Constructal law is a theory of the generation of design (configurations, patterns, geometry) in nature. According to this theory, natural design and the constructal law unite all animate and inanimate systems.The constructal law was stated by Adrian Bejan in 1996 as follows: "For a finite-size system to persist in time (to live), it must evolve in such a way that it provides easier access to the imposed currents that flow through it."The constructal law is receiving increased acceptance within the scientific community. "Constructal" is a word coined by Bejan to describe the natural tendency of flow systems (e.g. rivers, trees and branches,lungs, tectonic platesand engineered forms)to generate and evolve structures that increase flow access.