HPC User Report from K. Nusser (Institute of Process Machinery and Systems Engineering)

The complex flow field around a vehicle was analyzed and used in a hybrid fluid-structure-acoustic interaction workflow to determine the interior noise levels inside the passenger cabin.

Motivation and problem definition

The analysis of the acoustic behavior of flow fields has gained importance in recent years, especially in the automotive industry. The comfort of the driver is heavily influenced by the noise levels and characteristics, especially during long distance drives. With the help of numerical simulations, the acoustic properties of a car can be analyzed at an early stage of the development process. In this project, the flow-induced excitation of the structure and the radiation of sound into the passenger cabin is investigated on a simplified car geometry. This fluid-structure-acoustic interaction is solved using a hybrid approach, where a flow simulation is coupled to a separate structural and acoustic simulation.

Methods and codes

For the flow simulation, we use FASTEST-3D, an MPI-parallel finite volume solver that has been developed at the Friedrich-Alexander University Erlangen-Nürnberg since the early 1990s. It is used to solve the laminar and turbulent incompressible Navier-Stokes equations using either a Direct Numerical Simulation or Large-Eddy Simulation approach. It was optimized to increase performance, scalability and flexibility, making it suitable for current high-performance compute clusters.

Results

The turbulent flow field around the car model was simulated. Acoustic source terms were computed using acoustic analogies and exported to the structural and acoustic solver together with the hydrodynamic excitation on the structure. With these coupled simulations, it is possible to model the sound radiation into the passenger cabin. Using this approach, we were able to analyze the different excitation mechanisms separately and to investigate the mechanism of sound generation further.

Outreach

• Nusser K., Müller S., Scheit C., Oswald M., Becker S.: Large Eddy Simulation of the Flow Around a Simplified Car Model. Direct and Large-Eddy Simulation X, Springer, 2017, S. 243–249 (ERCOFTAC Series, Bd.24), DOI:10.1007/978-3-319-63212-4_30
• Becker S., Nusser K., Oswald M.: Aero-Vibro-Acoustic Wind Noise-Simulation Based on the Flow around a Car. SAE Technical Papers (2016), DOI:10.4271/2016-01-1804

Researcher’s Bio and Affiliation

Katrin Nusser studied Computational Engineering and is now a Ph.D. student in the group of Prof. Dr. Stefan Becker at the Institute of Process Machinery and Systems Engineering.