Up against the walls of turbulence

Better methods of measuring fluid motions would improve understanding of our atmosphere and oceans – and how they affect us  

What engineers and scientists call “wall turbulence” is a key factor in determining the environmental impacts of the movement of atmospheric components.

Defined simply as turbulence that results when fluids flow past various surfaces, wall turbulence affects the flux of water vapor and carbon dioxide from the ocean’s surface, which can have significant impacts on climate conditions and on the accumulation and movement of air pollutants.

Wall turbulence also causes drag on aircraft and ships, and in pipelines, and is important in the flows critical to many other engineered systems.

In the July 9 issue of Science, Arizona State University professor Ronald Adrian introduces advances in methods to more accurately model the buildup of wall turbulence and predict its movement and effects.

Adrian is a professor of mechanical and aerospace engineering in the School for the Engineering of Matter, Transport and Energy, one of ASU’s Ira A. Fulton Schools of Engineering.

Science, published by the American Association for the Advancement of Science, is one of the most prestigious science journals.

The problem Adrian discusses in his article, “Closing In on Models of Wall Turbulence,” concerns attempts to understand how the motions of atmospheric components are correlated and how energy is distributed.

The research, he writes, “relates to one of the grand challenges in the science and engineering of fluid dynamics”: developing governing equations that can be solved by numerical methods to reliably predict turbulent flow.

The difficulty comes in devising a reduced set of equations that applies generally, but still provides an accurate model on smaller scales so that the flow is computable on large high-performance computers.

Solving the problem would lead to improved methods for predicting important phenomena in the atmosphere, the oceans and in engineered systems.

Nonsubscribers to Science can request to see a full version of the article by contacting scipak@aaas.org.

Adrian is a member of the National Academy of Engineering and a Fellow of the American Physical Society and the America Institute of Aeronautics.

His research focus includes the space-time structure of turbulent fluid motion in wall flows and the study of unsteady shocks using ultra-high-speed optical methods.

He has made fundamental contributions to laser Doppler velocimetry, particle image velocimetry, and the optimal estimation method for analysis of turbulent flows.

Adrian has authored more than 175 journal articles and book chapters, and edited or co-edited 12 books on experimental fluid mechanics.