Energy simulation may explain turbulence mystery

Feb 26, 2009

(PhysOrg.com) -- A new 3D model linking magnetic fields to the transfer of energy in space might help solve a physics mystery first observed in the solar wind 15 years ago.

Scientists at The University of Alabama in Huntsville and Ruhr University in Bochum, Germany, developed the simulation while studying turbulence and energy transfer in the plasma carried away from the sun in the solar wind.

"We were attempting to understand the spacecraft observations that have seen this kind of turbulence," said Dr. Dastgeer Shaikh, an assistant professor in the Physics Department at UAHuntsville. "This was seen first by the Wind spacecraft launched in 1994, but has also been seen by other satellite instruments since then."

What Wind and the other spacecraft saw was particles in relatively small-scale solar wind eddies getting "hotter" than theories predicted they should get.

A theory published in 1941 by mathematician Andrey Kolmogorov established a generally accepted relationship between the size of eddies and the amount of energy released or dissipated: The smaller an eddy gets the more it interacts with its surroundings, so the greater the energy loss. This "lost" energy heats plasma in the solar wind.

The Kolmogorov law set the ratio between size and energy at 5/3: In a dynamic fluid, the amount of energy released should increase by a factor of five when the size of the eddy shrinks by two-thirds.

Except, apparently, in the solar wind and other regions influenced by magnetic fields. The Wind spacecraft and others found that in the solar wind's smaller eddies the link between size and energy jumps to 7/3, a 40 percent increase in the efficiency of energy transfer between larger and smaller plasma eddies in the turbulent solar wind.

The computer model developed by Shaikh and Dr. P.K. Shukla in Germany tries to explains the sudden increase by looking at the interaction between turbulent magnetic fields and the outward flowing currents of plasma ions and electrons.

"The magnetic field is responsible for energy cascades," said Shaikh. Constrained by magnetic fields, the small eddies serve to "damp" the wave energy in them.

"This is the same kind of thing that happens in a microwave oven," Shaikh said. "Microwaves are damped inside the food and release the energy that makes the food hot."

If small eddies in the solar wind are more efficient than expected at transferring energy, that might help explain the hot particles discovered by instruments aboard Wind and other spacecraft.

Results of this research were published earlier this month in the on-line edition of "Physical Review Letters."

Provided by University of Alabama in Huntsville

Explore further: New insights found in black hole collisions

add to favorites email to friend print save as pdf

Related Stories

Solar beam collectors, key to enhancing solar power

Mar 25, 2015

New technologies could soon bring more effective ways of harvesting solar power. That is the case with small size concentrated solar power, or CSP. It is a relatively new technology compared to the more mature photovoltaic ...

As wind power booms, Texas lawmakers consider yanking support

Mar 24, 2015

Thousands of wind turbines have sprung up across West Texas and up and down the Gulf Coast. Companies as diverse as Google and Dow Chemical are investing hundreds of millions of dollars in Texas in a race to lower their carbon ...

Top China weather expert warns on climate change

Mar 22, 2015

China's top weather official has issued a stark warning on climate change, saying that rising temperatures could have "huge impacts" on the world's most populous country, state media reported Sunday.

Protecting Earth from space weather

Mar 20, 2015

This week's spectacular glowing auroras in the night sky further south than usual highlighted the effect that 'space weather' can have on Earth.

Recommended for you

New insights found in black hole collisions

20 hours ago

New research provides revelations about the most energetic event in the universe—the merging of two spinning, orbiting black holes into a much larger black hole.

X-rays probe LHC for cause of short circuit

20 hours ago

The LHC has now transitioned from powering tests to the machine checkout phase. This phase involves the full-scale tests of all systems in preparation for beam. Early last Saturday morning, during the ramp-down, ...

Swimming algae offer insights into living fluid dynamics

23 hours ago

None of us would be alive if sperm cells didn't know how to swim, or if the cilia in our lungs couldn't prevent fluid buildup. But we know very little about the dynamics of so-called "living fluids," those ...

Fluctuation X-ray scattering

Mar 26, 2015

In biology, materials science and the energy sciences, structural information provides important insights into the understanding of matter. The link between a structure and its properties can suggest new ...

Hydrodynamics approaches to granular matter

Mar 26, 2015

Sand, rocks, grains, salt or sugar are what physicists call granular media. A better understanding of granular media is important - particularly when mixed with water and air, as it forms the foundations of houses and off-shore ...

User comments : 0

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.