Direct Numerical Simulation of the Two-Phase Interaction of Non-Uniform Structure in Fluid-Solid Systems

In this work, a direct numerical simulation (DNS) of the fluid particle two-phase flow system is performed. The DNS results span a rather wide parameter space: mean-flow Reynolds numbers on the order of 1 and 10, mean solid volume fractions from 0.1 to 0.4, solid-to-fluid density ratios from 2 to 1000 and elastic and moderately inelastic (restitution coefficient of 0.9) conditions. It can be observed from the results that non-uniform structures (clusters) appear inside the system. And as the parameters change, the particles distribution will exhibit a variety of structures. This paper focuses on the interphase interaction of different structures, considering not only the Reynolds number and the local concentration of the particles, but also the effect of the local concentration gradient of the particles. Unlike the averaging method of the two-fluid model, detailed information of particles is used for the local concentration of particles. A description of the non-uniform structure in the system is obtained by analyzing the phase interactions under different particle distribution structures.