Knowledge Bank

The scales of fast-swimming sharks contain riblet structures, micro-grooved surfaces aligned in the direction of fluid flow, that result in water moving efficiently over the surface. In previous studies, these riblet structures have shown a drag reduction effect of up to 10% when compared to a smooth, flat surface; however, these studies left the question of what is occurring around the riblets uninvestigated and they lacked thorough specimen variation. To explore the effects of riblet geometries on drag, three shark-skin inspired riblet configurations were created using ANSYS Fluent, a computational fluid dynamic (CFD) program. These models were created at a Reynolds number of 4200 based on entire channel width using the Large Eddy Simulation (LES) turbulence model. The lateral spacing between riblets was varied and vortex size, vortex location, and drag change was compared. This research found that as riblet lateral spacing was increased, the vortex height and width increased as well. This modeling information will help lead to a better understanding of riblets and allow for improving upon their design. The ultimate goal is to construct riblet designs that optimally reduce drag for various uses such as air, water, and oil flow in pipes and transportation applications of aircraft and ships.