Experimental study and numerical analysis on field on meandering channel and movement of woody debris

Abstract

It is known that woody debris flowing down rivers accumulates at bridge piers, intake facilities and other structures. The phenomenon can cause significant damage by flooding as well as destroy of buildings. To tackle with those problems, it is important to understand the mechanism behind woody debris flow and accumulation. In this study, an experiment was conducted focusing on woody debris in a meandering compound channel in order to analyze the mechanism of woody debris accumulation. In the experiment, particle tracking velocimetry (PTV) based on binary correlation analysis was applied both to tracer particles and to woody debris models to clarify the flow field and woody debris transport, and to enable study of the relationship between them. Also, the Lagrangian numerical simulation of drift wood using a simplified momentum equation was developed in order to reproduce the experimental result. The numerical study results confirmed that woody debris concentrated avoiding high shear regions in the channel, and this behavior seems to correspond with the characteristic motion of particles in fluid, which is known as "preferential motion".