Influence of a surfactant or salt on phase inversion in a water–oil pipe flow

Phase inversion experiments have been performed with a water–oil flow through a pipe to study the effect of the addition of a surfactant or of salt on the critical dispersed phase volume fraction (at the point of phase inversion). The addition of a surfactant caused a small change in the critical volume fraction, but the general form of the ambivalence region in the inversion map remained the same. The influence of salt was negligible.