Computational Modeling for Driftwood Collision Dynamics in Shallow Flows Considering Root Wad and Anisotropic Bed Friction

The present study developed a method for driftwood collision model to predict and understand the driftwood dynamics. We considered two types of driftwood collision motions: Discrete Element Method (DEM) and Particle Re-arrangement Method (PRM). PRM is a newly developed model to consider driftwood collision with large time step in the simulations, and it assumes that driftwood consists of share shape particles and is constant elastic. We analyzed the simulation results comparing among non-collision, DEM and PRM together with flume experiment. As a result, non-collision case showed indirect interaction among driftwoods due to their drag-force under the two-way (inter-action between water flow and driftwood) model, and DEM case indicated good agreement for the wood motion with physical collision same with the flume experiment however larger CPU time is required due to small time step (0.001 s). Therefore, PRM is expected as an efficient calculation method for driftwood collision dynamics.