  A zonal similarity analysis of friction factors in pipe flow of power law
fluids is presented. It uses the critical Reynolds number and friction factor
at transition as estimates of the normalised velocity and distance between the
wall and log-law layers and successfully collapses both Newtonian and
non-Newtonian data for laminar, transition and turbulent flows.
  Key words: zonal similarity analysis, friction factor, Reynolds number,
transition
