1flail 
/ˈfleɪl/ verb
flails; flailed; flail·ing /ˈfleɪl/ verb 1 : to move or swing your arms or legs in a wild and uncontrolled way [+ obj] ▪ They were flailing their arms to drive away the insects. [no obj] ▪ The wounded animal lay on the ground, flailing helplessly. ▪ He was wildly flailing about/around on the dance floor. ▪ He flailed away at the ball. [=he swung wildly at the ball] 2 [+ obj] : to strike or hit (something or someone) in a wild and uncontrolled way
▪ The bird's wings flailed the water.
▪ The bird's wings flailed the water.
