Flow in a Pipe Following an Abrupt Increase in Surface Roughness

Abstract

Measurements of velocity, turbulence intensity, and Reynolds stress distributions following a sudden increase in surface roughness of a pipe are reported. The wall shear stress increases abruptly to its final value and the pressure gradient is very nearly constant throughout the transition region. Reynolds stresses throughout much of the transition region reach values exceeding those in fully developed flow in the rough pipe. The need for knowledge of shear stress distributions for use in the calculation of velocity distributions is pointed out. A flow model is suggested.