aKyushu Institute of Technology
bKyushu University
Abstract :
The body of an ocarina is regarded as a Helmholtz resonator. Thus, we
can expect differences in sounding mechanism between ocarinas and
other air-jet instruments with a resonance pipe. Furthermore, ocarinas
are driven by cross blowing like transverse flutes so that the driving
mechanism with an air-jet should be different from that for vertical flues
like a recorder. In this paper, we numerically explore the sounding
mechanism of an ocarina from the view point of aeroacoustics with
compressible fluid simulation. We adopt compressible LES as a numerical
scheme of compressible fluid, which simultaneously reproduces fluid and
acoustic fields and with which we can investigate the interaction
between the fluid and acoustic fields near the mouth opening. Our 3D
model has numerical grids more than one hundred and 50 million to
reproduce detail behavior of air-jet motion, vortices and acoustic filed
near the mouth opening. We numerically observed an acoustic
oscillation with the Helmholtz resonance frequency in the body together
with the detail structure of fluid field.