Kyle Butler

Simulation of the Influence of Aspect Ratio on the Aerodynamics of Rectangular Prisms

AbstractA numerical simulation of three-dimensional flow around rectangular prisms (two dimensional) of different aspect ratios, ranging from 0.3 to 7.0, is conducted at a Reynolds number of 105, using large eddy simulation. This study identifies the influence of aspect ratio on the flow field around prisms and the attendant aerodynamics. Results show salient features in the flow field and associated pressure/aerodynamic forces caused by changes in the afterbody, which demonstrate good agreement with observations from wind tunnel experiments. A time-frequency analysis is introduced to identify the transient nature of fluctuations in the drag and lift coefficients, highlighting temporal variations in the frequency contents of these fluctuations and their resulting influence on force coefficients.

Downslope Gusty Wind Loading of Vehicles on Bridges

AbstractDownslope crosswind bora gusts impacting vehicles represent a significant traffic safety issue, and vehicles on bridges are particularly vulnerable to such crosswinds. Wind tunnel experiments were carried out to investigate the effects of the vertical wind incidence angle and vehicle position on the resulting transient aerodynamic loads. When considering accident risk for the vehicle/infrastructure scenario investigated in this study, the higher risk for vehicles exists at lower vertical wind incidence angles up to 30° and closer to the upwind edge of the bridge deck with respect to steady aerodynamic loads. Shed vortices and wind gusting determined the unsteady aerodynamic loading of a vehicle on the bridge. Effects of shed vortices decreased at larger vertical wind incidence angles, with the wind gusts driving the unsteady aerodynamic loads. Difficulties associated with vehicle maneuvering and stability in the upwind traffic lane in terms of unsteady aerodynamic loading are expected to occur at ...