The vortex structure behind an Ahmed reference model in the presence of a moving ground plane

Laser Doppler anemometry (LDA) data are presented for an Ahmed reference model employing various backlight angles. LDA velocity measurements are taken in a number of planes around and downstream of the model at a free-stream velocity of 25 m s−1. During the testing a rolling road provided ground simulation and six-component force data were recorded. Data from these experiments are compared to previous experimental data. It is found that the inclusion of the ground simulation and the consequent supporting strut produces a reduction in the size and strength of the vortices shed from the back end of the Ahmed model when compared with previous analysis. It is further concluded this effect is primarily a result of the overhead strut, and that the rolling road has little effect on these upper vortices. In addition, vortices shed from the underside of the model, not reported in previous experimental work, are found and analysed.