A note on the calculation of two-phase pressure losses

Abstract The calculation of axial differences in static pressure for two-phase flow along a pipe is discussed in relation to the evaluation of two-phase friction. Two-phase friction equations derived from mixing length theory are summarised. The equations compare favourably with data covering the following fluid conditions at the wall: bubble flow, wavy gas-liquid interface, flow with very small bubbles, attached wall bubbles, and dry wall.