On the structure and patterns of von Kármán vortices in two-dimensional high Reynolds number flows

Abstract

This study explores the dynamics and statistical patterns of coherent long-lived vortices spontaneously forming in bluff body wakes. The analysis is based on a series of two-dimensional direct numerical simulations performed for a wide range of Reynolds numbers. We demonstrate that the majority of coherent vortices beyond the recirculation zone are well represented by the canonical Lamb-Oseen solution. This observation is used to develop a low-order census of long-lived eddies in terms of their core sizes and vorticity magnitudes. We demonstrate that the increase in the Reynolds number (Re) leads to the systematic reduction in the initial core radii (r0), whereas the core vorticity (ζ0) increases. These dependencies exhibit singular behavior in the inviscid limit (Re → ∞), which is captured by the proposed explicit relations for r0(Re) and ζ0(Re).