INTRODUCTION ESDU CFD-BPG 09010 provides the Best Practice Guidelines recommended by ESDU for the CFD modelling of friction losses and flow characteristics in circular straight pipes with smooth walls. These Guidelines are based on the extensive ESDU CFD validation studies described in ESDU TN 08008 and ESDU TN 08009. This CFD Guide may be used in the modelling of industrial pipe-flow applications where pipes are part of more complex equipment@ such as aircraft ducts@ pipe fittings@ heat exchangers@ various components of power generation plants@ etc. It may also be used in more general CFD applications where straight pipes are used to set inlet and outlet boundary conditions. At inlet boundaries@ it may be used to set the length of the artificial inlet extension required for a natural development of duct boundary layers. At outlet boundaries@ this CFD Guide may be used to set the length of the artificial outlet extension required to reduce the influence of the outlet local fluid dynamics on the overall CFD predictions. This CFD Guide may be used with any finite volume Reynolds-Averaged Navier-Stokes (RANS) CFD code with low-Reynolds-number turbulence modelling and correlation-based ??bypass' transition modelling capabilities such as ANSYS CFX.