论文标题
湍流中的沉积颗粒的累积密度
Accumulated densities of sedimenting particles in turbulent flows
论文作者
论文摘要
我们通过直接数值模拟研究湍流对颗粒沉积层的影响。一种拉格朗日模型，其中将颗粒视为具有额外向下沉降速度的示踪剂与各向同性均匀的湍流集成在一起。我们研究颗粒在非肿瘤时期在平面上收集的空间分布。我们将所得的粗粒粒子密度与沿粒子轨迹的拉伸速率的历史以及密度投影到蓄能平面上的历史，并根据雷诺数数量和沉降速度分析了与均匀性的偏差。我们确定了在早期和混杂阶段的两个政策中出现的两个制度。在前者的制度中，引入了粒子分布中更多的不均匀性，以降低沉降速度或增加雷诺数的数量，而在后一种状态下趋势相反。在这两个方案之间发现了类似谐振的跨界，那里的不均匀性是最大的。
We study the effect of turbulence on a sedimenting layer of particles by means of direct numerical simulations. A Lagrangian model in which particles are considered as tracers with an additional downward settling velocity is integrated together with an isotropic homogeneous turbulent flow. We study the spatial distribution of particles when they are collected on a plane at non-asymptotic times. We relate the resulting coarse-grained particle density to the history of the stretching rate along the particle trajectory and the projection of the density onto the accumulation plane, and analyse the deviation from homogeneity in terms of the Reynolds number and the settling velocity. We identify two regimes that arise during the early and during the well-mixed stage of advection. In the former regime, more inhomogeneity in the particle distribution is introduced for decreasing settling velocity or increasing Reynolds number, while the tendencies are opposite in the latter regime. A resonant-like crossover is found between these two regimes, where inhomogeneity is maximal.
