Turbulent boundary layer development in the entrance region of a smooth round pipe

Feature of the turbulent boundary layer along a smooth round pipe is a fundamental to further study of inlet length and flow resistance, therefore, it has been of great significance both in practice and in theory. In this paper, the formulae for calculating the turbulent boundary layer thickness were obtained by solving the momentum integral equation of the boundary layer in which the assumption of the logarithmic law and the exponential law of velocity distribution were adopted. The method for calculating the mean flow velocity in the developing region of turbulent boundary layer in a round pipe was proposed. The relationship between the exponent n and the factor was studied and a formula for calculating the exponent n was obtained.