The “squirmer” model, a micro-swimming model driven by an imposed tangential velocity at the boundaries, is used to simulate the sedimentation behaviors of one and two elliptical active particles in a two-dimensional rectangular box. Six typical locomotion modes (including the steady vertically moving (SVM), steady inclined sliding (SIS), unilateral attracted oscillating (UAO), bilateral attracted oscillating (BAO), chaotic attracted oscillating (CAO), and up-down alternate tumbling (UAT)) are identified. The effects of particle aspect ratio (AR = 0.2∼1.0), self-propelling strength (β = −5∼5), swimming Reynolds number (Re_s = 0.1∼5.0), and density ratio of particle to fluid (γ = 1.01∼2.1) on the sedimentation behaviors of particles (the locomotion modes and the terminal Reynolds number (Re_t)), are discussed. It is concluded that the locomotion modes are closely relevant to AR, γ, and Re_s. The collision between particles only changes their orientations but is not sensitive to the final locomotion modes. At Re_s≥4.0, the modes of puller type particles change from UAO to SIS or SIS to UAT. Meanwhile, it is found that (ⅰ) particle's Re_t increases with AR when it is in SIS; a larger AR leads to a greater decay of Re_t when it is in UAO; the decay of Re_t is smooth when it is in BAO. (ⅱ) A large |β| results in a large Re_t for a particle in SIS, and it is more prominent for a puller type particle than a pusher type particle. (ⅲ) In the falling period, Re_s speeds up a pair of pusher type particles, while it is more prominent for the pusher type particle with a lower initial position; Re_s also speeds up both neutral type particles with a linear relationship of Re_t∼1.35Re_s. γ and Re_t are linear positive correlated for both a pair of pusher type particles and a pair of neutral type particles.

“蠕动”模型是一种由边界处施加的切向速度驱动的微游动模型，用于模拟二维矩形盒子中一个和两个椭圆形活性颗粒的沉降行为。六种典型的运动模式（包括稳态垂直运动（SVM）、稳态倾斜滑动（SIS）、单边吸引振荡（UAO）、双边吸引振荡（BAO）、混沌吸引振荡（CAO）和上下交替翻滚（UAT） )) 被识别。颗粒长宽比（AR  = 0.2∼1.0）、自推进强度（β  = -5∼5）、游动雷诺数（Re _s  = 0.1∼5.0）以及颗粒与流体的密度比（γ  = 1.01 ）的影响∼2.1）对颗粒的沉降行为（运动模式和终端雷诺数（Re _t））进行了讨论。结论是运动模式与AR、γ和Re _s密切相关。粒子之间的碰撞仅改变它们的方向，但对最终的运动模式并不敏感。当Re _s ≥4.0时，拉拔型粒子的模态从UAO变为SIS或SIS变为UAT。同时发现(ⅰ)粒子在SIS时Re _t随着AR的增加而增大；当处于 UAO 时，AR越大， Re _t的衰减越大；Re _t在 BAO 时衰减平滑。（二）大| β | 导致SIS 中粒子的Re _t较大，并且拉型粒子比推型粒子更显着。(ⅲ)在下降过程中，Re _s对一对推式粒子进行加速，且初始位置较低的推式粒子更为突出；Re _s还以Re _t ∼1.35 Re _s的线性关系加速两种中性粒子。γ和Re _t对于一对推动型粒子和一对中性型粒子均呈线性正相关。