--- _id: '10654' abstract: - lang: eng text: "Directed percolation (DP) has recently emerged as a possible solution to the century old puzzle surrounding the transition to turbulence. Multiple model studies reported DP exponents, however, experimental evidence is limited since the largest possible observation times are orders of magnitude shorter than the flows’ characteristic timescales. An exception is cylindrical Couette flow where the limit is not temporal, but rather the realizable system size. We present experiments in a Couette setup of unprecedented azimuthal and axial aspect ratios. Approaching the critical point to within less than 0.1% we determine five critical exponents, all of which are in excellent agreement with the 2+1D DP universality class. The complex dynamics encountered at \r\nthe onset of turbulence can hence be fully rationalized within the framework of statistical mechanics." acknowledged_ssus: - _id: M-Shop acknowledgement: "We thank T.Menner, T.Asenov, P. Maier and the Miba machine shop of IST Austria for their valuable support in all technical aspects. We thank Marc Avila for comments on the manuscript. This work was supported by a grant from the Simons Foundation (662960, B.H.). We acknowledge the European Research Council under the European Union’s Seventh Framework Programme (FP/2007-2013)/ERC Grant Agreement 306589 for financial support. K.A.\r\nacknowledges funding from the Central Research Development Fund of the University of Bremen, grant number ZF04B /2019/FB04 Avila Kerstin (”Independent Project for Postdocs”). L.K. was supported by the European Union’s Horizon 2020 Research and innovation programme under the Marie Sklodowska-Curie grant agreement No. 754411.\r\n" article_number: '014502' article_processing_charge: No article_type: original author: - first_name: Lukasz full_name: Klotz, Lukasz id: 2C9AF1C2-F248-11E8-B48F-1D18A9856A87 last_name: Klotz orcid: 0000-0003-1740-7635 - first_name: Grégoire M full_name: Lemoult, Grégoire M id: 4787FE80-F248-11E8-B48F-1D18A9856A87 last_name: Lemoult - first_name: Kerstin full_name: Avila, Kerstin last_name: Avila - first_name: Björn full_name: Hof, Björn id: 3A374330-F248-11E8-B48F-1D18A9856A87 last_name: Hof orcid: 0000-0003-2057-2754 citation: ama: Klotz L, Lemoult GM, Avila K, Hof B. Phase transition to turbulence in spatially extended shear flows. Physical Review Letters. 2022;128(1). doi:10.1103/PhysRevLett.128.014502 apa: Klotz, L., Lemoult, G. M., Avila, K., & Hof, B. (2022). Phase transition to turbulence in spatially extended shear flows. Physical Review Letters. American Physical Society. https://doi.org/10.1103/PhysRevLett.128.014502 chicago: Klotz, Lukasz, Grégoire M Lemoult, Kerstin Avila, and Björn Hof. “Phase Transition to Turbulence in Spatially Extended Shear Flows.” Physical Review Letters. American Physical Society, 2022. https://doi.org/10.1103/PhysRevLett.128.014502. ieee: L. Klotz, G. M. Lemoult, K. Avila, and B. Hof, “Phase transition to turbulence in spatially extended shear flows,” Physical Review Letters, vol. 128, no. 1. American Physical Society, 2022. ista: Klotz L, Lemoult GM, Avila K, Hof B. 2022. Phase transition to turbulence in spatially extended shear flows. Physical Review Letters. 128(1), 014502. mla: Klotz, Lukasz, et al. “Phase Transition to Turbulence in Spatially Extended Shear Flows.” Physical Review Letters, vol. 128, no. 1, 014502, American Physical Society, 2022, doi:10.1103/PhysRevLett.128.014502. short: L. Klotz, G.M. Lemoult, K. Avila, B. Hof, Physical Review Letters 128 (2022). date_created: 2022-01-23T23:01:28Z date_published: 2022-01-05T00:00:00Z date_updated: 2023-08-02T13:59:19Z day: '05' department: - _id: BjHo doi: 10.1103/PhysRevLett.128.014502 ec_funded: 1 external_id: arxiv: - '2111.14894' isi: - '000748271700010' pmid: - '35061458' intvolume: ' 128' isi: 1 issue: '1' language: - iso: eng main_file_link: - open_access: '1' url: https://arxiv.org/abs/2111.14894 month: '01' oa: 1 oa_version: Preprint pmid: 1 project: - _id: 260C2330-B435-11E9-9278-68D0E5697425 call_identifier: H2020 grant_number: '754411' name: ISTplus - Postdoctoral Fellowships - _id: 25152F3A-B435-11E9-9278-68D0E5697425 call_identifier: FP7 grant_number: '306589' name: Decoding the complexity of turbulence at its origin - _id: 238598C6-32DE-11EA-91FC-C7463DDC885E grant_number: '662960' name: 'Revisiting the Turbulence Problem Using Statistical Mechanics: Experimental Studies on Transitional and Turbulent Flows' publication: Physical Review Letters publication_identifier: eissn: - 1079-7114 issn: - 0031-9007 publication_status: published publisher: American Physical Society quality_controlled: '1' scopus_import: '1' status: public title: Phase transition to turbulence in spatially extended shear flows type: journal_article user_id: 4359f0d1-fa6c-11eb-b949-802e58b17ae8 volume: 128 year: '2022' ... --- _id: '513' abstract: - lang: eng text: 'We present an experimental setup that creates a shear flow with zero mean advection velocity achieved by counterbalancing the nonzero streamwise pressure gradient by moving boundaries, which generates plane Couette-Poiseuille flow. We obtain experimental results in the transitional regime for this flow. Using flow visualization, we characterize the subcritical transition to turbulence in Couette-Poiseuille flow and show the existence of turbulent spots generated by a permanent perturbation. Due to the zero mean advection velocity of the base profile, these turbulent structures are nearly stationary. We distinguish two regions of the turbulent spot: the active turbulent core, which is characterized by waviness of the streaks similar to traveling waves, and the surrounding region, which includes in addition the weak undisturbed streaks and oblique waves at the laminar-turbulent interface. We also study the dependence of the size of these two regions on Reynolds number. Finally, we show that the traveling waves move in the downstream (Poiseuille) direction.' article_number: '043904' author: - first_name: Lukasz full_name: Klotz, Lukasz id: 2C9AF1C2-F248-11E8-B48F-1D18A9856A87 last_name: Klotz orcid: 0000-0003-1740-7635 - first_name: Grégoire M full_name: Lemoult, Grégoire M id: 4787FE80-F248-11E8-B48F-1D18A9856A87 last_name: Lemoult - first_name: Idalia full_name: Frontczak, Idalia last_name: Frontczak - first_name: Laurette full_name: Tuckerman, Laurette last_name: Tuckerman - first_name: José full_name: Wesfreid, José last_name: Wesfreid citation: ama: 'Klotz L, Lemoult GM, Frontczak I, Tuckerman L, Wesfreid J. Couette-Poiseuille flow experiment with zero mean advection velocity: Subcritical transition to turbulence. Physical Review Fluids. 2017;2(4). doi:10.1103/PhysRevFluids.2.043904' apa: 'Klotz, L., Lemoult, G. M., Frontczak, I., Tuckerman, L., & Wesfreid, J. (2017). Couette-Poiseuille flow experiment with zero mean advection velocity: Subcritical transition to turbulence. Physical Review Fluids. American Physical Society. https://doi.org/10.1103/PhysRevFluids.2.043904' chicago: 'Klotz, Lukasz, Grégoire M Lemoult, Idalia Frontczak, Laurette Tuckerman, and José Wesfreid. “Couette-Poiseuille Flow Experiment with Zero Mean Advection Velocity: Subcritical Transition to Turbulence.” Physical Review Fluids. American Physical Society, 2017. https://doi.org/10.1103/PhysRevFluids.2.043904.' ieee: 'L. Klotz, G. M. Lemoult, I. Frontczak, L. Tuckerman, and J. Wesfreid, “Couette-Poiseuille flow experiment with zero mean advection velocity: Subcritical transition to turbulence,” Physical Review Fluids, vol. 2, no. 4. American Physical Society, 2017.' ista: 'Klotz L, Lemoult GM, Frontczak I, Tuckerman L, Wesfreid J. 2017. Couette-Poiseuille flow experiment with zero mean advection velocity: Subcritical transition to turbulence. Physical Review Fluids. 2(4), 043904.' mla: 'Klotz, Lukasz, et al. “Couette-Poiseuille Flow Experiment with Zero Mean Advection Velocity: Subcritical Transition to Turbulence.” Physical Review Fluids, vol. 2, no. 4, 043904, American Physical Society, 2017, doi:10.1103/PhysRevFluids.2.043904.' short: L. Klotz, G.M. Lemoult, I. Frontczak, L. Tuckerman, J. Wesfreid, Physical Review Fluids 2 (2017). date_created: 2018-12-11T11:46:54Z date_published: 2017-04-01T00:00:00Z date_updated: 2021-01-12T08:01:16Z day: '01' department: - _id: BjHo doi: 10.1103/PhysRevFluids.2.043904 intvolume: ' 2' issue: '4' language: - iso: eng main_file_link: - open_access: '1' url: https://arxiv.org/abs/1704.02619 month: '04' oa: 1 oa_version: Preprint publication: Physical Review Fluids publication_status: published publisher: American Physical Society publist_id: '7306' quality_controlled: '1' scopus_import: 1 status: public title: 'Couette-Poiseuille flow experiment with zero mean advection velocity: Subcritical transition to turbulence' type: journal_article user_id: 2DF688A6-F248-11E8-B48F-1D18A9856A87 volume: 2 year: '2017' ... --- _id: '1494' abstract: - lang: eng text: Turbulence is one of the most frequently encountered non-equilibrium phenomena in nature, yet characterizing the transition that gives rise to turbulence in basic shear flows has remained an elusive task. Although, in recent studies, critical points marking the onset of sustained turbulence have been determined for several such flows, the physical nature of the transition could not be fully explained. In extensive experimental and computational studies we show for the example of Couette flow that the onset of turbulence is a second-order phase transition and falls into the directed percolation universality class. Consequently, the complex laminar–turbulent patterns distinctive for the onset of turbulence in shear flows result from short-range interactions of turbulent domains and are characterized by universal critical exponents. More generally, our study demonstrates that even high-dimensional systems far from equilibrium such as turbulence exhibit universality at onset and that here the collective dynamics obeys simple rules. acknowledgement: We thank P. Maier for providing valuable ideas and supporting us in the technical aspects. Discussions with D. Barkley, Y. Duguet, B. Eckhart, N. Goldenfeld, P. Manneville and K. Takeuchi are gratefully acknowledged. We acknowledge the Deutsche Forschungsgemeinschaft (Project No. FOR 1182), and the European Research Council under the European Union’s Seventh Framework Programme (FP/2007-2013)/ERC Grant Agreement 306589 for financial support. L.S. and B.H. acknowledge research funding by Deutsche Forschungsgemeinschaft (DFG) under Grant No. SFB 963/1 (project A8). Numerical simulations were performed thanks to the CPU time allocations of JUROPA in Juelich Supercomputing Center (project HGU17) and of the Max Planck Computing and Data Facility (Garching, Germany). Excellent technical support from M. Rampp on the hybrid code nsCouette is appreciated. author: - first_name: Grégoire M full_name: Lemoult, Grégoire M id: 4787FE80-F248-11E8-B48F-1D18A9856A87 last_name: Lemoult - first_name: Liang full_name: Shi, Liang id: 374A3F1A-F248-11E8-B48F-1D18A9856A87 last_name: Shi - first_name: Kerstin full_name: Avila, Kerstin last_name: Avila - first_name: Shreyas V full_name: Jalikop, Shreyas V id: 44A1D772-F248-11E8-B48F-1D18A9856A87 last_name: Jalikop - first_name: Marc full_name: Avila, Marc last_name: Avila - first_name: Björn full_name: Hof, Björn id: 3A374330-F248-11E8-B48F-1D18A9856A87 last_name: Hof orcid: 0000-0003-2057-2754 citation: ama: Lemoult GM, Shi L, Avila K, Jalikop SV, Avila M, Hof B. Directed percolation phase transition to sustained turbulence in Couette flow. Nature Physics. 2016;12(3):254-258. doi:10.1038/nphys3675 apa: Lemoult, G. M., Shi, L., Avila, K., Jalikop, S. V., Avila, M., & Hof, B. (2016). Directed percolation phase transition to sustained turbulence in Couette flow. Nature Physics. Nature Publishing Group. https://doi.org/10.1038/nphys3675 chicago: Lemoult, Grégoire M, Liang Shi, Kerstin Avila, Shreyas V Jalikop, Marc Avila, and Björn Hof. “Directed Percolation Phase Transition to Sustained Turbulence in Couette Flow.” Nature Physics. Nature Publishing Group, 2016. https://doi.org/10.1038/nphys3675. ieee: G. M. Lemoult, L. Shi, K. Avila, S. V. Jalikop, M. Avila, and B. Hof, “Directed percolation phase transition to sustained turbulence in Couette flow,” Nature Physics, vol. 12, no. 3. Nature Publishing Group, pp. 254–258, 2016. ista: Lemoult GM, Shi L, Avila K, Jalikop SV, Avila M, Hof B. 2016. Directed percolation phase transition to sustained turbulence in Couette flow. Nature Physics. 12(3), 254–258. mla: Lemoult, Grégoire M., et al. “Directed Percolation Phase Transition to Sustained Turbulence in Couette Flow.” Nature Physics, vol. 12, no. 3, Nature Publishing Group, 2016, pp. 254–58, doi:10.1038/nphys3675. short: G.M. Lemoult, L. Shi, K. Avila, S.V. Jalikop, M. Avila, B. Hof, Nature Physics 12 (2016) 254–258. date_created: 2018-12-11T11:52:21Z date_published: 2016-02-15T00:00:00Z date_updated: 2021-01-12T06:51:08Z day: '15' department: - _id: BjHo doi: 10.1038/nphys3675 ec_funded: 1 intvolume: ' 12' issue: '3' language: - iso: eng month: '02' oa_version: None page: 254 - 258 project: - _id: 25152F3A-B435-11E9-9278-68D0E5697425 call_identifier: FP7 grant_number: '306589' name: Decoding the complexity of turbulence at its origin - _id: 2511D90C-B435-11E9-9278-68D0E5697425 grant_number: SFB 963 TP A8 name: Astrophysical instability of currents and turbulences publication: Nature Physics publication_status: published publisher: Nature Publishing Group publist_id: '5685' quality_controlled: '1' scopus_import: 1 status: public title: Directed percolation phase transition to sustained turbulence in Couette flow type: journal_article user_id: 3E5EF7F0-F248-11E8-B48F-1D18A9856A87 volume: 12 year: '2016' ... --- _id: '1664' abstract: - lang: eng text: Over a century of research into the origin of turbulence in wall-bounded shear flows has resulted in a puzzling picture in which turbulence appears in a variety of different states competing with laminar background flow. At moderate flow speeds, turbulence is confined to localized patches; it is only at higher speeds that the entire flow becomes turbulent. The origin of the different states encountered during this transition, the front dynamics of the turbulent regions and the transformation to full turbulence have yet to be explained. By combining experiments, theory and computer simulations, here we uncover a bifurcation scenario that explains the transformation to fully turbulent pipe flow and describe the front dynamics of the different states encountered in the process. Key to resolving this problem is the interpretation of the flow as a bistable system with nonlinear propagation (advection) of turbulent fronts. These findings bridge the gap between our understanding of the onset of turbulence and fully turbulent flows. acknowledgement: We acknowledge the Deutsche Forschungsgemeinschaft (Project No. FOR 1182), and the European Research Council under the European Union’s Seventh Framework Programme (FP/2007-2013)/ERC Grant Agreement 306589 for financial support. B.S. acknowledges financial support from the Chinese State Scholarship Fund under grant number 2010629145. B.S. acknowledges support from the International Max Planck Research School for the Physics of Biological and Complex Systems and the Göttingen Graduate School for Neurosciences and Molecular Biosciences. We acknowledge computing resources from GWDG (Gesellschaft für wissenschaftliche Datenverarbeitung Göttingen) and the Jülich Supercomputing Centre (grant HGU16) where the simulations were performed. author: - first_name: Dwight full_name: Barkley, Dwight last_name: Barkley - first_name: Baofang full_name: Song, Baofang last_name: Song - first_name: Mukund full_name: Vasudevan, Mukund id: 3C5A959A-F248-11E8-B48F-1D18A9856A87 last_name: Vasudevan - first_name: Grégoire M full_name: Lemoult, Grégoire M id: 4787FE80-F248-11E8-B48F-1D18A9856A87 last_name: Lemoult - first_name: Marc full_name: Avila, Marc last_name: Avila - first_name: Björn full_name: Hof, Björn id: 3A374330-F248-11E8-B48F-1D18A9856A87 last_name: Hof orcid: 0000-0003-2057-2754 citation: ama: Barkley D, Song B, Vasudevan M, Lemoult GM, Avila M, Hof B. The rise of fully turbulent flow. Nature. 2015;526(7574):550-553. doi:10.1038/nature15701 apa: Barkley, D., Song, B., Vasudevan, M., Lemoult, G. M., Avila, M., & Hof, B. (2015). The rise of fully turbulent flow. Nature. Nature Publishing Group. https://doi.org/10.1038/nature15701 chicago: Barkley, Dwight, Baofang Song, Mukund Vasudevan, Grégoire M Lemoult, Marc Avila, and Björn Hof. “The Rise of Fully Turbulent Flow.” Nature. Nature Publishing Group, 2015. https://doi.org/10.1038/nature15701. ieee: D. Barkley, B. Song, M. Vasudevan, G. M. Lemoult, M. Avila, and B. Hof, “The rise of fully turbulent flow,” Nature, vol. 526, no. 7574. Nature Publishing Group, pp. 550–553, 2015. ista: Barkley D, Song B, Vasudevan M, Lemoult GM, Avila M, Hof B. 2015. The rise of fully turbulent flow. Nature. 526(7574), 550–553. mla: Barkley, Dwight, et al. “The Rise of Fully Turbulent Flow.” Nature, vol. 526, no. 7574, Nature Publishing Group, 2015, pp. 550–53, doi:10.1038/nature15701. short: D. Barkley, B. Song, M. Vasudevan, G.M. Lemoult, M. Avila, B. Hof, Nature 526 (2015) 550–553. date_created: 2018-12-11T11:53:20Z date_published: 2015-10-21T00:00:00Z date_updated: 2021-01-12T06:52:22Z day: '21' department: - _id: BjHo doi: 10.1038/nature15701 ec_funded: 1 intvolume: ' 526' issue: '7574' language: - iso: eng main_file_link: - open_access: '1' url: http://arxiv.org/abs/1510.09143 month: '10' oa: 1 oa_version: Preprint page: 550 - 553 project: - _id: 25152F3A-B435-11E9-9278-68D0E5697425 call_identifier: FP7 grant_number: '306589' name: Decoding the complexity of turbulence at its origin publication: Nature publication_status: published publisher: Nature Publishing Group publist_id: '5485' quality_controlled: '1' scopus_import: 1 status: public title: The rise of fully turbulent flow type: journal_article user_id: 2DF688A6-F248-11E8-B48F-1D18A9856A87 volume: 526 year: '2015' ... --- _id: '1679' article_number: '091102' author: - first_name: Grégoire M full_name: Lemoult, Grégoire M id: 4787FE80-F248-11E8-B48F-1D18A9856A87 last_name: Lemoult - first_name: Philipp full_name: Maier, Philipp id: 384F7C04-F248-11E8-B48F-1D18A9856A87 last_name: Maier - first_name: Björn full_name: Hof, Björn id: 3A374330-F248-11E8-B48F-1D18A9856A87 last_name: Hof orcid: 0000-0003-2057-2754 citation: ama: Lemoult GM, Maier P, Hof B. Taylor’s Forest. Physics of Fluids. 2015;27(9). doi:10.1063/1.4930850 apa: Lemoult, G. M., Maier, P., & Hof, B. (2015). Taylor’s Forest. Physics of Fluids. American Institute of Physics. https://doi.org/10.1063/1.4930850 chicago: Lemoult, Grégoire M, Philipp Maier, and Björn Hof. “Taylor’s Forest.” Physics of Fluids. American Institute of Physics, 2015. https://doi.org/10.1063/1.4930850. ieee: G. M. Lemoult, P. Maier, and B. Hof, “Taylor’s Forest,” Physics of Fluids, vol. 27, no. 9. American Institute of Physics, 2015. ista: Lemoult GM, Maier P, Hof B. 2015. Taylor’s Forest. Physics of Fluids. 27(9), 091102. mla: Lemoult, Grégoire M., et al. “Taylor’s Forest.” Physics of Fluids, vol. 27, no. 9, 091102, American Institute of Physics, 2015, doi:10.1063/1.4930850. short: G.M. Lemoult, P. Maier, B. Hof, Physics of Fluids 27 (2015). date_created: 2018-12-11T11:53:26Z date_published: 2015-09-24T00:00:00Z date_updated: 2021-01-12T06:52:28Z day: '24' ddc: - '532' department: - _id: BjHo doi: 10.1063/1.4930850 file: - access_level: open_access checksum: 604bba3c2496aadb3efcff77de01ce6c content_type: application/pdf creator: system date_created: 2018-12-12T10:13:35Z date_updated: 2020-07-14T12:45:12Z file_id: '5019' file_name: IST-2017-748-v1+1_1.4930850.pdf file_size: 872366 relation: main_file file_date_updated: 2020-07-14T12:45:12Z has_accepted_license: '1' intvolume: ' 27' issue: '9' language: - iso: eng month: '09' oa: 1 oa_version: Published Version publication: Physics of Fluids publication_status: published publisher: American Institute of Physics publist_id: '5469' pubrep_id: '748' quality_controlled: '1' scopus_import: 1 status: public title: Taylor's Forest tmp: image: /images/cc_by.png legal_code_url: https://creativecommons.org/licenses/by/4.0/legalcode name: Creative Commons Attribution 4.0 International Public License (CC-BY 4.0) short: CC BY (4.0) type: journal_article user_id: 2DF688A6-F248-11E8-B48F-1D18A9856A87 volume: 27 year: '2015' ...