A new approach to invisibility cloaking goes beyond transformation optics and those tiresome Harry Potter analogies. It is instead for us at sea to shield floating objects, like oil rigs and ships, from rough waves and is based on the influence of the ocean floor's topography on the various "layers" of ocean water.
Reza Alam, assistant professor of mechanical engineering at the University of California, Berkeley, will describe at the American Physical Society's (APS) Division of Fluid Dynamics (DFD) meeting how the variation of density in ocean water can be used to cloak floating objects against incident surface waves
"The density of water in an ocean or sea typically isn't constant, mainly because of variations in temperature and salinity," explains Alam. "Solar radiation heats the upper layer of the water, and the flow of rivers and the melting of ice lowers the water density near the surface. Over time, these effects add up to form a stable density stratification of two layers – with the lighter fluid layer on top and the more dense fluid layer below it."
Stratified waters, much like regular surface waves, contain "internal waves," which are gravity waves that propagate between the two layers of water. For the same frequency of oscillation, however, internal waves travel at a much shorter wavelength and slower speed than surface waves.
Both wave types "feel" the ocean floor's influence, which generates an energy transfer.
Zeroing in on this energy transfer, Alam used computer simulations to transform a surface wave into internal wave as it approaches an object – meaning that the wave will pass beneath the object rather than crashing into it. And once the internal wave moves beyond the object, it can be transformed back into a surface wave.
This would be achieved by creating "corrugations" or wavy ripples that are tuned to a specific wavelength on the ocean floor in front of the floating object to be cloaked.
"Cloaking in seas by modifying the floor may play a role in protecting near-shore or offshore structures and in creating shelter for fishermen during storms," says Alam. "In reverse, it can cause the disappearance and reappearance of surface waves in areas where sandbars or any other appreciable bottom variations exist."
- PHYSICAL SCIENCES
- EARTH SCIENCES
- LIFE SCIENCES
- SOCIAL SCIENCES
Subscribe to the newsletter
Stay in touch with the scientific world!
Know Science And Want To Write?
- The Five Stages Of A Dying Theory
- Russian scientists increase DVD storage capacity million times
- Should Pregnant Women Be Concerned About BPA?
- President Elect Trump - Why Climate Change Is No Longer A Political Issue Outside The US
- Australopithecus Afarensis: ‘Lucy’ Was A Tree Climber?
- Neanderthals: Not So Dumb
- Time, Wittgenstein And Language Scaffolding
- "Yes for sure. If you need support then there are several facebook groups where you can meet other..."
- "Hi F,okay, I see your point of view. Yes, there are many feelings at play when one joins the bandwagon..."
- "Hi, I somehow disagree with your view of theorists: it was not belief or disbelief in the potential..."
- "Your really really positive and sure that nothing is going to happen please Mr walker i am actually..."
- "It was the same last Christmas. That was the first time I heard about all this but I expect it..."
- Annoying Studies’ Series: Newborn Weight Gain (Again!)
- Five PM? Time for Breakfast!
- Include Aerobic Fitness in Physical Exams, Heart Association Recommends
- Female Vervet Monkeys Assault Males that Do Not Participate in Fights
- Vaginal Ring Effective for HIV Infection Prevention
- Winter is No Wonderland