Air entrapment and its effect on pressure impulses in the slamming of a flat disc on water

The presence of ambient air in liquid-slamming events plays a crucial role influencing the shape liquid surface prior to impact, and distribution loads created upon impact. We study effect trapped on impact simplified geometry, by slamming horizontal flat disc onto stationary water bath at well-controlled velocity. show how trapping influences pressure peaks different radial locations disc, impulses are affected local differ from those obtained area-integrated (force) More specifically, we find that layer causes gradual buildup load before peak value is reached, this follows inertial scaling. Further, same localised impulse centre found be lower than corresponding (area-integrated) force entire disc. While close classical result Batchelor ( An Introduction Fluid Dynamics , Cambridge University Press, 1967, § 6.10) Glasheen & McMahon Phys. Fluids vol. 8, issue 1996, pp. 2078–2083), centre, where its thickest, lie closer theoretical estimation Peters et al. J. Mech. 724, 2013, 553–580) for an air-cushioned