Investigation into calibration of discrete element model parameters for scale-up and validation of particle-structure interactions under impact conditions

Discrete element method (DEM) is a popular numerical method used to understand the discontinuous flow of granular materials and optimise the design and operation of equipment. The impingement of granular material on to flat surfaces can involve complex flow dynamics and can be difficult to model using analytical techniques. There are a vast number of industrial applications where particle-to-structure interactions occur such as belt conveyor impact plate transfer stations consisting of a large number of particles and complex particulate behaviour. Classical analytical methods can be used to provide a quantitative description of the flow of granular material through a transfer point in regards to trajectory and velocity distribution but are generally limited to 2-D analysis. DEM methodology has been well established but there is a lack of detailed validation of DEM models to experimental data and methods to calibrate and scale-up DEM models to attain accurate predictions and results. This paper presents a detailed comparative analysis between classical analytical methods and DEM to predict the flow mechanisms associated with the deformation of granular material impacting a flat plate. Results from DEM simulations and analytical models are compared with experimental results from a variable-geometry conveyor transfer facility to validate and evaluate the numerical methods to solve granular flow problems. The study has focused on evaluating the ability to accurately model material discharge trajectories, the velocity of impact from the inflowing stream, the velocity of the material stream after impingement and the resultant forces on the impact plate. Methods to effectively calibrate the DEM material interaction parameters are also presented and evaluated to quantify the calibration methodology. A sensitivity analysis has been conducted to investigate the variation of DEM parameters and contact models on the impact reaction forces and examine effective techniques to scale parameters to reduce computational time and resources. (C) 2011 Elsevier B.V. All rights reserved.