Permeability prediction of bulk wheat for storage based on micro-computed tomography and lattice Boltzmann method

Abstract

During the study of grain storage ecosystems, the microstructure and permeability of bulk grain porous media are critical, which can influence fluid flow efficiency and mass transfer efficiency. In this study, the 3D pore structure of bulk grain porous media was reconstructed by X-ray micro computed tomography, and fluid permeability was investigated by the multi-relaxation-time (MRT) lattice-Boltzmann method (LBM). The results show that the representative elementary volume (REV) with voxel 300³ has a porosity of 34.78 % and an average pore diameter of 1241.37 μm, which can not only reflect the pore structures of the bulk grain pile, but also satisfy the subsequent permeability simulation calculations. The permeability results calculated by LBM can be used to visualise the fluid flow in the bulk grain pore space, and the comparison of the results with the Kozeny–Carman (K–C) equation, the Xu-Yu model, and the experimentally measured permeability demonstrates the accuracy and feasibility of the MRT-LBM method proposed in this paper for simulating the permeability of the bulk grain pile. The method provides a novel way for the research of grain storage ecosystem by numerical simulation method, which is conducive to the study of fluid flow and heat and moisture transfer mechanism in grain storage.