71th Annual Meeting of the APS Division of Fluid Dynamics (November 18, 2018 — November 20, 2018)

V0004: Vortex reconnection cascade via direct numerical simulation up to Re=40,000

  • jie yao, Texas Tech Univ
  • fazle hussain, Texas Tech Univ

Vortex reconnection is a fundamental topology transforming event. Such a topological transformation is considered to play a significant role in flow turbulence such as energy transfer, fine-scale mixing, and noise generation. Vortex reconnection was also found to play an essential role in the transition and friction drag production in the wall-bounded flows. In addition to their physical relevance, reconnection also represents a stand-alone mathematical problem related to the presence of finite time singularity (FTS) in the Euler equation. With direct numerical simulation up to Re=40000, we report here, for the first time, the evidence of vortex reconnection cascade scenario first proposed by Melander and Hussain (1988, CTR Report), where the remaining threads continue to undergo successive reconnections. This observation clearly demonstrates and confirms our long-standing claim that vortex reconnection is an important physical mechanism of turbulent energy cascade, particularly at high Reynolds numbers.

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