A new method for understanding turbulence could save the air industry billions of pounds in fuel costs

Breakthrough in understanding turbulence

A British scientist has helped to develop a new method of understanding the complex world of turbulence.

Southampton University academic Ati Sharma and a US-based colleague have pioneered an approach that will help designers create more efficient transport in the future.

Turbulence – the chaotic movement of fluids seen in everything from stream water to swirling smoke – has been described as one of the last unsolved problems of classical physics.

Devising a solution would reap huge benefits as reducing the turbulence-induced drag on a plane's wing by 30 per cent could save billions of pounds in fuel costs worldwide and associated emissions every year.

And the problem is only set to increase after researchers at two UK universities recently identified the likelihood of increased turbulence in aircraft over the coming half-century.

The new method developed by Dr Sharma, a senior lecturer in aerodynamics and flight mechanics, and Professor Beverley McKeon from the California Institute of Technology (Caltech), makes it simpler and cheaper for scientists to study the effects of wall turbulence – when a gas or liquid flows past solid surfaces at a reasonable rate.

"Although the equations that govern fluid flow were discovered in the early 1800s, nobody had figured out a way to predict recurring structure in wall turbulence directly from these equations," Dr Sharma said.

"The new work describes how wall turbulence can be broken down into constituent blocks that can be simply pieced together, Lego-like, to approach and eventually get back to the full equations."

When a few blocks, or sub-equations, are added together the results look like a full laboratory experiment but the calculations can be made on a laptop instead of a supercomputer.

Engineers now have a template to visually and mathematically identify order from the swirling flows, and will be able to use the information to improve on previous models of how turbulence works.

Leonardo da Vinci, the renaissance painter and scientist, was also interested in turbulence and drew pictures of the eddies and currents formed when a block was placed in water.

Prof McKeon, professor of aeronautics at Caltech's Graduate Aerospace Laboratories, described the ultimate application of their research, which has been published online in the Journal of Fluid Mechanics.

She said: "Imagine being able to shape not just an aircraft wing but the characteristics of the turbulence in the flow over it to optimise aircraft performance. It opens the doors for entirely new capabilities in vehicle performance that may reduce the consumption of even renewable or non-fossil fuels."

The University of Southampton is also organising the UK Turbulence Consortium (UKTC), a group of 27 academics and researchers from across eight universities, dedicated to undertaking turbulence simulation and scientific research.

Next month, the UKTC workshop 2013 will take place from 9 to 10 of September at Chilworth Manor Hotel, just outside Southampton, where members will present their latest findings as a culmination of five years of funding.

Using national high-performance computing resources, such as HECToR, the UKTC investigates fundamental aspects of turbulence using numerical simulations.

Richard Sandberg, Professor of Fluid Dynamics and Aeroacoustics at Southampton and lead PI for UKTC, said: “Despite its crucial importance in many applications, the complex nature of turbulence makes its accurate prediction extremely challenging.

“This makes the calculations connected to the study of turbulence correspondingly complicated and time-consuming. Without high-performance computing facilities, such as HECToR, many turbulence problems would just be impossible to address.”

The EPSRC has just announced further major funding for the UKTC of £11.7m over five years, which will increase the consortium to 31 academic members from 13 institutions. The funding includes around £11m worth of computing time on UK national supercomputing facilities.

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