On the prolong attachment of leading edge vortex on a flapping wing

In this paper, we take a fundamental approach to investigate the effect of spanwise flow on the prolonged attachment of leading edge vortex (LEV) on a flapping wing. By imposing a constant acceleration-constant velocity flow on elliptic wings of various sweep angles and angles of attack, our experimental and numerical results show that while spanwise flow per se has negligible influence on the prolong attachment of the LEV, vortex stretching can significantly delay detachment of the LEV, even for a small spanwise flow.