Influence of wing acceleration on the growth and trajectory of the leading-edge vortex

The presence of a stable leading-edge vortex (LEV) over an insect wing is responsible for the generation of high lift. The LEV stability is mediated by the rotational accelerations and their influence in the quasi-steady phase has been studied. However, understanding the LEV dynamics during the transient or accelerating phase of the wing motion is equally essential and has not received much attention. This study aims to understand the role of wing acceleration on the forces and flowfield evolving over a rotating wing. The wing acceleration will be experimentally varied while keeping the Reynolds number (Re = 1500), Rossby number (Ro =4.5), and aspect ratio (AR = 5) constant. The evolution of the circulatory lift force will be studied and correlated to the LEV circulation for different acceleration conditions. Furthermore, the trajectory of the LEV will be studied for different conditions. Preliminary flow visualization experiments have shown that increasing the wing acceleration increases vorticity production and leads to earlier separation. The flowfield data will be used to understand the correlation between the wing acceleration, LEV circulation, trajectory, and separation