Comparison of volume-of-fluid methods for surface tension-dominant two-phase flows

The capabilities of three volume-of-fluid methods for the calculation of surface tension-dominant two-phase flows are tested. The accurate calculation of the interface remains a problem for the volume-of-fluid method if the surface tension force plays an important role and the density ratios of the fluids in different phases are high. The result can be an artificial velocity field at the interface (“parasitic currents”), which can destabilize the interface significantly. The three different algorithms compared can be distinguished by their methods to compute the surface tension force, namely, the method using a kernel function for smoothing the discontinuity at the interface, a combined level-set and volume-of-fluid approach and a parabolic reconstruction of surface tension. The test cases consist of an equilibrium rod, a capillary wave and the Rayleigh–Taylor instability. The analytical solutions for each problem serve to examine the accuracy and the convergence behavior of each approach. Finally, the slow formation of a gas bubble at an underwater orifice was computed with the combined level-set and volume-of-fluid method and the results are compared with an analytical solution based on the Young–Laplace equation.