Comparing leading and trailing edge vortex circulation history with vortex identification and tracking methods

The instantaneous circulation of vortices shed from an unsteady pitching panel is studied to reveal the formation and shedding processes of leading edge vortices (LEV). The analysis processes a large amount of data from the 2D simulation of a flat plate undergoing a 45° pitch-up maneuver. Large scale lift loss on the panel is shown to correlate with the vortex shedding. The Eulerian Γ₁ and Q criteria, and Lagrangian coherent structures (LCS) analysis including both finite-time Lyapunov exponent (FTLE) and Lagrangian-Averagcd Vorticity Deviation (LAVD) are all applied at the center and boundary of the LEV to identify the vortex dynamics. This is compared with a calculation of the circulation. The identified LEV dynamics revealed by multiple vortex criteria matches with the circulation development and lift history in time, indicating a consistent timing of LEV formation, growth, shedding, etc.