Percolation and conductivity development of the rod networks within randomly packed porous media

摘要

A percolation-permeation-diffusion simulation and analysis scheme was proposed with Cellular Automata (CA) and Lattice Boltzmann method (LBM). The interconnection and transport properties of the carbon nanotube (CNT) network in the porous composite were investigated with the proposed scheme. The physical system was modelled as the rod-particle composite with an adjustable packing density of the porous medium, and experiment on the electrical resistivity development was conducted on the CNT-cement composite. A general trend that increased network content increased the electrical conductivity was observed both numerically and experimentally. The simulation-based study demonstrates that the densely packed porous medium can further enhance the connectivity and conductivity of the network within, especially with the shortened rod length. Representative elementary volume analysis was performed to determine the suitable size of the digital sample. It was found that heterogeneity caused locally enhanced transportability. The hydration product covering the CNT surface can introduce surface resistance to increase the elementary resistivity of the network to a magnification of tens times. The proposed simulation-analysis scheme is a generic method to evaluate the conductive network formed in porous media.