Discrete element method for multiscale modeling

A discrete element method (DEM) has been developed to provide highly accurate and detailed predictions of the Lagrangian particle phase. Especially in this study, DEM has been used together with an Eulerian approach for the fluid phase to look at interphase exchange phenomena in a multiphase-multiscale modeling approach. The drying process inside a fluidized bed coffee bean roaster has been chosen. Herein, heat, mass, and momentum transport are solved on a fluid cell level; heat, mass, and momentum transfer coefficients are solved at a particle scale level; and 1D temperature and moisture content profiles are solved inside each coffee bean on a sub-particle scale level. Therefore, this multiscale approach provides much more information compared to existing coffee bean roaster models. In this work, a detailed description of this method is provided and results on different scale levels have been discussed. Modeling data and experimental results are compared and found to be in good agreement.

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