401 2次元一様等方性Passive-Scalar場のDNS(G05-8 乱流,G05 流体工学)  [in Japanese] 401 Direct Numerical Simulation of Passive-Scalar Fields in Two-Dimensional Homogeneous Isotropic Turbulence  [in Japanese]

Passive-scalar fields in two-dimensional homogeneous isotropic turbulence with several Prandtle numbers (Pr) were investigated by means of the direct numerical simulation (DNS). In the time development, the thermal intensity was rapidly decreased at the low Pr. The thermal intensity spectra obey the power laws of k^<-1.4>, k^<-2> and k^<-5.9> in Pr=5, 1, 0.05 respectively. In the contour of the thermal dissipation rate, the remarkable increase of line structures was observed when Pr was high. In the multi-fractal analysis, we found the strong intermittency at high Prandtle number.