An on-road investigation into the conditions experienced by a heavy goods vehicle operating within the United Kingdom

MATLAB® Simulink® was used to model the wind speed, vehicle velocity and wind direction in conjunction with wind tunnel data in order to estimate the on-road drag coefficient. The results from the simulation found an average drag coefficient of 0.770, this value was close to the expected wind averaged drag coefficient of 0.805. This value differed from prior estimates as the logged on-road vehicle speeds were close to the maximum permitted, this resulted in a reduced effect from the wind direction and hence a reduced effective yaw angle. The average drag coefficient calculated corresponded to an average effective yaw angle of 7.1°.