Continuous and discrete models for the dynamic behaviors description of suspended sediment-fluid system

Dynamic behaviors of suspended sediment-fluid system play an important role in the transport of bedload and the evolution of riverbed, but the related mathematical models are deficient or limited. In this paper, two models, micropolar fluid model and fluid-particle coupling model, are adopted in the dynamic behaviors calculation of the suspended sediment-fluid system in lid-driven cavity. We first establish the discrete solution program for micropolar fluid governing equations, and analyze the dynamic behaviors of suspended sediment-fluid system under different microstructure parameters. Meanwhile, the dynamic behaviors calculations are carried out by CFD-DEM (Computational Fluid Dynamics-Discrete Element Method) numerical method, and the influences of suspended sediment diameter and concentration are investigated. The results show that micropolar fluid model and fluid-particle coupling model can effectively describe the dynamic behaviors of suspended sediment-fluid system. The influences of microstructure parameters and macro-properties of suspended sediment at given range are almost same, suggesting the definite relationships existed between micro- and macro- quantities. Based on the equivalent effects of microstructure parameters to macro-properties of suspended sediment, micropolar fluid model is expected to replace CFD-DEM method completely in the study of the large-scale dynamic behaviors of suspended sediment-fluid system.