Different topologies of natural vortex dislocations in Mode A wake

Abstract

The mode A wake behind a circular cylinder at Reynolds number 200 was simulated by directly solving the three-dimensional Navier–Stokes equations. A more detailed investigation of different topologies of natural vortex dislocations in the mode A wake was systematically described. In addition to the two-side natural vortex dislocation defined by Williamson [J. Fluid Mech. 243, 393–441 (1992)], three new topologies of vortex dislocations were identified. Additionally, the formation process and the mechanism of these newly identified dislocation topologies were addressed. The results in this Letter provide a more thorough understanding of the natural vortex dislocations in the mode A wake.