Visualization and Simulation of Air Flow Inside a Recorder

Understanding the Air Flow and Resonance Inside a Recorder

The sound of a woodwind instrument is greatly affected by slight differences in air flow. We support the design and development of recorders by flow visualization measurements called PIV and computer fluid simulations.

* PIV (Particle Image Velocimetry) is a method of fluid measurement. Smoke particles (several μm in diameter) called tracers are diffused in the air flow and irradiated with a high-intensity laser (Class 4). A high-speed camera (tens of thousands of frames per second) is used to capture the movement of the brightly illuminated particles irradiated by the laser, enabling visualization and quantification of the flow velocity distribution.

Detailed visualization and measurement of air flow

PIV is used to visualize and measure the air flow in the recorder tube in detail, which could not be observed directly before, and is utilized for shape design. The movie shows the flow field near the edge of a recorder tube during recorder blowing, obtained with PIV. It visualizes and quantifies the up-and-down oscillation of the jet that flows in from the left side and borders the edge.

Large-scale fluid flow simulation analyzes flow with sound waves

Using a large-scale fluid simulation with a supercomputer, we analyze the behavior of fluid including sound waves in detail and study the shape that can achieve the ideal feeling of blowing and tone. The movie shows the pressure and velocity distributions obtained from the simulation when blowing the lowest note of the recorder. It reproduces the pressure fluctuation in the center of the pipe and the up-and-down oscillation of the jet near the edge of the pipe.

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