Empirical Model for the Evolution of a Vortex-Pair Introduced into a Boundary Layer

A linear, empirical, low-order-model was developed with the aim of describing the evolution of a 2D vortex-pair ejected into a boundary layer from a slot-in-the-wall. The model describes the evolution of a counter-rotating pair of Lamb-Oseen vortices in the proximity of a wall on which a cross-flow Blasius boundary layer exits. Two inputs from experimental measurements are used. First, the initial locations where the vortices form and pinch-off from the excitation slot boundary layers. Second, the time evolution of the vortex circulation in still-air. With this input, the model predicts the trajectories and vorticity distribution during the interaction. Such a model could be a viable tool for the development of a low-order-model to be implemented as a simplified boundary condition in CFD simulations, with the aim of reducing the requirement to fully resolve the vicinity of the excitation slot in active flow control simulations.