CFD Simulation of Side Glass Surface Noise Spectra for a Bluff SUV

Simulation of local flow structures in the A-pillar/side glass region of bluff SUV geometries, typical of Land Rover vehicles, presents a considerable challenge. Features such as relatively tight A-pillar radii and upright windscreens produce flows that are difficult to simulate. However, the usefulness of aerodynamics simulations in the early assessment of wind noise depends particularly on the local accuracy obtained in this region. This paper extends work previously published by the author⁽¹⁾ with additional data and analysis. An extended review of the relevant published literature is also provided. Then the degree to which a commercial Lattice-Boltzman solver (Exa PowerFLOW^™) is currently able to capture both the local flow structure and surface pressure distribution (both time averaged and unsteady) is evaluated. Influential factors in the simulation are shown to be spatial resolution, turbulence and boundary layer modelling. It is demonstrated that, whilst reasonable predictions are obtained for the surface noise spectra, both the size and strength of the A-pillar vortex are substantially over-predicted. Finally an attempt is made to estimate the frequency range that the simulation could be reasonably expected to capture. This analysis suggests that the simulation is bounded by the limitations of the turbulence model, rather than spatial resolution.