Modeling the Dynamics of Partial Wetting Using Smoothed Particle Hydrodynamics (SPH)

The scientific description of wetting phenomena is a challenging problem on every considerable length-scale. Intermolecular interactions like the Van der Waals forces may act as driving force and give rise to interface and contact line dynamics. In this way appropriate physical models must be developed in order to describe surface tension phenomena on the continuum scale.

In this thesis a new approach based on a balance equation for the contact line is introduced, which completes the model of a two-phase system close to a solid boundary. Thus the Navier–Stokes equations are extended and now capable of describing interface and contact line dynamics. As a result the model shows equilibrium contact angles for systems at rest and moreover it reveals dynamic contact angles for moving interfaces. The complete numerical model is implemented and investigated using a Smoothed Particle Hydrodynamics (SPH) approach.

An application is shown with respect to the initial bubble formation process at an orifice. The impact of various flow rates along with different orifice geometries and wetting conditions is evaluated. The results reveal, that nowadays effective models for the estimation of bubble sizes undergo a significant error by neglecting wetting phenomena and that an optimization is necessary under certain conditions.