中文摘要：

分析了平行板间密集剪切颗粒流的平均速度、速度波动、区域划分和自扩散特性.为了分析以上问题，建立了平均固体体积分数为0.80剪切平行板间密集颗粒流的离散元物理模型.研究结果表明：间隙间颗粒的平均速度从上到下逐渐增大，波动速度恰好相反；纵向的平均速度、波动速度较小，这一点稀疏剪切颗粒流正相反；根据剪切率和平均速度大小把间隙间纵向区域依次划分为类固体、振荡和类流体区域，并得出了波动速度对剪切率的依赖关系；间隙间颗粒的自扩散主要集中在横向，而稀疏剪切颗粒流在纵向的自扩散同样较突出.通过对流变和扩散特性的模拟分析，直观地反映了颗粒的微观流变特性，有益于密集剪切颗粒流的流变机理的研究.

英文摘要：

The distribution of average velocities, fluctuation of velocities, regional definition, and granular self-diffusion char-acters in dense granular flows between sheared parallel plates are discussed. In order to study the above problems, we use computer-established discrete element model with an average solid fraction of 0.80. Theoretical results show that the average velocities decrease with increasing height, and are larger for the case of lower plate with greater velocity;the average velocities in y direction are close to 0 because there is no bulk motion in y direction. Flows of the lower plate with a greater velocity induce relatively greater fluctuation of velocities in the x and y directions, the fluctuation of velocities increases with the height and is larger in the area close to the upper plate. The flows consist of a “solid-like” area in the lower test region, but a“fluid-like”region in the upper, and an“oscillating”region in the middle of the channel. By tracking the movements of granules continually, variations of the mean-square self-diffusion relative displacements with square time are plotted, and the mean self-diffusion relative coe？cients are determined. As the fluctuation and self-diffusion analysis directly reflect the macroscopic properties of granules and provide bases and references for researching the flow mechanisms of“dense granular sheared flows”.