Constructal Theory of Design in Engineering and Nature

This is a brief in tro duc tion to an en gi neer ing the ory on the or i gin and gen er a tion of geo met ric form in all flow sys tems: the an i mate, the in an i mate and the en gi neered. The the ory is named constructal, and is based on the thought that it is nat u ral for cur rents to con struct for them selves in time paths of greater flow access. It is shown that this pro cess of flow path op ti mi za tion can be rea soned on the ba sis of prin ci ple: the max i mi za tion of global per for mance sub ject to fi nite-size con straints. One ex am ple is the gen er a tion of tree-shaped flow pat terns, as paths of least re sis tance be tween one point (source, sink) and an in fin ity of points (area, vol ume), as in the cir cu la tory, re spi ra tory and ner vous sys tems. An other is the gen er a tion of reg u lar spac ings in heat gen er at ing vol umes, such as swarms of hon ey bees. The op ti mized tree-flow ge om e tries ac count for allometric laws, e. g., the re la tion ship be tween the to tal tube con tact area and the body size, the pro por tion al ity be tween met a bolic rate and body size raised to the power 3/4, the pro por tion al ity be tween breath ing and heartbeating times and body size raised to the power 1/4, and the pro por tion al ity be tween the cruis ing speed of fly ing bod ies (in sects, birds, air planes) and body mass raised to the power 1/6. The op ti mized flow struc tures con sti tute ro bust de signs, and ro bust ness im proves as the com plex ity of the sys tem in creases. Flow ar chi tec tures that are more ef fi cient look more nat u ral.