Numerical approach
on drag reduction for automotive vehicles

Mateus
Brizotti, Patrick Rambaud and Florian Visentin

Alhough
a full modelisation of the car geometry is necessary to analyse the
real aerodynamics features of the car, a lot
of work can be done using a simplified car geometry which is called
Ahmed’s body. This geometry is modelised in scale 1/4th with Gambit
software. A
picture of such a geometry is represented in figure 1.

The
following dimensions are used in this project : L=1.044 m, H=0.288 m
and w=0.389 m. This geometry represents the rear window with an
inclination angle of 25°. The
window length la is equal to 0.222 m.

Below are two pictures of the 3D
Mesh that we made with Gambit software
and that we used to do the calculations with
starccm+ software.

This mesh contains 600 000 cells
divided as follows :

* 450 000 cells in
the volume where the vortices appears.

* 150 000 cells in the outer part of the whole
volume.