Development of a particle simulator for realistic clayey particles considering mechanical and electro-chemical forces - demystify microscopic mechanisms inside the 'house of cards' at micrometer scale

这个项目的目的是开发一个逼真的粘性粒子的粒子模拟器。离散元方法(DEM)被广泛认为是从颗粒尺度相互作用中研究颗粒材料复杂动力学的有力工具。在2021财年，我们开发了一个框架，使用一个挤出的3D多边形作为粒子形状，并在物体固定的参考系中解决基于单位四元数的粒子旋转问题。在这项工作的基础上，我们在2022财年的一个国际会议上进行了应邀演讲，并提交了一篇目前正在审查的期刊论文。DEM方法有三个主要组成部分：1)。粒子几何和粒子运动学(特别是粒子旋转)；2)粒子间相互作用(也称为力模型)；以及3)邻域检测。自2021财年开发第一个组件以来，我们的研究重点一直放在第二个组件上。对于粘土颗粒，由于分子间的相互作用，存在颗粒间的粘附力。为了模拟这种力，我们回顾了现有的关于粘接接触的研究，并进行了必要的适应。我们重点讨论了两种力模型：宏观的Johnson-Kendall-Roberts(JKR)理论和Anandarajah和Chen提出的基于微观Van-der-Waals力的公式。对于JKR理论，我们推导了可用于DEM模拟的力-位移关系。对于Anandarajah-Chen模型，对于倾斜的长方体粒子与无限长方体相互作用的模型，我们研究了必要的变化来模拟有限大小粒子之间的力。

The purpose of this project is to develop a particle simulator for realistic clayey particles. The Discrete Element Method (DEM) is widely recognized as a powerful tool for investigating the complex dynamics of granular materials from particle-scale interactions. In FY2021, we developed the framework using an extruded 3D polygon as the particle shape and solving unit-quaternion-based particle rotation in the body-fixed reference system. Based on this work, we gave an invited talk at an international conference in FY2022 and submitted a journal paper currently under review. There are three main components to a DEM approach: 1). Particle geometry and particle kinematics (especially particle rotation); 2) Interparticle interactions (also known as force models); and 3) Neighborhood detection. Since the first component was developed in FY2021, our research focus has been on the second component. For clayey particles, there are interparticle adhesion forces resulting from intermolecular interactions. To model such forces, we have reviewed existing research on adhesive contact and worked on necessary adaptations. We focus on two force models: a macroscopic Johnson-Kendall-Roberts (JKR) theory and microscopic Van-der-Waals force based formulation derived by Anandarajah and Chen. For the JKR theory, we derived a force-displacement relation that can be used for DEM simulations. For the Anandarajah-Chen model, which was derived for tilted cuboid particles interacting with an infinite wall, we investigated the necessary changes to model the forces between finite size particles.