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Computational Fluid Dynamics (CFD) is widely used in vehicle aerodynamics development today, but typically used to study one vehicle shape at a time. In order to be used for aerodynamic shape exploration and optimization the CFD simulation process has to be able to study a large set of design alternatives (vehicle shape variants) within the short period of time typically available in the overall aerodynamics development process. This paper reports the development and testing of a process, referred to as the 50:50:50 Method, which is developed to study a large set of design alternatives in a highly automated way, while ensuring that each design alternative is simulated with a high fidelity CFD simulation.

Thorough design exploration is essential for improving vehicle performance in various aspects such as aerodynamic drag. Shape optimization algorithms in combination with computational tools such as Computational Fluid Dynamics (CFD) play an important role in design exploration. The present work describes a Free-Form Deformation (FFD) approach implemented within a general purpose CFD code for parameterization and modification of the aerodynamic shape of real-life vehicle models. Various vehicle shape parameters are constructed and utilized to change the shape of a vehicle using a mesh morphing technique based on the FFD algorithm. Based on input and output parameters, a design of experiments (DOE) matrix is created. CFD simulations are run and a response surface is constructed to study the sensitivity of the output parameter (aerodynamic drag) to variations in each input parameter.

To-date the primary challenge in conducting aerodynamic CFD simulations of actual vehicles with realistically complex geometry has been the construction of a computational mesh. The CAD-to-Mesh processes used to-date have been laborious, often requiring many weeks of engineering time. In this paper we present a new technique to greatly expedite the CAD-to-Mesh process. The fundamentals of this technique are discussed followed by case studies that show that this technique can reduce the engineering time required for the CAD-to-Mesh process to just a few hours.

Computational Fluid Dynamics simulation of aero-acoustics requires a high fidelity mesh. For Direct simulations, a very good quality and reasonably refined mesh is required in the entire domain encompassing the source and receiver of the sound. A usual practice so far has been to use structured grid to mesh the geometries. For complex geometrical shapes, such as throttle body, creating a fully structured mesh becomes very tedious and could consume a lot of time. Once the computational model is in place, obtaining meaningful solution also takes a long time since the solution has to be run for quite the long time in order to capture reasonably accurate sound pressure data. The current paper focuses on both of these time-consuming aspects. A comparative study of three different mesh types in a throttle body geometry is considered.

The conventional approach for simulating external flow field over an automobile is to use body fitted (BF) mesh. However, depending on the geometrical complexity of the boundaries, grid generation and grid quality are major issues and take significant time and cost. Moreover, preparing a proper body fitted mesh requires manual intervention which makes it too difficult to automate the process of external aerodynamics simulation. A different approach is so called Immersed Boundary (IB) method. It provides a high level of flexibility in handling highly complex geometry. It is usually employed in conjunction with body non-conforming Cartesian grid. Thus, grid generation is greatly simplified. This method can tackle flows with complex stationary or moving boundaries with relative ease. This paper demonstrates the ease of use of the IB method compared to the BF method and possible use of the IB method to automate the external aerodynamics simulations.

The purpose of present study is to use Immersed Boundary (IB) method in flow field simulations of a simplified generic ground transportation system (GTS) at 0° yaw. The IB method is usually employed in conjunction with a body non-conforming Cartesian grid. Thus, grid generation is greatly simplified. This plays an important role in reducing the cost and time in design process. This paper demonstrates the ease of use of IB method compared to body fitted mesh method and possible use of IB method to automate the external aerodynamics simulations. Also in order to assess the accuracy, the results are compared with corresponding experimental data reported in literature.

The latest requirements for automotive cabin comfort require lower sound levels inside the cabin. There are many sources contributing to this noise of which fan is an important one. The blade passage noise of the cooling fan is often unpleasant and it is generally expensive to build and test different prototypes for optimum noise performance. Also, traditional unsteady computational approaches for predicting the fan noise are time and resource consuming and do not fit within the design cycle time. This paper proposes use of a steady state computational technique to predict the fan noise performance which provides for effective design study with optimum resources. The steady state data is used with the wave analogy to predict the overall sound pressure level. First, the computational results were validated with the experimental data for a base case and then parametric study was carried out to have optimum design.