From the physics of the register hole to the dynamics of woodwinds: numerical, analytical and experimental investigations for objective instrument making

Abstract: The birth of the clarinet is marked by the invention of the register hole, a small metallic tube inserted near the upper end of the instrument. Its opening enables a reliable transition between the first register, corresponding to the lower range, and the second register, located an octave and a fifth higher, for most fingerings of the instrument.

However, physical models of the clarinet struggle to reproduce this behavior: they often remain locked in the first register, even when they should produce a note in the second one. As a result, the clarinet cannot be studied in its essential function: the ability to change registers through the simple action of opening a hole. Within the framework of Buffet Crampon, the instrument manufacturer partnering this “Cifre” PhD, this discrepancy prevents any global optimization of the instrument’s design.

This gap between model and reality suggests that a decisive physical phenomenon has not yet been taken into account. Several studies, however, highlight the presence of localized nonlinear dissipation inside the clarinet. This effect appears for high acoustic velocities, at a geometric discontinuity, separating the flow and generating vortices and energy losses.

In this presentation, we demonstrate the decisive role of localized nonlinear dissipation in the register hole on the register transitions of the clarinet. We develop predictive tools validated by experiments and propose guidelines for the design and study of reed instruments.

Jury : 

    Jean-Pierre DALMONT -- Professeur, Le Mans Université -- Rapporteur,  Président du jury
    Vasileios CHATZIIOANNOU -- Senior Scientist, University of Music and Performing Arts Vienna -- Rapporteur
    Sébastien BAGUET -- Maître de conférences, INSA Lyon -- Examinateur
    Claudia FRITZ -- Chargée de recherche, CNRS, Institut Jean le Rond d'Alembert -- Examinatrice
    Christophe VERGEZ -- Directeur de recherche, CNRS, LMA, AMU -- Directeur de thèse
    Tom COLINOT -- Ingénieur-Chercheur, Buffet Crampon -- Co-encadrant de thèse
    Michaël JOUSSERAND -- RDI Director, Buffet Crampon -- Membre invité
    Florian MONTEGHETTI -- Maître de conférences, I2M, AMU -- Membre invité

La soutenance de thèse de Nathan Szwarcberg est prévue le 17 novembre à 8h30 - amphithéâtre du LMA