Hydrodynamic particle interactions in linear and radial viscosity gradients
Hydrodynamic particle interactions in linear and radial viscosity gradients
复制标题
线性和径向粘度梯度中的流体动力学颗粒相互作用
DOI：
10.1017/jfm.2022.421
复制
发表时间：
2021
影响因子：
3.7
通讯作者：
Ana
中科院分区：
文献类型：
--
作者：
Sebastian Ziegler;Ana
摘要：我们提出了一种通用的微扰计算方案，以确定具有空间变化粘度的低雷诺数流体中粒子的迁移率矩阵的前序校正。为此，我们利用洛伦兹倒数定理和远场近似中的反射方法。为了演示如何将该框架应用于特定的粘度场选择，我们首先研究有限尺寸、类界面、线性粘度梯度中的粒子。后者的程度应明显大于颗粒分离。考虑在这种奇数对称粘度梯度内对称和不对称放置颗粒的两种情况。因此，长程流场的衰减速度比恒定粘度流场慢一个数量级。粒子旋转和平移的自迁移率受到影响，而对于不对称放置，后者会出现额外的校正。与颗粒之间的流体动力学相互作用相关的迁移率项也需要以特定于放置的方式进行校正。虽然结果是针对两个粒子系统得出的，但它们也适用于多粒子系统。此外，我们还处理由温度与周围流体不同的两个颗粒引起的粘度梯度。假设流体温度和粘度之间存在线性关系，我们发现颗粒的自迁移率以及流体动力相互作用的迁移率项对于热颗粒而言增加，而对于冷颗粒则减少。
Abstract We present a versatile perturbative calculation scheme to determine the leading-order correction to the mobility matrix for particles in a low-Reynolds-number fluid with spatially variant viscosity. To this end, we exploit the Lorentz reciprocal theorem and the reflection method in the far field approximation. To demonstrate how to apply the framework to a particular choice of a viscosity field, we first study particles in a finite-size, interface-like, linear viscosity gradient. The extent of the latter should be significantly larger than the particle separation. Both situations of symmetrically and asymmetrically placed particles within such an odd symmetric viscosity gradient are considered. As a result, long-range flow fields are identified that decay by one order slower than their constant-viscosity counterparts. Self-mobilities for particle rotations and translations are affected, while for asymmetric placement, additional correction appears for the latter. The mobility terms associated with hydrodynamic interactions between the particles also need to be corrected, in a placement-specific manner. While the results are derived for the system of two particles, they apply also to many-particle systems. Furthermore, we treat the viscosity gradients induced by two particles with temperatures different from that of the surrounding fluid. Assuming a linear relation between fluid temperature and viscosity, we find that both the self-mobilities of the particles as well as the mobility terms for hydrodynamic interactions increase for hot particles and decrease for cold particles.
疏粘转向决定了微藻在粘度梯度中的运输
影响因子：
19.6
作者：
Stehnach, Michael R.;Waisbord, Nicolas;Walkama, Derek M.;Guasto, Jeffrey S.
通讯作者：
Guasto, Jeffrey S.