[{"date_published":"2018-03-19T00:00:00Z","citation":{"apa":"Choueiri, G. H., Lopez Alonso, J. M., & Hof, B. (2018). Exceeding the asymptotic limit of polymer drag reduction. Physical Review Letters. American Physical Society. https://doi.org/10.1103/PhysRevLett.120.124501","ieee":"G. H. Choueiri, J. M. Lopez Alonso, and B. Hof, “Exceeding the asymptotic limit of polymer drag reduction,” Physical Review Letters, vol. 120, no. 12. American Physical Society, 2018.","ista":"Choueiri GH, Lopez Alonso JM, Hof B. 2018. Exceeding the asymptotic limit of polymer drag reduction. Physical Review Letters. 120(12), 124501.","ama":"Choueiri GH, Lopez Alonso JM, Hof B. Exceeding the asymptotic limit of polymer drag reduction. Physical Review Letters. 2018;120(12). doi:10.1103/PhysRevLett.120.124501","chicago":"Choueiri, George H, Jose M Lopez Alonso, and Björn Hof. “Exceeding the Asymptotic Limit of Polymer Drag Reduction.” Physical Review Letters. American Physical Society, 2018. https://doi.org/10.1103/PhysRevLett.120.124501.","short":"G.H. Choueiri, J.M. Lopez Alonso, B. Hof, Physical Review Letters 120 (2018).","mla":"Choueiri, George H., et al. “Exceeding the Asymptotic Limit of Polymer Drag Reduction.” Physical Review Letters, vol. 120, no. 12, 124501, American Physical Society, 2018, doi:10.1103/PhysRevLett.120.124501."},"publication":"Physical Review Letters","article_processing_charge":"No","day":"19","scopus_import":"1","oa_version":"Preprint","intvolume":" 120","status":"public","title":"Exceeding the asymptotic limit of polymer drag reduction","_id":"328","user_id":"2DF688A6-F248-11E8-B48F-1D18A9856A87","issue":"12","abstract":[{"text":"The drag of turbulent flows can be drastically decreased by adding small amounts of high molecular weight polymers. While drag reduction initially increases with polymer concentration, it eventually saturates to what is known as the maximum drag reduction (MDR) asymptote; this asymptote is generally attributed to the dynamics being reduced to a marginal yet persistent state of subdued turbulent motion. Contrary to this accepted view, we show that, for an appropriate choice of parameters, polymers can reduce the drag beyond the suggested asymptotic limit, eliminating turbulence and giving way to laminar flow. At higher polymer concentrations, however, the laminar state becomes unstable, resulting in a fluctuating flow with the characteristic drag of the MDR asymptote. Our findings indicate that the asymptotic state is hence dynamically disconnected from ordinary turbulence. © 2018 American Physical Society.","lang":"eng"}],"type":"journal_article","language":[{"iso":"eng"}],"acknowledged_ssus":[{"_id":"SSU"}],"doi":"10.1103/PhysRevLett.120.124501","project":[{"_id":"25681D80-B435-11E9-9278-68D0E5697425","grant_number":"291734","name":"International IST Postdoc Fellowship Programme","call_identifier":"FP7"},{"grant_number":"306589","_id":"25152F3A-B435-11E9-9278-68D0E5697425","name":"Decoding the complexity of turbulence at its origin","call_identifier":"FP7"}],"quality_controlled":"1","isi":1,"oa":1,"main_file_link":[{"url":"https://arxiv.org/abs/1703.06271","open_access":"1"}],"external_id":{"isi":["000427804000005"]},"month":"03","volume":120,"date_created":"2018-12-11T11:45:51Z","date_updated":"2023-10-10T13:27:44Z","author":[{"id":"448BD5BC-F248-11E8-B48F-1D18A9856A87","first_name":"George H","last_name":"Choueiri","full_name":"Choueiri, George H"},{"full_name":"Lopez Alonso, Jose M","orcid":"0000-0002-0384-2022","id":"40770848-F248-11E8-B48F-1D18A9856A87","last_name":"Lopez Alonso","first_name":"Jose M"},{"first_name":"Björn","last_name":"Hof","id":"3A374330-F248-11E8-B48F-1D18A9856A87","orcid":"0000-0003-2057-2754","full_name":"Hof, Björn"}],"department":[{"_id":"BjHo"}],"publisher":"American Physical Society","publication_status":"published","year":"2018","acknowledgement":"The authors thank Philipp Maier and the IST Austria workshop for their dedicated technical support.","ec_funded":1,"publist_id":"7537","article_number":"124501"},{"author":[{"full_name":"Suri, Balachandra","first_name":"Balachandra","last_name":"Suri","id":"47A5E706-F248-11E8-B48F-1D18A9856A87"},{"full_name":"Tithof, Jeffrey","last_name":"Tithof","first_name":"Jeffrey"},{"full_name":"Grigoriev, Roman","last_name":"Grigoriev","first_name":"Roman"},{"last_name":"Schatz","first_name":"Michael","full_name":"Schatz, Michael"}],"date_updated":"2023-10-10T13:29:10Z","date_created":"2018-12-11T11:44:49Z","volume":98,"year":"2018","publication_status":"published","publisher":"American Physical Society","department":[{"_id":"BjHo"}],"doi":"10.1103/PhysRevE.98.023105","language":[{"iso":"eng"}],"oa":1,"external_id":{"isi":["000441466800010"],"arxiv":["1808.02088"]},"main_file_link":[{"url":"https://arxiv.org/abs/1808.02088","open_access":"1"}],"isi":1,"quality_controlled":"1","month":"08","oa_version":"Submitted Version","user_id":"2DF688A6-F248-11E8-B48F-1D18A9856A87","_id":"136","status":"public","title":"Unstable equilibria and invariant manifolds in quasi-two-dimensional Kolmogorov-like flow","intvolume":" 98","abstract":[{"text":"Recent studies suggest that unstable, nonchaotic solutions of the Navier-Stokes equation may provide deep insights into fluid turbulence. In this article, we present a combined experimental and numerical study exploring the dynamical role of unstable equilibrium solutions and their invariant manifolds in a weakly turbulent, electromagnetically driven, shallow fluid layer. Identifying instants when turbulent evolution slows down, we compute 31 unstable equilibria of a realistic two-dimensional model of the flow. We establish the dynamical relevance of these unstable equilibria by showing that they are closely visited by the turbulent flow. We also establish the dynamical relevance of unstable manifolds by verifying that they are shadowed by turbulent trajectories departing from the neighborhoods of unstable equilibria over large distances in state space.","lang":"eng"}],"issue":"2","type":"journal_article","date_published":"2018-08-13T00:00:00Z","publication":"Physical Review E","citation":{"short":"B. Suri, J. Tithof, R. Grigoriev, M. Schatz, Physical Review E 98 (2018).","mla":"Suri, Balachandra, et al. “Unstable Equilibria and Invariant Manifolds in Quasi-Two-Dimensional Kolmogorov-like Flow.” Physical Review E, vol. 98, no. 2, American Physical Society, 2018, doi:10.1103/PhysRevE.98.023105.","chicago":"Suri, Balachandra, Jeffrey Tithof, Roman Grigoriev, and Michael Schatz. “Unstable Equilibria and Invariant Manifolds in Quasi-Two-Dimensional Kolmogorov-like Flow.” Physical Review E. American Physical Society, 2018. https://doi.org/10.1103/PhysRevE.98.023105.","ama":"Suri B, Tithof J, Grigoriev R, Schatz M. Unstable equilibria and invariant manifolds in quasi-two-dimensional Kolmogorov-like flow. Physical Review E. 2018;98(2). doi:10.1103/PhysRevE.98.023105","apa":"Suri, B., Tithof, J., Grigoriev, R., & Schatz, M. (2018). Unstable equilibria and invariant manifolds in quasi-two-dimensional Kolmogorov-like flow. Physical Review E. American Physical Society. https://doi.org/10.1103/PhysRevE.98.023105","ieee":"B. Suri, J. Tithof, R. Grigoriev, and M. Schatz, “Unstable equilibria and invariant manifolds in quasi-two-dimensional Kolmogorov-like flow,” Physical Review E, vol. 98, no. 2. American Physical Society, 2018.","ista":"Suri B, Tithof J, Grigoriev R, Schatz M. 2018. Unstable equilibria and invariant manifolds in quasi-two-dimensional Kolmogorov-like flow. Physical Review E. 98(2)."},"day":"13","article_processing_charge":"No","scopus_import":"1"},{"intvolume":" 100","title":"Relaminarization by steady modification of the streamwise velocity profile in a pipe","status":"public","ddc":["530"],"user_id":"c635000d-4b10-11ee-a964-aac5a93f6ac1","_id":"422","file":[{"creator":"dernst","file_size":2210020,"content_type":"application/pdf","access_level":"open_access","file_name":"2018_FlowTurbulenceCombust_Kuehnen.pdf","checksum":"d7c0bade150faabca150b0a9986e60ca","date_created":"2018-12-17T15:52:37Z","date_updated":"2020-07-14T12:46:25Z","file_id":"5717","relation":"main_file"}],"oa_version":"Published Version","type":"journal_article","issue":"4","abstract":[{"lang":"eng","text":"We show that a rather simple, steady modification of the streamwise velocity profile in a pipe can lead to a complete collapse of turbulence and the flow fully relaminarizes. Two different devices, a stationary obstacle (inset) and a device which injects fluid through an annular gap close to the wall, are used to control the flow. Both devices modify the streamwise velocity profile such that the flow in the center of the pipe is decelerated and the flow in the near wall region is accelerated. We present measurements with stereoscopic particle image velocimetry to investigate and capture the development of the relaminarizing flow downstream these devices and the specific circumstances responsible for relaminarization. We find total relaminarization up to Reynolds numbers of 6000, where the skin friction in the far downstream distance is reduced by a factor of 3.4 due to relaminarization. In a smooth straight pipe the flow remains completely laminar downstream of the control. Furthermore, we show that transient (temporary) relaminarization in a spatially confined region right downstream the devices occurs also at much higher Reynolds numbers, accompanied by a significant local skin friction drag reduction. The underlying physical mechanism of relaminarization is attributed to a weakening of the near-wall turbulence production cycle."}],"page":"919 - 942","citation":{"ama":"Kühnen J, Scarselli D, Schaner M, Hof B. Relaminarization by steady modification of the streamwise velocity profile in a pipe. Flow Turbulence and Combustion. 2018;100(4):919-942. doi:10.1007/s10494-018-9896-4","apa":"Kühnen, J., Scarselli, D., Schaner, M., & Hof, B. (2018). Relaminarization by steady modification of the streamwise velocity profile in a pipe. Flow Turbulence and Combustion. Springer. https://doi.org/10.1007/s10494-018-9896-4","ieee":"J. Kühnen, D. Scarselli, M. Schaner, and B. Hof, “Relaminarization by steady modification of the streamwise velocity profile in a pipe,” Flow Turbulence and Combustion, vol. 100, no. 4. Springer, pp. 919–942, 2018.","ista":"Kühnen J, Scarselli D, Schaner M, Hof B. 2018. Relaminarization by steady modification of the streamwise velocity profile in a pipe. Flow Turbulence and Combustion. 100(4), 919–942.","short":"J. Kühnen, D. Scarselli, M. Schaner, B. Hof, Flow Turbulence and Combustion 100 (2018) 919–942.","mla":"Kühnen, Jakob, et al. “Relaminarization by Steady Modification of the Streamwise Velocity Profile in a Pipe.” Flow Turbulence and Combustion, vol. 100, no. 4, Springer, 2018, pp. 919–42, doi:10.1007/s10494-018-9896-4.","chicago":"Kühnen, Jakob, Davide Scarselli, Markus Schaner, and Björn Hof. “Relaminarization by Steady Modification of the Streamwise Velocity Profile in a Pipe.” Flow Turbulence and Combustion. Springer, 2018. https://doi.org/10.1007/s10494-018-9896-4."},"publication":"Flow Turbulence and Combustion","date_published":"2018-01-01T00:00:00Z","scopus_import":"1","has_accepted_license":"1","article_processing_charge":"Yes (via OA deal)","day":"01","department":[{"_id":"BjHo"}],"publisher":"Springer","publication_status":"published","year":"2018","volume":100,"date_updated":"2024-03-28T23:30:36Z","date_created":"2018-12-11T11:46:23Z","related_material":{"record":[{"id":"7258","relation":"dissertation_contains","status":"public"}]},"author":[{"first_name":"Jakob","last_name":"Kühnen","id":"3A47AE32-F248-11E8-B48F-1D18A9856A87","orcid":"0000-0003-4312-0179","full_name":"Kühnen, Jakob"},{"full_name":"Scarselli, Davide","id":"40315C30-F248-11E8-B48F-1D18A9856A87","orcid":"0000-0001-5227-4271","first_name":"Davide","last_name":"Scarselli"},{"full_name":"Schaner, Markus","first_name":"Markus","last_name":"Schaner","id":"316CE034-F248-11E8-B48F-1D18A9856A87"},{"full_name":"Hof, Björn","orcid":"0000-0003-2057-2754","id":"3A374330-F248-11E8-B48F-1D18A9856A87","last_name":"Hof","first_name":"Björn"}],"publist_id":"7401","ec_funded":1,"file_date_updated":"2020-07-14T12:46:25Z","project":[{"grant_number":"306589","_id":"25152F3A-B435-11E9-9278-68D0E5697425","call_identifier":"FP7","name":"Decoding the complexity of turbulence at its origin"}],"isi":1,"quality_controlled":"1","tmp":{"name":"Creative Commons Attribution 4.0 International Public License (CC-BY 4.0)","legal_code_url":"https://creativecommons.org/licenses/by/4.0/legalcode","short":"CC BY (4.0)","image":"/images/cc_by.png"},"oa":1,"external_id":{"isi":["000433113900004"]},"language":[{"iso":"eng"}],"doi":"10.1007/s10494-018-9896-4","month":"01"},{"month":"01","doi":"10.1038/s41567-017-0018-3","language":[{"iso":"eng"}],"main_file_link":[{"url":"https://arxiv.org/abs/1711.06543","open_access":"1"}],"oa":1,"external_id":{"isi":["000429434100020"]},"quality_controlled":"1","isi":1,"project":[{"name":"Decoding the complexity of turbulence at its origin","call_identifier":"FP7","grant_number":"306589","_id":"25152F3A-B435-11E9-9278-68D0E5697425"},{"call_identifier":"H2020","name":"Eliminating turbulence in oil pipelines","grant_number":"737549","_id":"25104D44-B435-11E9-9278-68D0E5697425"}],"publist_id":"7360","ec_funded":1,"author":[{"id":"3A47AE32-F248-11E8-B48F-1D18A9856A87","orcid":"0000-0003-4312-0179","first_name":"Jakob","last_name":"Kühnen","full_name":"Kühnen, Jakob"},{"last_name":"Song","first_name":"Baofang","full_name":"Song, Baofang"},{"full_name":"Scarselli, Davide","first_name":"Davide","last_name":"Scarselli","id":"40315C30-F248-11E8-B48F-1D18A9856A87","orcid":"0000-0001-5227-4271"},{"full_name":"Budanur, Nazmi B","first_name":"Nazmi B","last_name":"Budanur","id":"3EA1010E-F248-11E8-B48F-1D18A9856A87","orcid":"0000-0003-0423-5010"},{"id":"3BE60946-F248-11E8-B48F-1D18A9856A87","orcid":"0000-0003-4844-6311","first_name":"Michael","last_name":"Riedl","full_name":"Riedl, Michael"},{"last_name":"Willis","first_name":"Ashley","full_name":"Willis, Ashley"},{"last_name":"Avila","first_name":"Marc","full_name":"Avila, Marc"},{"full_name":"Hof, Björn","first_name":"Björn","last_name":"Hof","id":"3A374330-F248-11E8-B48F-1D18A9856A87","orcid":"0000-0003-2057-2754"}],"related_material":{"record":[{"id":"12726","status":"public","relation":"dissertation_contains"},{"id":"14530","status":"public","relation":"dissertation_contains"},{"status":"public","relation":"dissertation_contains","id":"7258"}]},"date_updated":"2024-03-28T23:30:36Z","date_created":"2018-12-11T11:46:36Z","volume":14,"year":"2018","acknowledgement":"We acknowledge the European Research Council under the European Union’s Seventh Framework Programme (FP/2007-2013)/ERC Grant Agreement 306589, the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme (grant agreement no. 737549) and the Deutsche Forschungsgemeinschaft (Project No. FOR 1182) for financial support. We thank our technician P. Maier for providing highly valuable ideas and greatly supporting us in all technical aspects. We thank M. Schaner for technical drawings, construction and design. We thank M. Schwegel for a Matlab code to post-process experimental data.","publication_status":"published","publisher":"Nature Publishing Group","department":[{"_id":"BjHo"}],"day":"08","article_processing_charge":"No","scopus_import":"1","date_published":"2018-01-08T00:00:00Z","publication":"Nature Physics","citation":{"ista":"Kühnen J, Song B, Scarselli D, Budanur NB, Riedl M, Willis A, Avila M, Hof B. 2018. Destabilizing turbulence in pipe flow. Nature Physics. 14, 386–390.","ieee":"J. Kühnen et al., “Destabilizing turbulence in pipe flow,” Nature Physics, vol. 14. Nature Publishing Group, pp. 386–390, 2018.","apa":"Kühnen, J., Song, B., Scarselli, D., Budanur, N. B., Riedl, M., Willis, A., … Hof, B. (2018). Destabilizing turbulence in pipe flow. Nature Physics. Nature Publishing Group. https://doi.org/10.1038/s41567-017-0018-3","ama":"Kühnen J, Song B, Scarselli D, et al. Destabilizing turbulence in pipe flow. Nature Physics. 2018;14:386-390. doi:10.1038/s41567-017-0018-3","chicago":"Kühnen, Jakob, Baofang Song, Davide Scarselli, Nazmi B Budanur, Michael Riedl, Ashley Willis, Marc Avila, and Björn Hof. “Destabilizing Turbulence in Pipe Flow.” Nature Physics. Nature Publishing Group, 2018. https://doi.org/10.1038/s41567-017-0018-3.","mla":"Kühnen, Jakob, et al. “Destabilizing Turbulence in Pipe Flow.” Nature Physics, vol. 14, Nature Publishing Group, 2018, pp. 386–90, doi:10.1038/s41567-017-0018-3.","short":"J. Kühnen, B. Song, D. Scarselli, N.B. Budanur, M. Riedl, A. Willis, M. Avila, B. Hof, Nature Physics 14 (2018) 386–390."},"page":"386-390","abstract":[{"text":"Turbulence is the major cause of friction losses in transport processes and it is responsible for a drastic drag increase in flows over bounding surfaces. While much effort is invested into developing ways to control and reduce turbulence intensities, so far no methods exist to altogether eliminate turbulence if velocities are sufficiently large. We demonstrate for pipe flow that appropriate distortions to the velocity profile lead to a complete collapse of turbulence and subsequently friction losses are reduced by as much as 90%. Counterintuitively, the return to laminar motion is accomplished by initially increasing turbulence intensities or by transiently amplifying wall shear. Since neither the Reynolds number nor the shear stresses decrease (the latter often increase), these measures are not indicative of turbulence collapse. Instead, an amplification mechanism measuring the interaction between eddies and the mean shear is found to set a threshold below which turbulence is suppressed beyond recovery.","lang":"eng"}],"type":"journal_article","oa_version":"Preprint","_id":"461","user_id":"c635000d-4b10-11ee-a964-aac5a93f6ac1","status":"public","title":"Destabilizing turbulence in pipe flow","intvolume":" 14"},{"publist_id":"6136","file_date_updated":"2020-07-14T12:44:39Z","acknowledgement":"This work was supported by the family of late G. Robinson, Jr. and NSF Grant DMS-1211827. ","year":"2017","publisher":"Springer","department":[{"_id":"BjHo"}],"publication_status":"published","author":[{"last_name":"Budanur","first_name":"Nazmi B","orcid":"0000-0003-0423-5010","id":"3EA1010E-F248-11E8-B48F-1D18A9856A87","full_name":"Budanur, Nazmi B"},{"full_name":"Cvitanović, Predrag","last_name":"Cvitanović","first_name":"Predrag"}],"volume":167,"date_updated":"2021-01-12T06:49:07Z","date_created":"2018-12-11T11:50:44Z","month":"05","oa":1,"quality_controlled":"1","doi":"10.1007/s10955-016-1672-z","language":[{"iso":"eng"}],"type":"journal_article","issue":"3-4","abstract":[{"text":"Systems such as fluid flows in channels and pipes or the complex Ginzburg–Landau system, defined over periodic domains, exhibit both continuous symmetries, translational and rotational, as well as discrete symmetries under spatial reflections or complex conjugation. The simplest, and very common symmetry of this type is the equivariance of the defining equations under the orthogonal group O(2). We formulate a novel symmetry reduction scheme for such systems by combining the method of slices with invariant polynomial methods, and show how it works by applying it to the Kuramoto–Sivashinsky system in one spatial dimension. As an example, we track a relative periodic orbit through a sequence of bifurcations to the onset of chaos. Within the symmetry-reduced state space we are able to compute and visualize the unstable manifolds of relative periodic orbits, their torus bifurcations, a transition to chaos via torus breakdown, and heteroclinic connections between various relative periodic orbits. It would be very hard to carry through such analysis in the full state space, without a symmetry reduction such as the one we present here.","lang":"eng"}],"_id":"1211","user_id":"3E5EF7F0-F248-11E8-B48F-1D18A9856A87","intvolume":" 167","title":"Unstable manifolds of relative periodic orbits in the symmetry reduced state space of the Kuramoto–Sivashinsky system","status":"public","ddc":["530"],"pubrep_id":"782","file":[{"creator":"system","content_type":"application/pdf","file_size":2820207,"access_level":"open_access","file_name":"IST-2017-782-v1+1_BudCvi15.pdf","checksum":"3e971d09eb167761aa0888ed415b0056","date_updated":"2020-07-14T12:44:39Z","date_created":"2018-12-12T10:18:01Z","file_id":"5319","relation":"main_file"}],"oa_version":"Submitted Version","scopus_import":1,"has_accepted_license":"1","day":"01","citation":{"ista":"Budanur NB, Cvitanović P. 2017. Unstable manifolds of relative periodic orbits in the symmetry reduced state space of the Kuramoto–Sivashinsky system. Journal of Statistical Physics. 167(3–4), 636–655.","ieee":"N. B. Budanur and P. Cvitanović, “Unstable manifolds of relative periodic orbits in the symmetry reduced state space of the Kuramoto–Sivashinsky system,” Journal of Statistical Physics, vol. 167, no. 3–4. Springer, pp. 636–655, 2017.","apa":"Budanur, N. B., & Cvitanović, P. (2017). Unstable manifolds of relative periodic orbits in the symmetry reduced state space of the Kuramoto–Sivashinsky system. Journal of Statistical Physics. Springer. https://doi.org/10.1007/s10955-016-1672-z","ama":"Budanur NB, Cvitanović P. Unstable manifolds of relative periodic orbits in the symmetry reduced state space of the Kuramoto–Sivashinsky system. Journal of Statistical Physics. 2017;167(3-4):636-655. doi:10.1007/s10955-016-1672-z","chicago":"Budanur, Nazmi B, and Predrag Cvitanović. “Unstable Manifolds of Relative Periodic Orbits in the Symmetry Reduced State Space of the Kuramoto–Sivashinsky System.” Journal of Statistical Physics. Springer, 2017. https://doi.org/10.1007/s10955-016-1672-z.","mla":"Budanur, Nazmi B., and Predrag Cvitanović. “Unstable Manifolds of Relative Periodic Orbits in the Symmetry Reduced State Space of the Kuramoto–Sivashinsky System.” Journal of Statistical Physics, vol. 167, no. 3–4, Springer, 2017, pp. 636–55, doi:10.1007/s10955-016-1672-z.","short":"N.B. Budanur, P. Cvitanović, Journal of Statistical Physics 167 (2017) 636–655."},"publication":"Journal of Statistical Physics","page":"636-655","date_published":"2017-05-01T00:00:00Z"},{"scopus_import":1,"month":"04","day":"01","publication":"Physical Review Fluids","main_file_link":[{"url":"https://arxiv.org/abs/1704.02619","open_access":"1"}],"oa":1,"citation":{"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.","short":"L. Klotz, G.M. Lemoult, I. Frontczak, L. Tuckerman, J. Wesfreid, Physical Review Fluids 2 (2017).","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.","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","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.","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"},"quality_controlled":"1","date_published":"2017-04-01T00:00:00Z","doi":"10.1103/PhysRevFluids.2.043904","language":[{"iso":"eng"}],"article_number":"043904","type":"journal_article","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."}],"issue":"4","publist_id":"7306","user_id":"2DF688A6-F248-11E8-B48F-1D18A9856A87","_id":"513","year":"2017","status":"public","publication_status":"published","title":"Couette-Poiseuille flow experiment with zero mean advection velocity: Subcritical transition to turbulence","department":[{"_id":"BjHo"}],"publisher":"American Physical Society","intvolume":" 2","author":[{"orcid":"0000-0003-1740-7635","id":"2C9AF1C2-F248-11E8-B48F-1D18A9856A87","last_name":"Klotz","first_name":"Lukasz","full_name":"Klotz, Lukasz"},{"id":"4787FE80-F248-11E8-B48F-1D18A9856A87","first_name":"Grégoire M","last_name":"Lemoult","full_name":"Lemoult, Grégoire M"},{"last_name":"Frontczak","first_name":"Idalia","full_name":"Frontczak, Idalia"},{"first_name":"Laurette","last_name":"Tuckerman","full_name":"Tuckerman, Laurette"},{"full_name":"Wesfreid, José","first_name":"José","last_name":"Wesfreid"}],"date_created":"2018-12-11T11:46:54Z","date_updated":"2021-01-12T08:01:16Z","volume":2,"oa_version":"Preprint"},{"publication_identifier":{"issn":["00280836"]},"day":"11","month":"01","scopus_import":1,"language":[{"iso":"eng"}],"date_published":"2017-01-11T00:00:00Z","doi":"10.1038/541161a","page":"161 - 162","quality_controlled":"1","citation":{"chicago":"Hof, Björn. “Fluid Dynamics: Water Flows out of Touch.” Nature. Nature Publishing Group, 2017. https://doi.org/10.1038/541161a.","short":"B. Hof, Nature 541 (2017) 161–162.","mla":"Hof, Björn. “Fluid Dynamics: Water Flows out of Touch.” Nature, vol. 541, no. 7636, Nature Publishing Group, 2017, pp. 161–62, doi:10.1038/541161a.","apa":"Hof, B. (2017). Fluid dynamics: Water flows out of touch. Nature. Nature Publishing Group. https://doi.org/10.1038/541161a","ieee":"B. Hof, “Fluid dynamics: Water flows out of touch,” Nature, vol. 541, no. 7636. Nature Publishing Group, pp. 161–162, 2017.","ista":"Hof B. 2017. Fluid dynamics: Water flows out of touch. Nature. 541(7636), 161–162.","ama":"Hof B. Fluid dynamics: Water flows out of touch. Nature. 2017;541(7636):161-162. doi:10.1038/541161a"},"publication":"Nature","issue":"7636","publist_id":"7116","abstract":[{"text":"Superhydrophobic surfaces reduce the frictional drag between water and solid materials, but this effect is often temporary. The realization of sustained drag reduction has applications for water vehicles and pipeline flows.\r\n\r\n","lang":"eng"}],"type":"journal_article","volume":541,"oa_version":"None","date_updated":"2021-01-12T08:07:49Z","date_created":"2018-12-11T11:47:43Z","author":[{"full_name":"Hof, Björn","first_name":"Björn","last_name":"Hof","id":"3A374330-F248-11E8-B48F-1D18A9856A87","orcid":"0000-0003-2057-2754"}],"department":[{"_id":"BjHo"}],"publisher":"Nature Publishing Group","intvolume":" 541","title":"Fluid dynamics: Water flows out of touch","status":"public","publication_status":"published","year":"2017","_id":"651","user_id":"4435EBFC-F248-11E8-B48F-1D18A9856A87"},{"date_published":"2017-04-01T00:00:00Z","citation":{"chicago":"Shi, Liang, Björn Hof, Markus Rampp, and Marc Avila. “Hydrodynamic Turbulence in Quasi Keplerian Rotating Flows.” Physics of Fluids. American Institute of Physics, 2017. https://doi.org/10.1063/1.4981525.","short":"L. Shi, B. Hof, M. Rampp, M. Avila, Physics of Fluids 29 (2017).","mla":"Shi, Liang, et al. “Hydrodynamic Turbulence in Quasi Keplerian Rotating Flows.” Physics of Fluids, vol. 29, no. 4, 044107, American Institute of Physics, 2017, doi:10.1063/1.4981525.","ieee":"L. Shi, B. Hof, M. Rampp, and M. Avila, “Hydrodynamic turbulence in quasi Keplerian rotating flows,” Physics of Fluids, vol. 29, no. 4. American Institute of Physics, 2017.","apa":"Shi, L., Hof, B., Rampp, M., & Avila, M. (2017). Hydrodynamic turbulence in quasi Keplerian rotating flows. Physics of Fluids. American Institute of Physics. https://doi.org/10.1063/1.4981525","ista":"Shi L, Hof B, Rampp M, Avila M. 2017. Hydrodynamic turbulence in quasi Keplerian rotating flows. Physics of Fluids. 29(4), 044107.","ama":"Shi L, Hof B, Rampp M, Avila M. Hydrodynamic turbulence in quasi Keplerian rotating flows. Physics of Fluids. 2017;29(4). doi:10.1063/1.4981525"},"publication":"Physics of Fluids","day":"01","scopus_import":1,"oa_version":"Submitted Version","intvolume":" 29","status":"public","title":"Hydrodynamic turbulence in quasi Keplerian rotating flows","user_id":"4435EBFC-F248-11E8-B48F-1D18A9856A87","_id":"662","issue":"4","abstract":[{"lang":"eng","text":"We report a direct-numerical-simulation study of the Taylor-Couette flow in the quasi-Keplerian regime at shear Reynolds numbers up to (105). Quasi-Keplerian rotating flow has been investigated for decades as a simplified model system to study the origin of turbulence in accretion disks that is not fully understood. The flow in this study is axially periodic and thus the experimental end-wall effects on the stability of the flow are avoided. Using optimal linear perturbations as initial conditions, our simulations find no sustained turbulence: the strong initial perturbations distort the velocity profile and trigger turbulence that eventually decays."}],"type":"journal_article","language":[{"iso":"eng"}],"doi":"10.1063/1.4981525","project":[{"name":"Astrophysical instability of currents and turbulences","grant_number":"SFB 963 TP A8","_id":"2511D90C-B435-11E9-9278-68D0E5697425"}],"quality_controlled":"1","main_file_link":[{"url":"https://arxiv.org/abs/1703.01714","open_access":"1"}],"oa":1,"publication_identifier":{"issn":["10706631"]},"month":"04","volume":29,"date_updated":"2021-01-12T08:08:15Z","date_created":"2018-12-11T11:47:47Z","author":[{"first_name":"Liang","last_name":"Shi","full_name":"Shi, Liang"},{"orcid":"0000-0003-2057-2754","id":"3A374330-F248-11E8-B48F-1D18A9856A87","last_name":"Hof","first_name":"Björn","full_name":"Hof, Björn"},{"full_name":"Rampp, Markus","first_name":"Markus","last_name":"Rampp"},{"full_name":"Avila, Marc","first_name":"Marc","last_name":"Avila"}],"publisher":"American Institute of Physics","department":[{"_id":"BjHo"}],"publication_status":"published","year":"2017","publist_id":"7072","article_number":"044107"},{"publist_id":"6198","file_date_updated":"2020-07-14T12:44:36Z","article_number":"40012","author":[{"full_name":"Altmeyer, Sebastian","orcid":"0000-0001-5964-0203","id":"2EE67FDC-F248-11E8-B48F-1D18A9856A87","last_name":"Altmeyer","first_name":"Sebastian"},{"first_name":"Younghae","last_name":"Do","full_name":"Do, Younghae"},{"last_name":"Lai","first_name":"Ying","full_name":"Lai, Ying"}],"volume":7,"date_updated":"2023-09-20T11:28:49Z","date_created":"2018-12-11T11:50:28Z","year":"2017","department":[{"_id":"BjHo"}],"publisher":"Nature Publishing Group","publication_status":"published","publication_identifier":{"issn":["20452322"]},"month":"01","doi":"10.1038/srep40012","language":[{"iso":"eng"}],"external_id":{"isi":["000391269700001"]},"tmp":{"name":"Creative Commons Attribution 4.0 International Public License (CC-BY 4.0)","legal_code_url":"https://creativecommons.org/licenses/by/4.0/legalcode","short":"CC BY (4.0)","image":"/images/cc_by.png"},"oa":1,"isi":1,"quality_controlled":"1","abstract":[{"lang":"eng","text":"We investigate fundamental nonlinear dynamics of ferrofluidic Taylor-Couette flow - flow confined be-tween two concentric independently rotating cylinders - consider small aspect ratio by solving the ferro-hydrodynamical equations, carrying out systematic bifurcation analysis. Without magnetic field, we find steady flow patterns, previously observed with a simple fluid, such as those containing normal one- or two vortex cells, as well as anomalous one-cell and twin-cell flow states. However, when a symmetry-breaking transverse magnetic field is present, all flow states exhibit stimulated, finite two-fold mode. Various bifurcations between steady and unsteady states can occur, corresponding to the transitions between the two-cell and one-cell states. While unsteady, axially oscillating flow states can arise, we also detect the emergence of new unsteady flow states. In particular, we uncover two new states: one contains only the azimuthally oscillating solution in the configuration of the twin-cell flow state, and an-other a rotating flow state. Topologically, these flow states are a limit cycle and a quasiperiodic solution on a two-torus, respectively. Emergence of new flow states in addition to observed ones with classical fluid, indicates that richer but potentially more controllable dynamics in ferrofluidic flows, as such flow states depend on the external magnetic field."}],"type":"journal_article","pubrep_id":"743","oa_version":"Published Version","file":[{"file_id":"4802","relation":"main_file","date_updated":"2020-07-14T12:44:36Z","date_created":"2018-12-12T10:10:16Z","checksum":"694aa70399444570825099c1a7ec91f2","file_name":"IST-2017-743-v1+1_srep40012.pdf","access_level":"open_access","creator":"system","file_size":4546835,"content_type":"application/pdf"}],"user_id":"c635000d-4b10-11ee-a964-aac5a93f6ac1","_id":"1160","intvolume":" 7","title":"Dynamics of ferrofluidic flow in the Taylor-Couette system with a small aspect ratio","ddc":["532"],"status":"public","article_processing_charge":"No","has_accepted_license":"1","day":"06","scopus_import":"1","date_published":"2017-01-06T00:00:00Z","citation":{"ista":"Altmeyer S, Do Y, Lai Y. 2017. Dynamics of ferrofluidic flow in the Taylor-Couette system with a small aspect ratio. Scientific Reports. 7, 40012.","apa":"Altmeyer, S., Do, Y., & Lai, Y. (2017). Dynamics of ferrofluidic flow in the Taylor-Couette system with a small aspect ratio. Scientific Reports. Nature Publishing Group. https://doi.org/10.1038/srep40012","ieee":"S. Altmeyer, Y. Do, and Y. Lai, “Dynamics of ferrofluidic flow in the Taylor-Couette system with a small aspect ratio,” Scientific Reports, vol. 7. Nature Publishing Group, 2017.","ama":"Altmeyer S, Do Y, Lai Y. Dynamics of ferrofluidic flow in the Taylor-Couette system with a small aspect ratio. Scientific Reports. 2017;7. doi:10.1038/srep40012","chicago":"Altmeyer, Sebastian, Younghae Do, and Ying Lai. “Dynamics of Ferrofluidic Flow in the Taylor-Couette System with a Small Aspect Ratio.” Scientific Reports. Nature Publishing Group, 2017. https://doi.org/10.1038/srep40012.","mla":"Altmeyer, Sebastian, et al. “Dynamics of Ferrofluidic Flow in the Taylor-Couette System with a Small Aspect Ratio.” Scientific Reports, vol. 7, 40012, Nature Publishing Group, 2017, doi:10.1038/srep40012.","short":"S. Altmeyer, Y. Do, Y. Lai, Scientific Reports 7 (2017)."},"publication":"Scientific Reports"},{"oa_version":"Submitted Version","user_id":"c635000d-4b10-11ee-a964-aac5a93f6ac1","_id":"1087","intvolume":" 813","title":"Speed and structure of turbulent fronts in pipe flow","status":"public","abstract":[{"lang":"eng","text":"Using extensive direct numerical simulations, the dynamics of laminar-turbulent fronts in pipe flow is investigated for Reynolds numbers between and 5500. We here investigate the physical distinction between the fronts of weak and strong slugs both by analysing the turbulent kinetic energy budget and by comparing the downstream front motion to the advection speed of bulk turbulent structures. Our study shows that weak downstream fronts travel slower than turbulent structures in the bulk and correspond to decaying turbulence at the front. At the downstream front speed becomes faster than the advection speed, marking the onset of strong fronts. In contrast to weak fronts, turbulent eddies are generated at strong fronts by feeding on the downstream laminar flow. Our study also suggests that temporal fluctuations of production and dissipation at the downstream laminar-turbulent front drive the dynamical switches between the two types of front observed up to."}],"type":"journal_article","date_published":"2017-02-25T00:00:00Z","citation":{"ista":"Song B, Barkley D, Hof B, Avila M. 2017. Speed and structure of turbulent fronts in pipe flow. Journal of Fluid Mechanics. 813, 1045–1059.","apa":"Song, B., Barkley, D., Hof, B., & Avila, M. (2017). Speed and structure of turbulent fronts in pipe flow. Journal of Fluid Mechanics. Cambridge University Press. https://doi.org/10.1017/jfm.2017.14","ieee":"B. Song, D. Barkley, B. Hof, and M. Avila, “Speed and structure of turbulent fronts in pipe flow,” Journal of Fluid Mechanics, vol. 813. Cambridge University Press, pp. 1045–1059, 2017.","ama":"Song B, Barkley D, Hof B, Avila M. Speed and structure of turbulent fronts in pipe flow. Journal of Fluid Mechanics. 2017;813:1045-1059. doi:10.1017/jfm.2017.14","chicago":"Song, Baofang, Dwight Barkley, Björn Hof, and Marc Avila. “Speed and Structure of Turbulent Fronts in Pipe Flow.” Journal of Fluid Mechanics. Cambridge University Press, 2017. https://doi.org/10.1017/jfm.2017.14.","mla":"Song, Baofang, et al. “Speed and Structure of Turbulent Fronts in Pipe Flow.” Journal of Fluid Mechanics, vol. 813, Cambridge University Press, 2017, pp. 1045–59, doi:10.1017/jfm.2017.14.","short":"B. Song, D. Barkley, B. Hof, M. Avila, Journal of Fluid Mechanics 813 (2017) 1045–1059."},"publication":"Journal of Fluid Mechanics","page":"1045 - 1059","article_processing_charge":"No","day":"25","scopus_import":"1","author":[{"full_name":"Song, Baofang","last_name":"Song","first_name":"Baofang"},{"last_name":"Barkley","first_name":"Dwight","full_name":"Barkley, Dwight"},{"full_name":"Hof, Björn","orcid":"0000-0003-2057-2754","id":"3A374330-F248-11E8-B48F-1D18A9856A87","last_name":"Hof","first_name":"Björn"},{"first_name":"Marc","last_name":"Avila","full_name":"Avila, Marc"}],"volume":813,"date_created":"2018-12-11T11:50:04Z","date_updated":"2023-09-20T11:47:22Z","year":"2017","department":[{"_id":"BjHo"}],"publisher":"Cambridge University Press","publication_status":"published","ec_funded":1,"publist_id":"6290","doi":"10.1017/jfm.2017.14","language":[{"iso":"eng"}],"acknowledged_ssus":[{"_id":"ScienComp"}],"main_file_link":[{"url":"https://arxiv.org/abs/1603.04077","open_access":"1"}],"external_id":{"isi":["000394376400044"]},"oa":1,"project":[{"call_identifier":"FP7","name":"Decoding the complexity of turbulence at its origin","grant_number":"306589","_id":"25152F3A-B435-11E9-9278-68D0E5697425"}],"isi":1,"quality_controlled":"1","publication_identifier":{"issn":["00221120"]},"month":"02"}]