Free-Surface Viscous Flow Computations - Validation of URANS Code FreSCo

In this paper, the free-surface modelling in MARIN’s URANS code FRESCO is analysed and tested. FRESCO is a finite-volume code using a two-phase Volume-Of-Fluid approach to handle free-surfaces. After a description of code and method, attention is paid to wave generation and propagation. More specifically, the objective of this study is to assess if the code can model correctly travelling waves of 2nd order Stokes type and what it requires to do so with a quality needed for engineering purposes. Analysis of the effect of numerical schemes and of discretisation errors (via grid-refinement studies) is reported. Dispersion and diffusion errors are quantified by comparison with analytical solutions. Furthermore, two typical benchmark freesurface problems, viz. a 3D Dam-breaking flow and the Duncan foil test case, are used to illustrate the current capabilities of FRESCO. The results are validated against experiments and numerical data available in the literature. The results here shown indicate that FRESCO comes up to expectation, but also that issues such as compressive convection schemes and non-reflective boundary conditions require further research.