Vascularized Smart Materials: Designed Porous Media for Self-Healing and Self-Cooling

Constructal theory regards the generation of flow configuration as a natural (physics) phenomenon, and attributes this phenomenon 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 report a fundamental study of how to vascularize a volume so that fluid flow and function (e.g., cooling, sensing, maintenance, repair, healing) reaches every point of the material. The examples are architectures that deliver healing fluid to all the crack sites that may occur randomly through the material. In one concept, a grid of interconnected channels is built into the material, and is filled with pressurized healing fluid. It is shown that the optimization of the ratio of channel diameters cuts in half the time of fluid delivery to the crack. In the second concept, one stream flows steadily through the material and bathes it volumetrically. The steam enters through one point, distributes itself as a river delta, reconstitutes itself as a river basin, and exits through one point. In the third, the solid body is vascularized with trees that alternate with upside-down trees. The flow through all the trees is in one direction, from one side of the body to the other. It is shown that the choice of the tree-tree configuration has a decisive impact on the global performance of the vascularized composite.