Constructal multi-scale and multi-objective structures

This is a review of recent progress on constructal design made in two directions: multi-scale flow structures, and multi-objective design. The first direction is associated with the maximization of heat transfer rate density in a fixed volume in the limit of decreasing length scales, where boundary layers touch, and optimized channels are no longer slender. In the first example of this type, spacings are optimized based on the intersection of asymptotes method. In the second, the heat transfer density is further increased by placing progressively smaller plates in the entrances of the channels formed by the first generation of plates. In the third example, the placement of discrete heat sources on a vertical wall with natural and forced convection is optimized. The second direction is the discovery of architectures that result from two competing objectives, for example, mechanical strength and thermal insulation. It is shown that the internal configuration of a cavernous brick wall can be deduced from the clash between the two objectives. The same concept can be used to optimize the shape and structure of support beams that must be strong and, at the same time, must resist sudden attack by intense heating.