Improved Simulation of Flows with Free-Surface Waves by Optimizing the Angle Factor in the HRIC InterfaceSharpening Scheme

In finite-volume-based simulations with free-surface waves, it is usually desired to obtain a sharp interface between both fluid phases. A widely used approach for interface-capturing and sharpening is the combination of the volume-of-fluid method with the HRIC scheme. The HRIC scheme contains a user-defined parameter, the angle factor, which influences the magnitude of the interface-sharpening. The present work demonstrates that the optimum value for the angle factor is case dependent: too small values can cause substantial flow disturbances, such as vorticity production within the wave and the occurrence of parasitic wave components, whereas too large values can cause excessive dissipation of wave energy. The optimum value for the angle factor was found to depend on the wave steepness, the aspect ratio of the grid cells, on the cell size and to a lesser degree on the time step size. Results from an extensive parameter study are presented, which can provide guidance for optimizing the angle factor for flow simulations of free-surface wave propagation. Further, two methods are presented which can be used to determine the optimum value of the angle factor. The magnitude of errors that can occur due to improper choices of the angle factor are discussed and recommendations are given to increase the accuracy of flow simulations with free-surface waves.