DEM-CFD coupling simulation and optimization of an inside-filling air-blowing maize precision seed-metering device

•Maize particles were created by EDEM software using the bonded particle model (BPM).•Seed motion and airflow field characteristics of seed-metering device were simulated.•The drag force and differential pressure were used to evaluate the cleaning and pressing performance.•The optimum structure of seed-metering plate was obtained through simulation and verified via experiments.