Thesis defence : Alexis THIBAULT

"Modelling, analysis and simulation of dissipative acoustics in porous or rough tubes; application to wind instruments".

  • Research
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Alexis Thibault, a doctoral student at the Laboratoire de Mathématiques et de leurs Applications at the Université de Pau et des Pays de l'Adour, will be defending his thesis entitled "Modelling, analysis and simulation of dissipative acoustics in porous or rough tubes; application to wind instruments". For his research work, he was hosted by the STMS Laboratory (Ircam-Sorbonne University-CNRS-Ministère de la Culture) at Ircam, as part of the S3AM team (Systems and sound signals: audio/acoustics, instruments). His thesis was under the co-direction of Juliette Chabassier (LMA Pau) and Thomas Hélie (STMS Lab). He was co-supervised by Henri Boutin (Sorbonne University, STMS Lab).

The spresentation will take place in the Salle Stravinsky at Ircam, but can also be followed live on Ircam's YouTube channel:


  • Eliane BÉCACHE, ENSTA Paris, Rapporteur
  • Stefan BILBAO, Université d'Edimbourg (Royaume-Uni), Rapporteur
  • Jean-Pierre DALMONT, Université du Mans, Examiner
  • Denis MATIGNON, ISAE-SUPAERO, Examiner
  • Fabrice SILVA, CNRS, Laboratoire de Mécanique et d'Acoustique, Examiner
  • Henri BOUTIN, Sorbonne Université, STMS Lab, Thesis Co-Director
  • Juliette CHABASSIER, Université de Pau et des Pays de l'Adour, Thesis Co-Director
  • Thomas HÉLIE, CNRS, STMS Lab, Thesis Co-Supervisor


This thesis work focuses on advanced modelling and simulation of acoustics in wind instruments, in particular with respect to acoustic losses at the walls. First, we develop and validate robust simulation methods for non-dissipative acoustics, using 1D spectral finite element techniques and different energy-preserving numerical schemes. Next, we extend the Zwikker-Kosten model to include viscothermal dissipation in conical, porous or rough-walled tubes, using a small-scale averaging approach with respect to wavelength. Experimental measurements corroborate the roughness model. Finally, we demonstrate the well-posedness of the Zwikker-Kosten model in the time domain using the theory of diffusive representations, and develop power-balanced numerical methods for simulating dissipative acoustics. These results strengthen the simulation methods for wind instruments, offering new perspectives on acoustic dissipation linked to wall roughness, with potential implications for instrument making, heritage preservation and musicology. What's more, these methods are being made available to the community thanks to the publication of the source code in the openwind library (url:


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