Modeling electrokinetic flows with the discrete ion stochastic continuum overdamped solvent algorithm,Physical Review E

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Modeling electrokinetic flows with the discrete ion stochastic continuum overdamped solvent algorithm
Physical Review E ( IF 2.2 ) Pub Date : 2022-09-19 , DOI: 10.1103/physreve.106.035104
D R Ladiges ₁ , J G Wang ₁ , I Srivastava ₁ , A Nonaka ₁ , J B Bell ₁ , S P Carney ₂ , A L Garcia ₃ , A Donev ₄

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In this article we develop an algorithm for the efficient simulation of electrolytes in the presence of physical boundaries. In previous work the discrete ion stochastic continuum overdamped solvent (DISCOS) algorithm was derived for triply periodic domains, and was validated through ion-ion pair correlation functions and Debye-Hückel-Onsager theory for conductivity, including the Wien effect for strong electric fields. In extending this approach to include an accurate treatment of physical boundaries we must address several important issues. First, the modifications to the spreading and interpolation operators necessary to incorporate interactions of the ions with the boundary are described. Next we discuss the modifications to the electrostatic solver to handle the influence of charges near either a fixed potential or dielectric boundary. An additional short-ranged potential is also introduced to represent interaction of the ions with a solid wall. Finally, the dry diffusion term is modified to account for the reduced mobility of ions near a boundary, which introduces an additional stochastic drift correction. Several validation tests are presented confirming the correct equilibrium distribution of ions in a channel. Additionally, the methodology is demonstrated using electro-osmosis and induced-charge electro-osmosis, with comparison made to theory and other numerical methods. Notably, the DISCOS approach achieves greater accuracy than a continuum electrostatic simulation method. We also examine the effect of under-resolving hydrodynamic effects using a “dry diffusion” approach, and find that considerable computational speedup can be achieved with a negligible impact on accuracy.

中文翻译：

用离散离子随机连续体过阻尼溶剂算法模拟电动流动

在本文中，我们开发了一种算法，用于在存在物理边界的情况下有效模拟电解质。在以前的工作中，离散离子随机连续介质过阻尼溶剂 (DISCOS) 算法是针对三重周期域推导出来的，并通过离子-离子对相关函数和德拜-休克尔-昂萨格电导率理论进行了验证，包括强电场的维恩效应。在扩展这种方法以包括对物理边界的准确处理时，我们必须解决几个重要问题。首先，描述了将离子与边界的相互作用合并所需的扩散和插值算子的修改。接下来，我们讨论对静电求解器的修改，以处理固定电位或介电边界附近电荷的影响。还引入了一个额外的短程电位来表示离子与固体壁的相互作用。最后，修改干扩散项以考虑边界附近离子迁移率的降低，这引入了额外的随机漂移校正。提出了几个验证测试，以确认离子在通道中的正确平衡分布。此外，该方法使用电渗透和感应电荷电渗透进行了演示，并与理论和其他数值方法进行了比较。值得注意的是，DISCOS 方法比连续静电模拟方法具有更高的精度。我们还使用“干扩散”方法检查了解析不足的流体动力学效应的影响，并发现可以实现相当大的计算加速，而对准确性的影响可以忽略不计。

更新日期：2022-09-19

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