Volume-of-Fluid simulations of multiphase flows with high surface tension and curvature using a tensile force method with pressure jump correction

Accurate modeling of surface tension forces in Computational Fluid Dynamics (CFD) simulations of multiphase flow is crucial for applications such as droplet formation and jet breakup, especially for interfaces with high surface tension and curvature. This work integrates a Tensile Force (TF) method in a geometric Volume-of-Fluid (VOF) solver. Unlike the Continuum Surface Force (CSF) model, the TF method calculates the surface tension force directly at the interface location, thus reducing the smearing of the force around the interface. Combination with a Pressure Jump Correction (PJC) further reduces the magnitude of the forces at the interface. This lowers the intensity of problematic spurious currents and allows the simulation of multiphase flows with high surface tension and curvature, which is typically challenging for the CSF method. We validate the TF method through several simulation test cases. Results show that the TF method reduces spurious velocities by an order of magnitude compared to the CSF model. The TF accurately models capillary instability in cases where the CSF model fails. Additionally, the TF model is combined with Adaptive Mesh Refinement (AMR) and Large Eddy Simulation (LES) to simulate droplet breakup. Typical features of the bag-breakup regime are successfully reproduced. Diameters and velocities of secondary droplets are predicted with reasonable agreement to experimental data. Simulation of primary breakup of a liquid aluminium jet in the gas atomization process demonstrates the TF model in industrially relevant conditions. • Tensile force model with pressure jump correction for surface tension forces in VOF. • Spurious currents reduced compared to continuum surface force model. • Captures breakup of interfaces with high surface tension, like metal melt droplets. • Coupled with AMR and LES to resolve interface dynamics and turbulent interactions. • Robustness shown via simulation of liquid aluminium breakup in gas atomization.