A Pore-Scale Model for Quantifying Airflow Paths through Grain Bulks

A commercial discrete element software package (PFC3D) was used to develop a model to simulate pore structures of grain beds. Based on the simulated structure of a grain bed, an algorithm reported in the literature was adopted and modified to determine airflow paths in the grain bed by treating the grain bed as a series of four-particle tetrahedrons. Critical characteristic parameters of the airflow path were predicted, including path length (tortuosities), width, and local turning angle (change in airflow direction at a location in the grain bed). The predicted tortuosities were in good agreement with the range of tortuosity values reported in the literature for porous beds consisting of spherical particles. The average path width was in the range of 0.83 to 5.93 mm. The local turning angles were mostly in the 0° to 10° range. Keywords: Airflow, Discrete element method, Grain bed, Pore structure, Tortuosity.