Application of main flow data in the determination of boundary shear stress in smooth closed ducts

Boundary shear stress plays an important role in momentum and mass transfers, but it is very difficult to determine experimentally. This paper develops a new method which can evaluate the boundary shear stress using the main flow data based on Momentum Balance Method (MBM). A theoretical relationship between the boundary shear stress and parameters of main flow region is established. The obtained results from MBM agree well with other methods, indicating that the new method is reasonable and reliable. The significant contribution of MBM is that the local boundary shear stress accurately and quickly can be determined by application of this new method . Hence, MBM may provide a useful tool for hydraulic engineers who need a simple and easy way to measure the boundary shear stress