Comparative study between a discrete vortex method and an immersed boundary-lattice Boltzmann method in 2D flapping flight analysis

Numerical analysis of the flapping flight of insects has attracted great attention because of the expectation for insect-inspired micro air vehicles. A lot of numerical methods for the insect flight have been proposed, and they can be classified into two categories: inviscid flow solvers and viscous flow solvers. The discrete vortex method (DVM) has been regarded as a successful method in the first category, and the immersed boundary-lattice Boltzmann method (IB-LBM) has recently been developed as an efficient method in the second category. However, a detailed comparative study between these methods has not been sufficiently performed. In this study, we compare the DVM with the IB-LBM in two-dimensional flapping flight analysis. As a result, it is found that the aerodynamic forces obtained by the DVM are comparable to those by the IB-LBM, when the effect of separated vortices is not so accumulated, and when the forward speed of the model is smaller than the flapping speed. In addition, the DVM has a difficulty in estimating the aerodynamic torque. In terms of the computational time, the DVM is much faster than the IB-LBM. This result suggests that the DVM can be used for massive parametric studies or optimizations in flapping flight analysis, although there remain many issues in its accuracy.