Investigation of coherent structures and dynamics using POD and DMD of a separated airfoil subjected to ZNMF jet forcing

Abstract

Proper Orthogonal Decomposition (POD) and Dynamic Mode Decomposition (DMD)are applied to the unsteady separated flowfield over aNACA- 0015 airfoil with periodic zero-net-mass-flux (ZNMF) jet forcing at the leading edge at an angle of attack α = 18o and chord based Reynolds number of Re = 3 × 104. This study presents experimental data for the forced flow case and recovers the dominant coherent structures and temporal characteristics that describe the evolution of the velocity perturbation. The dominant frequencies are identified by the DMD eigenvalues and the corresponding spatialmodes are compared to the dominant POD modes.