パッシブスカラー乱流におけるスカラーフラックススペクトルの振る舞い(乱流熱物質拡散・伝達(2),一般講演)

概要

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Scaling law of scalar flux spectrum (velocity-scalar cospectrum) in the inertial convective range of a passive scalar turbulence under a uniform mean scalar gradient is examined using direct numerical simulation with resolution up to 2048^3 grid points. When the Reynolds number R_λ is increased up to R_λ=585, the scalar flux spectrum tends to the power law κ^<-7/3> which was predicted by Lumley (1964, 1967), and a nondimensional constant is found to be C_<uθ>=1.50±0.08 at R_λ=585. It is found that R_λ-effect on the scaling of the scalar flux spectrum is well compensated by using the mean molecular destruction of scalar flux ε^^-_<uθ>. The R_λ-dependence of C_<uθ> is also examined by comparing with those of previous studies and its asymptotic state at infinite Reynolds number is discussed.
日本流体力学会の論文
2007-08-06