Comparison of drag models in shallow flow for spherical particle trajectory

Abstract

Numerical models play a significant role in predicting the movement of floating debris. One significant force in predicting a floating object’s motion is the drag force. Many empirical methods of drag coefficient (CD) have emerged over the years to estimate the drag force of spherical particles. This study aims to simulate different CD of spherical particle trajectory utilizing TELEMAC2D software. The simulation is compared with an Eulerian–Lagrangian one-way coupling discrete element model (DEM). A floating spherical object of radius 0.02 m and density 500 kg ms−1 was released in a steady flow of 0.4 m water depth and velocity 0.5 ms−1. The simulated trajectory of the particle within the initial five seconds agrees closely with the DEM simulation, but all six drag coefficient formulas overestimated the distance after five seconds. Therefore, different empirical drag formulas exhibit similar estimations towards the movement of floating debris, and the models’ accuracy can be improved with detailed physics of the floating object.