The attack angle of oscillating dolphin flukes increases rapidly at the initiation of upstrokes and downstrokes, reaching a maximum within the first third of the stroke. 攻角在整个拍动的三分之一的路程的时候已经增加到最大了。
Mean values range from 4.6 to 17.5° for Tursiops, although maximum values approach 30° at low velocities (Fish, 1993b). The maximum attack angle is 22.5 to 24° for Lagenorhynchus (Lang and Daybell, 1963). 攻角一般都不是很大。
The attack angles observed for dolphins are higher than would be expected compared to non-oscillating
airfoils and hydrofoils. 生物学家观察到的攻角，要比非振动翼和hydrofoils的期望值要大。因此海豚是大攻角运动的。
An oscillating foil can function at high attack angles because of dynamic stall or delayed stall caused by unsteady effects. 振动翼能够以较大攻角工作得益于非定常效应带来的dynamic stall或delayed stall.
High lift and high efficiency are associated with the formation of a leading-edge vortex. The leading-edge
vortex augments lift by enhancing the circulation around the foil. Circulation is the difference between velocities above and below the foil. Enhanced circulation produces an increased pressure difference between the surfaces of the foil resulting in increased lift and thrust. 前缘涡流能够增加上下翼面的速度差，从而增加升力和阻力。
Another unsteady mechanism for enhanced lift and thrust production is wake capture (Dickinson et al., 1999). ... ... The flow induced at the end of one stroke increases the water's velocity at the beginning of the next stroke, thereby increasing both lift and thrust that are directly proportional to the square of the velocity. Orientation of the force vectors is dependent on the the phase relationship between rotation and translation. 在一个拍动周期的末尾由于周围水流已经被上个周期加速，因此可以提升本周期的升阻力，升阻力大小和速度平方成正比，方向与运动的相位有关。
Vortical flow control by the dynamic stall mechanism may increase thrust production for dolphin flukes. Within the range of reduced frequencies for dolphins (Fish, 1993b, 1998a), the average lift caused by unsteady effects is 2 to 3.2 times higher than steady lift (Maresca et al., 1979). The high angles of attack achieved by dolphins would promote the formation of a leading-edge vortex, particularly at the initiation of a stroke. 进行涡控制可获得2 - 3.2倍的平均推力。大攻角能够提升前缘涡流的效应。
