In this paper we develop a methodology for the mesoscale simulation of strong electrolytes. The methodology is an extension of the fluctuating immersed-boundary approach that treats a solute as discrete Lagrangian particles that interact with Eulerian hydrodynamic and electrostatic fields. In both algorithms the immersed-boundary method of Peskin is used for particle-field coupling. Hydrodynamic interactions are taken to be overdamped, with thermal noise incorporated using the fluctuating Stokes equation, including a “dry diffusion” Brownian motion to account for scales not resolved by the coarse-grained model of the solvent. Long-range electrostatic interactions are computed by solving the Poisson equation, with short-range corrections included using an immersed-boundary variant of the classical particle-particle particle-mesh technique. Also included is a short-range repulsive force based on the Weeks-Chandler-Andersen potential. This methodology is validated by comparison to Debye-Hückel theory for ion-ion pair correlation functions, and Debye-Hückel-Onsager theory for conductivity, including the Wien effect for strong electric fields. In each case, good agreement is observed, provided that hydrodynamic interactions at the typical ion-ion separation are resolved by the fluid grid.

中文翻译：

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电解质建模的离散离子随机连续介质超阻尼溶剂算法

在本文中，我们开发了一种用于中尺度模拟强电解质的方法。该方法是波动沉浸边界方法的扩展，该方法将溶质视为与欧拉流体动力场和静电场相互作用的离散拉格朗日粒子。在这两种算法中，都采用Peskin的浸入边界方法进行粒子场耦合。流体动力学相互作用被认为是过度阻尼的，使用波动的Stokes方程并入了热噪声，包括“干扩散”布朗运动，以解决溶剂的粗粒度模型无法解析的水垢。通过求解泊松方程可计算出远程静电相互作用，其中包括使用经典颗粒-颗粒-颗粒-网格技术的浸入边界变体进行的短距离校正。还包括基于Weeks-Chandler-Andersen势的短程排斥力。通过与用于离子-离子对相关函数的Debye-Hückel理论和用于电导率（包括强电场的Wien效应）的Debye-Hückel-Onsager理论进行比较，验证了该方法的有效性。在每种情况下，只要流体网格解决了典型离子-离子分离时的流体动力学相互作用，就可以观察到良好的一致性。