Dynamics of settling particles is studied by particle resolved direct numerical simulation in periodic domain. The main aim of this study is to explain the effects of momentum response time on the average drag force of settling process for different solid volume fractions. The response time is varied by changing the settling fluid, solid volume fraction and Reynolds number. Simulations showed that the particles with larger response times are negligibly affected by fluid. Thus, the average drag force acting on larger response times particles is nearly same as the average drag force on fixed particles. However, for particles with smaller response times, particles develop microstructures and velocity fluctuations during settling process. This behavior of low response time settling particles results in significant deviation of average drag force from the average drag force on fixed particles. At the end of paper, an improved and better drag correlation is proposed for performing mesoscopic simulations.

通过周期域内的粒子解析直接数值模拟研究沉降粒子的动力学。这项研究的主要目的是解释动量响应时间对不同固体体积分数下沉降过程平均阻力的影响。通过改变沉降液，固体体积分数和雷诺数来改变响应时间。模拟表明，具有较大响应时间的粒子受流体影响很小。因此，作用在较大响应时间粒子上的平均阻力与固定粒子上的平均阻力几乎相同。但是，对于响应时间更短的粒子，粒子在沉降过程中会形成微观结构和速度波动。低响应时间沉降颗粒的这种行为导致平均阻力与固定颗粒上的平均阻力显着偏离。在论文的最后，提出了一种改进的，更好的阻力相关性，以进行介观模拟。