On the effect of boat-tails on a simplified heavy vehicle geometry under crosswinds

The flow around a Ground Transport System (GTS), is numerically investigated using steady RANS model; SST, at a Reynolds number of . This paper focuses on the effect of crosswinds on the near-wake structure of the GTS with and without boat-tails. Upon the emanation of crosswinds, a quadratic increase in the drag coefficient was observed, as a function of the yaw angle. Such an increase is attributed to the break in the symmetry of near-wake structure and three, streamwise vortices emanating from the leading edges of the GTS. Boat-tail with a slant angle of , at zero yaw, has resulted in a reduction of up to, relative to the baseline GTS. The reduction is consistent with previous studies on various simplified geometries. Such reduction is a resultant of a smaller wake length, coupled with an overall increase in the pressure in the wake, consequently increasing the mean base pressure coefficient. Higher boat-tail angles have resulted in an increase in CD, whereas, under crosswind, reduction in is observed. Boat-tails have additionally resulted in a quasi-symmetric near-wake structure, under crosswinds, acting as a blockage and preventing the interaction between the three streamwise vortices and the near-wake.