The discussion clarifies the mechanics of leg movement in swimming, specifically how downward kicks contribute to forward propulsion. It emphasizes that the downward kick generates significant upward resistance from the water, while the upward movement encounters less resistance, resulting in a net forward thrust. Additionally, the effectiveness of leg movement is enhanced by the synchronization of hip and knee motion, which allows for a more efficient kick. The conversation also highlights that kicking helps reduce suction behind the swimmer, further aiding forward motion.
PREREQUISITESSwimmers, coaches, sports physiologists, and anyone interested in optimizing swimming techniques and understanding the physics of movement in water.
marcusl said:I'm speaking of vortices in the fluid, not rotational motion of a flagellum. At the low Reynolds numbers that Purcell considers, inertia effects are negligible compared to viscous effects (he points out that inertial forces die away in distance of order 0.1 Angstrom!). How are vortex rings sustained in that regime?