Department of Earth Science and Engineering, Imperial College London, SW7 2AZ, United Kingdom.
J Colloid Interface Sci. 2011 Feb 1;354(1):380-5. doi: 10.1016/j.jcis.2010.10.039. Epub 2010 Nov 10.
This paper introduces a simple method for modelling non-spherical particles with a fixed contact angle at an interface whilst also providing a method to fix the particles orientation. It is shown how a wide variety of particle shapes (spherical, ellipsoidal, disc) can be created from a simple initial geometry containing only six vertices. The shapes are made from one continuous surface with edges and corners treated as smooth curves not discontinuities. As such, particles approaching cylindrical and orthorhombic shapes can be simulated but the contact angle crossing the edges will be fixed. Non-spherical particles, when attached to an interface can cause large distortions in the surface which affect the forces acting on the particle. The model presented is capable of resolving this distortion of the surface around the particle at the interface as well as allowing for the particle's orientation to be controlled. It is shown that, when considering orthorhombic particles with rounded edges, the flatter the particle the more energetically stable it is to sit flat at the interface. However, as the particle becomes more cube like, the effects of contact angle have a greater effect on the energetically stable orientations. Results for cylindrical particles with rounded edges are also discussed. The model presented allows the user to define the shape, dimensions, contact angle and orientation of the particle at the interface allowing more in-depth investigation of the complex phenomenon of 3D film distortion around an attached particle and the forces that arise due to it.
本文介绍了一种在界面上对具有固定接触角的非球形颗粒进行建模的简单方法，同时还提供了一种固定颗粒方向的方法。文中展示了如何从仅包含六个顶点的简单初始几何形状中创建各种形状的颗粒（球形、椭圆形、盘形）。这些形状由一个连续的表面构成，边缘和角部处理为光滑曲线而非不连续的折线。因此，可以模拟接近圆柱形和正交形状的颗粒，但穿过边缘的接触角将被固定。当非球形颗粒附着在界面上时，可能会导致表面的大变形，从而影响颗粒上的作用力。本文提出的模型能够解决界面处颗粒周围表面的这种变形问题，并且允许控制颗粒的方向。结果表明，当考虑具有圆形边缘的正交颗粒时，颗粒越平坦，在界面上保持平坦的能量稳定性就越高。然而，随着颗粒变得越来越像正方体，接触角的影响对能量稳定取向的影响就越大。对具有圆形边缘的圆柱形颗粒的结果也进行了讨论。所提出的模型允许用户定义颗粒在界面上的形状、尺寸、接触角和取向，从而可以更深入地研究由于附着颗粒而导致的三维薄膜变形的复杂现象以及由此产生的力。
