A DEM/FFT approach to simulate the effective thermal conductivity of granular media

A numerical method to compute the Effective Thermal Conductivity (ETC) of granular media surrounded by a stagnant fluid is presented. Based on geometry and size grains, Representative Volume Elements (RVE) created using Discrete Element Method (DEM) while ETC this RVE estimated with Fast Fourier Transform (FFT) computations. To bridge gap between DEM FFT, discretization algorithm (voxelization convex polyhedra) was developed. Since their physical properties are poorly defined, “fuzzy” voxels associated solid–gas interfaces or solid–solid contacts, domains inherent in medium, clearly identified during step. The assignment extreme these voxels, assuming negligible radiation, allows establish lower upper bounds. This methodology applied Uranium dioxide particles immersed Helium; packed beds for which experimental data available literature. First, effect sizes simulated investigated optimal values ratio defined. Next, significant deviation DEM-FFT bounds, observed at high solid gas conductivity contrasts, exhibits key role computed ETCs. An improved modelling based Knudsen correction therefore proposed. new shown adequately bound estimate considered (?100) thermal contrasts.