On the Implementation of Surface Tension Within a VOF Framework

Abstract

A balanced-force algorithm for predicting free surface flow with surface tension on general curvilinear coordinate systems is presented in this thesis. The well-established Continuum Surface Force (CSF) method is employed to model surface tension forces. One of the primary challenges of the CSF method is the generation of spurious currents in the vicinity of the interface. To address this issue, the presented algorithm reduces imbalances between pressure gradients and surface tension forces to the solver’s tolerance, effectively eliminating the first source of spurious currents. The remaining task is to adequately estimate curvature, which cannot be directly obtained using the abruptly varying volume fraction field. Three well known curvature estimation techniques within the Volume of Fluid (VOF) framework are implemented: Laplacian Filter, Convolution Method, and Height Functions. The algorithm is then validated through several benchmark cases, and the parameters associated with each of the curvature estimation techniques are refined to enhance the solution’s accuracy.