Geometrical influence on decay rates of low-order azimuthal modes in turbulent axisymmetric wakes

The dynamics of coherent structures in turbulent wakes are of particular interest in aero- and hydrodynamic applications, as they have a relationship with the drag on a body. Understanding the primary coherent structures within a wake and their dynamics can help us further understand and develop turbulence models. In this work, the influence of initial geometry on the decay of coherent structures in turbulent axisymmetric wakes is investigated at a Reynolds number Re = 26,000. The rate at which the first azimuthal mode decays, associated with vortex shedding, is strongly influenced by initial conditions. The downstream location where the double-helix mode, the second azimuthal mode, dominates for the disk is consistent with those found in the literature, however, it can be moved further downstream by modifying the initial geometry of the wake generating plate.