Explore the fascinating world of how different spherical objects behave when they hit water vertically. Uncover the surprising findings that challenge the long-held belief about flat objects experiencing the highest impact forces.
The Surprising Tip-Off — Incredible Curvature
It has traditionally been thought that the largest hydrodynamic forces on flat objects occur when they enter water edge first. But a study by researchers at Naval Undersea Warfare Center Division Newport and Brigham Young University, in collaboration with King Abdullah University of Science and Technology (KAUST), is giving the lie to that conventional wisdom.
The researchers developed a novel experimental configuration with shapes they attached to an instrumented body on which they had built in an accelerometer. This enabled them to measure the forces in water that these items were subject to. However, to their surprise, the impact forces became less severe when the nose of the object flattened out–in contradiction to what they expected.
But the big discovery was that the curvature of these spherical objects played a huge role in how big they could the impact forces get. Early on during their analysis, the team noticed that as the nose flattened an air cushion pocket got trapped between the nose and water upon contact. That airs layer acted like a cushion, and the impact forces on the object were greatly reduced
An Informative Look At The The Air Layer Effect
Curvature of the object’s nose had a major impact on the height of trapped air layer. Less cushioning compared to a flat nose, the reason was a more stable and slightly curved nose that reduced air layer height causing less than the desired outcome.
This finding also defies the common assumption that flat objects generate maximum splash forces in water. What the researchers actually discovered, however, was that even a small bit of positive curvature at the tip of a blunt body could bring in vastly more impact force than what had been measured for flat-nosed bodies.
The researchers reason that this arises from a tug of war between hydrodynamic forces and the trapped air layer that pushes water up against these bubbles. When the object is struck, this air layer absorbs some of the impact energy, reducing the force that the object experiences.
As such, these results have significant implications for the design and creation of objects and technologies that must move fast in water. An understanding to variations in the hydrodynamic forces based on the kind of curvatures can aid mechanical engineers and scientists in realizing further on it to improve a better accuracy for these systems.
Conclusion
Belden & Co. conducted a study that revealed a remarkable aspect of how spherical objects impact the hydrodynamics of water. A lot of r&d could now be fuelled in the field of water based technologies and systems since the legacy belief that high impact forces are felt by flat objects have been challenged by the researchers. The results, presented at the APS Meeting of the Division of Fluid Dynamics, demonstrate that the curvature of an object can have a large influence on how hard it is hit and that ever so slightly positive curvature can be better than a complete flat surface. This may open a door to develop next generation of high-performance and energy-efficient waterborne systems for various applications such as in naval engineering or sports/recreation.
