Assessment of sharp- and continuous-interface methods for drop in static equilibrium

Among the successful approaches for treating multiphase problems involving an interface, the continuous-interface method often handles the surface force via a locally integrated body force formulation. On the other hand, the sharp-interface method treats each phase separately while coordinating them via an explicit interface treatment. The sharp interface method computationally more demanding, but the continuous interface method can create spurious velocity in the interface region, which compromises the solution accuracy. Furthermore, the large property jumps often observed between liquid and vapor phases can influence the numerical accuracy, and needs to be investigated. In order to quantitatively demonstrate the relative performance of the sharp- and continuous-interface methods, we have considered a spherical drop in static equilibrium to highlight the role of the interface treatment. It is shown that the sharp-interface method is second-order accurate while the continuous-interface method is first-order. Furthermore, the sharp interface method is insensitive to the property jumps.