{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,3,27]],"date-time":"2026-03-27T06:15:18Z","timestamp":1774592118124,"version":"3.50.1"},"reference-count":0,"publisher":"Cambridge University Press (CUP)","license":[{"start":{"date-parts":[[1999,4,25]],"date-time":"1999-04-25T00:00:00Z","timestamp":924998400000},"content-version":"unspecified","delay-in-days":0,"URL":"https:\/\/www.cambridge.org\/core\/terms"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["J. Fluid Mech."],"published-print":{"date-parts":[[1999,4,25]]},"abstract":"<jats:p>Confined vortex breakdown generated by a rotating cone within a closed cylindrical \n\ncontainer has been studied both by numerical simulation and by experimental \n\ntechniques. A comprehensive investigation of the various flow regimes has been carried out \n\nby flow visualization. From laser\u2013Doppler measurements of the entire flow field (three \n\nvelocity components) detailed maps of the time-averaged flow structures for single and \n\ndouble breakdown have been constructed. Three-dimensional time-dependent simulations \n\nof steady and unsteady breakdown have been performed. Steady numerical and \n\nexperimental flow fields obtained at Reynolds number 2200 for a gap ratio of 2 show \n\nnotable agreement. At critical Reynolds numbers of approximately 3095, for a gap \n\nratio of 2, and 2435, for a gap ratio of 3, the flow was observed becoming unsteady. \n\nThe periodic behaviour exhibited by the unsteady flow suggested the occurrence of a \n\nsupercritical Hopf bifurcation. This conjecture was confirmed by the evolution of the \n\noscillation amplitude as a function of criticality, measured for a gap ratio of 3. The \n\ndynamical behaviour of unsteady vortex breakdown structures is depicted by numerical \n\nsimulation of two distinct oscillatory regimes, at Reynolds numbers 2700 and 3100. A \n\nthorough analysis of the numerical results has shown that whereas the former regime \n\nis characterized by the steady oscillation of closely axisymmetric breakdowns, the latter \n\ndisplays precession of breakdown structures about the central axis. Additionally, it \n\nwas observed that the mode bringing about the Hopf bifurcation is non-axisymmetric, \n\nwith azimuthal periodicity of \u03c0\/2 radians. From examination of measured velocity \n\npower spectra at higher Reynolds numbers, a transition scenario was also educed. In \n\nthe present case, the Ruelle\u2013Takens\u2013Newhouse theorem has been shown to apply.<\/jats:p>","DOI":"10.1017\/s002211209900436x","type":"journal-article","created":{"date-parts":[[2002,7,27]],"date-time":"2002-07-27T13:23:06Z","timestamp":1027776186000},"page":"287-323","source":"Crossref","is-referenced-by-count":30,"title":["Confined vortex breakdown generated by a rotating cone"],"prefix":"10.1017","volume":"385","author":[{"given":"J. C. F.","family":"PEREIRA","sequence":"first","affiliation":[]},{"given":"J. M. M.","family":"SOUSA","sequence":"additional","affiliation":[]}],"member":"56","published-online":{"date-parts":[[1999,4,25]]},"container-title":["Journal of Fluid Mechanics"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.cambridge.org\/core\/services\/aop-cambridge-core\/content\/view\/S002211209900436X","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2019,6,7]],"date-time":"2019-06-07T20:23:51Z","timestamp":1559939031000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.cambridge.org\/core\/product\/identifier\/S002211209900436X\/type\/journal_article"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[1999,4,25]]},"references-count":0,"alternative-id":["S002211209900436X"],"URL":"https:\/\/doi.org\/10.1017\/s002211209900436x","relation":{},"ISSN":["0022-1120","1469-7645"],"issn-type":[{"value":"0022-1120","type":"print"},{"value":"1469-7645","type":"electronic"}],"subject":[],"published":{"date-parts":[[1999,4,25]]}}}