A simple vortex approach to complex two-wing unsteady flapping problems in 2D applied to insect flight study

ABSTRACT The secrets of the flapping of insects with two pairs of wings, primarily dragonflies, have been revealed experimentally and numerically. Although there exist many excellent experimental studies, numerical study is limited due to the highly demanding nature of the numerical approach to the unsteady flapping problems. Recently, we have developed a vortex-based method for the single-wing flapping problems in 2D. The simplicity and the accuracy of the method developed have encouraged us to extend the method to problems with two pairs of wings; the outcome is reported in this paper. We consider the species with a long wing span for which the flow field in the span direction is constant and treated as 2D.