Numerical study for the function of moving pad on tone hole acoustics

Abstract

In this poster, we will discuss numerical methods for calculating a tone hole model with a moving pad of woodwind instrument by using compressible Large Eddy Simulation (LES), i.e., how to treat moving boundary problems. There are three stages of numerical methods to treat a moving pad on a tone hole. The 1st stage is the simplest method in which a dynamical mesh technique is not employed. It is so called “Stop Motion.” The numerical conditions of the distance between the pad and the top of the tone hole are set to adequate points to discuss the effect of the distance, e.g., we set it to 0 mm (i.e., the tone hole is closed by a pad), 0.5 mm, 1 mm, 2 mm, 3 mm, and 5 mm. In the second stage, while a dynamical mesh technique is employed, on the other hand, it does not treat the condition with topological change of the boundary, i.e., in this situation, the distance changes from/into 0 mm. The third stage is a full dynamical mesh technique which provides a method for treating moving boundary problems with topological changes. As the results of calculation, we will also report how the pitch is changed with fingering, and how the fluid field and acoustical field behave around the tone hole when it is changed, comparing with experimental study on the function of tone holes reported by Keefe [1]. Keefe, D.H. ``Experiments on the single woodwind tone hole'', J. Acoust. Soc. Am., 72 688-699 (1982).