Using the discrete element method to develop collisional dissipation rate models that incorporate particle shape

Abstract

Discrete Element Method simulations of Homogeneous Cooling Systems (HCS) are used to develop a collisional dissipation rate model for non-spherical particle systems that can be incorporated in a two-fluid multiphase flow framework. Two types of frictionless, elongated particle models are compared in the HCS simulations: glued-sphere and true cylinder. Simulation results show that the ratio of translational to rotational granular temperatures is equal to one for the true cylindrical particles with particle aspect ratios (AR) greater than one and glued-sphere particles with AR >1.5, while the temperature ratio is less than one for glued-sphere particles with 1 < AR <1.5. The total collisional dissipation rate, which is associated with both translational and rotational granular temperature change rates, increases linearly with the particle aspect ratio. Thus, a collisional dissipation rate model for the elongated cylinders is developed by a simple modification of the existing spherical particle model.The error bar and extended black dotted lines represent the standard deviation of the measurements from 10 simulations with 100 particles. (Glued-sphere particles, AR 5 4, and a s 5 0.2).