制标题
双流体模型、致密离散颗粒模型和 CFD-DEM 方法对冲击气固流建模的比较
DOI：
10.1016/j.powtec.2013.12.056
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发表时间：
2014-03
影响因子：
5.2
通讯作者：
Junwu Wang
中科院分区：
文献类型：
--
作者：
Xizhong Chen;Junwu Wang
气固流已经通过各种多相模型进行了数值研究，但没有一个模型适合工业中遇到的所有问题。不同的研究人员选择了不同的多相模型来满足他们的特定要求；因此，非常需要全面了解这些模型的优点和缺点。在本研究中，通过模拟通道中撞击粒子射流的流动模式，对现有的三种多相模型，包括二流体模型（TFM）、致密离散粒子模型（DDPM）和计算流体动力学与离散元模型相结合（CFD-DEM）方法进行了比较。根据所使用的固体浓度，粒子射流在撞击时可以合并为单个射流或相互交叉（粒子轨迹交叉效应）。与 CFD-DEM 方法相比，TFM 和 DDPM 方法的优点是计算量要求较低，但代价是存在更多的不确定性。使用CFD-DEM方法获得的模拟结果作为基准数据，结果表明：（i）TFM无法像以前的研究那样预测任何情况下众所周知的粒子轨迹交叉效应（Desjardins et al.,Journal of Computational Chemistry2008, 227, 2514–2539），但可以很好地重现合并情况； (ii) 由于对颗粒-颗粒相互作用的处理过于简单化，DDPM 未能预测出现两种颗粒射流的情况，这凸显了需要采用正确的方法来表示真实的颗粒-颗粒相互作用，以及稠密气-固流中体积排斥效应（颗粒不能重叠）的重要性； (iii)定量比较表明，三种模型的预测结果存在较大差异，凸显了DDPM和TFM进一步改进的要求。
Gas–solid flows have been numerically investigated by various multiphase models, none of which is suitable for all the problems encountered in industries. Different multiphase models have been chosen by different researchers to meet their specific requirements; therefore, it is highly desirable to have a comprehensive understanding of the merits and drawbacks of these models. In this study, three existing multiphase models, including a two-fluid model (TFM), a dense discrete particle model (DDPM) and a combined computational fluid dynamics and discrete element model (CFD-DEM) method, are compared by simulating the flow patterns of impinging particle jet in a channel. Depending on the solid concentration used, the particle jets can either merge into a single jet or cross through each other (particle trajectory crossing effect) when they are impinging. The TFM and the DDPM methods have the advantage of less computational demanding compared to the CFD-DEM method, with the cost of more uncertainties. Using the simulation results obtained from the CFD-DEM method as the benchmark data, it was shown that (i) the TFM fails to predict the well-known particle trajectory crossing effect in any cases as in previous studies (Desjardins et al.,Journal of Computational Physics2008, 227, 2514–2539) but can reproduce the merging cases reasonably well; (ii) the DDPM fails to predict the cases where the two particle jets are emerging due to the over-simplified treatment of particle–particle interactions, highlighting the requirement of a proper way to represent the realistic particle–particle interactions and the importance of volume exclusion effect (the particles cannot overlap) in dense gas–solid flows; and (iii) quantitative comparisons show there are major differences between the results predicted by the three models, highlighting the requirement of further improvement of DDPM and TFM.
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