Assessment of the interface compression scheme in the volume-of-fluid modeling of circular hydraulic jumps

This study addresses the accuracy of the standard interFoam solver of the OpenFOAM library for the simulation of circular hydraulic jumps (CHJs). The volume-of-fluid (VOF) method implemented in the interFoam uses an antidiffusive flux under the interface compression scheme to prohibit numerical diffusion. However, some shortcomings of this compression scheme have been reported in the literature. These shortcomings are due to the interface over-sharpening, which eventually results in an incorrect prediction of pressure field and thus surface tension forces, especially when the interface undergoes sudden deviations, for example, in CHJs. A CHJ can occur in the radial-outspreading of vertically downward free-surface liquid jets impinging upon a horizontal plate. The aim is to reveal whether the interFoam solver accurately simulates large distortions at the jump and also flow structures in the jump region. Different flow structures in the jump region are produced by placing an obstacle with varying height at the edge of the impinged plate. The results show that the transition sequence between jump structures, predicted by the standard interFoam solver, does not follow the consecutive occurrence reported in the literature. The reason is the large gradients around the interface for the phase field predicted by the standard interFoam solver. However, a revised form of the interFoam solver, called SMICFoam, amends the interface compression scheme and calculates interfacial forces applying the continuum surface stress (CSS) method.