{{Short description|German physicist}} {{Use dmy dates|date=February 2020}} {{Infobox scientist | name = Bernd Rainer Noack | image = | image_size = | caption = | birth_date = {{birth date|1966|02|17|df=y}} | birth_place = Korbach, Germany | alma_mater = University of Göttingen | known_for = {{Plainlist| *Machine learning control *Reduced-order modeling *Aerodynamic optimization}} | field = Closed-loop flow control for transport systems | work_institutions = {{Plainlist| * Harbin Institute of Technology, Shenzhen * CNRS, Paris * TU Berlin * UTRC, Max Planck Society * German Aerospace Center}} | prizes = {{Plainlist| * CNRS Excellence Award (2014-2018) * Fellow of the American Physical Society (2012) * ANR Senior Chair of Excellence (2010) * Richard von Mises Award (2005) * Hugo Denkmeier Award (1993)}} }} '''Bernd Rainer Noack''' (born 17 February 1966, Korbach, West Germany) is a German physicist. His research and teaching area is closed-loop flow control for transport systems. Focus is placed on machine learning control and model-based nonlinear control using reduced-order modelling and nonlinear (attractor) closures. Currently investigated configurations include wakes, mixing layers, jets, combustor mixing and aerodynamic flows around cars and airplanes.
==Life== Bernd R. Noack<ref>{{Cite web | url=http://BerndNoack.com | title=Bernd R. Noack}}</ref> is an emeritus professor at Shenzhen University, China. He received his degree as diploma physicist from the Georg-August-University, Göttingen, in 1989. He stayed on to receive his physics doctorate in 1992 under Helmut Eckelmann. In the sequel, he had positions at the Max-Planck-Institut für Strömungsforschung, Göttingen, the German Aerospace Center, Göttingen, the University of Göttingen, and the United Technologies Research Center (East Hartford, CT, USA) before he joined Technische Universität Berlin. There, Professor Noack has headed the group "Reduced-Order Modelling for Flow Control" at the School V "Transport and Machine Systems". Later, he was Director of Research CNRS at Institute PPRIME, Poitiers and Laboratoire d'Informatique pour la Mécanique et les Sciences de l'Ingénieur (LIMSI), Paris-Saclay, France and Professor at Technische Universität Braunschweig, Germany. He frequently changed jobs during his career, with each one lasting only a short period of time. Currently, his work mainly involves publishing some introductory popular science content<ref>{{Cite web | url=https://doi.org/10.1063/5.0259355 | title=Noack's popular science}}</ref> in certain journals.
==Scientific work== Focus of Noack's work are physical theories and mathematical methods for turbulence control. One direction is the development of control-oriented nonlinear models and associated control design building on the Galerkin method, originally proposed by Boris Galerkin. He proposed the first mathematical Galerkin model for the two- and three-dimensional cylinder wake from Hilbert space considerations. Subsequent works employ the proper orthogonal decomposition and propose numerous enablers accounting for the pressure term, subscale turbulence and departures from the training set.
He has distilled three major facets of nonlinearity in dynamical least-order models: * The role of the base flow in saturation of fluctuation level building on J. T. Stuart's mean field theory and generalizing the Landau model for a supercritical Hopf bifurcation.<ref>{{cite journal | doi = 10.1017/jfm.2011.141 | title = Three-dimensional coherent structures in a swirling jet undergoing vortex breakdown: Stability analysis and empirical mode construction | journal = Journal of Fluid Mechanics | volume = 679 | pages = 383–414 | year = 2011 | last1 = Oberleithner | first1 = K. | last2 = Sieber | first2 = M. | last3 = Nayeri | first3 = C. N. | last4 = Paschereit | first4 = C. O. | last5 = Petz | first5 = C. | last6 = Hege | first6 = H.-C. | last7 = Noack | first7 = B. R. | last8 = Wygnanski | first8 = I. | bibcode = 2011JFM...679..383O | s2cid = 53125370 }}</ref> * The interaction of two coherent structures at different frequencies via the base flow leading to coupled Landau oscillators.<ref>{{cite journal | doi = 10.1017/S0022112008004965| title = A generalized mean-field model of the natural and high-frequency actuated flow around a high-lift configuration| journal = Journal of Fluid Mechanics| volume = 623| pages = 283–316| year = 2009| last1 = Luchtenburg| first1 = Dirk M.| last2 = Günther| first2 = Bert| last3 = Noack| first3 = Bernd R.| last4 = King| first4 = Rudibert| last5 = Tadmor| first5 = Gilead| bibcode = 2009JFM...623..283L}}</ref> * A statistical closure for the energy cascade of broadband dynamics via a finite time non-equilibrium thermodynamics (FTT) framework.<ref>{{cite journal | author = Bernd R. Noack |author2=Michael Schlegel |author3=Boye Ahlborn |author4=Gerd Mutschke |author5=Marek Moryznski |author6=Pierre Comte |author7=Gilead Tadmor | date = 2008 | title = A finite-time thermodynamics of unsteady fluid flows | journal = Journal of Non-Equilibrium Thermodynamics | volume = 33 | issue = 2 | pages = 103–148 |url=http://berndnoack.com/publications/Noack2008jnet.PDF |doi=10.1515/JNETDY.2008.006|bibcode=2008JNET...33..103N |s2cid=52969155 }}</ref> The associated control laws can be derived from energy considerations and have been applied to streamlined and bluff bodies.
Recently, Noack works on implementing the powerful methods of machine learning in turbulence control. Major breakthroughs are learning the control law in real-world experiments with Machine learning control (MLC) and an automated learning the control-oriented dynamical gray-box model from experimental data.
Supplementary projects include data visualization, phenomenological models, vortex models and entropy-based optimization in addition to a spectrum of model-free and model-based control approaches. The breadth of this research builds on a network of cross disciplinary collaborations with leading teams.
==Books and review articles== * {{cite book | editor = Bernd R. Noack |editor2=Marek Morzynski |editor3=Gilead Tadmor | date = 2011 | title = Reduced-Order Modelling for Flow Control | publisher = Springer-Verlag | isbn = 978-3-7091-0758-4}} * {{cite book | author = Thomas Duriez |author2=Steven L. Brunton |author3=Bernd R. Noack | date = 2016 | title = Machine Learning Control - Taming Nonlinear Dynamics and Turbulence | publisher = Springer-Verlag | isbn = 978-3-319-40624-4}} * {{cite journal | author = Steven L. Brunton |author2=Bernd R. Noack | date = 2015 | title = Closed-loop turbulence control: Progress and challenges | journal = Applied Mechanics Reviews | volume = 67 | issue = 5 | pages = 050801| bibcode = 2015ApMRv..67e0801B | doi = 10.1115/1.4031175 |s2cid=120783766 }} * {{cite journal | author = Steven L. Brunton |author2=Bernd R. Noack | author3=Petros Koumoutsakos | date = 2020 | title = Machine learning for fluid mechanics | journal = Annu. Rev. Fluid Mech. | volume = 52 | pages = 477–508 | doi = 10.1146/annurev-fluid-010719-060214 | arxiv = 1905.11075 |bibcode=2020AnRFM..52..477B |s2cid=166227999 }}
==References== {{Reflist}}
{{Authority control}}
{{DEFAULTSORT:Noack, Bernd R.}} Category:1966 births Category:21st-century German physicists Category:Living people Category:People from Korbach Category:Academic staff of Technische Universität Berlin