Anti-diffusion method for coupled level set and volume of fluid, volume of fluid, and tangent of hyperbola for interface capturing methods

In this paper, we propose an anti-diffusion method to effectively prevent flotsams (non-physical tiny droplets and bubbles) and/or diffusion of the VOF (volume of fluid) function that occur in CLSVOF (coupled level set and volume of fluid), VOF (volume of fluid), and THINC (tangent of hyperbola for interface capturing) methods. In the proposed method, VOF functions that are not 1 or 0 and exist at a certain distance from the interface are identified as flotsams and/or diffusion (Cad), and these VOF functions (Cad) are moved to the transition region around the interface, where the VOF value is between 0 and 1, using a conservative advection method to prevent flotsams and/or diffusion. Additionally, the proposed method allows for some control over the position to which Cad is moved within the transition region. As a result of applying the proposed anti-diffusion method to various benchmark tests and droplet problems, it was found that the proposed method effectively suppresses flotsams and/or diffusion while ensuring conservation. In some cases, the anti-diffusion method even improves interface capture accuracy. Furthermore, investigating the impact of the position to which Cad is moved revealed that when handling Cad occurring on the gas side (liquid side), moving Cad as far as possible from the gas side (liquid side) increases the effectiveness of flotsams suppression.