Simulation and structural characterisation of the packing of particles

2017-02-27T01:35:12Z (GMT) by Wang, Chuncheng
Particle packing, the assembly of particles, is very common in our daily life and different industries. The size of particles ranges from as small as atoms to as big as stars in the universe. The previous research mainly focuses on the packing of spheres at the micrometre and millimetre scales. By the means of numerical simulations, extensive structural analysis of these packings has been conducted. However, the packing of particles of other sizes and non-spherical shapes is relatively few in the literature. This PhD project aims to systematically investigate a series of packings in different length scales and with different shapes. The size of the particles covered in this study is as small as 20 nm to as big as stars in the universe, and the shape of particles includes spheres and non-spheres. This PhD thesis is separated into two parts. The first part consists of three components focusing on ‘big particles’ from micrometre to millimetre and to the stars in the universe. The first component deals with the structural analysis and statistical description of the packing of fine particles and coarse particles. The second component investigates the non-spherical particle packing while the third one focuses on the packing of stars in the universe. The second part of the thesis focuses on the nanoparticles in the very loose packings with porosity larger than 0.9, which is divided into three components including modelling, structural analysis and dynamics. Except for the second component in the first part in which the coordinates of the stars are obtained from the existing database, the other packings are obtained by using numerical simulations based on discrete element method (DEM). Different algorithms are adopted in the DEM models to simulate different packing systems, while the model is always validated by comparing the results with experiments. The micro-structures of these packing systems are investigated by various analysis methods, which, very interestingly, give consistent and comparable results. The dynamics in the simulated packing process is also examined, and the effect of the material properties on the dynamics and the final packing is comprehensively studied. This thesis generates a lot of original findings, including the proposal of a structural framework to enclose all clusters in the packing, the connection of stars with normal particles on the earth, and filling in the blank of the simulation of the nano-packing in the literature.