Effects of advance ratio on elytra-hindwing interaction in forward flying Coleopteran beetle

Abstract

In the present study, numerical simulations are performed to explore the significance of elytron-hindwing interaction in the forward flying Coleopteran beetle. The study investigates the effects of hindwing stroke amplitude (A/c) and advance ratio (J), (which is defined as the ratio of the incoming air velocity to the wing flapping velocity), on the aerodynamic forces. The wing kinematics of a Coleopteran beetle is constructed by using a combination of translation and rotation motion. The elytron is modeled by using a cambered airfoil that mimics the real geometry of the beetle wing, and the hindwing is modeled by using an elliptical profile. The results indicate that the beetle cruises with a constant velocity at approximately J = 0.3 in the tandem wing arrangement. It is observed that the angle of the net force vector relative to the stroke plane tilts systematically according to the flying speed. The influence of vortex structures on the beetle aerodynamic forces is analyzed. The elytron-hindwing interaction is found to be beneficial to the vertical force generation of hindwing as well as for the elytron when J > 0.0. The vortices interaction is observed during the downstroke period, and the leading edge vortex (LEV) of the elytron is captured by LEV of the hindwing that enhances the total vertical force. During the upstroke translation phase, the combined trailing edge vortex of elytron interacts/merges with the LEV of the hindwing and increases the horizontal force.