Searching for a mesh-independent sub-grid model for CFD simulation of gas–solid riser flows
Searching for a mesh-independent sub-grid model for CFD simulation of gas–solid riser flows
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DOI：
10.1016/j.ces.2009.04.024
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发表时间：
2009-08
影响因子：
4.7
通讯作者：
Bona Lu;W. Wang;Jinghai Li
中科院分区：
文献类型：
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作者：
Bona Lu;W. Wang;Jinghai Li
本文旨在研究网格尺寸对双流体模型（TFM）应用的影响，并由此尝试寻找一种与网格无关的子网格模型来模拟气固提升管流动。为此，我们进行了一系列的TFM模拟在一个周期性的域与各种网格分辨率和阻力关闭。在这些阻力模型中，EMMS/矩阵模型的简化版本被选为讨论的重点。结果发现，TFM模拟与均匀阻力模型达到其数值渐近解时，网格规模是小到10倍的颗粒直径，但它仍然无法捕捉的特征S形轴向空隙率分布和高度高估的固体通量。通过比较，EMMS/矩阵模型似乎达到了一个网格独立的解决方案的亚网格结构的拖曳力的影响，并成功地预测轴向空隙率分布和固体通量均匀的粗网格。因此，细网格TFM模拟气固提升管流动是不够的。我们需要对异质结构进行亚网格建模。
This work aims to examine the effects of grid size in applying the two-fluid model (TFM), and thereby attempts to search for a mesh-independent sub-grid model for simulating gas–solid riser flows. To this end, we performed a series of TFM simulations over a periodic domain with various grid resolutions and drag closures. Of these drag models, EMMS/matrix model in its simplified version was chosen to be the focus of discussion. It was found that TFM simulation with a homogeneous drag model reaches its numerically asymptotic solution when the grid scale is as small as 10 times the particle diameter, but it still fails to capture the characteristic S-shaped axial voidage profile and highly over-predicts the solids flux. By comparison, EMMS/matrix model seems to reach a mesh-independent solution of the effect of sub-grid structures on the drag force, and predict successfully the axial voidage profile and the solids flux with even coarse grid. Therefore, the fine-grid TFM simulation is inadequate for gas–solid riser flows. We need sub-grid modeling of the heterogeneous structure.