Experimental modeling of Bora wind loads on vehicles

Abstract

the Bora is a very strong and gusty downslope wind that blows from the northeast across the coastal mountain ranges on the eastern coast of the Adriatic Sea. It creates substantial difficulties for engineering infrastructure, traffic, and life in general. While the effects of the quasi-steady turbulent atmospheric boundary layer flow on road vehicles are currently fairly well known, the Bora wind also creates unsteady aerodynamic loads on these vehicles, which are still not fully understood. these gust effects on road vehicles have thus been experimentally examined here. this study was conducted on a small-scale road vehicle model, which to our knowledge is the first study of this type. Particular emphasis was placed on the aerodynamic forces and moments experienced by the road vehicle related to the strength and frequency of the Bora wind gusts, the vertical wind incidence angle, and the vehicle position on the bridge. in the experiments regarding the wind gust strength and frequency, the road vehicle model was placed in the upwind traffic lane at zero horizontal and vertical flow incidence angles. The effect of the vertical wind incidence angle and vehicle position was analyzed for the road vehicle model placed in the upwind, middle, and downwind traffic lanes of the bridge-deck section model, where the horizontal flow incidence angle was zero, while the vertical flow incidence angle was studied from 0° to 50°. The experiments were carried out in the transient flow field simulator of the nathaz modeling laboratory at the University of notre dame, Usa. the results reveal some important findings. Regarding the wind gust strength and frequency experiments, the aerodynamic loads rose linearly with increasing gust strength and were concurrently affected by vortex shedding and wind gusting phenomena. the steady aerodynamic loads were generally higher for a road vehicle closer to the upwind edge of the bridge decks. The wind gusting of the Bora can cause difficulties for the maneuvering of road vehicles and for their stability in the upwind traffic lane, while the risk for road vehicles in the downwind traffic lanes was predominantly a