论文标题
沉淀期间质量极球的动力学
Dynamics of Mass Polar Spheroids During Sedimentation
论文作者
论文摘要
由于存在有效的远程力，重力下沉积颗粒的动力学非常复杂。当颗粒具有明确定义的对称轴和不均匀密度的极性时，最近的理论预测表明，倾斜的物体将排斥并植入一个物体会弱吸引。我们使用质量极性Proalte球体测试了这些预测，这些球体由2 mM球组成。我们通过组合不同密度的球体来探测不同的面余口粮（$κ$）和质量偏移中心（$χ$）。在准二维（2D）和三个=尺寸（3D）腔室中进行了实验。通过光学跟踪单个颗粒的运动，我们发现动力学是通过降低的迁移率矩阵模型来很好地描述的，该模型可以通过分析求解。成对的颗粒表现出有效的排斥，它们的分离大致缩放为〜$（κ-1）/χ^{0.39} $，即更倾斜或质量较小的质量不对称的颗粒具有更强的排斥作用。在3D中，$χ> 0 $的粒子的分布比$χ= 0 $颗粒的分布更均匀，并且均匀度随$κ$增加而增加，这表明有效的2体排斥表现为大量颗粒。
The dynamics of sedimenting particles under gravity are surprisingly complex due to the presence of effective long-ranged forces. When the particles are polar with a well-defined symmetry axis and non-uniform density, recent theoretical predictions suggest that prolate objects will repel and oblate ones will weakly attract. We tested these predictions using mass polar proalte spheroids, which are composed of 2 mm spheres glued together. We probed different aspect rations ($κ$) and center of mass offsets ($χ$) by combining spheres of different densities. Experiments were done in both quasi-two-dimensional (2D) and three=dimensional (3D) chambers. By optically tracking the motion of single particles, we found that the dynamics were well-described by a reduced mobility matrix model that could be solved analytically. Pairs of particles exhibited an effective repulsion, and their separation roughly scaled as ~$(κ-1)/χ^{0.39}$, i.e. particles that were more prolate or had smaller mass asymmetry had stronger repulsion effects. In 3D, particles with $χ>0$ were distributed more uniformly than $χ=0$ particles, and the degree of uniformity increased with $κ$, indicating that the effective 2-body repulsion manifests for a large number of particles.
