Numerical analysis of the effects of riblets on drag reduction of a flat plate

In recent years, marine transportation as well as land and air transportation has become in the centre of attention. There has been an attempt to reduce the drag exerted on vessels by various methods, such as rough surfaces and base bleed. Study of the high-speed seawater animals like sharks and dolphins has triggered the use of riblets on the hull of marine vessels. The use of riblet is easy among various methods of skin friction drag reduction. For this reason, there is an interest for construction and optimization of riblet as an efficient and economical way. In this research, the shark’s skin was modeled for the first time in ANSYS CFX using Computational Fluid Dynamics, through analyzing the effects of riblet on a submerged flat plate. Different types of riblet based on height and space between micro channels were studied, and then a comparison between a riblet-covered plate and a smooth plate in various velocities were performed. It was found that by selecting the most appropriate type of riblet, 11 % drag reduction can be attained. Then, by comparing different types of riblets, the best type for drag reduction was selected. Furthermore, the obtained results were compared with the available experimental data.