Implementation of the VOF method in the DLR TAU code

Abstract

The DLR TAU code is enhanced with the volume-of-fluid method (VOF) for a reconstruction of the fluid interface. The compressible Reynolds-Averaged-Navier-Stokes equations are discretized by a finite volume technique using tetrahedra, pyramids, prisms and hexahedra. TAU subdivides the either structured or unstructured primary grid into tetrahedra on which the pre-processing solver computes the initial volume-of-fluid distribution. The initial distribution is defined to be rectangular, parabolical, spherical or a combination of the aforementioned. For the consideration of surface ten-sion forces, a continuum surface force method (CSF) is implemented. Due to the application on structured as well as on unstructured grids, the volume-of-fluid values are smoothed with a Laplacian type smoother for a stable calculation of the interface curvature. The continuum surface force algorithm is validated with a test case in which surface tension results in a transition from a cubical shape to a stable spherically shaped bubble in the absence of any external forces.