Author(s): N. Dharmasiri
Linked Author(s):
Keywords: Friction Factor; Skin Friction; Form Drag; Open Channel Flow; Reynolds Number; Flow Separation
Abstract: Many previous studies have suggested the division of total resistance into skin friction and form drag, without explaining the underlying mechanism of their contribution. This study has investigated the actual physics of this phenomenon, while re-examining Einstein's principle of “summation of boundary shear stress” and extending the method developed by Yang and Tan. The method of “flow separation” behind a roughness element has been extensively examined. The study further evaluates the friction factor for all flow regimes in uniform open channel flow, concerning the transition between fully smooth and fully rough turbulent flows and the developed relationship has been tested and verified against Nikuradse's experimental data. The study also quantifies the relationship between the form drag and the volume of flow separation, while contributing a novel approach to the hydraulic engineers in their flow resistance calculations.
Year: 2011