epiugvof: Efficient polytope intersection for unsplit geometric VOF methods on arbitrary grids

The software package includes FORTRAN routines with improved accuracy and computational efficiency, along with added capabilities, to perform analytic and geometric operations involving intersections between half-spaces or hyperplanes and 2- or 3- polytopes (polygons or polyhedra, either convex or non-convex) that typically arise in advanced volume of fluid (VOF) methods on arbitrary grids. To show the new capabilities and performance improvements, the proposed tools have been included in a PLIC (piecewise linear interface calculation) reconstruction method (the conservative level contour interface reconstruction, CLCIR, method) and two advection methods: a fluid-volume intersection advection (FVIA) method (the edge-matched flux polyhedron advection, EMFPA, method) and a new wetted-area time-integration advection (WATIA) method. A test program has been implemented to deform a spherical fluid body under a prescribed velocity field using the different reconstruction and advection methods on several structured and unstructured grids.