Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Trees, forests and the Eiffel tower reveal theory of design in nature

18.08.2008
What do a tree and the Eiffel Tower have in common?

According to a Duke University engineer, both are optimized for flow. In the case of trees, the flow is of water from the ground throughout the trunk, branches and leaves, and into the air. The Eiffel Tower's flow carries stresses throughout the structure without collapsing under its own weight or being downed by the wind.

For most engineers, the laws governing fluid and solid mechanics like these examples are like oil and water – they just don't mix.

However, a theory developed by Adrian Bejan, J.A. Jones Professor of Mechanical Engineering at Duke's Pratt School of Engineering and colleague Sylvie Lorente, professor of civil engineering at the University of Toulouse, France, explains how these disparate forces can co-exist within the same theory.

"We believe that the main function of the tree is to facilitate the flow of water from the ground and into the atmosphere," Bejan said. "To achieve that function, the tree is ideally designed to not only maximize the flow of water, but in order to be successful in the real world, it must also be able to withstand the stresses of the wind. It is exquisitely designed to do just that."

The constructal theory, which Bejan started describing in 1996, is based on the principle that flow systems evolve to balance and minimize imperfections, reducing friction or other forms of resistance, so that the least amount of useful energy is lost. While the tree is the most common model used by Bejan to explain the theory, other similar examples exist in nature, such as the rivers and streams that make up a delta or the intricate airways of the lungs.

In their latest theoretical formulation, the engineers focused on fundamental principles to explain the "designedness" of nature, or why things are constructed the way they are. Using the constructal theory, they deduced the structure of the individual tree, as well as its root system and its place in the forest, as a microcosm of the flow of water in nature.

This new application of the constructal theory was published early online in the Journal of Theoretical Biology. Bejan and Lorente's work was supported by the Air Force Office of Scientific Research.

"The tree is a physical flow architecture that has evolved to meet two main objectives – maximum mechanical strength against wind and maximum access for water coming from the ground through the tree and into the atmosphere," Bejan said. "In the larger sense, the forest itself is a flow system with the same mechanical properties and functions as the individual tree, facilitating the flow of water across the globe."

As the branches grow out from the trunk, the ratio of their circumferences decreases in proportion to the trunk's decreasing circumference as it rises.

"Winds come in many speeds, but their ultimate effect is cutting off trunks, branches and leaves, so whatever is too long or sticks out too much is shaved off," Bejan said. "So the pattern of the tree is the result of the never-ending assault by the wind."

The resulting patterns and proportions, like the similar ones of the Eiffel Tower, are predicted by the constructal theory, Bejan said.

"If the purpose of a tree was not to transport water, it would look like the Eiffel Tower," said Bejan, half jokingly. "It looks like Mr. (French engineer Gustave) Eiffel, without knowing it, designed a structure that corresponds with our constructal theory."

Richard Merritt | EurekAlert!
Further information:
http://www.duke.edu

Further reports about: Bejan Design Eiffel Eiffel Tower Nature Theory atmosphere constructal microcosm root system

More articles from Life Sciences:

nachricht Decoding the genome's cryptic language
27.02.2017 | University of California - San Diego

nachricht New risk factors for anxiety disorders
24.02.2017 | Julius-Maximilians-Universität Würzburg

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Safe glide at total engine failure with ELA-inside

On January 15, 2009, Chesley B. Sullenberger was celebrated world-wide: after the two engines had failed due to bird strike, he and his flight crew succeeded after a glide flight with an Airbus A320 in ditching on the Hudson River. All 155 people on board were saved.

On January 15, 2009, Chesley B. Sullenberger was celebrated world-wide: after the two engines had failed due to bird strike, he and his flight crew succeeded...

Im Focus: Breakthrough with a chain of gold atoms

In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport

In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport

Im Focus: DNA repair: a new letter in the cell alphabet

Results reveal how discoveries may be hidden in scientific “blind spots”

Cells need to repair damaged DNA in our genes to prevent the development of cancer and other diseases. Our cells therefore activate and send “repair-proteins”...

Im Focus: Dresdner scientists print tomorrow’s world

The Fraunhofer IWS Dresden and Technische Universität Dresden inaugurated their jointly operated Center for Additive Manufacturing Dresden (AMCD) with a festive ceremony on February 7, 2017. Scientists from various disciplines perform research on materials, additive manufacturing processes and innovative technologies, which build up components in a layer by layer process. This technology opens up new horizons for component design and combinations of functions. For example during fabrication, electrical conductors and sensors are already able to be additively manufactured into components. They provide information about stress conditions of a product during operation.

The 3D-printing technology, or additive manufacturing as it is often called, has long made the step out of scientific research laboratories into industrial...

Im Focus: Mimicking nature's cellular architectures via 3-D printing

Research offers new level of control over the structure of 3-D printed materials

Nature does amazing things with limited design materials. Grass, for example, can support its own weight, resist strong wind loads, and recover after being...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Booth and panel discussion – The Lindau Nobel Laureate Meetings at the AAAS 2017 Annual Meeting

13.02.2017 | Event News

Complex Loading versus Hidden Reserves

10.02.2017 | Event News

International Conference on Crystal Growth in Freiburg

09.02.2017 | Event News

 
Latest News

New pop-up strategy inspired by cuts, not folds

27.02.2017 | Materials Sciences

Sandia uses confined nanoparticles to improve hydrogen storage materials performance

27.02.2017 | Interdisciplinary Research

Decoding the genome's cryptic language

27.02.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>