Drag Reduction Using Microcavity on Flat Surface

Abstract

Abstract This research focuses on the study of drag reduction under the application of microcavity on a 2D flat plate using Detach Eddy Simulation(DES). The study found a maximum of 39.34% reduction in shear stress for laminar flow and 35.4% for turbulent flow under the application of microcavity. A microcavity surface is usually defined as a surface textured with microscale holes. The fundamental phenomenon behind the reduction in shear stress for both laminar and turbulent flow may be comprehended to be due to the appearance of vortices inside the cavity which results in the instigation of a slip velocity at the interface of the vortices inside the cavity and the fluid flow. However, it has also been found that in comparison to smooth surface, the overall drag for the cavity surface is higher in the laminar flow regime and a maximum of 24.57% change in overall drag reduction is observed in the turbulent flow regime. The physical reason behind the appearance of a higher overall drag in the laminar flow regime could be because of the earlier appearance of flow separation. It is also observed in the turbulent flow regime, that the strength of turbulent fluctuations of the smooth surface is far stronger than that of the cavity wall thereby resulting in the reduction of shear stress, delay in the transition to turbulent flow and flow separation.