How Earth's rotation affects vortices in nature

French researchers develop sophisticated mathematical model to study the behavior of earthly vortices, like hurricanes and ocean currents

2013-10-15

(Press-News.org) VIDEO: This is a view from above of the growing and spiraling wave field emitted by a geophysical vortex due to the radiative instability. The black circle represents a boundary of...
Click here for more information.

WASHINGTON, D.C. Oct. 15, 2013 -- What do smoke rings, tornadoes and the Great Red Spot of Jupiter have in common? They are all examples of vortices, regions within a fluid (liquid, gas or plasma) where the flow spins around an imaginary straight or curved axis. Understanding how geophysical (natural world) vortices behave can be critical for tasks such as weather forecasting and environmental pollution monitoring.

In a new paper in the journal Physics of Fluids, researchers Junho Park and Paul Billant of the CNRS Laboratoire d'Hydrodynamique in France describe their study of one such geophysical vortex behavior, radiative instability, and how it is affected by two factors, density stratification and background rotation.

Radiative instability is a phenomenon that alters the behavior of fluid flows and can deform a vortex. The "radiative" tag refers to the fact that it is an instability caused by the radiation of waves outward from a vortex.

"These waves can exist as soon as there is a density stratification -- a variation of densities -- throughout the vertical column of the vortex," Park said. "In this study, we have considered how background rotation -- in this case, the rotation of the Earth -- impacts them."

Examples of density stratification in nature, Park explained, include the decrease in air density as one moves higher in the atmosphere or the increase in water density due to salinity and temperature with increasing ocean depth. "So, the waves in our mathematical model are somewhat analogous to waves on the ocean surface," he said. "Likewise, the impact from background rotation on our modeled waves serves as an equal for the impact of the Coriolis force caused by the Earth's rotation."

"What we learned from our models is that strong background rotation suppresses the radiative instability, a characteristic that had been expected but whose dynamics had never been studied precisely," Park said. "We've now developed a sophisticated mathematical means to explain this phenomenon, and that's important to being better able to study and understand the behavior of geophysical vortices such as hurricanes and ocean currents."

Park said that he and Billant next plan to study instability behaviors in vortices with non-columnar shapes. "For example," he said, "there are pancake-shaped flows called Mediterranean eddies, or meddies, that would be worth studying since we know they affect the mixing of the components that make up the ocean ecosystem."

### The article, "Instabilities and waves on a columnar vortex in a strongly-stratified and rotating fluid" by Junho Park and Paul Billant appears in the journal Physics of Fluids. See: http://dx.doi.org/10.1063/1.4816512

ABOUT THE JOURNAL Physics of Fluids is devoted to the publication of original theoretical, computational, and experimental contributions to the dynamics of gases, liquids, and complex or multiphase fluids. See: http://pof.aip.org

ELSE PRESS RELEASES FROM THIS DATE:

An optical switch based on a single nano-diamond

2013-10-15

A recent study led by researchers of the ICFO (Institute of Photonic Sciences) demonstrates that a single nano-diamond can be operated as an ultrafast single-emitter optical switch operating at room temperature. The scientific results of this study have been published in Nature Physics. Electronic transistors have become a key component to modern electronics, drastically improving the speed of information processing of current technologies. An electronic transistor is a semiconductor device used to amplify and switch electronic signals. The much sought after optical ...

Women leave their handprints on the cave wall

2013-10-15

VIDEO: Dean Snow, emeritus professor of anthropology, Penn State, discusses handprints on cave walls and the methods he used to determine if they were male or femaile. Click here for more information. Plaster handprints from kindergarten, handprint turkeys, handprints outside Grauman's Chinese Theater in Hollywood -- are all part of modern life, but ancient people also left their handprints on rocks and cave walls. Now, a Penn State anthropologist can determine the sex of ...

Adding citrus fiber to meatballs improves nutritional quality, does not affect taste

2013-10-15

COLUMBIA, Mo. -- Many American diets fall short of meeting nutritional guidelines resulting in burgeoning obesity rates and health problems across the nation. Statistics show that most Americans consume only half of the daily recommended amount of dietary fiber. Now, a research team at the University of Missouri is addressing the fiber deficit by including citrus fiber in ground beef while retaining the quality and taste of the meat. Ayca Gedikoglu, a doctoral student studying food science in the MU College of Agriculture, Food and Natural Resources, and Andrew Clarke, ...

How do consumers see a product when they hear music?

2013-10-15

Shoppers are more likely to buy a product from a different location when a pleasant sound coming from a particular direction draws attention to the item, according to a new study in the Journal of Consumer Research. "Suppose that you are standing in a supermarket aisle, choosing between two packets of cookies, one placed nearer your right side and the other nearer your left. While you are deciding, you hear an in-store announcement from your left, about store closing hours," write authors Hao Shen (Chinese University of Hong Kong) and Jaideep Sengupta (Hong Kong University ...

Why do discounts backfire when you make consumers wait?

2013-10-15

Consumers like to reap the benefits of discounts immediately (not later), according to a new study in the Journal of Consumer Research. Consumers enjoy discounted products much less if they have to wait for them. "Price promotions are common in the marketplace. For consumers, these promotions translate into real economic savings, guide buying decisions, encourage trial of new products, and make consumers feel smart and good about themselves," write authors Leonard Lee (Columbia University) and Claire I. Tsai (University of Toronto). But sometimes discounts backfire, especially ...

VIP loyalty programs: Consumers prefer awards they can share

2013-10-15

Consumers appreciate being able to share their perks with others, and will sacrifice exclusivity to do so, according to a new study in the Journal of Consumer Research. "Companies spend billions of dollars each year on customer loyalty or VIP programs in an effort to reward loyal customers and make them feel both special and a sense of status," write authors Brent McFerran (University of Michigan) and Jennifer J. Argo (University of Alberta). Many loyalty programs, like airline lounges, luxury boxes, and hotel rooms extend benefits to guests of the VIP, or "an entourage." ...

Brief memory test 'ages' older adults

2013-10-15

You're only as old as you feel, or so the saying goes. Now, research suggests that a simple memory test can have a noticeable impact on just how old some older adults feel, aging them about five years in the span of five minutes. The findings are published in Psychological Science, a journal of the Association for Psychological Science. "Previous work shows that how old one feels — one's subjective age — predicts significant health outcomes, even better than one's chronological age predicts these outcomes," says senior researcher Lisa Geraci of Texas A&M University. "These ...

Home away from home: What makes consumers support their favorite businesses?

2013-10-15

When a shop is authentic and the workers are friendly, it can feel like a second home for consumers, according to a new study in the Journal of Consumer Research. "People often feel strongly attached to particular places. Such places typically include their homes, but can also include commercial places such as stores and restaurants," write authors Alain Debenedetti (Université Paris Est – IRG), Harmen Oppewal (Monash University), and Zeynep Arsel (Concordia University). "How do people develop and experience place attachment when the place concerns a commercial setting, ...

Unearthed: A treasure trove of jewel-like beetles

2013-10-15

The bottomless pit of insect biodiversity has yielded a treasure trove of new species of jewel-like clown beetles. In a paper published today in the journal ZooKeys, Michael Caterino and Alexey Tishechkin of the Santa Barbara Museum of Natural History describe 85 new species in the genus Baconia, renowned for their brilliant coloration and bizarrely flattened body forms. The new species bring the genus up to 116 total species. The new species, mainly from North and South America, were discovered through studies of numerous museum collections, as well as the authors' own ...

Documenting, reporting & researching health effects of CEWs inadequate, finds expert panel

2013-10-15

Ottawa (October 15th, 2013) A new expert panel report, entitled The Health Effects of Conducted Energy Weapons, was released today by the Council of Canadian Academies in collaboration with the Canadian Academy of Health Sciences. The assessment was conducted by a 14-member panel of distinguished multidisciplinary experts and chaired by the Honourable Justice Stephen T. Goudge from the Court of Appeal for Ontario. The Expert Panel was asked to consider the state of knowledge about the medical and physiological impacts of conducted energy weapons (CEWs). Based ...