Interaction between compressible fluid and sound in a flue instrument

In order to study the generation of (aerodynamic) sound in flue instruments, we numerically apply Howe’s energy corollary for a 2D model of flue instrument. Howe’s energy corollary enables us to estimate the energy transfer between fluid flow and acoustic field. To implement it, separating the acoustic field from the fluid flow is needed. However the complete method to numerically achieve it has not been established yet. In this work, we develop an approximate method, which has been recently proposed in their experimental studies by Yoshikawa et al (2012 J. Sound Vib. 331 2558-2577) and others, and we apply it to the simulation of the model instrument. We first calculate fluid flow and acoustic oscillation simultaneously by a compressible fluid solver. Next referring to the information on the acoustic oscillation obtained we set up a pressure source on an acoustic solver and reproduce almost the same acoustic oscillation with it. Combining those results, we are able to calculate Howe’s energy corollary. The numerical result shows that the aerodynamic sound is generated from the oscillating jet rather than the vortices shed by the collision of it with the edge of the mouth opening, namely vortex shedding