Numerical simulation of flow over flapping wings in tandem: Wingspan effects

We report direct numerical simulations of a pair wings in horizontal tandem configuration, to analyze the effect their aspect ratio on flow and aerodynamic performance system. The are immersed uniform free-stream at Reynolds number Re = 1000, they undergo heaving pitching oscillation with Strouhal St 0.7. ratios forewing hindwing vary between 2 4. system is dictated by interaction trailing edge vortex (TEV) shed induced leading formed hindwing. similar that an isolated wing irrespective hindwing, small modulating produced forewing-hindwing interactions. On other hand, clearly affected forewing's TEV. Tandem configurations larger than result quasi-two-dimensional structure latter. This yields 8% increase time-averaged thrust coefficient no change its propulsive efficiency.