Calibration of a numerical model for the transport of floating wooden debris

Abstract

The paper describes the calibration of a numerical model to simulate the 2D motion of floating rigid bodies. The proposed model follows a one-way coupling Eulerian-Lagrangian approach, in which the solution of the Shallow Water Equations (SWE) is combined with the Discrete Element Method (DEM) to compute the displacement of rigid bodies. Floating bodies motion is computed by adapting the Maxey-Riley equation to the case of semi-submerged bodies at high Reynolds number. In order to account for the flow velocity distribution along the body axis, the elements are divided into shorter subsections. A specific formulation is proposed to calculate the rotation of wooden cylinders, by computing the angular momentum. The model includes also a term of added inertia, which accounts for the resistance to rotation and requires the calibration of a specific inertia coefficient. A series of flume experiments is performed to calibrate the model. The 2D trajectories of floating spheres and the linear and angular displacement of cylinders are recorded in stationary conditions. The comparison between the experimental data and the simulation shows that the numerical results are in agreement with the experimental ones, although less accuracy is observed in the reproduction of the angular displacement.