Simulation of the adhesion-moments caused by van der Waals-interactions between rough particles and smooth walls in gaseous environment

颗粒-颗粒和颗粒-壁面接触对颗粒-集体的运动行为至关重要。特别是在具有扁平或粗糙度的非球形物体处，关于接触伙伴的滑动、旋转和翻转的预期相互作用的分配（散射）的尺度（位置）和宽度的信息不足。在这个子项目的前两年的工作中，人们试图实现以下两个主要目标：发展光滑球体的滑动、旋转和翻转模型，以及在气体环境中面对光滑壁面的两点接触的粗糙球体。创建用于计算接触伙伴的粘附力矩的完整分布函数的模拟。这两个目标的共同点是描述对由剪切力、扭转力和弯曲力引起的外部载荷的抵抗。在过去的两年里，粒子生成程序得到了改进，以更好地适应真实的条件。研究了原子间的粘附力与原子壁距的关系。此外，已经在模拟中实现了不同的原子晶格和材料孔隙度。根据粘附力和力矩的计算数据已经与其他PiKo子项目的实验结果进行了比较。考察了粗糙颗粒粘附力矩的各向异性行为。在接下来的两年里，模拟粒子的表面应该会受到进一步的影响。应将大量不同几何形状的粗糙度放置在表面上，并研究它们对粘附力和力矩的影响。无法测量粘附力矩，目前尚未计划在SPP PiKo内进行测量。因此，该部现有的环境扫描电子显微镜（ESEM）应升级，配备显微操作器和弹簧台。利用该设备可以测量颗粒的粘附力矩和滑动阻力。模拟的基本基础仍然是计算所涉及的接触伙伴的原子或分子之间的离散相互作用，并将其叠加到总相互作用中。

Particle-particle and particle-wall contacts are crucial for the movement behaviour of particle-collectives. Particularly at non spherical objects with flattening or roughnesses there is insufficient information of scale (position) and broadness of the allocation (scattering) of the expected interactions concerning sliding, rotating and overturning of the contact-partners. For the first two years of work on this sub-project one tried to achieve the following two main goals: Development of models for sliding, rotating and overturning of the smooth sphere with flattening and the rough sphere with two point contact facing a smooth wall in gaseous environment. Creation of a simulation for the calculation of complete distribution functions of the adhesion moments of the contact-partners. Common ground of both goals is the description of resistance against external loads caused by shear, torsion and bending forces. In the last two years the particle-building-routine was improved to fit real conditions better. The dependency of the adhesion force built up by an atom and its wall distance has been examined. Further there have been implemented different atomic lattices and a material porosity into the simulation. The calculated data according to adhesion-force and -moment have been compared to the experimental results of other PiKo sub-projects. The anisotropic behaviour of the adhesion-moment for the rough particle was examined. In the next two years the surface of the simulated particle should be influenced further. A bigger number of roughnesses with different geometry should be placed on the surface and their influence on both the adhesion-force and the -moment should be investigated. The measurement of the adhesion-moment is not possible and by now not planned within the SPP PiKo. Therefore the existing ESEM (Environmental Scanning Electron Microscope) of the Department should be upgraded with a micromanipulator and a spring table. With this equipment it would be possible to measure the adhesion-moment and the sliding-resistance force of particles. The fundamental basis of the simulation is still the calculation of the discrete interactions between the involved atoms or molecules of the contact partners and the superpositioning of those to a total interaction.