Improvements in CFD Simulation of Aero-Acoustics in a Throttle Body 2009-01-0768

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 mesh types range from fully hexahedral to a hex-dominant mesh (with tetrahedral elements near the walls and hexahedral elements in the core) to a full polyhedral mesh. The transient simulation speedup is achieved using the Non-Iterative transient solver. Sound spectrum results from the three simulations show that the SPL at the first frequency peak is captured well by all the three meshes. The comparison of spectrum with test data too looks reasonably good for all the three simulations.