Computational assessment of distribution of plate-type windborne debris*

In the severe wind such as typhoon, major wind damages are caused by windborne debris, some of which results from the damaged structures, others from loose-laid objects. Due to limitations of previous experiments and resulting analysis, relatively uniform wind has been considered, whereas three-dimensionality of surrounding wind field is very important to trace the trajectory of windborne debris. In this paper, computational investigation is presented to demonstrate the importance and the role of the three-dimensional wind field in the trajectory of windborne debris. Unsteady Navier-tokes equation is solved for the turbulent flow around a three-dimensional structure. Loose-laid plate-type windborne debris is launched at a prescribed wind speed and the trajectory is computed based on the equation of motion and 3D turbulent wind velocity computed from the simulation. Interests are put on the effects of boundary layer on the trajectory and the comparisons are made between the trajectories in the uniform flow and the boundary layer. The results show that the trajectory is heavily dependent on the vertical component of wind velocity and the vertical gradient of inflow.