Maximum flow access in heat exchangers, heat generating bodies and inanimate flow systems: Constructal law and the emergence of shapes and structures in thermo-fluid mechanics: Comment on “The emergence of design in pedestrian dynamics: Locomotion, self-organization, walking paths and constructal law” by Antonio F. Miguel

Abstract

The evolution and the emergence of new design theory in thermo-fluid mechanics has led to the generation of shapes and structures in heat generating bodies and heat exchangers, which perform optimally under global constraints. Constructal theory, design and self-organization in nature [1–3], ideally, have been adopted as an optimization technique for the development of a procedure that is capable of allocating and optimizing a fixed global space constraint using physical laws. These physical laws define the future way toward emergence of evolutionary design. It has been applied in all facets of life; from humanity and nature to science and engineering [1–4]. Constructal law is a theory about the time direction of global optimization and it explains in a simple manner shapes that arise in nature. Flow architecture comes from a principle of maximization of flow access, in time, and in flow configuration that is free to morph [1,5]. It is not surprising that in the outstanding review by Miguel [6], constructal law has been used to predict the emergence of design in pedestrian dynamics. Based on this law, shapes and configurations that arise in pedestrian dynamics are explained and predicted in a simple manner. This simple law can be extended to natural flow systems, for example in nature, water always takes the path of least flow resistance in the course of navigation in a river basin [1,2,7]. Thermodynamically, every system exhibits a level of imperfection due to entropy generation and leads to degradation of performance of the system [8–11]. However, the system must adjust itself to operate maximally by optimizing the process and geometric configuration of the system, to reduce the entropy. In heat transfer [12], the peak temperature must be minimized at every hot spot of a system for better thermal performance and to avoid thermal stress by optimizing shape and geometry. An engineering applications of constructal theory, which is the geometric and shape optimization, especially in heat transfer analysis, has been highlighted by Bello-Ochende et al. [11,12], Olakoyejo et al. [13], and Kim et al. [14].