(n.) Production Logging. The velocity of fluid moving through a pipe, defined as the volumetric flow rate of that fluid divided by the cross-sectional area. In monophasic flow, it is equal to the mean velocity of the fluid. In multiphase flow, it is not a physically real velocity but is a convenient parameter for analysis. See: Flow Regime, Flow Structure, Laminar Flow, Multiphase Flow, Turbulent Flow