Seemingly universal geometric forms unite the flow systems of engineering and nature. In this groundbreaking book, Adrian Bejan considers the design and optimization of engineered systems and discovers a relationship to the generation of geometric form in natural systems. The idea that shape and structure spring from the struggle for better performance in both engineering and nature is the basis of his new constructal theory: the objective and constraints principle in engineering is the same mechanism underlying the geometry in natural flow systems. From heat exchangers to river channels, Bejan draws many parallels between the engineered and natural worlds. Numerous illustrations, examples, and homework problems make this an ideal text for engineering design courses. Its provocative ideas will also appeal to a broad range of readers in engineering, natural sciences, economics, and business.