@incollection{ZanounJehringEgbers, author = {Zanoun, El-Sayed and Jehring, Lothar and Egbers, Christoph}, title = {Development of miniature flow sensor for aerodynamic applications}, language = {en} } @incollection{JehringZanounEgbers, author = {Jehring, Lothar and Zanoun, El-Sayed and Egbers, Christoph}, title = {Fortschritte bei der Entwicklung und Anwendung eines miniaturisierten Sensors f{\"u}r wandnahe Str{\"o}mungen}, language = {de} } @incollection{ZanounDurstEgbers, author = {Zanoun, El-Sayed and Durst, F. and Egbers, Christoph}, title = {Flow Developments in Smooth Wall Circular Duct Facility}, language = {en} } @incollection{ZanounDurstEgbers, author = {Zanoun, El-Sayed and Durst, F. and Egbers, Christoph}, title = {Mean Flow Properties in Smooth Pipe Flow Experiment}, language = {en} } @incollection{ZanounDurstEgbers, author = {Zanoun, El-Sayed and Durst, F. and Egbers, Christoph}, title = {High Reynolds Number Fully Developed Turbulent Pipe Flows}, language = {en} } @incollection{JehringZanounKito, author = {Jehring, Lothar and Zanoun, El-Sayed and Kito, Mizuki}, title = {Vermessung wandnaher Str{\"o}mungen unter Verwendung eines neuartigen miniaturisierten Sensor-Moduls}, language = {de} } @article{ZanounDurstNagib, author = {Zanoun, El-Sayed and Durst, F. and Nagib, H. M.}, title = {Response to "Comment on 'Evaluating the law of the wall in two-dimensional fully developed turbulent channel flows' "}, language = {en} } @incollection{JehringZanoun, author = {Jehring, Lothar and Zanoun, El-Sayed}, title = {Reducing environmental impact by mean of active flow control}, language = {en} } @incollection{ZanounDurstNagib, author = {Zanoun, El-Sayed and Durst, F. and Nagib, H. M.}, title = {Assessment of Scaling Laws in Fully Developed Turbulent Pipe and Channel Flows}, language = {en} } @incollection{ZanounDurstNagib, author = {Zanoun, El-Sayed and Durst, F. and Nagib, H. M.}, title = {Scaling Laws for Turbulent Channel and Pipe Flows over a Wide Range of Reynolds Number}, language = {de} } @incollection{ZanounEgbersJehring, author = {Zanoun, El-Sayed and Egbers, Christoph and Jehring, Lothar}, title = {Modified Optical and Thermal Anemometers for Laminar and Turbulent Boundary Layers Investigation}, language = {en} } @inproceedings{ZanounEgbersJehring, author = {Zanoun, El-Sayed and Egbers, Christoph and Jehring, Lothar}, title = {New Approach for Wall Shear Stress Measurements}, language = {en} } @incollection{KitoZanounJehringetal., author = {Kito, Mizuki and Zanoun, El-Sayed and Jehring, Lothar and Egbers, Christoph}, title = {Laser-Doppler Anemometry in Turbulent Boundary Layers Induced by Different Tripping Devices Compared with Recent Theories}, language = {en} } @inproceedings{ZanounDurstJehringetal., author = {Zanoun, El-Sayed and Durst, F. and Jehring, Lothar and Egbers, Christoph}, title = {The Darcy Friction Factor and the von K{\´a}rm{\´a}n Constant in Pipe Flow Experiment}, language = {en} } @misc{ZanounDurstSalehetal., author = {Zanoun, El-Sayed and Durst, F. and Saleh, O. and Al-Salaymeh, Ahmed}, title = {Wall skin friction and mean velocity profiles of fully developed turbulent pipe flows}, series = {Experimental Thermal and Fluid Science}, volume = {32}, journal = {Experimental Thermal and Fluid Science}, number = {1}, issn = {0894-1777}, doi = {10.1016/j.expthermflusci.2007.04.002}, pages = {249 -- 261}, language = {en} } @inproceedings{DetersGuillermEgbersetal., author = {Deters, T. and Guillerm, R. and Egbers, Christoph and Zanoun, El-Sayed}, title = {Influence of thermal convection in Taylor-Couette flows}, language = {en} } @inproceedings{JehringZanounEgbers, author = {Jehring, Lothar and Zanoun, El-Sayed and Egbers, Christoph}, title = {Untersuchung von ebenen Wandgrenzschichten mit verschiedenen optischen Messverfahren, Fachtagung}, language = {de} } @inproceedings{JehringZanounEgbers, author = {Jehring, Lothar and Zanoun, El-Sayed and Egbers, Christoph}, title = {Near-wall flow measurements by means of miniaturized LDV flow sensor combined with hot-film anemometry}, language = {en} } @inproceedings{ZanounEgbersGuoetal., author = {Zanoun, El-Sayed and Egbers, Christoph and Guo, Xiaoai and Riebel, Ulrich}, title = {Experimental and Numerical Investigations of Isothermal Fluid-Particle Flows in Vertical Cuvette}, language = {en} } @misc{ZanounKitoEgbers, author = {Zanoun, El-Sayed and Kito, Mizuki and Egbers, Christoph}, title = {A Study on Flow Transition and Development in Circular and Rectangular Ducts}, language = {en} } @article{DetersEgbersZanounetal., author = {Deters, T. and Egbers, Christoph and Zanoun, El-Sayed and Guillerm, R.}, title = {Influence of thermal convection in Taylor-Couette flows}, language = {en} } @misc{ZanounDurst, author = {Zanoun, El-Sayed and Durst, F.}, title = {Momentum transport and turbulent kinetic energy production in plane-channel flow}, language = {en} } @misc{ZanounDurst, author = {Zanoun, El-Sayed and Durst, F.}, title = {The physics of heat transfer from hot-wires in the proximity of walls of different materials}, language = {en} } @misc{ZanounDurstNagib, author = {Zanoun, El-Sayed and Durst, F. and Nagib, H. M.}, title = {Refined Cf relation for turbulent channels and consequences for high Re experiments}, language = {en} } @inproceedings{MotuzKornilovJehringetal., author = {Motuz, Vasyl and Kornilov, Vladimir and Jehring, Lothar and Zanoun, El-Sayed and Egbers, Christoph}, title = {Control of turbulent boundary layer using microblowing through a perforated surface}, series = {15. International Conference on the Methods of Aerophysical Research, Nov. 1-6, 2010, Novosibirsk, Russia, part 1}, booktitle = {15. International Conference on the Methods of Aerophysical Research, Nov. 1-6, 2010, Novosibirsk, Russia, part 1}, address = {Novosibirsk}, pages = {188 -- 189}, language = {en} } @misc{KoenigZanounJehringetal., author = {K{\"o}nig, Franziska and Zanoun, El-Sayed and Jehring, Lothar and Egbers, Christoph}, title = {On the behavior of the inner peak in turbulent pipe flow}, language = {en} } @misc{KoenigZanounOengueneretal., author = {K{\"o}nig, Franziska and Zanoun, El-Sayed and {\"O}ng{\"u}ner, Emir and Egbers, Christoph}, title = {The CoLaPipe - The new Cottbus large pipe test facility at Brandenburg University of Technology Cottbus-Senftenberg}, series = {Review of scientific instruments}, volume = {85}, journal = {Review of scientific instruments}, number = {7}, issn = {1089-7623}, doi = {10.1063/1.4884717}, pages = {075115-1 -- 075115-9}, language = {en} } @inproceedings{OenguenerZanounEgbers, author = {{\"O}ng{\"u}ner, Emir and Zanoun, El-Sayed and Egbers, Christoph}, title = {Turbulent Pipe Flow Structure Analysis in CoLa-Pipe}, series = {Book of abstracts, 85th Annual Meeting of the International Association of Applied Mathematics and Mechanics, March 10 - 14, 2014, Erlangen}, booktitle = {Book of abstracts, 85th Annual Meeting of the International Association of Applied Mathematics and Mechanics, March 10 - 14, 2014, Erlangen}, publisher = {Gesellschaft f{\"u}r Angewandte Mathematik und Mechanik}, pages = {S. 493}, language = {en} } @inproceedings{ZanounKoenigAlMutairietal., author = {Zanoun, El-Sayed and K{\"o}nig, Franziska and Al-Mutairi, Fahad M. and Egbers, Christoph and {\"O}ng{\"u}ner, Emir}, title = {On the Application of Hot Wires and Pitot Tubes in Pipe and Channel Flows}, series = {HEFAT 2014, 10th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, 6 - 9 July 2014 Orlando, Florida}, booktitle = {HEFAT 2014, 10th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, 6 - 9 July 2014 Orlando, Florida}, doi = {10.13140/2.1.3766.7521}, pages = {7}, language = {en} } @inproceedings{OenguenerKoenigZanounetal., author = {{\"O}ng{\"u}ner, Emir and K{\"o}nig, Franziska and Zanoun, El-Sayed and Egbers, Christoph}, title = {Experimentelle Untersuchung der turbulenten Rohrstrukturen bei hohen Reynolds Zahlen}, series = {GALA - Fachtagung Lasermethoden in der Str{\"o}mungsmesstechnik, 22. Fachtagung, 9. - 11. September 2014, Karlsruhe}, booktitle = {GALA - Fachtagung Lasermethoden in der Str{\"o}mungsmesstechnik, 22. Fachtagung, 9. - 11. September 2014, Karlsruhe}, publisher = {GALA}, address = {Karlsruhe}, isbn = {978-3-9816764-0-2}, pages = {S. 24}, language = {de} } @misc{ZanounJehringEgbers, author = {Zanoun, El-Sayed and Jehring, Lothar and Egbers, Christoph}, title = {Three measuring techniques for assessing the mean wall skin friction in wall-bounded flows}, series = {Thermophysics and Aeromechanics}, volume = {21}, journal = {Thermophysics and Aeromechanics}, number = {2}, issn = {1531-8699}, pages = {179 -- 190}, language = {en} } @incollection{OenguenerZanounKoenigetal., author = {{\"O}ng{\"u}ner, Emir and Zanoun, El-Sayed and K{\"o}nig, Franziska and Egbers, Christoph}, title = {Structure Investigation in Pipe Flow at High Reynolds Numbers}, publisher = {Springer}, address = {Berlin}, isbn = {978-3-319-29130-7}, pages = {217 -- 220}, language = {en} } @misc{ZanounOenguenerEgbers, author = {Zanoun, El-Sayed and {\"O}ng{\"u}ner, Emir and Egbers, Christoph}, title = {Conventional measuring probes in the wall layer of turbulent subsonic ducted flows}, series = {Thermophysics and Aeromechanics}, volume = {23}, journal = {Thermophysics and Aeromechanics}, number = {3}, issn = {1531-8699}, pages = {329 -- 342}, language = {en} } @inproceedings{OenguenerDittmarMeyeretal., author = {{\"O}ng{\"u}ner, Emir and Dittmar, Mirko and Meyer, P. and Zanoun, El-Sayed and Egbers, Christoph}, title = {Wall-bounded turbulent Structures in pipe flow based on streamwise and cross-sectional PIV at Re=10^4-10^5}, series = {11th European Fluid Mechanics Conference, Sept. 12-16, 2016, Sevilla, Spain}, booktitle = {11th European Fluid Mechanics Conference, Sept. 12-16, 2016, Sevilla, Spain}, language = {en} } @inproceedings{ZanounEgbersOenguener, author = {Zanoun, El-Sayed and Egbers, Christoph and {\"O}ng{\"u}ner, Emir}, title = {Integral Flow parapeters for evaluating the law of the wall in pipe and channel facilities}, series = {11th European Fluid Mechanics Conference, Sept. 12-16, 2016, Sevilla, Spain}, booktitle = {11th European Fluid Mechanics Conference, Sept. 12-16, 2016, Sevilla, Spain}, language = {en} } @inproceedings{SevlamOenguenerPeixinhoetal., author = {Sevlam, Kamal and {\"O}ng{\"u}ner, Emir and Peixinho, Jorge and Zanoun, El-Sayed and Egbers, Christoph}, title = {Wall pressure fluctuations in developing turbulent pipe flow}, series = {Book of abstracts, School ISTROF 2016, Instabilities and Turbulence in Strato-Rotational Flows, July 11-13th, 2016, Le Havre}, booktitle = {Book of abstracts, School ISTROF 2016, Instabilities and Turbulence in Strato-Rotational Flows, July 11-13th, 2016, Le Havre}, language = {en} } @inproceedings{OenguenerZanounEgbers, author = {{\"O}ng{\"u}ner, Emir and Zanoun, El-Sayed and Egbers, Christoph}, title = {Streamwise Auto-Correlation Analysis in Turbulent Pipe Flow Using Particle Image Velocimetry at High Reynolds Numbers}, series = {Progress in Turbulence VII, Proceedings of the iTi Conference in Turbulence 2016}, booktitle = {Progress in Turbulence VII, Proceedings of the iTi Conference in Turbulence 2016}, editor = {{\"O}rl{\"u}, Ramis and Talamelli, Alessandro and Peinke, Joachim and Oberlack, Martin}, publisher = {Springer}, address = {Cham}, isbn = {978-3-319-57933-7}, pages = {107 -- 112}, language = {en} } @inproceedings{OenguenerZanounFiorinietal., author = {{\"O}ng{\"u}ner, Emir and Zanoun, El-Sayed and Fiorini, Tommaso and Bellani, Gabriele and Shahirpour, Amir and Egbers, Christoph and Talamelli, Alessandro}, title = {Wavenumber Dependence of Very Large-Scale Motions in CICLoPE at 4800 ≤ Reτ ≤ 37.000}, series = {Progress in Turbulence VII, Proceedings of the iTi Conference in Turbulence 2016}, booktitle = {Progress in Turbulence VII, Proceedings of the iTi Conference in Turbulence 2016}, editor = {{\"O}rl{\"u}, Ramis and Talamelli, Alessandro and Peinke, Joachim and Oberlack, Martin}, publisher = {Springer}, address = {Cham}, isbn = {978-3-319-57933-7}, pages = {101 -- 106}, language = {en} } @inproceedings{EgbersShahirpourOengueneretal., author = {Egbers, Christoph and Shahirpour, Amir and {\"O}ng{\"u}ner, Emir and Zanoun, El-Sayed}, title = {Spectral Analysis of Large Scale Structures in Fully Developed Turbulent Pipe Flow}, series = {88th Annual Meeting of the International Association of Applied Mathematics and Mechanics GAMM, March 6-10, 2017, Weimar, Germany, Book of abstracts}, booktitle = {88th Annual Meeting of the International Association of Applied Mathematics and Mechanics GAMM, March 6-10, 2017, Weimar, Germany, Book of abstracts}, pages = {S. 46}, language = {en} } @inproceedings{ZanounOenguenerMotuzetal., author = {Zanoun, El-Sayed and {\"O}ng{\"u}ner, Emir and Motuz, Vasyl and Egbers, Christoph and Fiorini, Tommaso and {\"O}rl{\"u}, Ramis and Bellani, Gabriele and Talamelli, Alessandro}, title = {Direct and in-direct measurement of momentum structure in ColaPipe}, series = {16th European Turbulence Conference, 21-24 August, 2017, Stockholm, Sweden}, booktitle = {16th European Turbulence Conference, 21-24 August, 2017, Stockholm, Sweden}, pages = {1}, language = {en} } @misc{ZanounOenguenerShahirpouretal., author = {Zanoun, El-Sayed and {\"O}ng{\"u}ner, Emir and Shahirpour, Amir and Merbold, Sebastian and Egbers, Christoph}, title = {Spectral Analysis of Large Scale Structures in Fully Developed Turbulent Pipe Flow}, series = {Proceedings in applied mathematics and mechanics : PAMM}, volume = {17}, journal = {Proceedings in applied mathematics and mechanics : PAMM}, number = {1}, issn = {1617-7061}, doi = {10.1002/pamm.201710293}, pages = {647 -- 650}, language = {en} } @misc{SelvamOenguenerPeixinhoetal., author = {Selvam, Kamal and {\"O}ng{\"u}ner, Emir and Peixinho, Jorge and Zanoun, El-Sayed and Egbers, Christoph}, title = {Wall pressure in developing turbulent pipe flows}, series = {Journal of Fluids Engineering}, volume = {140}, journal = {Journal of Fluids Engineering}, number = {8}, issn = {1528-901X}, pages = {7}, language = {en} } @inproceedings{ZanounOenguenerEgbersetal., author = {Zanoun, El-Sayed and {\"O}ng{\"u}ner, Emir and Egbers, Christoph and Bellani, Gabriele and Talamelli, Alessandro}, title = {One-Dimensional Flow Spectra and Cumulative Energy from Two Pipe Facilities}, series = {iTi 2018 Conference on Turbulence VIII, September 5-7, 2018, Bertinoro, Italy, Book of abstract}, booktitle = {iTi 2018 Conference on Turbulence VIII, September 5-7, 2018, Bertinoro, Italy, Book of abstract}, pages = {S. 100}, language = {en} } @inproceedings{ZanounMotuzEgbersetal., author = {Zanoun, El-Sayed and Motuz, Vasyl and Egbers, Christoph and Keller, J. and D{\"o}rner, K.}, title = {Stereoscopic-PIV and Hot Wire Measurements in Pipe Flow at Relatively High}, series = {Proceedings of the 5th International Conference on Experimental Fluid Mechanics, Munich 2018}, booktitle = {Proceedings of the 5th International Conference on Experimental Fluid Mechanics, Munich 2018}, editor = {K{\"a}hler, Christian J. and Hain, Rainer and Scharnowski, Sven and Fuchs, Thomas}, publisher = {Institute of Fluid Mechanics and Aerodynamics, Universit{\"a}t der Bundeswehr}, address = {Neubiberg}, isbn = {978-3-943207-32-3}, doi = {10.18726/2018_2}, pages = {877 -- 882}, language = {en} } @misc{ZanounEgbersOerlietal., author = {Zanoun, El-Sayed and Egbers, Christoph and {\"O}rli, Ramis and Fiorini, Tommaso and Bellani, Gabriele and Talamelli, Alessandro}, title = {Experimental evaluation of the mean momentum and kinetic energy balance equations in turbulent pipe flows at high Reynolds number}, series = {Journal of Turbulence}, volume = {20}, journal = {Journal of Turbulence}, number = {5}, issn = {1468-5248}, doi = {10.1080/14685248.2019.1628968}, pages = {285 -- 299}, language = {en} } @misc{ZanounEgbersDewidar, author = {Zanoun, El-Sayed and Egbers, Christoph and Dewidar, Yasser}, title = {Two-Point Velocity Correlations in Fully Developed Turbulent Pipe Flow at Shear Reynolds Number of Reτ ≈ 4000}, series = {Proceedings in Applied Mathematics and Mechanics : (PAMM)}, volume = {20}, journal = {Proceedings in Applied Mathematics and Mechanics : (PAMM)}, number = {1}, issn = {1617-7061}, doi = {10.1002/pamm.202000330}, pages = {4}, language = {en} } @misc{RichterZanounEgbers, author = {Richter, Stefan and Zanoun, El-Sayed and Egbers, Christoph}, title = {Investigation of Large Scale Motion Interaction with the Near-Wall Turbulence}, series = {Proceedings in applied mathematics and mechanics : PAMM}, volume = {20}, journal = {Proceedings in applied mathematics and mechanics : PAMM}, number = {1}, issn = {1617-7061}, doi = {10.1002/pamm.202000331}, pages = {2}, language = {en} } @misc{ZanounEgbersNagibetal., author = {Zanoun, El-Sayed and Egbers, Christoph and Nagib, H. M. and Durst, F. and Bellani, Gabriele and Talamelli, Alessandro}, title = {Wall friction relations in wall-bounded shear flows}, series = {European Journal of Mechanics - B/Fluids}, volume = {Vol. 89}, journal = {European Journal of Mechanics - B/Fluids}, issn = {1873-7390}, doi = {10.1016/j.euromechflu.2021.03.007}, pages = {171 -- 179}, language = {en} } @misc{RichterZanounPeixinhoetal., author = {Richter, Stefan and Zanoun, El-Sayed and Peixinho, Jorge and Egbers, Christoph}, title = {Pipe Flow Development and Transition in CoSmaPipe Facility}, series = {Proceedings in applied mathematics and mechanics : PAMM}, volume = {23}, journal = {Proceedings in applied mathematics and mechanics : PAMM}, number = {1}, issn = {1617-7061}, doi = {10.1002/pamm.202300001}, language = {en} } @misc{ZanounDewidarEgbers, author = {Zanoun, El-Sayed and Dewidar, Yasser and Egbers, Christoph}, title = {Reynolds number dependence of azimuthal and streamwise pipe flow structures}, series = {Journal of Fluid Mechanics}, volume = {Vol. 973}, journal = {Journal of Fluid Mechanics}, issn = {0022-1120}, doi = {10.1017/jfm.2023.700}, pages = {1 -- 36}, language = {en} } @misc{ELSheikhELBatshZanounetal., author = {EL-Sheikh, Mohamed and EL-Batsh, Hesham M. and Zanoun, El-Sayed and Attia, Ali M. A.}, title = {Numerical and experimental investigations of flow separation control through a linear compressor cascade}, series = {Discover applied sciences}, volume = {6}, journal = {Discover applied sciences}, number = {9}, publisher = {Springer International Publishing}, address = {Cham}, issn = {3004-9261}, doi = {10.1007/s42452-024-05982-3}, pages = {1 -- 24}, abstract = {Modern large-scale gas turbines are equipped with high-pressure ratio compressors to increase engine work and its overall efficiency. Flow separation and energy losses are also two interrelated phenomenon associated with changes in compressor loading level and performance. This paper examines therefore the control of flow separation using a passive-control technique. An arced divergent-convergent slot grooved from the blade pressure side to its suction side was adopted to control flow separation, reducing the losses through a linear compressor cascade. The spanwise location of the slot was selected based on CFD simulations where the corner separation was predicted. The slot height in the spanwise direction was selected to be 8\% of the blade height at the end-wall side. The present work was performed experimentally and numerically at an inlet Reynolds number, Rec=ρV∞C/μ=2.98×105, covering a wide range of incidence angles from +6∘to-6∘. The experimental work was carried out using a linear cascade test section consisting of six NACA 65-009 blade profiles integrated into a low-speed wind tunnel. A five-hole pressure probe system was used to obtain main flow parameters. Numerically, four turbulence models, including Spalart-Allmaras (S-A) model, Realizable (R k-ε) model, Shear-Stress Transport (SST k-ω) model, and Reynolds Stress model (RSM) were tested to predict the velocity and pressure fields. Good agreement between the experimental measurements and the numerical results, which were obtained using the RSM turbulence model in terms of velocity profiles and total pressure downstream of blades. It was observed also that the use of the arced-slotted blades for positive incident angles was more effective in reducing the separation than the negative and zero incident angles, approaching a maximum value of 33\% for 6° with enhanced blade loading reaching 17.6\%. It is to be concluded that, the use of arced slotted blade improves the compressor performance specially for positive incident angles.}, language = {en} } @misc{DurstZanoun, author = {Durst, Franz and Zanoun, El-Sayed}, title = {Laminar pipe flow instability : a theoretical-experimental perspective}, series = {Fluids}, volume = {10}, journal = {Fluids}, number = {8}, publisher = {MDPI}, address = {Basel}, issn = {2311-5521}, doi = {10.3390/fluids10080216}, pages = {1 -- 21}, abstract = {This paper revisits the theoretically predicted inherent stability of fully developed laminar pipe flow, which remains unconfirmed by experimental evidence. A recently developed theory of pipe-flow stability/instability addresses the gap between experimental observations and classical theoretical predictions by accounting for a parallel secondary flow through the pipe's roughness layer that accompanies the main stream. This secondary flow alters the near-wall velocity profile in the rough-wall region, creating an inflection point that promotes shear-driven instabilities and triggers the laminar-to-turbulent transition. A stability factor 𝑆=𝐷𝑐/𝐷 is introduced, where D is the nominal pipe diameter and 𝐷𝑐 refers to the critical pipe diameter. The pipe flow remains laminar and stable for 𝑆>1.0, and becomes unstable for 𝑆<1. Various experimental findings are theoretically derived, and the laminar-to-turbulent transition is identified at 𝑆=1.0. Particular attention is paid to the dependence of flow transition on both pipe diameter and pipe length. Rather than relying on a critical Reynolds number 𝑅𝑒𝑐, this study proposes the critical pipe diameter 𝐷𝑐 as the key parameter governing the laminar pipe flow instability, where 𝑅𝑒𝑐 refers here to the condition-dependent threshold at which laminar pipe flow becomes unstable and transition to turbulence occurs. The present analysis further suggests that instability arises only if the pipe length L exceeds a critical threshold 𝐿𝑐, that is, 𝐿>𝐿𝑐. The theoretical treatment presented provides deeper physical insights into the onset of laminar pipe flow instability including the phenomenon of reverse transition. It also distinguishes between natural and forced flow transitions, providing a refined understanding of the transition process. Finally, suggestions for future experimental work are made to further validate or challenge this new theoretical perspective on pipe flow instability.}, language = {en} }