C. R. Mecanique 347 (2019) 271–272
Contents lists available atScienceDirect
Comptes Rendus Mecanique
www.sciencedirect.com
Patterns and dynamics: homage to Pierre Coullet / Formes et dynamique : hommage à Pierre Coullet
Foreword
ThisthematicissueoftheComptesrendusMecanique isdedicatedto PierreCoullet,adefinitelyoriginalcharacter inthe scientificlandscape.PierrestudiedattheUniversityofNice,whereheobtainedaMasterthesis(so-calledthèsedetroisième cycleatthetime)supervisedbyEnriqueTirapeguionthetopicoftherenormalizationgroupinfieldtheory.Hethengothis PhD(thèsed’État)underthesupervisionofJean Coste.Thisresearch ledhim,inan unexpectedway,toexploittheideas of fixedpointandfunctionalequationinadomainfullyoriginalatthetime:whereasthebifurcationofalimitcyclebyperiod doubling was well known,the discovery by Pierreand CharlesTresser ofan infiniteset of period doubling bifurcations in a finite range of parameters, together with its properties of universality, was a complete surprise. This research has openedanewfieldinthetheoryofbifurcationsandofdynamicalsystemswithafewdegreesoffreedom.Thesewonderful theoreticalworkshavegivenrisetomanyapplicationsandnewexperiments.Notably,fluidmechanicsexperimentsdirected himnaturallytothestudyofchaoticphenomenainspatiallyextendedsystems,withmanydegreesoffreedom.
Pierrehasan originalview aswellasaverydeepunderstandingoftheunderlyingphysicalmechanisms.However,his mostsalientcharacteristic is,perhaps, thedesire to experience noveltyin science,in technologyandin life, ashemade innovations since hisearly scientific age.In themid 1980’s,heswitchedfrom thestudyoffinite-dimensional dynamical systemstotheunderstandingofpartialdifferentialequations(PDE’s).Verysoonheunderstoodthatthequalitativebehav- ior ofpartialdifferentialequationsrequires intensivenumericalsimulations.He broughtafirst pairofAppleMcIntosh to the “Laboratoirede physique théorique”atParc Valrose inNice. Hisfirst studyconcerned thecomplex Ginzburg–Landau equation,atopiconwhichhereceivedthehelpofhisnowformerstudentsLionelGilandJocelyneLega.
He was one of the first to understand that nonlinear optics belonged also to this field. This led him to predict the existence of a regime of turbulence mediated by optical vortices, a regime indeed observed afterwards (Fig. 1). In his
Fig. 1.Curvedmirrorwithconcaveandconvexdomains:illustrationoftheproblemofgeometricaberrationandmultipleimages(problemposedbyPtolemy andsolvedinthesimplecaseofasphericalconcavemirrorbyIbnal-Haitham).Thephotographer’sfaceappearsthreetimesintheimage.Onceisolated,in themiddlerightandthendoubled,inthevicinityofasaddlenodebifurcationintheupperpartofthepicture,slightlytotherightofitscenter.Artwork conceptionbyPierreCoullet,picturebySergioRica.
https://doi.org/10.1016/j.crme.2019.03.009
1631-0721/©2019PublishedbyElsevierMassonSASonbehalfofAcadémiedessciences.ThisisanopenaccessarticleundertheCCBY-NC-NDlicense (http://creativecommons.org/licenses/by-nc-nd/4.0/).
272 Patterns and dynamics: homage to Pierre Coullet / Formes et dynamique : hommage à Pierre Coullet
quest forthebest,Pierregot a fewadvanced Sunsparc workstationsandheandhis team(particularly Kjartan Emilsson) developedoriginalinteractivenumericalsimulations,largelyrecognizedasarevolutionaryinnovation.Themainpurposeof aninteractivenumericalsimulation(insteadofsimulationrunninginbatch)isthattheusercaninteractwiththesimulation, changingthevaluesofthecontrolparameters duringthecomputation itselfforinstance,withtheroutinethatsimulatesa physical systemgoverned byelementary ruleslikein PDE’s.Thistool madepossibleabig stepforwardinthequalitative understanding ofthebehaviorofPDE’s.It isimpossibletoenumeratethemanydirectorindirectnewideas generatedin this way.Today heprograms andteaches Swifth(the language forMacOS) always withthe samepassionasin hisearly days.Asacommonprinciple,Pierrealwaysexperiencesthelasttechnologicalreleaseoreverythinghecouldusetosolvea problemorexpressanideainabetterway,adistinctfeatureofPierre’scharacter.
These remarkableachievementsearned hima well-deservedscientific recognitionnationally andabroadtestified bya number of awards: Langevin Prize of the French Physical Society (1990), C.S. Freycinet Prize of the French Academy of Sciences (1991), Silvermedal oftheCNRS(1993),Foreign memberoftheChilean AcademyofSciences (1999),Humboldt Prize(Germany,2000),HolweckPrizefromtheSFPandIOP(2001).
Remainingthe sameveryinventiveandprolificresearcher,Pierreisspending muchtime andeffortsinthe trainingof young researchersandinimproving thepedagogy ofphysicsat alllevels, includingtoprimary andhighschool teachers, tothegeneralpublic,andwithinadvancedsessionsinprestigiousinstitutesandfoundations.Hispassionforthehistoryof sciencehasleadhimtoareconsider,fromamodernpointofview,someclassicalproblemsinopticsandmechanics.
He puts a lot of energy to successfully federate actions forresearch in his University. Remaining at the forefront of worldwideresearch,withmultiplecollaborationsandabusyactivity,hehaskeptintactthegaietyofhischaracterandhis friendlyandoptimisticpersonality.
We wish you,dear Pierre, tocontinue withyourgood moodandtostay onthistrajectoryof aman andaresearcher withjustasmuchinventivenessandbeautifuldiscoveries.
Pierre Collet Centredephysiquethéorique,CNRSUMR7644,Écolepolytechnique,91128Palaiseaucedex,France Christophe Josserand,Yves Pomeau LadHyX,CNRS,Écolepolytechnique,Palaiseau,France E-mailaddresses:christophe.josserand@polytechnique.edu(C.Josserand),yves.pomeau@gmail.com(Y.Pomeau) Sergio Rica FacultaddeIngenieríayCiencias,UniversidadAdolfoIbáñez,Santiago,Chile PhysicsCenter,UniversidadAdolfoIbáñez,Santiago,Chile E-mailaddress:sergio.rica@uai.cl Emmanuel Villermaux∗ Aix–MarseilleUniversité,CNRS,CentraleMarseille,IRPHE,Marseille,France E-mailaddress:emmanuel.villermaux@univ-amu.fr Availableonline1April2019
*Correspondingauthor.
