Stably-stratified flows are characterised by the presence of internal gravity waves (IGWs), which constitute a barrier for mass, heat, momentum and species vertical transport. In this paper, the dynamics of semi- and neutrally-buoyant particles in three-dimensional, stably-stratified turbulent channel flow is investigated, using direct numerical simulations (DNS), one-way coupled with a Lagrangian particle tracking (LPT) routine. The fluid is characterised by a shear Reynolds number $R{e}_{\tau }=1000$ and a shear Richardson number $R{i}_{\tau }=200,$ such that the turbulence is sustained only in the near-wall region; whereas IGWs are observed at the core of the channel. Four sets of particles with a Stokes number $St=0.044$ or 0.0044 and a particle-to-fluid density ratio ${\rho }_r=1.0$ or 0.8, are released into the system from eleven wall-parallel planes. The particle number for each set is one million. A qualitative analysis of the particle trajectories confirms that particles released in the near-wall region are significantly influenced by the near-wall vortices and show chaotic pathlines. In contrast, particles released at the channel core exhibit smooth oscillating movements which are determined by IGWs. These different qualitative behaviours correspond to different evolution of the particle swarms: swarms of particles released at the channel core are characterised by a narrow distribution of accelerations, a slower-growing pair dispersion and an almost stationary vertical position of the swarm centre of mass compared to those released in the near-wall region.

稳定分层的流的特征是内部重力波（IGW）的存在，它们构成了质量，热量，动量和物质垂直传输的障碍。在本文中，使用直接数值模拟（DNS）和拉格朗日粒子跟踪（LPT）例程，研究了在三维，稳定分层的湍流通道中的半浮力和中性浮力粒子的动力学。流体的特征在于剪切雷诺数$\mathrm{[R}{Ë}_{\tau }=1000$ 和剪切理查森数 $\mathrm{[R}{\mathrm{一世}}_{\tau }=200，$使得湍流仅在近壁区域得以维持；而IGW是在通道的核心处观察到的。四组带斯托克斯数的粒子$\mathrm{小号}Ť=0.044$ 或0.0044以及粒子与流体的密度比 ${\rho }_{\mathrm{[R}}=1.0$或0.8，从十一个平行于墙壁的平面释放到系统中。每组的粒子数为一百万。对粒子轨迹的定性分析证实，在近壁区域释放的粒子受到近壁涡旋的显着影响，并显示出混沌的路径。相反，在通道核心释放的颗粒表现出由IGW确定的平稳的振荡运动。这些不同的定性行为对应于粒子群的不同演化：在通道核心处释放的粒子群具有以下特征：加速度分布较窄，对的散布速度较慢，且粒子群质心的垂直位置与那些在近壁地区释放的人。