C214 一様等方性乱流中の2粒子拡散過程と構造抽出に関する研究(C-21 乱流熱物質移動および反応流(3),一般講演)

概要

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The purpose of this study is to elucidate the relation between a growth of two-particle distance and the fine-scale structures of turbulence by the three-dimentional direct numerical simulation (DNS). It is shown that the Lagrangian burst of particle-pair occured in the "straining stagnation region", where Δ<0 (Δ is the value of discriminant of the characteristic equation which is defined by Δ=(Q/3)^3+(R/2)^2, where Q and R are the 2nd and 3rd invariance of the velocity gradient tensor). The scaling law of <l^2>〜τ^γ (l and τ are the separation distance and the diffusion time) has been investigated. It is found that the relation of γ=6/D_s is useful, where D_s is the power exponent of n_s≈C_sL^<-3>(L/η)^<D_s> (L and η are integral length scale and Kolmogorov microscale; n_s is the number of straining stagnation points; C_s is a dimensionless number).
日本流体力学会の論文
2004-08-09