Numerical approach on drag reduction for automotive vehicles

Mateus Brizotti, Patrick Rambaud and Florian Visentin

Table of contents

        As ecology has become an important issue in today’s society, the industry has to take some steps towards improving the ecological impact of its products. It is now known that global warming is closely linked to CO2 emissions whose automotive industry contribution is about 20%.

            To reduce these emissions, the car companies are carrying out researches to reduce the consumption of fuel and thus to reduce CO2 emissions. Different ways can lead to the achievment of this goal and an important one consists in optimizing car designs in order to enhance aerodynamics features and especially to reduce the car drag coefficient.

           Dynamic control of the flow around the car is believed to be one possible solution to reduce the drag coefficient. The vortex control generated using blowing slits is considered in this project. The breakdown of a longitudinal vortex originating from a three-dimensional body is examined in the perspective of reducing the aerodynamic drag of bodies. The breakdown is characterized by an abrupt disintegration of the vortical core and the appearance of a recirculation zone. The vortex breakdown is induced by a continuous and uniform blowing distributed on the separation line related to the formation and the development of the vortex.

         Numerical simulations are used to modelise the car geometry and to analyse flow features with respect to the vortex control at the rear of the car.