Hydrodynamic interactions between solutes in multiparticle collision dynamics
Hydrodynamic interactions between solutes in multiparticle collision dynamics
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DOI：
10.1103/physreve.98.053301
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发表时间：
2018-11-01
影响因子：
2.4
通讯作者：
Jardat, Marie
中科院分区：
文献类型：
--
作者：
Dahirel, Vincent;Zhao, Xudong;Jardat, Marie
多粒子碰撞动力学（MPCD）使我们能够模拟流体动力学，包括流体动力学和热波动。它的主要用途涉及复杂流体，其中溶剂与浓缩溶质相互作用，无论它们是胶体颗粒，聚合物还是电解质。一个关键的困难是如何将流体与溶质颗粒耦合，同时又不失去MPCD方法在计算效率方面的关键优势。在本文中，我们研究了在碰撞步骤中与流体耦合的溶质的动力学性质，即当流体颗粒之间发生局部动量交换时。我们量化了进行动量交换的体积（碰撞单元的大小）如何限制溶质的流体动力学大小。此外，我们还表明，该体积应小于溶质的结构尺寸。在这些约束条件下，我们发现1-1电解质溶液的流体动力学性质与Fuoss-Onsager电解质动力学理论预测的行为相似，并且我们量化了该理论对2-1和2-2电解质的局限性。然而，同样清楚的是，用这种方法不能定量地将扩散时间标度映射到真实系统的时间标度。
Multiparticle collision dynamics (MPCD) enables us to simulate fluid dynamics including both hydrodynamics and thermal fluctuations. Its main use concerns complex fluids, where the solvent interacts with concentrated solutes, whether they are colloidal particles, polymers, or electrolytes. A key difficulty concerns the way one couples the fluid to the solute particles, without losing the key advantages of the MPCD method in term of computational efficiency. In this paper, we investigate the dynamical properties of solutes that are coupled to the fluid within the collision step, i.e., when local momentum exchange between fluid particles occurs. We quantify how the volume where momentum exchange is performed (the size of the collision cells) constrains the hydrodynamic size of the solute. Moreover, we show that this volume should be taken smaller than the structural size of the solutes. Within these constraints, we find that the hydrodynamic properties of a 1-1 electrolyte solution are similar to the behavior predicted by the Fuoss-Onsager theory of electrolyte dynamics, and we quantify the limitations of the theory for 2-1 and 2-2 electrolytes. However, it is also clear that mapping the diffusion timescale to that of a real system cannot be done quantitatively with this methodology.