Optimization of kinematic parameters of dragonfly wing section in hovering flight

An optimal analysis of the corrugated wing section of the dragonfly Aeshna cyanea is conducted under hovering flight conditions to investigate its aerodynamic performance. In hovering flight mode, the insect keeps a stationary position in the air with zero forward velocity by flapping its wings. The analysis aims to determine the optimal kinematic conditions for achieving maximum mean lift coefficient ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mrow> <mml:msub> <mml:mover accent="true"> <mml:mi>C</mml:mi> <mml:mo>¯</mml:mo> </mml:mover> <mml:mrow> <mml:mi>L</mml:mi> <mml:mi>m</mml:mi> <mml:mi>a</mml:mi> <mml:mi>x</mml:mi> </mml:mrow> </mml:msub> </mml:mrow> </mml:math> ) and minimum mean drag coefficient ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mrow> <mml:msub> <mml:mover accent="true"> <mml:mi>C</mml:mi> <mml:mo>¯</mml:mo> </mml:mover> <mml:mrow> <mml:mi>D</mml:mi> <mml:mi>m</mml:mi> <mml:mi>i</mml:mi> <mml:mi>n</mml:mi> </mml:mrow> </mml:msub> </mml:mrow> </mml:math> ) to enhance aerodynamic performance. The plunging and pitching motion of the wing section during hovering is modelled using the dynamic mesh approach based on the Arbitrary Lagrangian-Eulerian (ALE) formulation, which accounts for moving boundaries undergoing rigid body motion within the fluid domain. The study reveals that the optimal kinematic parameters for achieving superior aerodynamic performance vary based on the required lift and the corresponding drag. By employing surrogate models and multi-objective optimization techniques, the Pareto Optimal Front (POF) is constructed with maximum mean lift and minimum mean drag as the objective functions. The optimized design point showing the highest lift generation and efficiency but at a significantly higher power cost, indicating a clear trade-off between lift generation and energetic demand. The POF provides a comprehensive design framework, enabling the identification of corresponding drag and optimal kinematic parameters for a given lift requirement, and vice versa, to achieve an optimal aerodynamic configuration. Designers can select suitable kinematics from POF design chart by specifying the required lift or thrust for a given MAV mission.