AbstractsEngineering

Many multiphase-flows are governed by capillarity and wettability such as spray painting and ink-jet printing applications, cooling devices of small scaled microchips and inside internal combustion engines referring to the fuel injection. The contact angle is a decisive parameter when such a system is analyzed. If the contact angle is in the bounds of the hysteresis, the contact line is pinned (immobile). An accurate numerical simulation is not trivial because of the contact line singularity, a good measure of the contact line velocity as well as the realization of pinning. In this study, the implementation of the dynamic contact angle is extended, accounting for contact line pinning as well as the dynamic behavior in the advancing and receding phase. In short, the whole contact angle hysteresis is realized. The implementation has been validated by considering the cases of a drop impact on a horizontal surface, the simulation of drops on inclined surfaces and drops exposed to a shear flow. Moreover, the wetting of geometrically complex surfaces has been investigated and an approach for the modeling of the geometrical influence on a flat wall by a boundary condition is presented.