NUMERICAL STUDY OF PARTICLE DIAMETER EFFECT ON OSCILLATORY SHEET FLOW TRANSPORT WITH MOVABLE BED SIMULATOR

Abstract

Numerical simulation of the sediment transport based on the Lagrangian method is one of the most viable methods to investigate the complex mechanism of oscillatory sheet flow. Not only the flow unsteadiness with containing sediment particles, which respond to the flow acceleration and deceleration process, but also the interparticle collision of the moving particles complicate the simulation task. In this study, the sediment motion is simulated with the aid of the Movable Bed Simulatorcode based on DEM model in which the frequent collision of the moving particles is sophisticatedly modeled. And the particle diameter effect on the developing time-dependent process of sheet flow transport is investigated, using three different diameter sizes of sediment. The different tendency in sheet flow transport can be explained as a relaxation process related to the time lag of flow velocity and the sedimentmotion, which responds to the flow acceleration and deceleration. Also, the time lag of the sediment motion in the sheet flow layer is evidently influenced by the particle diameter size.