Stability and coherent structures in the wake of axisymmetric Bluffbodies

Abstract

The coherent structures observed in the turbulent wake of axisymmetric bluffbodies are investigated. Concepts from hydrodynamic stability are used to derive low-dimensional mathematical models based on a weakly nonlinear analysis of the governingNavier-Stokes equations that describe the temporal amplitude evolution of the coherent structures in the near wake. Forced experiments applying axisymmetric pulsed-jet blowing on the base of the body are performed to validate the models.Very good quantitative agreement between model predictions and experiments is obtained, showing for the first time that Landau-type models are capable of describing the dynamic behavior of a three-dimensional turbulent wake.