3D THINC/WLIC code, 2D THINC/WLIC code
The THINC/WLIC (tangent of hyperbola for interface capturing/weighed line interface calculation) scheme is a type of VOF (Volume of Fluids) methods. The scheme is easy to implement but relatively accurate. Although the THINC/WLIC scheme is not the most accurate VOF method, the ratio of [accuracy]/[implementation cost] may be the best.
Kensuke Yokoi, Efficient implementation of THINC scheme: a simple and practical smoothed VOF algorithm, Journal of Computational Physics, 226, 1985 (2007)