Optimal streaks in the wake of a blunt-based axisymmetric bluff body and their influence on vortex shedding

We compute the optimal perturbations of azimuthal wavenumber m THAT maximize the spatial energy growth in the wake of a blunt-based axisymmetric bluff body. Optimal perturbations with m≠0 lead to the amplification of streamwise streaks in the wake. When forced with finite amplitude m≠1, optimal perturbations have a stabilizing effect on large-scale unsteady vortex shedding in the wake. We show that m≥2 modes, which are forced with zero mass flux, can significantly reduce the amplitude of the unsteady lift force exerted on the body. When combined with low levels of base bleed, these perturbations can completely suppress the unsteadiness in the wake with reduced levels of mass injection in the flow.