Abstract:

This paper presents a novel simulation technique based on the hybrid computational fluid dynamics (CFD)-boundary-element method (BEM) and the aeroacoustic Time-Reversal (TR) source localisation method to analyse the flow-induced noise generated at the Aeolian tone due to a circular cylinder located in a low Mach number flow. To this end, the hybrid CFD-BEM method is used to obtain the far-field acoustic spectrum of (1) the direct acoustic pressure field generated by flow over the cylinder, (2) the acoustic field scattered by the cylinder and (3) the total acoustic field at all four computational boundaries. The acoustic spectrum shows the occurrence of an Aeolian tone for all three cases whereby the acoustic pressure time-history at the boundary nodes is synthesised by assuming a sinusoidal signal at the Aeolian tone frequency. The aeroacoustic TR simulation was implemented by numerically solving a set of 2-D Linearised Euler Equations (LEE) and enforcing the time-reversed acoustic pressure history as input at the computational boundaries. The TR source maps indicate a lateral quadrupole source nature due to the direct field whilst a lift-dipole source nature is indicated due to the scattered and total acoustic pressure fields. The results of the TR simulations is consistent with previous works, thereby demonstrating the validity of the novel technique proposed in this work for analysing flow-induced noise problems.