一様等方性乱流の直接数値計算 : パッシプスカラ変動の減衰

概要

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Direct numerical simulations of three-dimensional homogeneous isotropic turbulence with temperature diffusion were performed by using a spectral method with 64^3 Fourier modes. Temperature fluctuation was not so large, so we assumed that temperature is a passive scalar. We simulated two cases with Prandlt numbers of 0.71 and 0.20. During the decaying period, the turbulent kinetic energy dissipation rate decayed exponentially with time and the microscale Reynolds number changed from 30 to 17. Spectral distribution of the passive scalar fluctuation spread more widely than that of velocity fluctuation in the case of a Prandtl number of 0.71. In the case of a Prandtl number of 0.20, spectral distribution did not spread as widely, but two-point autocorrelation of the temperature fluctuation showed a negative value at large distance, which shows predominancy of the low wave number components.
社団法人日本機械学会の論文
1991-12-25