On three-dimensional bluff body wake symmetry breaking with free-stream turbulence and residual asymmetry

Abstract

The paper reports on the bi-stable turbulent wake dynamics of a three-dimensional bluff body. It is shown that the occurrence of the switching between the two wake states decreases as the turbulent intensity of the incoming flow is made larger by an additional upstream grid. A detailed analysis of the jumps statistics indicates that the turbulent fluctuation of each wake state is also decreased. It is concluded that the states switching is thus triggered by large fluctuations produced by the wake instabilities and not by those of the incoming flow. It is also shown that increasing the free-stream turbulence intensity reinforces the permanent asymmetry of each state and increases the wake sensitivity to residual asymmetries.