Higher order dynamic mode decomposition to identify decay in trailing vortices

Abstract

We conduct three-dimensional measurements of the velocity field using stereo PIV in the turbulent wake of a wing model based on a NACA0012 airfoil, for an angle of attack of 9 degrees, and Reynolds number 40000 up to 32 chords from the wing. These experimental results are compared with theoretical models of trailing vortices, Batchelor [2] and Moore and Saffman [3], to determine the parameters of the turbulent wake vortex. Three different zones are identified based on the vortex strength: near, middle and far fields. We make use of Higher Order Dynamic Mode Decomposition (HODMD) to give a better understanding of the most relevant modes within these three regions. We observe that vortex decay in the middle field is related with the HODMD modes. Thus, the information given by this study is useful to test proof-of-concept of future active control for vortex alleviation.