Turbulent skin-friction drag (Df,c) refers to the aerodynamic drag that arises from the frictional resistance between a solid surface, such as an airfoil or wing, and a turbulent fluid flow (usually air). It is a component of the total drag experienced by an object moving through a fluid medium, and it results from the interaction between the fluid’s turbulent motion and the object’s surface. Turbulent flow is characterized by chaotic and irregular movement of fluid particles, with eddies, swirls, and mixing occurring throughout the flow field. As the turbulent fluid interacts with the surface of the object, it generates fluctuating shear stresses at the boundary layer, leading to increased frictional drag compared to laminar flow.Â
- (Df,c)turbulent: Turbulent skin-friction drag per unit span
- q∞: Dynamic pressure of the freestream flow
- c: Chord length of the airfoil or wing
- (Cf,c)turbulent: Skin-friction drag coefficient under turbulent flow conditions