摘要:
运用事件驱动算法研究颗粒混合物在垂直振动容器中的振荡现象.容器被具有一定高度的隔板分成相等大小的两个小室,并采用半径相差一倍的两种颗粒.研究结果表明,颗粒振荡周期随两种颗粒密度比的减少而急剧增加.通过计算在垂直方向上两种颗粒高度之比随颗粒密度的变化关系,说明决定颗粒振荡与否的主要因素并不是"巴西坚果效应"或"反巴西坚果效应".通过计算颗粒温度,发现颗粒振荡取决于颗粒混合气体的小颗粒温度.当小颗粒温度大于一定值时,颗粒混合气体发生颗粒振荡现象.根据Vifidi等提出的流体动力学模型,文中对该模型做出相应的修改,加入密度因子,从而可以解释颗粒振荡周期与颗粒密度比的关系.
Abstract:
The oscillation phenomena for granular mixture within a vertically vibrated container are investigated with the event-driven method. The container consists of two rooms with equal size separated by a clapboard with certain height, and two kinds of granules with the radius of one twice as larger as the other are used. Investigation results indicate that the period of oscillation of granula sharply increases with the decrease of the ratio of density between two kinds of particles. The relations of the ratio of density to the ratio of vertical height of the two kinds of particles are calculated, which shows that the main factor of granular oscillation is not the " Brazil nut effect" or " reverse Brazile nut effect". The granular temperature is calculated and found to be relevant to oscillations of mixture. When the temperature of the small particle is above a certain value, oscillations of granular mixture occur. According to hydromechanical equations proposed by Viridi et al. , these equations are correspondly modified and may explain the relations between the period of oscillation and the ratio of granular density.
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