AI 中文总结
本研究采用颗粒分辨直接数值模拟，揭示颗粒雷诺数超1时水平振荡会改变两个沉降球形颗粒的DKT动力学，影响接触阶段时长与取向，为相关颗粒相互作用研究提供物理框架。
AI 中文摘要
本研究探究水平振荡对粘性流体中受重力沉降的两个单分散球形颗粒的拖曳-接触-翻滚（DKT）动力学的影响。采用颗粒分辨直接数值模拟方法，系统改变振荡频率和振幅，评估其对单个颗粒行为、颗粒间相互作用及颗粒排列取向的影响。结果表明，仅当颗粒雷诺数$Re_p$（定义为振荡诱导惯性力与粘性力的比值）超过1时，振荡对DKT的影响才显著。在该区域内，振荡会改变DKT过程的时间特征：中等振幅倾向于延长接触阶段，而较大振幅则缩短接触阶段。此外，振荡会影响颗粒的重新取向：在低$Re_p$时，颗粒在整个相互作用过程中保持初始取向；随着$Re_p$增大，颗粒更倾向于沿垂直于振荡方向排列。通过分析单个颗粒周围振荡诱导的压力场来解释这些发现，该压力场随$Re_p$增大呈现出愈发显著的横向各向异性，对应的横向流体作用力也愈发各向异性，为观测到的颗粒相互作用和取向改变提供了一致的物理基础。这些发现为理解水平振荡如何控制重力沉降过程中二元颗粒-颗粒相互作用及取向提供了物理框架。
英文摘要
We investigate the effects of horizontal oscillations on the drafting--kissing--tumbling (DKT) dynamics of two monodisperse spherical particles settling under gravity in a viscous fluid. Applying particle-resolved direct numerical simulations, we systematically vary the oscillation frequency and amplitude to assess their impact on the behavior of individual particles, their mutual interaction, and the orientation of the particle arrangement. The results demonstrate that the oscillatory effects on DKT become significant only when the particle Reynolds number $Re_p$, defined as the ratio of oscillation-induced inertial to viscous forces, exceeds unity. In this regime, oscillations alter the temporal characteristics of the DKT process, with moderate amplitudes tending to prolong and larger amplitudes to reduce the kissing phase. Moreover, oscillations affect particle reorientation. At low $Re_p$, the particles maintain their initial orientation throughout the interaction, whereas an increasing $Re_p$ promotes a preferential alignment perpendicular to the direction of oscillation. We explain these findings by analyzing the oscillation-induced pressure fields surrounding the individual particles, which develop increasingly pronounced lateral anisotropy with increasing $Re_p$. The corresponding lateral hydrodynamic forcing likewise becomes increasingly anisotropic, providing a consistent physical basis for the observed modification of particle interactions and reorientation. These findings provide a physical framework for understanding how horizontal oscillations govern binary particle--particle interactions and orientation during gravitational settling.
CommentsAccepted for Physical Review Fluids
