中文摘要：

接近另一个粒子的一个沉浸的稳固的粒子的三维的直接模拟，或一面扁平的墙，被进行调查沉浸的粒子的水动力学影响的力学。模拟方法用一个固定格子系统基于一个修改沉浸的边界方法。当粒子分离距离变得比格子间距小时，接近接触说明在粒子之间的液体层的水动力学抵抗效果，一个微层模型被开发允许在内的压力侧面的决心没有忽视层流动的惯性的力量微层。压力力量然后在粒子运动的方程被考虑。有在文学报导的试验性的结果的模拟结果的比较被显示证实在这研究介绍的模型。模拟揭示液体的复杂三维的流动领域和来临的粒子的运动。当粒子的分离距离是时，在粒子的不稳定的运动引起的差距的液体压力显著地被增加不到大约粒子的十分之一直径。因此，接近粒子的速度开始在这个位置由于水动力学抵抗力量减少。

英文摘要：

A three-dimensional direct simulation of an immersed solid particle approaching another particle, or a flat wall, is conducted to investigate the mechanics of hydrodynamic impact of immersed particles. The simulation method is based on a modified immersed boundary method using a fixed grid system. When the particle separation distance becomes smaller than grid spacing, to account for the hydrodynamic resistance effect of liquid layer between particles near contact, a microlayer model is developed to allow determination of the pressure profile within the micro-layer without neglecting the inertial force of the layer flow. The pressure force is then taken into account in equation of particle motion. Comparisons of the simulation results with the experimental results reported in the literature are shown to substantiate the model presented in this study. The simulations reveal the complex three-dimensional flow field of the liquid and the motion of the approaching particle. The fluid pressure in the gap caused by the unsteady motion of the particle is significantly increased when the separation distance of particles is less than about one-tenth diameters of particle. Therefore the velocity of approaching particle starts to decrease due to the hydrodynamic resistance force at this position.