Design Aspects of Riblets for Fluid Drag Reduction A Review

Most of the fluid dynamic applications rely on the use of energy to either facilitate movement of solid or solid bodies through fluids as well as maintaining fluid motion over the surface of a solid body (Rohr, Anderson, and Reidy, 1989). The two cases require energy in overcoming the available drag force (Walsh, 1990). Due to the increased demand of energy to facilitate the success of various dynamic applications, the world is witnessing increased interest of promoting energy conservation activities, with researchers being on the front line to identify alternative means of reducing consumption (Breus et al, 1993). As a result, the world is experiencing increased research activities to determine and recommend appropriate ways of reducing drag effects in transport pipelines, vehicles, and airplanes as well as in other industrial applications (Hage, BechertBruse, 2000, Walsh, 1990).The discovery of the phenomena to reduce drag force boosted the effort among researchers involved in actualizing its effects (Virk, 1971). Many researchers have been trying to come up with appropriate measures that will enable in reducing the impacts of drag force on both the economy and the environment (Alfredsson and Johansson,1989). Many researchers have presented their explanation concerning the effects and cause of drag force between a fluid and solid boundary (El-Samni, Chun, and Yoon, 2007). Findings by many researchers associate drag force with friction losses taking place as a result of fluid flow in a thin layer that is adjacent to a given solid boundary (Itoh, 2006, Walsh, M. J. Lindemann, 1984). Any flow taking place outside the layer in consideration is considered frictionless since the velocity around it is only affected by boundary shear (Bushnell, 2003). Drag is generated by the boundary layer near the wall due tothe viscous interaction that exists between the fluid and the surface (Lumley, 1972).