210 秩序渦近傍と乱流場との相互作用・秩序渦の崩壊

概要

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The interaction between a columnar vortex (Lamb-Oseen vortex) and initially isotropic homogeneous turbulence (produced by a DNS of decaying turbulence) is investigated numerically. After a columnar vortex is introduced, the intense vortices are wrapped around the vortex core. The velocity field of small scale eddies near the vortex core becomes statistically axisymmetric, within a period of two or three revolutions of the columnar vortex (t ≈ 2). The axial velocity dominates near the core surface ('blocking' effect) but the radial velocity dominates away from the vortex core. The linear rapid distortion theory explains well the statistics of turbulence if t < 2,whereas it fails for larger times. The two-point velocity correlation functions saturate t ≈ 5 and decay for t > 6. Bending waves of large amplitude are excited on the columnar vortex, which seems to induce its destruction.
社団法人日本機械学会の論文
2000-07-31