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一億個オーダの離散粒子反応シミュレーションのためのモデルアルゴリズムとコード開発

用于模拟 1 亿个粒子量级离散粒子反应的模型算法和代码开发

基本信息

批准号：
13555205
负责人：
HORIO Masayuki
金额：
$ 8.9万
依托单位：
Tokyo University of Agriculture and Technology
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2001
资助国家：
日本
起止时间：
2001 至 2003
项目状态：
已结题

项目摘要

Although numerical description of particulate systems has recently been achieved a dramatic progress by the development of discrete element method (DEM) simulation technique originally proposed by Cundall and Strack (1979), it is evident that any realistic particulate system in industries contains billions of particles and that even for a current computer it is almost impossible to directly simulate them. The present work is a new challenge to large-scale DEMs starting from a scaling consideration on the governing equations taking into account cohesiveness and non-uniform particle properties.For large-scale DEM simulation, the "Similar Particle Assembly (SPA) Model" was proposed for large-scale DEM simulation of particulate systems. The model includes the scaling law for the motion of particles in an assembly, which is derived from the equations of motion of particles. In the SPA model the motion of multiple particles whose diameter, density and chemical composition are the same is rep … More resented by one particle, which is called a representative particle. A representative particle occupies the same volume as the sum of the volume of represented particles and has the same density and chemical composition. The local assembly of different particles in the ginal bed is supposed to be maintained in the bed of representative particles. With the SPA model the flow of the bed of representative particles of a certain magnification can be made similar to that of the original particles with a much less computation load. The most significant aspect of the SPA model is that it can be applied to beds of cohesive particles as well as particles of non-uniform sizes. The model was validated by numerical simulation of a two-dimensional bed of non-cohesive particles of equal properties, a bed of particles of two different densities and cohesive particles up to the magnification of 6.Moreover, particle size distribution was introduced into the conventional three-dimensional DEM simulation code with some modification in both theoretical modeling and computational scheme for the calculation of particle-fluid interaction force. The 3-dimensional simulation for non-uniform particle size system was carried out by using the modified scheme. The bubble with clear wake phase was observed when the particle size distribution was considered. On the other hand, the bed behavior was slugging-like when the particle size distribution was not considered. Less

虽然颗粒系统的数值描述最近通过 Cundall 和 Strack (1979) 最初提出的离散元法 (DEM) 模拟技术的发展取得了巨大的进步，但很明显，工业中任何现实的颗粒系统都包含数十亿个颗粒，即使对于当前的计算机来说，也几乎不可能直接模拟它们。目前的工作是对大规模DEM的新挑战，从考虑内聚性和非均匀颗粒特性的控制方程的尺度考虑开始。对于大规模DEM模拟，提出了“相似粒子组装（SPA）模型”用于颗粒系统的大规模DEM模拟。该模型包括集合中粒子运动的比例定律，该定律源自粒子运动方程。在SPA模型中，直径、密度和化学成分相同的多个粒子的运动由一个粒子代表，称为代表粒子。代表性颗粒所占的体积与所代表颗粒的体积之和相同，并且具有相同的密度和化学成分。最终床中不同颗粒的局部组装应该保持在代表性颗粒的床中。利用SPA模型，一定放大倍数的代表性颗粒床的流动可以与原始颗粒的流动相似，而计算量要小得多。 SPA 模型最重要的方面是它可以应用于粘性颗粒床以及尺寸不均匀的颗粒。通过对同等性质的二维非粘性颗粒床、两种不同密度的颗粒床和粘性颗粒的放大倍数为6的数值模拟验证了模型的有效性。此外，在传统的三维DEM模拟程序中引入了粒度分布，并对颗粒-流体相互作用力计算的理论模型和计算方案进行了一些修改。利用改进方案对非均匀粒径体系进行了三维模拟。当考虑粒径分布时，观察到具有清晰尾流相的气泡。另一方面，当不考虑粒度分布时，床层行为呈段塞状。较少的