Identification of vortex-induced-response parameters in time domain

A single-degree-of-freedom mathematical model for describing vortex-induced response of a structure at "lock-in" includes certain aeroelastic parameters that need to be extracted from wind tunnel tests. The methods available in the literature for extraction of these parameters have certain limitations that inhibit accuracy in the extracted parameters of certain bluff-body sections. In the work reported herein, a new approach, which can be universally applied for the identification of vortex-shedding parameters even in turbulent-flow situations, has been proposed based on the concepts of invariant imbedding and nonlinear filtering theory. The new approach has been verified through experiments in the wind tunnel for both smooth and turbulent flow situations. The classical case of a circular cylinder has been employed to verify the accuracy of the approach. Experiments were also conducted with a circular-cylindrical section (rough surface) and two bridge-deck configurations to test the new approach on different types of cross sections.