CFD-DEM 模型并行化及其在流化床气固流动中的应用

摘要

General domain coverage method (GDCM) was proposed to determine the region for each computing node efficiently by comparing all cell nodes, where these regions were helpful for Host to identify which computing node solid particle belongs to. Particle information was passed among host and nodes with the help of Fluent UDFs. The parallel algorithm for CFD-DEM model was developed successfully to simulate gas-solids flows in the fluidized beds (FBs) which were meshed in arbitrary shapes. Based on the comparison of calculation efficiency between parallel algorithm and serial algorithm, the bubble behaviors were studied in a FB with an immersed tube in a single jet FB, and the solids exchange behaviors between two half beds were simulated and compared with experimental results in a dual leg FB. The simulation results showed that the particle information was passed between host and nodes efficiently by parallel algorithm. It was efficient for GDCM to determine which computing node particles are in. The simulated bubbling frequency (about 3 Hz) was similar as Rong’s simulation result. Compared with Bokkers’ simulated and experimental jetting bubble size, the more similar bubble size and solid velocity vectors around the bubble were obtained by the parallel algorithm. The solid exchange between two half beds in both forms of the first (~1 Hz) and second (>2 Hz) domain frequency was simulated, which was similar as the experimental result.%提出广义区域覆盖法用于定位计算节点区域，利用 Fluent 软件的 UDFs 实现颗粒信息在计算节点间高效、准确地传递，建立了适用于非正交网格的 CFD-DEM 模型并行求解方法，在探讨并行模型计算效率的基础上对埋管流化床和单孔射流流化床内的气泡行为及双支腿流化床半床间的颗粒交换行为进行了数值模拟研究并对比实验结果。结果表明：CFD-DEM 模型并行求解方法能够快速传递及收集计算节点内的颗粒信息；广义区域覆盖法降低了颗粒在计算节点内的定位时间，提高了模型的并行计算效率；能够捕获与 Rong 等一致的埋管周围气泡行为（其频率约为3 Hz），获得了与 Bokkers 等结果接近的单孔射流气泡尺寸及颗粒速度矢量分布，双支腿流化床半床间颗粒交换行为与实验结果一致，第一主频约为1 Hz，第二主频大于2 Hz。