Aeroacoustic analysis of oboe reeds with compressible direct numerical simulation

A two-dimensional model of an oboe reed is studied numerically with a direct numerical simulation (DNS) of the compressible Navier-Stokes equations to investigate the sound generation mechanism from the viewpoint of aeroacoustics. The numerical tool is extremely accurate due to the smallest mesh size on the order of micrometers and successfully reproduces the details of fluid motion and acoustic vibrations inside and outside the reed. Particular attention is paid to the effect of reed vibration on the sound generation mechanism. When the reeds are fixed and a periodically varying flow is injected through the fixed reed slit, an aerodynamics sound created inside the reeds is an almost monotone including a few overtones. On the other hand, when a flow is injected through periodically vibrating reeds from an oral cavity, more overtone components are observed and the pressure waveforms are similar to those observed in the experiment. This indicates that the richness of the overtones of the double-reed instrument is mainly attributed to the aerodynamic sound created by the flow injected through vibrating reeds and the bore, a linear resonator, just enhances characteristics of the instrument, e.g., formant.