The unsteady aerodynamics of insect wings with rotational stroke accelerations, a systematic numerical study

To generate aerodynamic forces required for flight, two-winged insects ( Diptera ) move their wings back and forth at high wing-beat frequencies. This results in exceptionally wing-stroke accelerations, consequently relatively acceleration-dependent fluid forces. Quasi-steady force models have reasonable success relating the generated to instantaneous wing motion kinematics. However, existing approaches model stroke-rate stroke-acceleration effects independently from each other, which might be too simplified capturing complex unsteady aerodynamics of accelerating wings. Here, we use computational-fluid-dynamics simulations systematically explore how flow dynamics depend on rate, acceleration wing-planform geometry. Based this, developed calibrated a novel insect with stroke accelerations. includes improved versions translational-force added-mass model, identify third component by interaction two. term reflects delay bound-circulation build-up as accelerates. The physical interpretation this effect is analogous Wagner experienced starting rest. show that can modelled context flapping stroke-acceleration-dependent correction model. Our revised viscous component, small but not negligible. We subsequently applied our new realistic kinematics hovering Dipteran insects, quasi-steady approach. revealed stroke-acceleration-related contribute substantially lift drag production, particularly high-frequency mosquito