European Turbulence Conference 2015

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12:15
15 mins

Relation between enstrophy production and geometry near the turbulent/non-turbulent interface in free shear flows
Tomoaki Watanabe, Carlos da Silva, Yasuhiko Sakai, Kouji Nagata

Session: Jets and Wakes 1
Session starts: Tuesday 25 August, 10:30
Presentation starts: 12:15
Room: Room E

Tomoaki Watanabe (Nagoya University)
Carlos da Silva (Instituto Superior Técnico)
Yasuhiko Sakai (Nagoya University)
Kouji Nagata (Nagoya University)

Abstract:
In many free shear flows, such as mixing layers, wakes and jets exhibit a sharp turbulent/non-turbulent interface (TNTI) separating regions of turbulent and non-turbulent or potential flow. In the present work the dependence of enstrophy production on the interface geometry near the TNTI is investigated by using direct numerical simulations (DNS) of a shear free turbulence (SFT) and a temporally developing planar jet (PJET). It is shown that the geometry of the TNTI has impacts on the mechanism governing enstrophy dynamics within the interface layer itself. In particular it is shown that enstrophy production within the turbulent sublayer is primarily associated with a convex shape of the interface both the SFT and PJET.