Water impact dynamics on ultra-soft sheet floating membranes at supersonic speeds

We study water enty of a fast heavy sphere onto a floating ultra-elastic floating film at very high speeds. The impact energy is first absorbed in stretching the hyperelastic film, followed by release into the fluid during a recoil phase of the film, and eventually dissipated in turbulent fluid motion. High speed digital image correlation (3D-DIC) and particle image velocimetry (PIV) are used to track the 3D deformations of the membrane and the flow evolution. The elastic wavefront on the membrane propagates radially following a t^(2/3) power law. We show that in the limit of extreme softness, the membrane interface deforms almost identically to that of conventional water entry. We develop a modified elastic Rayleigh-Plesset formulation for cavity shape and evolution.