Vascularized multi-functional materials and structures Adrian Bejan 1 and Sylvie Lorente 2 1 Department of Mechanical Engineering and Materials Science, Duke University, Durham, NC 27708-0300, USA, dalford@duke.edu 2 National Institute of Applied Sciences, Laboratory of Materials and Durability of Constructions 31077 Toulouse, France, lorente@insa-toulouse.fr Keywords: Constructal, vascular, multi-functional, self-cooling, self-healing, smart materials Abstract. Here we draw attention to the development of smart materials with embedded vasculatures that provide multiple functionality: volumetric cooling, self-healing, mechanical strength, etc. Vascularization is achieved by using tree-shaped (dendritic) and grid-shaped flow architectures. As length scales become smaller, dendritic vascularization provides dramatically superior volumetric bathing and transport properties than the use of bundles of parallel microchannels. Embedded grids of channels provide substantially better volumetric bathing when the channels have multiple diameters that are selected optimally and put in the right places. Two novel dendritic architectures are proposed: trees matched canopy to canopy, and trees that alternate with upside down trees. Both have optimized length scales and layouts. Flow architectures are derived from principle, in accordance with constructal theory, not by mimicking nature. Trees or parallel channels? The current literature reveals a surge of interest in bio-inspired designs of flow architectures that promise superior properties, for example, distributed and high-density heat and mass transfer. Chief among the new architectures are the tree-shaped (dendritic) designs. A significant stimulus for this new direction is the emergence of constructal theory as a means to explain biological and geophysical design, and as a method for developing new concepts for flow architectures [1-3]. Tree-shaped flow structures have multiple scales that are distributed nonuniformly through the flow space. Trees are everywhere, and their occurrence can be deduced based on a physics principle [the constructal law: “For a finite-size flow system to persist in time (to live) it must evolve in such a way that it provides easier and easier access to the currents that flow through it”]. The constructal law has become an addition to the thermodynamics of non-equilibrium systems with configuration [4, 5]. Figure 1 shows our proposal to vascularize a body so that it is bathed volumetrically by a stream that flows from one side to the other [6]. Each tree connects a point with a straight line. The need to install trees that alternate with upside-down trees comes from the rectangular shape of the line-to-line space. The fluid flows in the same direction through all the trees, e.g., upward in Fig. 1. This Figure 1 Alternating trees for connecting the points of one line with the points of another line [6]. Advanced Materials Research Vols. 47-50 (2008) pp 511-514 Online available since 2008/Jun/12 at www.scientific.net © (2008) Trans Tech Publications, Switzerland doi:10.4028/www.scientific.net/AMR.47-50.511 All rights reserved. No part of contents of this paper may be reproduced or transmitted in any form or by any means without the written permission of TTP, www.ttp.net. (ID: 152.14.119.202, NCSU North Carolina State University, Raleigh, USA-03/09/14,15:48:27)