MULTI MODES FOR THE VORTEX SHEET-TUBE TRANSFORMATION PROCESS AND VISCOELASTIC EFFECT

摘要

A process for formation of the stretched spiral vortex was investigated using the DNS data of homogeneous turbulence. It was shown that vortex tube was generated not by a rolling up of single vortex sheet but through an interaction of dual sheets. Depending on the alignment of vorticity vectors on vortex tube and vortex sheets which emanate from vortex tube, three modes of configuration were shown to exist. Frequency of appearance of three modes and its implication for turbulence generation was discussed in isotropic and sheared flows.