A comparative study of transient capillary rise using direct numerical simulations

The rise of liquid in capillaries, or between two parallel plates as the 2D variant thereof, represents a challenging test case for two-phase flow solvers without a full analytic solution. Four different numerical approaches are compared for the rise of liquid, also providing reference data being of high relevance for capillarity-dominated wetting processes. The used methods are an Arbitrary Lagrangian-Eulerian method (OpenFOAM solver interTrackFoam), a geometric Volume of Fluid code (FS3D), an algebraic Volume of Fluid method (OpenFOAM solver interFoam), and a level-set based extended discontinuous Galerkin discretization (BoSSS). While the transient rise height shows excellent agreement between the different implementations, the velocity fields at the interface demonstrate a different level of local accuracy of the available approaches. Reducing the slip length reduces the overall dynamics of the system, thus yielding a qualitative change in the rise behavior - a behavior that is not covered by simplified ODE models. The obtained rise height results are vailable online: http://dx.doi.org/10.25534/tudatalib-173 (C) 2020 The Author(s). Published by Elsevier Inc.