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Automotive aerodynamic research often focuses on strongly simplified car models, such as the Ahmed body and the SAE model. Due to their high degree of abstraction, however, interference effects are often neglected which leads to an unrealistic representation of the flow field. Consequently, these results cannot be directly used for the aerodynamic optimization of production vehicles. On the other hand, aerodynamic investigations of real production vehicles are often limited due to the restricted availability of the geometric data. Therefore, a new realistic generic car model for aerodynamic research — the DrivAer body — is proposed. This paper focuses on the development of the model, summarizes first experimental results of the different configurations of the fastback geometry and compares them to numerical simulations performed using the open source software OpenFOAM®.

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For the efficient simulation of fluid flows governed by a wide range of scales a wavelet-based adaptive multi-resolution solver on heterogeneous parallel architectures is proposed for computational fluid dynamics. Both data-and task-based parallelisms are used for multicore and multi-GPU architectures to optimize the efficiency of a high-order wavelet-based multi-resolution adaptative scheme with a 6th-order adaptive central-upwind weighted essentially non-oscillatory scheme for discretization of the governing equations. A modified grid-block data structure and a new boundary reconstruction method are introduced. A new approach for detecting small scales without using buffer levels is introduced to obtain additional speed-up by minimizing the number of required blocks. Validation simulations are performed for a double-Mach reflection with different refinement criteria. The simulations demonstrate accuracy and computational performance of the solver.

Wheel aerodynamics of passenger cars has recently been under close investigation due to its influence on the aerodynamic forces on the vehicle. In modern wind-tunnels the wheel rotation can be resembled close to reality, while, in their CFD development process, car manufactures rely on simplified models for considering rotating wheels. In this paper, model-scale generic and production wheels are investigated experimentally, in respect of the influence of geometry, camber and a brake disc. The data is used to assess the accuracy of CFD simulations using open-source software and their applicability in a manufacturer's CFD process.

This report addresses the interior design of a 40% scaled wind tunnel model of a generic medium-sized car geometry — the so-called DrivAer body. The model was designed for being investigated inside the wind tunnel facility at the Technische Universität München, which was recently upgraded by a single-belt ground simulation system. The wind tunnel model is very modular: it features several exchangeable parts, such as three exchangeable rear ends, three different underbody configurations, and different wheel rim geometries. In addition to this, the engine compartment is equipped with a model heat exchanger to adjust the mass flow rate through the underhood area. Apart from the model itself, we would also like to introduce some of the measurement equipment that we used during our wind tunnel tests, for example a set of five independent force balances. Furthermore, a method to account for the falsifying rolling resistance of the wheels is shown. Finally, results of experiments to determine the aerodynamic drag generated at the front and the rear axes of the vehicle will be discussed and a small data base of drag values for various vehicle configurations will be provided.