Vascularized materials as designed porous media

Constructal theory considers the generation of flow configuration as a natural (physics) phenomenon, and attributes it to a physics principle (the constructal law): ‘For a flow system to persist in time (to survive) it must evolve in such a way that it provides easier and easier access to the currents that flow through it’. Special among the engineered flow architectures derived from the constructal law are the tree-shaped (dendritic) designs. They are invading technological domains in which they were not used previously (manufacturing, electronics cooling, fuel cells). In this paper we review our group's recent progress on the vascularization of solid structures so that fluid flow and function (e.g. cooling, sensing, maintenance, repair, self-healing) reach every point of the material. Examples are tree-shaped architectures that cover a disc-shaped body, vascularized heat exchangers, and a new class of vascularization in which trees alternate with upside down trees in order to provide maximum flow access across a slab. It is shown that the choice of tree–tree configuration has a decisive impact on the global performance of the vascularized composite. Copyright © 2008 John Wiley & Sons, Ltd.