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Titolo:
Characteristics of internal vortical structures in a merged turbulent spot
Autore:
Makita, H; Nishizawa, A;
Indirizzi:
Toyohashi Univ Technol, Dept Mech Engn, Aichi 4418580, Japan Toyohashi Univ Technol Aichi Japan 4418580 ch Engn, Aichi 4418580, Japan Natl Aerosp Lab, Fluid Sci Res Ctr, Tokyo 1828522, Japan Natl Aerosp Lab Tokyo Japan 1828522 id Sci Res Ctr, Tokyo 1828522, Japan
Titolo Testata:
JOURNAL OF TURBULENCE
, volume: 2, anno: 2001,
pagine: 1 - 14
SICI:
1468-5248(20010726)2:<1:COIVSI>2.0.ZU;2-N
Fonte:
ISI
Lingua:
ENG
Soggetto:
LAMINAR BOUNDARY-LAYER; HAIRPIN VORTICES; SUBSTRUCTURES; MOTION; FLOW;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Physical, Chemical & Earth Sciences
Engineering, Computing & Technology
Citazioni:
31
Recensione:
Indirizzi per estratti:
Indirizzo: Makita, H Toyohashi Univ Technol, Dept Mech Engn, 1-1 Tenpaku Cho, Aichi 4418580, Japan Toyohashi Univ Technol 1-1 Tenpaku Cho Aichi Japan 4418580 apan
Citazione:
H. Makita e A. Nishizawa, "Characteristics of internal vortical structures in a merged turbulent spot", J TURBUL, 2, 2001, pp. 1-14

Abstract

Interaction phenomena between two turbulent spots were investigated in a zero pressure-gradient laminar boundary layer. Two types of hotwire rakes, a16-channel I- and a 30-channel X-probe gave clear instantaneous vortical motion inside the spots, showing that the single spot was an aggregation of many small-scale hairpin vortices accompanied by upwashes and downwashes around their legs. The legs, a pair of counter-rotating longitudinal vortices, were identified by the existence of streaky velocity-defect and -excess regions at the bottom of the spot. As the spot grew downstream, the number of longitudinal vortices increased, though its wingtips were always accompanied by upwashes. When two spots were produced in parallel and merged with each other, the upwash of the low-speed fluid was strongly enhanced in theirmerged part through the mutual interaction between the longitudinal vortices at their inside wingtips. Resultant unstable inflectional velocity profile gave birth to several spanwise vortices around the top of the merged part. These intensified spanwise vortices conformed the heads of horseshoe vortices and grew larger than those around the head of non-interacting isolated spots. Such strengthened horseshoe vortices possibly maintain their geometric identity to the turbulent boundary layer further downstream and initiate the turbulent bulges in it.

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Documento generato il 23/01/20 alle ore 13:10:27