AM06-11-020 空間発展混合層の乱流遷移機構(境界層とせん断流・遷移(5),一般講演)

概要

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To investigate the relationship between characteristics of coherent fine scale eddies (CFSEs) and turbulence transition, a direct numerical simulation (DNS) of spatially-developing turbulent mixing layer with Re_<ω,0>=700 was conducted. The large-scale coherent structures; Kelvin-Helmholtz roller and rib vortex, do not disappear in the transition process and in the fully-developed state, while they are composed of lots of CFSEs. The most expected diameter of the CFSEs is about 8η and does not change in the process of the turbulence transition, whereas the most expected maximum azimuthal velocity of CFSEs decreases from 2.0u_κ to 1.2u_κ. The strain rate acting on the center of CFSEs tends to become weak during the transition, whereas the most expected eigenvalues ratio is maintained to be α:β:γ=-5:1:4. In addition, the phase averaged energy dissipation rate on the major axis of CFSE becomes low during the turbulence transition.
日本流体力学会の論文
2006-09-05