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In order to meet the customers comfort requirements, reduction of noise in the passenger compartment is one of the primary concerns in the automotive industry. Moreover, for a better reactivity to the market, vehicle development time tends to be shorter and shorter. Instead of constructing many prototypes and running a lot of tests, numerical simulation has to take a bigger part in the design of cars. This would be a cheaper and quicker way of testing many new solutions. We have developed for several years a numerical model, combining by Finite Element Method (FEM) and Boundary Element Method (BEM), for computing the vibro-acoustic behaviour of a fully trimmed car with engine and power train. This model allows prediction of the structure borne sound field due to the engine and wheels excitations at low frequencies (0-200 Hz).

Nowadays, the interior vehicle noise due to the exterior aerodynamic field is an emerging topic in the acoustic design of a car. In particular, the turbulent aerodynamic pressure generated by the air flow encountering the windshield and the side windows represents an important interior noise source. As a consequence PSA Peugeot Citroën is interested in the numerical prediction of this aerodynamic noise generated by the car windows with the final objective of improving the products design and reducing this noise. In the past, several joint studies have been led by PSA and Free Field Technologies on this topic. In those studies an efficient methodology to predict the noise transmission through the side window has been set up. It relies on a two steps approach: the first step involves the computation of the exterior turbulent field using an unsteady CFD solver (in this case EXA PowerFlow).