The Dynamics of Coherent Structures in a Turbulent Wake behind a Body of Revolution at Re_D=5000

The study on coherent structures gives intuitive understanding of turbulent flows. This work focuses on the dynamics of coherent structures that are formed in the wake past an axisymmetric body at Re_D=5000. The data used is gathered over 790 vortex shedding cycles from a direct numerical simulation. Characteristic motions of the wake, such as vortex shedding, bubble pumping, precession of wake barycenters, etc., are related to coherent structures by the dominant frequencies that can be cast in a non-dimensional form by Strouhal scaling St_D=fD/U_∞. Power spectra analysis, azimuthal Fourier analysis and modal analysis are employed to identify the frequencies and visualize the corresponding coherent structures.