Nature-inspired solutions to bluff body aerodynamic problems: A review

This review investigates the nature-inspired techniques for the optimization of the aerodynamic forces on bluff bodies. To provide a rich understanding of these nature-inspired phenomena, three distinct zones of the species fishes (nektons), birds (avians) and the fast running land animals are considered. This allows contextualizing different capabilities of the species in different environmental necessities. The review follows a trend in which drag reduction capabilities of individual parts of these species, including body shape & size, tails, fins, surface structure, wings, and wingtips, have been explored in detail. By focusing on specific parts, the review examined the methods and physics involved, which provides space to narrate the development of ideas and our current understanding of the nature-inspired drag reduction and their application to bluff body aerodynamics. Consequently, nature-inspired promising areas for future endeavor related to the bluff body has been discussed in detail. It was found that, though, aerospace field has found several bird inspired application but the bluff body flow modification have only few. Similar is the case with fishes and land animals which have not been explored yet for aerodynamic use on the bluff bodies. The crucial importance of passive devices are also highlighted along with the review of their application on the bluff bodies inspired by nature. Furthermore, several of nature-inspired techniques are proposed and compared to facilitate the research in this direction. It provides a fundamental method to develop nature-inspired flow control devices for the bluff bodies.