Treetop canopies are the image Duke University engineers believe will help them control liquid flow in new materials. Researchers at the University are focusing their efforts on the creation of a “smart” material, which acts like human skin, delivering liquid healing agents through a network similar to blood vessels.

The materials to be developed will include next generation aircraft and rocket “skins” that are able to self-repair when damaged or overheated.

"Examples of this branching design tendency are everywhere in nature, from the channels making up river deltas to the architecture of the human lung, where cascading pathways of air tubes deliver oxygen to tissues," said Adrian Bejan, J.A. Jones Professor of Mechanical Engineering at Duke's Pratt School of Engineering in a recent news story.

In 1996, Bejan described the laws of constructal theory, which he believed could aid in the creation of “smart” materials.

This theory is derived from the principle that flow systems will evolve to minimize imperfections and reduce resistance, so that the least amount of useful energy is lost.

"We examined a flow system that looks more like the canopy-to-canopy model and found it to be more efficient than models in use now that are made up of parallel flow channels," said Bejan. "We believe that this strategy will allow for the design of progressively more complex vascular flow systems."

It was not only found that flow is maximized by these branching larger-to-smaller-to-larger systems, but the researchers have discovered that in order to maintain this efficiency, the tree vasculature needs to become more complex as the flow increases.