Air Flow Visualization and Simulation Technology for Woodwind Instruments
Understanding the Air Flow and Resonance Inside a Recorder
The shape of a recorder greatly influences the way your breath flows through it, as well as its resonance characteristics. We employ flow visualization measurements called PIV* and large-scale flow simulations to achieve the ideal playability and sound.
* PIV (Particle Image Velocimetry) is a method for measuring an air flow field. The target flow field is seeded with tracer particles (several micrometers in diameter) that are then irradiated with a high-intensity laser (Class 4). The flow velocity field can be visualized using a high-speed camera (tens of thousands of frames/second) that captures the movement of the particles illuminated brightly by the laser.
Visualization and Measurement of Air Flow in High Resolution
Thanks to PIV, recorder designers can observe the air flow inside a recorder in a way that was not possible before. The following videos, obtained with PIV, show the flow field around the edge while a recorder is being played. You can see that the jet coming from the left moves up and down across the edge.
Large-Scale Flow Simulation to Analyze Entire Air Flow, Including Sound Waves
ULarge-scale flow simulation using a supercomputer allows us to analyze all kinds of fluid dynamical phenomenon, including sound waves. This helps us find a recorder geometry that achieves the ideal playability and sound. This video shows the pressure distribution and velocity distribution that are obtained by a simulation of playing the lowest note on a recorder. You can see the pressure antinode at the center of the tube as well as the jet motion, moving up and down around the edge.