We present a parametric finite element approximation of two-
phase flow with insoluble surfactant. This free boundary problem is given by the Navier–Stokes equations for the two-phase flow in the bulk, which are coupled to the transport
equation for the insoluble surfactant on the interface that separates the two phases. We combine the evolving surface finite element method with an approach previously introduced by the authors for two-phase Navier–Stokes flow, which maintains good mesh properties. The derived finite element approximation of two-phase flow with insoluble surfactant can be shown to be stable. Several numerical simulations demonstrate the practicality of our numerical method.