Full Program »

GENERATION MECHANISM OF HIERARCHY OF COHERENT VORTICES IN TURBULENCE

PDF
0.8MB

DNS of turbulence at high Reynolds numbers (up to Rλ=680) sustained by steady force in a periodic cube have been conducted to show that (i) coherent vortices, which are identified by the band-pass filtering of Fourier components, in the inertial range have tubular shapes, (ii) these vortex tubes are created due to vortex stretching in strain fields around 2—10 times-larger-scale vortex tubes, (iii) in this vortex stretching process anti-parallel pairs of vortex tubes tend to be created simultaneously, and they create further smaller vortices effectively, (iv) turbulence sustained by the steady force becomes quasi-periodic in time, and its period is about 20 eddy turnover time irrespective of the Reynolds number.

Author(s):

Susumu Goto    
Osaka University
Japan

Genta Kawahara    
Osaka University
Japan