CeLyA, laboratory of excellence for Acoustics in Lyon, organized a Winter School on the Acoustics of Porous Materials during the 12-13-14 February 2013 under the coordination of François-Xavier Bécot.

The timetable and slides of the lectures given during these 3 days are reported below:
(Nota Bene: to access the PDF versions of the slides you will be prompted for a login and a password. Check your email to find this information)

Tue. 12 FebWed. 13 FebThu. 14 Feb
08:00 – 09:00Welcome breakfast &
Presentation of CeLyA
Characterization technique I:
direct methods
(Raymond Panneton)
Numerics I-a:
FEM approaches
(Peter Göransson)
09:00 – 12:30Modeling I:
a brief history
(Luc Jaouen)
Characterization technique II
inverse methods
(Raymond Panneton)
Numerics I-b:
FEM approaches
(Peter Göransson)
14:00 – 16:00Modeling II:
scaling approaches
(Claude Boutin)
Experience feedback I:
material production
(Sylvain Berger)
Numerics II-a:
other approaches
(Olivier Dazel)
16:30 – 18:30Modeling III:
time domain models,
outdoor sound propagation
(Timothy Van Renterghem)
Experience feedback II:
material assembling
(Arnaud Duval)
Numerics II-b:
other approaches
(Olivier Dazel)

The results of the satisfaction questionnaire are compiled in this PDF file. Be sure that CeLyA will analyze these results and the individual comments (which do not appear on this PDF file) for future summer or winter schools.

Lectures’ contents

Modeling I : a brief history

It is often said that porous media theory started with Biot's series of papers in 1956. Actually, earlier works also brought fundamental insights into the physics of porous material research. In addition, some models, might there be analytical or numerical, may have been unfairly mistaken or misunderstood. This first talk will attempt to draw the global history of the research in the field of acoustical porous media. As an introduction of the seminar, the talk will cover theoretical models, characterization techniques, numerical methods. The aim of this talk is to pave a common background for attendees which are coming with various tuitions and experiences.
Lecture given by L. Jaouen

Modeling II : scaling approaches

Porous media research inherently involves various scales of observation. From the microscale related to the pore size and skeleton morphology, one gains the information about the dissipation mechanisms implied in the material behaviour. From the arrangement of the pores and the distribution of the sizes, global performance of the material may be retrieved. Other intermediate scales may also be considered to account for heterogeneities or porosity networks. This talk will aim at presenting the different techniques which exist to go from one scale to the other. Acoustics, mechanics and flow in porous media will be considered. Keywords for this talk comprise homogenisation, micro-macro approaches and morphological modelling.
Lecture given by C. Boutin

Modeling III : time domain models and outdoor sound propagation

Due to the dissipative nature of porous media, it is convenient to adopt frequency domain models. However, this type of representation poses difficulties when directly translating to a time-domain representation. Time domain modelling has become in recent years a mature numerical technique in acoustics, and is most useful to simulate moving sound sources, in noise control applications involving a broad spectrum like road traffic noise, to include nonlinear effects, etc. The time-domain calculation schemes most often used nowadays in outdoor sound propagation (FDTD, PSTD, TLM) are briefly reviewed. The main focus will be on the finite-difference time-domain technique, and detailed information will be provided concerning numerical accuracy, stability and computational cost. The characteristics largely change when the sound propagation medium is moving, which is often an importance influence in outdoor sound propagation applications due to the presence of wind. The different ways of including porous materials into these models will be discussed, with their pro’s and contra’s. Hybrid modelling between time-domain and frequency-domain models, with the purpose of reducing computational cost, will also be discussed.
Lecture given by T. Van Renterghem

Characterization techniques I : direct approaches
Characterization techniques II : inverse approaches

The relevance and accuracy of the input information related to porous materials is critical. A wide range of techniques have been designed to access the parameters which populate the predicting models. A first category includes direct approaches where a single or a set of parameters are directly measured. Measurement techniques involve techniques among ultrasonics, acoustics, mechanics and fluid dynamics. The second category comprises inverse techniques which consist in assuming a behaviour model of the porous material and determining the set of parameters which best fit measured data. These two categories are complementary and will be presented and discussed alongside.
Lectures given by R. Panneton

Experience feedback I : material production
Experience feedback II : material assembling

From theory to practice may summarize these two talks. How these tools could serve the material manufacturing while coping with mounting constraints, package assembling, production limitations ? These lectures will present how predicting models and characterization techniques could be used in an industrial context. Each of these talks will be given by the research group leaders of two worldwide leading material manufacturers. Examples will address applications sound packages comprising fibrous materials, felts, foams, granular materials, a wide range in the context of noise control in Buildings, Automotive, Railway, Aircraft and Aerospace, Domestic appliances, Equipment.
Lectures given jointly by S. Berger & A. Duval

Numerics I – FEM : theories
Numerics I – FEM : implementations

With ever increasing computational capabilities, finite element models are now matured enough to be directly involved in the design process of porous materials and sound packages. This talk aims at presenting the basis of the finite element method dedicated to porous media modelling. Classical models together with alternate representations will be discussed. Some basic implementations and practical examples will be proposed to the attendees. Special attention will be paid to convergence and stability criteria, and numerical efficiency of the implemented models.
Lectures given by P. Göransson

Numerics II – Other approaches

Recently, a number of approaches have been proposed as robust alternatives to purely finite element models. Among these, one could quote the Transfer Matrix Method (TMM), the Wave Based Method (WBM), the Discontinuous Galerkin Methods (DGM) and the Statistical Energy Analysis (SEA), as the most renown. In addition, hybrid models combining finite element models with analytical approaches have proved to be accurate and numerically efficient. This talk will present the principles of several alternates approaches together with practical examples of successful applications of this type of models.
Lectures given by O. Dazel

Invited lecturers

Luc Jaouen

Dr. Luc Jaouen is co-founder and co-manager of MATELYS (France). He is also co-founder of SAPEM cycle of conferences. He has a broad experience of porous media theory. His works cover experimental techniques for both acoustical and mechanical parameter characterization and theoretical modeling of multi-scale materials. From his work at MATELYS, he has a unique experience of the application of porous media research to address industrial concerns. He is also the founder of the APMR website (Acoustical Porous Media Recipes) you are currently browsing.
MATELYS has been awarded the Research Gold Decibel in 2011 in France and Industry Award from the French Acoustical Society in 2012.

Claude Boutin

Claude Boutin holds a Professor position at ENTPE (France). He is widely renown as a specialist of the so-called homogenisation approaches and up-scaling techniques. He is involved in pioneer works related to double porosity media and morphological modelling both from analytical and numerical approaches. His works have found applications in a wide range of fields, from seismic wave propagation and high rise buildings to micro-porous mechanics and double porosity sound absorbers.

Timothy Van Renterghem

Timothy Van Renterghem has a long-term experience with time domain approaches and is known in the community as a specialist of this type of implementation. Being Professor in the Acoustic group of Gent Univ. (Belgium), he is author or co-author of about 30 peer-reviewed journal publications. He is associate editor for Acta Acustica united with Acustica, the journal of the European Acoustic Association in the field of atmospheric acoustics. He teaches courses on environmental noise, instrumentation, and numerical acoustics at Ghent University in Belgium.

Raymond Panneton

Raymond Panneton is Professor at GAUS lab (Univ. de Sherbrooke - Canada), known among the world's specialists of characterisation techniques for acoustical porous media. He has proposed several techniques which are now commonly used by the community. He has supervised over twenty Master and PhD works related to porous material characterisation. His works spans direct and indirect approaches for the determination of the acoustical, elastical and damping parameters.

Sylvain Berger

Dr. Sylvain Berger is in charge of the acoustic R&D at Saint-Gobain Isover and involved in the acoustic transverse program of Saint Gobain group, which brands (Isover, Eurocoustic, St Gobain Glass, Gypse, ADFORS...) comprise Buildings, Automotive, Railway, Aeronautics, Marine, Domestic appliances applications. He will bring his critical view about the gap crossing from characterisation techniques, predicting models and performance achievement in a highly competitive context and ever shorter time-to-market demands.

Arnaud Duval

Ing. Arnaud Duval is the innovation and research director at Faurecia Acoustic and Soft Trim Division, which is a major automotive supplier working with leading automotive manufacturers. He has lead several cutting edge innovations to industrial standards. He co-authored a dozen of patents related to materials manufacturing and assembling and more than 25 engineering papers. He has been nominated official "Senior Expert" in the field of acoustics for the Faurecia group.

Peter Göransson

Peter Göransson is Professor at the Marcus Wallenberg lab at KTH (Sweden) and is recognized as a world's specialist of the finite element method. He has collaborated to pioneer works related to convergence criteria and proposed several improvements of the numerical efficiency of porous media models. He is daily collaborating with leading manufacturing companies for Automotive, Railway, Aeronautics and Aerospace applications. His talk will be closely coordinated with that of Dr. Olivier Dazel related to numerical techniques other than purely finite element methods.

Olivier Dazel

Dr.-HDR Olivier Dazel, assistant professor at LAUM (Univ. du Maine-France), has a long track record of successful applications of advanced mathematical techniques for the implementation of porous numerical models. His work is long devoted to the improvement of the efficiency, convergence and accuracy of computational approaches dedicated to porous media. He is also a leading actor for the development of advanced teaching techniques for vibro-acoustics. He will present the numerical methods which are not purely finite element implementations, namely statistical energy analysis (SEA), transfer matrix method (TMM), wave based method and other hybrid approaches. His talk will be closely coordinated with that of Prof. Peter Göransson about purely finite element methods.