【作者】 齐艳丽；

【导师】 慕青松；

【作者基本信息】 兰州大学 ， 固体力学， 2006， 硕士

【摘要】 本文在麦克斯维妖(Maxwell’s Demon)实验的基础上,采用数值模拟的方法对受垂直激振作用的颗粒物质进行了研究。 基本模型采用有两个相同小室的容器。两小室用挡板隔开,距底板一定高度的挡板上开有一个小孔,容器底板做简谐振动。在设定的容器内,颗粒的初始速度和位置坐标随机分布后不仅要考虑颗粒自身运动,还要考虑颗粒与颗粒、颗粒与侧壁、颗粒与底板的碰撞,并在程序中通过设置碰撞条件来判断是否发生碰撞。所有的模拟都考虑重力的作用,因此颗粒在两次碰撞之间做抛体运动,这是颗粒物质的数值模拟研究中一种新的方法,本文应用此方法得到如下模拟结果: 1,半径不同、材料也不同的两种颗粒在外动力激励下有类似于“化学钟”的振荡现象——两种颗粒在A、B两室交替聚集且呈周期性变化,但这种现象是否稳定,还需要进一步的研究。 2,一种颗粒起始分布在一个小室,经过激振后发现有交换现象,但是这种振荡交换现象不稳定,随着时间的演化,颗粒最终均匀分布在两个小室。 3,半径不同但材料相同的两种颗粒在外动力激励下,发现当频率较大时,颗粒聚集在大颗粒多的小室;当频率较小时,颗粒聚集在小颗粒多的小室;当频率很大时,颗粒均匀分布在两个小室。更多还原

【Abstract】 Based on the Maxwell Demon experiment, a dilute compartmentalized granular materials in a gravitational field shaken vertically is investigated by some numerical simulations.The simulated system is confined in an open box contains N circular particles. The box is divided into two equally sized compartments by a wall which has a hole at finite height. The bottom of the box has a simple harmonic vibration. The initial speed and position of the particles are given randomly. All particles move as paraboloid manner in the simulation. It’s the first time that this way is advanced in the research of granular materials. We got some results with this method as follows:1. The granular system consisting of two species of particles has a cyclic oscillation similar to the chemical oscillations—the two species of particles cluster alternately in the two compartments. This is consistent with experiment result qualitatively. However, the stability of the phenomenon needs to be investigated farther.2. When the system is composed of a species of particles with the same diameter located at one compartment initially, there is atemporary alternate cluster-----the particles cluster alternately inthe two compartments, but some time later the phenomenon suddenly disappears and is replaced by the uniform distribution inthe two compartments.3. According to the experiment results, the granular materials made up of a species of particles with different diameters is found to cluster competitively: The grains cluster in the compartment initially containing mainly big particles, for high frequency. The grains cluster in the one containing mainly small particles, for low frequency.更多还原