Optimizing large wind farms

Team from US and Belgium calculates best spacing for turbines is farther apart

2010-11-24

(Press-News.org) WASHINGTON, D.C., November 23, 2010 -- Wind farms around the world are large and getting larger. Arranging thousands of wind turbines across many miles of land requires new tools that can balance cost and efficiency to provide the most energy for the buck.

Charles Meneveau, who studies fluid dynamics at Johns Hopkins University, and his collaborator Johan Meyers from Leuven University in Belgium, have developed a model to calculate the optimal spacing of turbines for the very large wind farms of the future. They will present their work today at the American Physical Society Division of Fluid Dynamics (DFD) meeting in Long Beach, CA.

"The optimal spacing between individual wind turbines is actually a little farther apart than what people use these days," said Meneveau.

The blades of a turbine distort wind, creating eddies of turbulence that can affect other wind turbines farther downwind. Most previous studies have used computer models to calculate the wake effect of one individual turbine on another.

Starting with large-scale computer simulations and small-scale experiments in a wind tunnel, Meneveau's model considers the cumulative effects of hundreds or thousands of turbines interacting with the atmosphere.

"There's relatively little knowledge about what happens when you put lots of these together," said Meneveau.

The energy a large wind farm can produce, he and his coworkers discovered, depends less on horizontal winds and more on entraining strong winds from higher in the atmosphere. A 100-meter turbine in a large wind farm must harness energy drawn from the atmospheric boundary layer thousands of feet up.

In the right configuration, lots of turbines essentially change the roughness of the land -- much in the same way that trees do -- and create turbulence. Turbulence, in this case, isn't a bad thing. It mixes the air and helps to pull down kinetic energy from above.

Using as example 5 megawatt-rated machines and some reasonable economic figures, Meneveau calculates that the optimal spacing between turbines should be about 15 rotor diameters instead of the currently prevalent figure of 7 rotor diameters.

INFORMATION:

The presentation, "Optimization of turbine spacing in the fully developed wind turbine array boundary layer is at 1:42 p.m. on Tuesday, November 23, 2010 in the Long Beach Convention Center Room: 102B. ABSTRACT: http://meetings.aps.org/Meeting/DFD10/Event/134047

This work is funded by the National Science Foundation's "Energy for Sustainability" program.

IMAGE: An image is available to accompany this story. Contact jbardi@aip.org

CAPTION: Instantaneous streamwise velocity magnitudes on three perpendicular planes across a wind turbine array boundary layer, obtained from computer simulation. The dark semicircles denote the positions of the wind turbines and the blue regions behind them denote the meandering wakes. Such simulations have been used to develop a model for wind farm roughness length, from which optimal wind turbine spacings can be deduced. Optimal spacing is found to be about 15 diameters.

CREDIT: Reporters may use this image so long as they credit Johan Meyers at Katholieke Universiteit, Leuven (Belgium), and Charles Meneveau, Johns Hopkins University, Baltimore, MD (USA).

MORE MEETING INFORMATION

The 63rd Annual DFD Meeting is hosted this year by the University of Southern California, California State University Long Beach, California Institute of Technology, and the University of California, Los Angeles.

It will be held at the Long Beach Convention Center, located in downtown Long Beach, California. All meeting information, including directions to the Convention Center is at: http://www.dfd2010.caltech.edu/

USEFUL LINKS

Main meeting Web site:
http://www.dfd2010.caltech.edu/

Search Abstracts:
http://meetings.aps.org/Meeting/DFD10/SearchAbstract

Directions to Convention Center:
http://www.longbeachcc.com/

PRESS REGISTRATION

Credentialed full-time journalist and professional freelance journalists working on assignment for major publications or media outlets are invited to attend the conference free of charge. If you are a reporter and would like to attend, please contact Jason Bardi (jbardi@aip.org, 301-209-3091).

ONSITE WORKSPACE FOR REPORTERS

A reserved workspace with wireless internet connections will be available for use by reporters in the Promenade Ballroom of the Long Beach Convention Center on Sunday, Nov. 21 and Monday, Nov. 22 from 8:00 a.m. to 5:00 p.m. and on Tuesday, Nov. 23 from 8:00 a.m. to noon. Press announcements and other news will be available in the Virtual Press Room (see below).

VIRTUAL PRESS ROOM

The APS Division of Fluid Dynamics Virtual Press Room will be launched in mid-November and will contain dozens of story tips on some of the most interesting results at the meeting as well as stunning graphics and videos. The Virtual Press Room will serve as starting points for journalists who are interested in covering the meeting but cannot attend in person. See: http://www.aps.org/units/dfd/pressroom/index.cfm

GALLERY OF FLUID MOTION

Every year, the APS Division of Fluid Dynamics hosts posters and videos that show stunning images and graphics from either computational or experimental studies of flow phenomena. The outstanding entries, selected by a panel of referees for artistic content, originality and ability to convey information, will be honored during the meeting, placed on display at the Annual APS Meeting in March of 2011, and will appear in the annual Gallery of Fluid Motion article in the September 2011 issue of the American Institute of Physics' journal, Physics of Fluids.

This year, selected entries from the 28th Annual Gallery of Fluid Motion will be hosted as part of the Fluid Dynamics Virtual Press Room. In mid-November, when the Virtual Press Room is launched, another announcement will be sent out.

ABOUT THE APS DIVISION OF FLUID DYNAMICS

The Division of Fluid Dynamics of the American Physical Society (APS) exists for the advancement and diffusion of knowledge of the physics of fluids with special emphasis on the dynamical theories of the liquid, plastic and gaseous states of matter under all conditions of temperature and pressure. See: http://www.aps.org/units/dfd/

[Attachments] See images for this press release:

ELSE PRESS RELEASES FROM THIS DATE:

Lyfish-inspired pumps

2010-11-24

WASHINGTON, D.C., November 23, 2010 -- To the causal aquarium visitor, the jellyfish doesn't seem to be a particularly powerful swimmer; compared to a fish, it glides slowly and peacefully. But for Janna Nawroth, a graduate student at the California Institute of Technology in Pasadena, the undulations of this simple invertebrate hold secrets that may make possible a new generation of tiny pumps for medical applications and soft robotics -- work she describes today at the American Physical Society Division of Fluid Dynamics (DFD) meeting in Long Beach, CA "Most pumps ...

Heating nanoparticles to kill tumor cells

2010-11-24

WASHINGTON, D.C., November 23, 2010 -- Magnetic fluid hyperthermia (MFH) is a promising new cancer treatment that essentially "fries" cells inside tumors. The procedure has been used successfully in prostate, liver, and breast tumors. Magnetic nanoparticles (each billionths of a meter in size) are injected into the body intravenously and diffuse selectively into cancerous tissues. Add a high-frequency magnetic field, and the particles heat up, raising the temperature of the tumor cells. "The entire tumor volume is heated above a threshold treatment temperature -- typically ...

Secrets of sharks' success

2010-11-24

WASHINGTON, D.C., November 23, 2010 -- New research from the University of South Florida suggests that one of the evolutionary secrets of the shark's success hides in one of its tiniest traits -- flexible scales on the bodies of these peerless predators that make them better hunters by allowing them to change directions while moving at full speed. The key to this ability lies in the fact that the scales control water flow separation across the creatures' bodies, says Amy Lang of the University of Alabama who will present work she performed with her colleagues at the University ...

What makes flies attack?

2010-11-24

Pity the poor female fruit fly. Being a looker is simply not enough, it seems. If you're to get a date, much less a proposal, you must also smell and act like a girl. Otherwise, you might just have a fight on your hands. Read more in next week's issue of the online, open access journal PLoS Biology. As with most animals, Drosophila face the problem of distinguishing between a potential mate and a potential competitor. If, when meeting a second fruit fly, a male fly thinks "female," he'll begin courting her. But if he senses another male, he'll fight. What triggers these ...

New study: Mexico's forest communities excel in good management, outperform other strategies for capturing carbon to slow climate change

2010-11-24

### El Consejo Civil Mexicano para la Silvicultura Sostenible, A.C. (the Mexican Civil Council for Sustainable Forestry, known as CCMSS) is a non-profit, non-governmental organization that encourages and promotes conservation of forest ecosystems that are managed by the forest communities themselves. Known as Manejo Forestal Comunitario, or MFC, this system is supported by CCMSS members, who work in collaboration with communities and ejidos to put in place sustainable practices in forest management and improve the development, conservation, industrialization and commercialization ...

Combining aerobic and resistance training appears helpful for patients with diabetes

2010-11-24

Performing a combination of aerobic exercise and resistance training was associated with improved glycemic levels among patients with type 2 diabetes, compared to patients who did not exercise, according to a study in the November 24 issue of JAMA. The level of improvement was not seen among patients who performed either aerobic exercise or resistance training alone. Although it is generally accepted that regular exercise provides substantial health benefits for individuals with type 2 diabetes, the exact exercise type (aerobic vs. resistance vs. both) has been unclear. ...

Less invasive method for determining stage of lung cancer shows benefits

2010-11-24

A comparison of two strategies to determine the stage of suspected non-small cell lung cancer (NSCLC) finds that the less invasive method is more effective at identifying a type of lung cancer that has spread, and may result in a reduction of unnecessary surgical procedures and associated adverse effects for certain patients, according to a study in the November 24 issue of JAMA. Lung cancer is the most commonly diagnosed cancer worldwide (1.35 million/year) and also the most frequent cause of cancer death (1.2 million/year). Determining the stage of cancer is an important ...

Fecal immunochemical testing best and most cost-effective method for screening for colorectal cancer

2010-11-24

Annual screening by fecal immunochemical testing—a test that detects blood in the stool, has high sensitivity and specificity, and might improve participation rates through increased patient acceptability—reduces the risk of colorectal cancer and colorectal cancer related deaths, and reduces healthcare costs in comparison to all other screening strategies and to no screening. These are the conclusions of a complete economic evaluation performed by Braden Manns and colleagues from the University of Calgary, Alberta, Canada, and published in this week's PLoS Medicine. Clinical ...

Expanding tuberculosis control in China: Combining domestic and foreign investment

2010-11-24

China had an estimated 1.3 million new cases of tuberculosis (TB) in 2008, of which 112,000 were multi-drug resistant (MDR-TB). Over the period 2001, TB was the second largest cause of death among China's 39 notifiable communicable diseases. In a Policy Forum, published in this week's PLoS Medicine, Zhong-wei Jia (Peking University) and colleagues from Beijing, China, report on how a combination of increased domestic funding, supplemented by foreign loans and donations, led to a dramatic increase in TB case finding. The authors also highlight the way in which changes in ...

Imaging with neutrons: Magnetic domains shown for the first time in 3-D

2010-11-24

Every magnetic material is divided into such magnetic domains. Scientists call them "Weiss domains" after physicist Pierre-Ernest Weiss, who predicted their existence theoretically more than a hundred years ago. In 1907, he recognized that the magnetic moments of atoms within a bounded domain are equally aligned. All pursuit of this theory has so far been limited to two-dimensional images and material surfaces. Accordingly, researchers have only ever been able to see a domain in cross section. Together with colleagues from the German Federal Institute for Materials Research ...

Optimizing large wind farms

ELSE PRESS RELEASES FROM THIS DATE:

LAST 30 PRESS RELEASES: