--- _id: '422' 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. article_processing_charge: Yes (via OA deal) author: - first_name: Jakob full_name: Kühnen, Jakob id: 3A47AE32-F248-11E8-B48F-1D18A9856A87 last_name: Kühnen orcid: 0000-0003-4312-0179 - first_name: Davide full_name: Scarselli, Davide id: 40315C30-F248-11E8-B48F-1D18A9856A87 last_name: Scarselli orcid: 0000-0001-5227-4271 - first_name: Markus full_name: Schaner, Markus id: 316CE034-F248-11E8-B48F-1D18A9856A87 last_name: Schaner - first_name: Björn full_name: Hof, Björn id: 3A374330-F248-11E8-B48F-1D18A9856A87 last_name: Hof orcid: 0000-0003-2057-2754 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 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. 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. 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. short: J. Kühnen, D. Scarselli, M. Schaner, B. Hof, Flow Turbulence and Combustion 100 (2018) 919–942. date_created: 2018-12-11T11:46:23Z date_published: 2018-01-01T00:00:00Z date_updated: 2024-03-28T23:30:36Z day: '01' ddc: - '530' department: - _id: BjHo doi: 10.1007/s10494-018-9896-4 ec_funded: 1 external_id: isi: - '000433113900004' file: - access_level: open_access checksum: d7c0bade150faabca150b0a9986e60ca content_type: application/pdf creator: dernst date_created: 2018-12-17T15:52:37Z date_updated: 2020-07-14T12:46:25Z file_id: '5717' file_name: 2018_FlowTurbulenceCombust_Kuehnen.pdf file_size: 2210020 relation: main_file file_date_updated: 2020-07-14T12:46:25Z has_accepted_license: '1' intvolume: ' 100' isi: 1 issue: '4' language: - iso: eng month: '01' oa: 1 oa_version: Published Version page: 919 - 942 project: - _id: 25152F3A-B435-11E9-9278-68D0E5697425 call_identifier: FP7 grant_number: '306589' name: Decoding the complexity of turbulence at its origin publication: Flow Turbulence and Combustion publication_status: published publisher: Springer publist_id: '7401' quality_controlled: '1' related_material: record: - id: '7258' relation: dissertation_contains status: public scopus_import: '1' status: public title: Relaminarization by steady modification of the streamwise velocity profile in a pipe 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: c635000d-4b10-11ee-a964-aac5a93f6ac1 volume: 100 year: '2018' ...