{"date_published":"2015-04-08T00:00:00Z","project":[{"_id":"25152F3A-B435-11E9-9278-68D0E5697425","call_identifier":"FP7","name":"Decoding the complexity of turbulence at its origin","grant_number":"306589"}],"main_file_link":[{"open_access":"1","url":"https://arxiv.org/abs/1508.06559"}],"day":"08","status":"public","ec_funded":1,"publication":"Journal of Fluid Mechanics","quality_controlled":"1","external_id":{"arxiv":["1508.06559"]},"user_id":"2DF688A6-F248-11E8-B48F-1D18A9856A87","publist_id":"5265","abstract":[{"text":"Transition to turbulence in straight pipes occurs in spite of the linear stability of the laminar Hagen-Poiseuille flow if both the amplitude of flow perturbations and the Reynolds number Re exceed a minimum threshold (subcritical transition). As the pipe curvature increases, centrifugal effects become important, modifying the basic flow as well as the most unstable linear modes. If the curvature (tube-to-coiling diameter d/D) is sufficiently large, a Hopf bifurcation (supercritical instability) is encountered before turbulence can be excited (subcritical instability). We trace the instability thresholds in the Re - d/D parameter space in the range 0.01 ≤ d/D\\ ≤ 0.1 by means of laser-Doppler velocimetry and determine the point where the subcritical and supercritical instabilities meet. Two different experimental set-ups are used: a closed system where the pipe forms an axisymmetric torus and an open system employing a helical pipe. Implications for the measurement of friction factors in curved pipes are discussed.","lang":"eng"}],"publisher":"Cambridge University Press","article_processing_charge":"No","language":[{"iso":"eng"}],"issue":"5","citation":{"ieee":"J. Kühnen, P. Braunshier, M. Schwegel, H. Kuhlmann, and B. Hof, “Subcritical versus supercritical transition to turbulence in curved pipes,” <i>Journal of Fluid Mechanics</i>, vol. 770, no. 5. Cambridge University Press, 2015.","ama":"Kühnen J, Braunshier P, Schwegel M, Kuhlmann H, Hof B. Subcritical versus supercritical transition to turbulence in curved pipes. <i>Journal of Fluid Mechanics</i>. 2015;770(5). doi:<a href=\"https://doi.org/10.1017/jfm.2015.184\">10.1017/jfm.2015.184</a>","chicago":"Kühnen, Jakob, P Braunshier, M Schwegel, Hendrik Kuhlmann, and Björn Hof. “Subcritical versus Supercritical Transition to Turbulence in Curved Pipes.” <i>Journal of Fluid Mechanics</i>. Cambridge University Press, 2015. <a href=\"https://doi.org/10.1017/jfm.2015.184\">https://doi.org/10.1017/jfm.2015.184</a>.","apa":"Kühnen, J., Braunshier, P., Schwegel, M., Kuhlmann, H., &#38; Hof, B. (2015). Subcritical versus supercritical transition to turbulence in curved pipes. <i>Journal of Fluid Mechanics</i>. Cambridge University Press. <a href=\"https://doi.org/10.1017/jfm.2015.184\">https://doi.org/10.1017/jfm.2015.184</a>","short":"J. Kühnen, P. Braunshier, M. Schwegel, H. Kuhlmann, B. Hof, Journal of Fluid Mechanics 770 (2015).","mla":"Kühnen, Jakob, et al. “Subcritical versus Supercritical Transition to Turbulence in Curved Pipes.” <i>Journal of Fluid Mechanics</i>, vol. 770, no. 5, R3, Cambridge University Press, 2015, doi:<a href=\"https://doi.org/10.1017/jfm.2015.184\">10.1017/jfm.2015.184</a>.","ista":"Kühnen J, Braunshier P, Schwegel M, Kuhlmann H, Hof B. 2015. Subcritical versus supercritical transition to turbulence in curved pipes. Journal of Fluid Mechanics. 770(5), R3."},"doi":"10.1017/jfm.2015.184","scopus_import":1,"author":[{"orcid":"0000-0003-4312-0179","id":"3A47AE32-F248-11E8-B48F-1D18A9856A87","first_name":"Jakob","full_name":"Kühnen, Jakob","last_name":"Kühnen"},{"full_name":"Braunshier, P","last_name":"Braunshier","first_name":"P"},{"last_name":"Schwegel","full_name":"Schwegel, M","first_name":"M"},{"first_name":"Hendrik","last_name":"Kuhlmann","full_name":"Kuhlmann, Hendrik"},{"orcid":"0000-0003-2057-2754","first_name":"Björn","id":"3A374330-F248-11E8-B48F-1D18A9856A87","full_name":"Hof, Björn","last_name":"Hof"}],"article_number":"R3","year":"2015","type":"journal_article","date_created":"2018-12-11T11:54:17Z","date_updated":"2021-01-12T06:53:31Z","month":"04","volume":770,"_id":"1837","title":"Subcritical versus supercritical transition to turbulence in curved pipes","department":[{"_id":"BjHo"}],"intvolume":"       770","oa_version":"Preprint","oa":1,"publication_status":"published","article_type":"original"}