Soft sphere water impact

Highly compliant elastic spheres possess remarkable water skipping capabilities. Furthermore, when impacting normal to a free-surface, elastomeric spheres deform significantly and begin to vibrate producing unique nested cavities. In this talk, we reveal the coupling between water impact and material response, and discuss the interesting body dynamics that result. The most remarkable of these behaviors is the ability for elastic spheres to skip hundreds of times over a great distance on the water surface. We show that for certain values of a dimensionless ratio of material shear modulus to fluid inertia forces, a stable deformation mode is sustained in the sphere, thus enabling this `water-walking' behavior. This same dimensionless ratio characterizes the water entry of soft spheres perpendicular to the free-surface as well. We show how the material response alters the traditional cavity behavior and force characteristics normally observed for rigid sphere water entry.