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Impacts of Free-falling Spheres on a Deep Liquid Pool with Altered Fluid and Impactor Surface Conditions
Published on: February 17, 2019
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Elastic spheres can walk on water
Jesse Belden1, Randy C Hurd2, Michael A Jandron1
1Naval Undersea Warfare Center Division Newport, 1176 Howell Street, Newport, Rhode Island 02841, USA.
Nature Communications
|February 5, 2016
Summary
Softer elastic spheres skip better on water by deforming into a disk shape. This favorable geometry and orientation, driven by wave propagation and material properties, enhance water-skipping dynamics.
Area of Science:
- Fluid Dynamics
- Materials Science
- Physics of Impact
Background:
- Water-skipping of rigid objects is well-studied.
- Elastic spheres show better water-skipping but their impact physics are not well understood.
- The effect of material compliance on water impact is largely unknown.
Purpose of the Study:
- To investigate the water impact physics of highly compliant elastic spheres.
- To understand how material properties influence water-skipping ability.
- To elucidate the mechanisms behind superior water-skipping in softer spheres.
Main Methods:
- Experimental observations of elastic sphere water impact.
- Numerical modeling of fluid-elastic body interaction.
- Analysis of sphere deformation and dynamic orientation during impact.
Main Results:
- Compliant spheres naturally deform into a disk-like shape upon water impact.
- Sphere shape evolution is governed by elastic wave propagation.
- Skipping dynamics depend on wave speed and the ratio of shear modulus to hydrodynamic pressure.
- Softer spheres exhibit enhanced water-skipping compared to stiffer ones.
Conclusions:
- The disk-like deformation and orientation are key to efficient water-skipping for compliant spheres.
- Understanding fluid-elastic interactions advances models for inflatable craft and aquatic toys.
- Material compliance significantly impacts water impact dynamics and object trajectory.
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