SPRINGER BRIEFS IN MATHEMATICS Jan S. Hesthaven Gianluigi Rozza Benjamin Stamm Certified Reduced Basis Methods for Parametrized Partial Differential Equations 123 SpringerBriefs in Mathematics Series editors Nicola Bellomo, Torino, Italy Michele Benzi, Atlanta, USA Palle E.T. Jorgensen, Iowa City, USA Tatsien Li, Shanghai, China Roderick V.N. Melnik, Waterloo, Canada Otmar Scherzer, Vienna, Austria Benjamin Steinberg, New York, USA Lothar Reichel, Kent, USA Yuri Tschinkel, New York, USA G. George Yin, Detroit, USA Ping Zhang, Kalamazoo, USA SpringerBriefsinMathematicsshowcasesexpositionsinallareasofmathematics andappliedmathematics.Manuscriptspresentingnewresultsorasinglenewresult inaclassicalfield,newfield,oranemergingtopic,applications,orbridgesbetween newresultsandalreadypublishedworks,areencouraged.Theseriesisintendedfor mathematicians and applied mathematicians. BCAM SpringerBriefs Editorial Board Enrique Zuazua BCAM—Basque Center for Applied Mathematics & Ikerbasque Bilbao, Basque Country, Spain Irene Fonseca Center for Nonlinear Analysis Department of Mathematical Sciences Carnegie Mellon University Pittsburgh, USA Juan J. Manfredi Department of Mathematics University of Pittsburgh Pittsburgh, USA Emmanuel Trélat Laboratoire Jacques-Louis Lions Institut Universitaire de France Université Pierre et Marie Curie CNRS, UMR, Paris Xu Zhang School of Mathematics Sichuan University Chengdu, China BCAM SpringerBriefs aims to publish contributions in the following disciplines: Applied Mathematics, Finance, Statistics and Computer Science. BCAM has appointed an Editorial Board, who evaluate and review proposals. 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Hesthaven Gianluigi Rozza (cid:129) Benjamin Stamm fi Certi ed Reduced Basis Methods for Parametrized Partial Differential Equations 123 Jan S.Hesthaven Benjamin Stamm EPFL-SB-MATHICSE-MCSS Laboratoire Jacques-Louis Lions EcolePolytechnique Fédérale deLausanne SorbonneUniversités,UPMCUnivParis06, EPFL CNRS Lausanne Paris Cedex 05 Switzerland France Gianluigi Rozza SISSAMathLab International Schoolfor AdvancedStudies Trieste Italy ISSN 2191-8198 ISSN 2191-8201 (electronic) SpringerBriefs inMathematics ISBN978-3-319-22469-5 ISBN978-3-319-22470-1 (eBook) DOI 10.1007/978-3-319-22470-1 LibraryofCongressControlNumber:2015946080 SpringerChamHeidelbergNewYorkDordrechtLondon ©TheAuthor(s)2016 Thisworkissubjecttocopyright.AllrightsarereservedbythePublisher,whetherthewholeorpart of the material is concerned, specifically the rights of translation, reprinting, reuse of illustrations, recitation, broadcasting, reproduction on microfilms or in any other physical way, and transmission orinformationstorageandretrieval,electronicadaptation,computersoftware,orbysimilarordissimilar methodologynowknownorhereafterdeveloped. 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Printedonacid-freepaper SpringerInternationalPublishingAGSwitzerlandispartofSpringerScience+BusinessMedia (www.springer.com) To our families and friends Preface During the past decade, reduced order modeling has attracted growing interest in computationalscienceandengineering.Itnowplaysanimportantroleindelivering high-performancecomputing(andbridgingapplications)acrossindustrialdomains, from mechanical to electronic engineering, and in the basic and applied sciences, including neurosciences, medicine, biology, chemistry, etc. Such methods are also becoming increasingly important in emerging application domains dominated by multi-physics, multi-scale problems as well as uncertainty quantification. This book seeks to introduce graduate students, professional scientists, and engineers to a particular branch in the development of reduced order modeling, characterized by the provision of reduced models of guaranteed fidelity. This is a fundamentaldevelopmentthatenablestheusertotrusttheoutputofthemodeland balancetheneedsforcomputationalefficiencyandmodelfidelity.Thetextdevelops theseideasbypresentingthefundamentalswithagraduallyincreasingcomplexity; comparisons are made with more traditional techniques and the performance illustratedbymeansofafewcarefullychosenexamples.Thebookdoesnotseekto replace review articles on the topics (such as [1–5]) but aims to widen the per- spectives on reduced basis methods and to provide an integrated presentation. The text begins with a basic setting to introduce the general elements of certified reduced basis methods for elliptic affine coercive problems with linear compliant outputs and then gradually widens the field, with extensions to non-affine, non-compliant, non-coercive operators, geometrical parametrization and time- dependent problems. Wewouldliketopointoutsomeoriginalingredientsofthetext.Chapter3guides the reader through different sampling strategies, providing a comparison between classictechniquesbasedonsingularvaluedecomposition(SVD),properorthogonal decomposition(POD),andgreedyalgorithms.Inthiscontextitalsodiscussesrecent results on a priori convergence in the context of the concept of the Kolmogorov N-width[6].Chapter4containsathoroughdiscussionofthecomputationoflower boundsforstabilityfactorsandacomparativediscussionofthevarioustechniques. Chapter 5 focuses on the empirical interpolation method (EIM) [7], which is emerging as a standard element to address problems exhibiting non-affine vii viii Preface parametrizations and nonlinearities. It is our hope that these last two chapters will provide a useful overview of more recent material, allowing readers who wish to address more advanced problems to pursue the development of reduced basis methods for applications of interest to them. Chapter 6 offers an overview of a numberofmoreadvanceddevelopmentsandisintendedmoreasanappetizerthanas a solution manual. Throughout the text we provide some illustrative examples of applications in computational mechanics to guide readers through the various topics. All of the mainalgorithmicelementsareoutlinedbygraphicalboxestoassistthereaderinhis or her efforts to implement the algorithms, emphasizing a matrix notation. An appendix with mathematical preliminaries is also included. This book is loosely based on a Reduced Basis handbook available online [8], and we thank the co-author of this handbook, our colleague Anthony T. Patera (MIT),forhisencouragement,support,andadviceduringthewritingofthebook.It benefitsfromourlong-lastingcollaborationwithhimandhismanyco-workers.We wouldliketoacknowledgeallthosecolleagueswhocontributedatvariouslevelsin thepreparationofthismanuscriptandtherelatedresearch.Inparticular,we would like to thank Francesco Ballarin and Alberto Sartori for preparing representative tutorialsandthenewopen-sourcesoftwarelibraryavailableasacompaniontothis book at http://mathlab.sissa.it/rbnics. An important role, including the provision of useful feedback, was also played by our very talented and motivated students attending regular doctoral and master classes at EPFL and SISSA (and ICTP), tutorials in Minneapolis and Savannah, and several summer/winter schools on the topic in Paris, Cortona, Hamburg, Udine (CISM), Munich, Sevilla, Pamplona, Barcelona, Torino, and Bilbao. Lausanne, Switzerland Jan S. Hesthaven Trieste, Italy Gianluigi Rozza Paris, France Benjamin Stamm June 2015 References 1. C. Prudhomme, D.V. Rovas, K. Veroy, L. Machiels, Y. Maday, A.T. Patera, G. Turinici, Reliablereal-timesolutionofparametrizedpartialdifferentialequations:reduced-basisoutput boundmethods.J.FluidsEng.124,70–80(2002) 2.A.Quarteroni,G.Rozza,A.Manzoni,Certifiedreducedbasisapproximationforparametrized PDEandapplications.J.MathInd.3(2011) 3.G.Rozza,FundamentalsofreducedbasismethodforproblemsgovernedbyparametrizedPDEs andapplications,inCISM Lecturesnotes“SeparatedRepresentationandPGDbasedmodel reduction:fundamentalsandapplications”(SpringerVienna,2014) Preface ix 4. G. Rozza, P. Huynh, N.C. Nguyen, A.T. Patera, Real-Time Reliable Simulation of Heat Transfer Phenomena, in ASME, Heat Transfer Summer Conference collocated with the InterPACK09 and 3rd Energy Sustainability Conferences, American Society of Mechanical Engineers(2009),pp.851–860 5.G.Rozza,P.Huynh,A.T.Patera,Reducedbasisapproximationandaposteriorierrorestimation foraffinelyparametrizedellipticcoercivepartialdifferentialequations:Applicationtotransport andcontinuummechanics.Arch.Comput.MethodsEng.15,229–275(2008) 6.P.Binev,A.Cohen,W.Dahmen,R.DeVore,G.Petrova,P.Wojtaszczyk,Convergencerates forgreedyalgorithmsinreducedbasismethods.SIAMJ.Math.Anal.43,1457–1472(2011) 7. M. Barrault, Y. Maday, N.C. Nguyen, A.T. Patera, An empirical interpolation method: applicationtoefficientreduced-basisdiscretizationofpartialdifferentialequations.C.R.Math. 339,667–672(2004) 8. A.T. Patera, G. Rozza, Reduced Basis Approximation and A Posteriori Error Estimation for ParametrizedPartialDifferentialEquations,CopyrightMIT2007,MITPappalardoGraduate MonographsinMechanicalEngineering,http://www.augustine.mit.edu,2007 Contents 1 Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 1.1 Historical Background and Perspectives. . . . . . . . . . . . . . . . 2 1.2 About this Book. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 1.3 Software Libraries with Support for Reduced Basis Algorithms and Applications . . . . . . . . . . . . . . . . . . . . . . . 6 References. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 2 Parametrized Differential Equations . . . . . . . . . . . . . . . . . . . . . . 15 2.1 Parametrized Variational Problems . . . . . . . . . . . . . . . . . . . 15 2.1.1 Parametric Weak Formulation. . . . . . . . . . . . . . . . . 16 2.1.2 Inner Products, Norms and Well-Posedness of the Parametric Weak Formulation . . . . . . . . . . . . 16 2.2 Discretization Techniques. . . . . . . . . . . . . . . . . . . . . . . . . . 17 2.3 Toy Problems. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 2.3.1 Illustrative Example 1: Heat Conduction Part 1. . . . . 20 2.3.2 Illustrative Example 2: Linear Elasticity Part 1. . . . . 22 References. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25 3 Reduced Basis Methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27 3.1 The Solution Manifold and the Reduced Basis Approximation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28 3.2 Reduced Basis Space Generation. . . . . . . . . . . . . . . . . . . . . 31 3.2.1 Proper Orthogonal Decomposition (POD). . . . . . . . . 32 3.2.2 Greedy Basis Generation . . . . . . . . . . . . . . . . . . . . 34 3.3 Ensuring Efficiency Through the Affine Decomposition. . . . . 37 3.4 Illustrative Examples. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39 3.4.1 Illustrative Example 1: Heat Conduction Part 2. . . . . 39 3.4.2 Illustrative Example 2: Linear Elasticity Part 2. . . . . 41 3.5 Summary of the Method . . . . . . . . . . . . . . . . . . . . . . . . . . 42 References. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43 xi