Heat and mass transfer characteristics of granular materials under shear actions

The heat and mass transfer characteristics of granular flow are of great significance for the design and operation of various industrial applications for treating granular materials. This paper aims to reveal the laws of granular diffusivity and effective thermal conductivity (ETC) of granular flow under different shear actions. Discrete element method simulations of granular shear flow, mass and heat transfer process are conducted. The detailed behaviors of particle motion, diffusion, as well as heat transfer under different shear actions are investigated. Expressions of volume fraction and granular diffusivity with inertial number are proposed. Two different mechanisms of contact heat conduction and fluctuation heat transfer are distinguished based on the analysis of granular flow and diffusion characteristics. Expressions of contact thermal conductivity and apparent fluctuation conductivity with inertial number are proposed. Moreover, an analogy analysis of the apparent thermal diffusivity to mass diffusivity is conducted, and the ratio is 0.5934 in this study.