%T Structural changes of laminar separation bubbles induced by global linear instability
%I Cambridge University Press
%A Daniel Rodríguez Álvarez
%A Vassilios Theofilis
%X The topology of the composite flow fields reconstructed by linear superposition of a two-dimensional boundary layer flow with an embedded laminar separation bubble and its leading three-dimensional global eigenmodes has been studied. According to critical point theory, the basic flow is structurally unstable; it is shown that in the presence of three-dimensional disturbances the degenerate basic flow topology is replaced by a fully three-dimensional pattern, regardless of the amplitude of the superposed linear perturbations. Attention has been focused on the leading stationary eigenmode of the laminar separation bubble discovered by Theofilis; the composite flow fields have been fully characterized with respect to the generation and evolution of their critical points. The stationary global mode is shown to give rise to a three-dimensional flow field which is equivalent to the classical U-shaped separation, defined by Hornung & Perry, and induces topologies on the surface streamlines that are resemblant to the characteristic stall cells observed experimentally.
%V 655
%P 280-305
%L upm7671
%J Journal of Fluid Mechanics
%R 10.1017/S0022112010000856
%D 2010