von Kármán乱流中の大規模時空間変動とエネルギカスケードの動力学

抄録

Kolmogorov’s local equilibrium hypothesis claims that the statistics of small-scale motion of turbulence are independent of its large-scale spatio-temporal fluctuation. This is the basis of the “K41” picture of the universality in small-scale turbulence. However, the validity of this hypothesis and its relationship with the energy cascade dynamics are not fully understood. In the present study, von Kármán flow is examined by experiments and numerical simulations. By PIV experiments, we obtain results consistent with DNS in a periodic box, i.e. spatially intermittent small-scale clusters of vortices and a very long temporal fluctuation.