Effects of two-dimensional reed oscillation on airflow and sound generation in a single-reed instrument

Abstract

While two-dimensional (2D) reed oscillation modes of single-reed woodwind instruments have been reported in previous studies, little is known about their effects on airflow and sound generation. In this study, we conducted aeroacoustic simulations of a clarinet mouthpiece and resonator coupled with one-dimensional (1D) and 2D reed deformation models and investigated the changes in flow and sound generation due to the 2D reed vibration. The 1D and 2D reeds were modeled using 1D beam and thin plate theories, respectively, whereas the three-dimensional airflow was simulated by solving the compressible Navier–Stokes equations. The self-sustained oscillations of the 2D reed model mainly exhibited a flexural mode at the fundamental frequency, which is consistent with previous observations. Complex torsional modes were observed only at higher harmonic frequencies. A comparison between the 1D and 2D reed models demonstrated that the 2D reed opened later at the side face of the mouthpiece than the 1D reed owing to the torsional mode, which changed the time variation of the flow rate into the mouthpiece and the far-field sound in the high-frequency range. These results suggest the importance of the torsional deformation characteristics of reeds on the timbre of single-reed instruments.