Abstract
PurposeThe discrete element method (DEM) can be used in agricultural fields such as crop sowing, harvesting, and crop transportation. Nevertheless, modeling complex crops as appropriately shaped particles remains challenging. The modeling of particles and the calibration of input parameters are important for simulating the realistic behaviors of particles using the DEM.MethodsIn this study, particle models representing the morphological characteristics and size deviations of garlic cloves were proposed. Additionally, the coefficients of friction were analyzed as the contact parameters of the particles based on the heap formation experiments and simultations of the swing-arm method using 150 garlic cloves.ResultsThe simulation results were analyzed that the residual number of particles, a bulk property that can be measured simply in the experiment, is related to the coefficients of friction. In the heap formation experiments with low particle counts, the bulk properties were more clearly differentiated by the residual number of particles than the angle of repose. Moreover, the bulk properties similar to the actual garlic could not be expressed as a spherical particle model. Thus, an equation for predicting the residual number of particles was derived for the non-spherical garlic clove particle model. Five sets of coefficients of friction were presented using the prediction equation, and all the simulation results were close to the actual residual number of particles and angle of repose of the garlic.ConclusionsAlthough the sizes of garlic cloves have a wide distribution, appropriate inter-particle contact parameters could be predicted. Therefore, the calibration process of the DEM can be shortened using the proposed prediction equation for the residual number of particles with non-spherical particles.
Highlights
The discrete element method (DEM) is often applied in various particle technology fields, and studies have recently been conducted through numerical analyses or simulations
The deviations of the garlic clove particles with three different thickness particle models were confirmed to be similar to the actual garlic size distribution
The angle of repose (AOR) and residual number of particles were measured through an experiment using the swing-arm method to derive the coefficients of friction between the particles
Summary
The discrete element method (DEM) is often applied in various particle technology fields, and studies have recently been conducted through numerical analyses or simulations. Discrete element analysis was first introduced by Cundall and Strack (1979) for analyzing the behavior of soil grains. A DEM analysis program was recently developed and is J. Eng. analysis interval is dependent on the parameters and particle size, the required overall analysis time may vary (Ng 2006; Lommen et al, 2014). Studies have been conducted to measure the various parameters of actual minerals and agricultural products for application in DEM simulations (Chandramohan and Powell, 2005; Horabik and Molenda, 2016; Nam et al, 2018)
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