CFD-based optimization for automotive aerodynamics

The car drag reduction problem is a major topic in the automotive industry because of its close link with fuel consumption reduction. Until recently, a computational approach of this problem was unattainable because of its complexity and its computational cost. A first attempt in this direction has been presented by the present author as part of a collaborative work with the French car manufacturer Peugeot Citroen PSA [4]. This article described the drag minimization of a simplified 3D car shape with a global optimization method that coupled a Genetic Algorithm (CA) and a second-order Broyden-Fletcher- Goldfarb-Shanno (BFCS) method. The present chapter is intended to give a more detailed version of this work as well as its recent improvements. An overview of the main characteristics of automotive aerodynamics and a detailed presentation of the car drag reduction problem are respectively proposed in Sects. 7.1 and 7.2. Section 7.3 is devoted to the description of various fast and global optimization methods that are then applied to the drag minimization of a simplified car shape discussed in Sect. 7.4. Finally in Sect. 7.5, the chapter ends by proposing the applicability of CFD-based optimization in the field of airplane engines.