## 3 Results
### Flow around the DrivAer Model
The pressure coefficient distribution on the symmetry plane \(y=0\) shows the same behaviour of the simplified DrivAer model (see Figure 9). Differences are evident for the \(c_{P}\) distribution on the plane \(z=0.06\) that intersects the wheels, shown in Figure 15. The flow accelerates from the stagnation point and detaches near the front wheel. In the doors region the pressure recovers slowly. After the second flow separation at the rear wheel, there is a sudden pressure recovery in the rear part of the model. However, the simulation predicts a separation bubble that reattaches just before the end of the model. The predicted distribution is in good agreement with the WMLES simulations of [PERSON] et al. (2012). The comparison between the predicted results presented in this section and in Section 3.1 (see Figures 12 and 15) puts in evidence the importance of the wheels in the prediction of the side flow field. Figure 16 shows the time-averaged pressure coefficient contours on the body (top-left), underbody (top-right), the windshield (middle-left), the front side window (middle-right) and the back window (bottom). The views and the scales of the pressure coefficient contours for the windshield, the front side window and the back window are the same used by [PERSON] et al. (2011) to ease the comparison. The distribution on the top and bottom view can be compared with the LES results of [PERSON] et al. (2013), showing a good agreement. A discrepancy can be observed in the front part of the bottom distribution, where the predicted results show a separation that generates a sudden decrease of the pressure. Moreover, near the A-pillar the low pressure region is less evident in the predicted results due to the absence of the rear mirrors. The \(c_{P}\) contours on the windshield and on the back window are very close to the reference. In the central zone of the back window there is a small low pressure region that is not present in the reference RANS simulations, which suggests the presence of a small detached zone at the junction between the roof and the back window. Moreover, in contrast to the simulation without the wheel, the location of vortex in the A-pillar zone is now in agreement with the references, even if the low pressure region is more widespread for the absence of the rear mirror. Figure 14: DrivAer model—Polynomial degree distribution \(\mathbb{P}^{n}\) of the solution from the lateral **(left)** and the front **(right)** point of view. Figures 17 and 18 show the time-averaged \(x\)-velocity contours on the slices \(x/L=(0.173,0.273,0.423)\) and \(x/L=(0.88,0.98,1.10)\), respectively. In particular, the slice at \(x/L=0.173\) cuts the wheel, showing the flow field inside the wheel house, which is characterised by a negative \(x\)-velocity. In fact, the flow inside the wheel house follows the direction prescribed by the wheel angular velocity. Moreover, near the ground contact, two counter rotating vortices generated ahead of the wheel are observed. The slice at \(x/L=0.273\) shows that vortical structures created by the wheel are convected downstream, influencing the side flow field. Finally, the slice at \(x/L=0.423\) intersects the A-pillar and  
Figure 16: DrivAer model—Time-averaged pressure coefficient distribution on the body (**top-left**), the underbody (**top-right**), the windshield (**middle-left**), the front side window (**middle-right**) and the back window (**bottom**). Figure 15: DrivAer model—Time-averaged pressure coefficient distribution on the \(z=0.06\) plane. shows the A-pillar vortex that is convected downstream. The slices on the rear part of the model are the same used by [PERSON] et al. [6]. The contours are in agreement with the IDDES simulations. In particular, the slice at \(x/L=0.88\) shows the vortical structures created by the rear wheel and the small separation on the back window. The slices at \(x/L=0.98\) and \(x/L=1.10\) show the development of the wake.