Numerical modelling of large wood logs transport using CFD-DEM coupling approach

The movement of large wood in high-volume fast-moving flood flows can cause extensive damage to both in-stream structures and flood plains. Understanding the trajectory and the factors influencing the log motion is essential for enhancing the resilience of flood control structures.This study introduces an innovative Eulerian-Lagrangian numerical method for modeling large wood transport and interaction with hydraulic structures. The method is based on the dynamic coupling of Computational Fluid Dynamics (CFD) for flow hydrodynamics (Eulerian) with a Discrete Element Method (DEM) for wood motion (Lagrangian).The model was applied to simulate the transport and interaction of large wood with flood control structures, using a 1:16 scale laboratory model of the Springbank off-stream storage reservoir on the Elbow River in Calgary, Canada. The model's performance was evaluated by comparing predictions of log pathways and jam formation on the structure with observed data from a physical testing study previously conducted at the National Research Council Canada (NRC).Results demonstrate that the developed CFD-DEM numerical model efficiently predicts large wood transport and behavior across structural configurations. This tool offers a cost-effective and practical approach to assessing structural resilience against large wood jam risks and identifying optimal mitigation strategies. By enabling the exploration of scenarios impractical to study experimentally, it supports the development of more robust and adaptive flood control systems to address the growing large wood transport risks associated with climate change.