Parameter calibration for the discrete element simulation model of commercial organic fertilizer

The parameters of a discrete element simulation model for commercial organic fertilizer particles were obtained both quickly and accurately, so that the uniformity and stability of the fertilizer discharged from the feeder may be studied using the discrete element simulation method. This study screened out the parameters which significantly influenced the repose angle of the commercial organic fertilizer using the Plackett-Burman test. Then, a model for the quadratic regression response surface of the repose angle vs the parameters was established through a Box-Behnken experiment with the measured repose angle of the fertilizer particles as the optimization index. The optimization results showed that the rolling friction coefficient and static friction coefficient between the fertilizer particles, as well as the optimal simulation parameter for the Johnson-Kendall-Roberts surface energy were 0.056, 0.355 and 0.011 J m(-2), respectively. A discrete element simulation test was carried out with the optimal simulation parameters, and the repose angle error of the simulation test was found to be 0.40% relative to that of the physical test, which proved the accuracy and validity of the simulation parameters for the discrete element model of the organic fertilizer. The simulation results may provide the basic parameters for establishing a discrete element model of commercial organic fertilizer particles and investigating the performance of organic fertilizer feeders using the simulation method.