Numerical analysis of drag reduction of fish scales inspired Ctenoid-shape microstructured surfaces

Improving marine vehicles performance by reducing energy consumption, decreasing environmental pollution, increasing speed and range has always been the goal of engineers for optimal designs. Nowadays, inspiration from nature is one of the scientists' approaches to solve many engineering problems. The researchers, by mimicking the skin of some marine species, such as fast swimming sharks, dolphins and sailfishes have been succeeded to design and fabricate drag reducing microstructured surfaces. In this research, after describing various types of fish scales, a Ctenoid-shape microstructure is designed by inspiration from bony fish scales. Then, the designed microstructures with various dimensions are implemented on an underwater hydrodynamic model to evaluate its ability to reduce drag force. Models numerically analyzed at different Reynolds numbers for turbulent flow regime utilizing the k-ω SST turbulence model. Furthermore, the effects of Ctenoid-shape microstructure on the different drag components including form drag and friction drag have been examined separately. The results indicated that the Ctenoid-shape microstructured surfaces applied to the underwater hydrodynamic model in the optimum condition have reduce the total drag force on average 20% in turbulent flow range.