Transient flow over generic rear view mirror using computational fluid dynamics

摘要

The present paper is an attempt to investigate the transient flow over generic rear view mirror with different turbulent models, Reynolds numbers and model yawing angles using computational fluid dynamics (CFD) with identical grid, second order schemes and the incompressible assumption. Average pressure coefficient, standard deviation (SD) of velocity and pressure fluctuations, power spectral density (PSD) of flow parameters were taken into consideration. Mean pressure coefficient on the surface of the mirror in good agreement with the experimental data available from literature indicates that both detached eddy simulation (DES) and large eddy simulation (LES) have ability to predict the flow field of mirror. Further discussion can be found that flow separation is the key factor leading to large σ(Cp'') value of the rear face and the instability of shear layer leads to a large velocity fluctuation. The distribution of pressure and velocity fluctuations is symmetric when the mirror is 0°. The PSD of pressure fluctuations shows that most of its energy focuses on low frequency and those sensors which locate at the separation zone have larger fluctuation than it is at other zones. All findings help us to better understand the transient flow mechanism of rear view mirror, and it is beneficial to control the aerodynamic noise generated by mirror.