A kinematic analysis of flow dynamics and aerodynamic performance in the clap-and-fling motion

This study is focused toward the analysis of fluid dynamics associated with the clap-and-fling motion of insect wings. In this regard, a numerical framework based on a moving non-uniform grid block and the multi-relaxation time lattice Boltzmann method is utilized. This study investigates the impact of key kinematic parameters such as angle of attack alpha(0) ( 20 degrees-50 degrees), percentage overlap between pitching and sweeping xi ( 0%-100%), and the Reynolds number Re ( 20-200), on the aerodynamic lift, drag, and power requirements. A data-driven reduced order model is proposed that accurately predicts the instantaneous lift [CL(t)] and drag [C-D(t)] that enabled a parametric analysis of their cycle-averaged or mean values. Based on this analysis, xi is identified as the most influential parameter for enhancing lift, while Re is most effective in reducing power and drag. The leading and trailing edge vortices during the pitch and sweep phases play a crucial role in directly affecting C-L(t). These effects are highlighted for various parameters through the examination of vortex patterns and pressure contours. Wing-wake interaction is found to augment cycle-averaged lift as xi increases but is detrimental at high values of alpha 0. Additionally, a set of Pareto-optimal solutions representing the ideal kinematics that maximize lift for a given input power is presented, offering valuable insight for the design and advancement of future flapping wing aerial vehicles.