Numerical Investigation of Drag Reduction Mechanism in Laminar Flow Regime using Rectangular Riblets

This paper aims to introduce an efficient and passive method in order to reduce the amount of drag exerted on the surfaces of the objects moving in the water. The flow regime is considered as laminar. The desired method is to use rectangular riblets being perpendicular to the flow direction. Two-dimensional computational fluid dynamics is utilized to resolve the flow field around the ribbed surfaces. The effects of geometrical parameters of riblets including width and height as well as free-stream velocity on the amount of drag reduction are numerically calculated. The numerical results certify the efficiency of rectangular riblets as a drag reduction tool in the laminar flow regime. Maximum amount of the drag reduction is about 8.7% achieved for the riblets width of 0.1 millimeter and at free-stream velocity of 10 m/s.