Probabilistic Analysis of Debris Motion in Steady-State Currents for Varying Initial Debris Orientation and Flow Velocity Conditions

Abstract

Floodborne debris impact loads depend on several factors, including debris orientation and velocity. Due to the random nature of turbulent flood flows, debris motions are inherently random. This study presents a probabilistic characterization of debris motions in steady-state currents with relatively high Reynolds numbers. An item of debris was released, multiple times, in the open channel flows, at two angles and three current velocities. The debris motions were recorded via a camera. The characteristics of the debris motions including the trajectory, orientation, and velocity were extracted using image processing and were analyzed statistically. The results indicate that the debris orientation and lateral displacement followed a Gaussian distribution. The current velocity and release angle had a smaller effect on the debris lateral displacement than did the orientation. The analysis also highlights the combined effect of the current velocity and release angle on the lateral displacement and orientation of the debris. Empirical relationships were developed for estimating the mean trajectory and orientation of debris in steady currents, as a function of the release angle, and Froude number.