  Dynamic wetting plays an important role in the physics of multiphase flow,
and has significant influence on many industrial and geotechnical applications.
In this work, a modified smoothed particle hydrodynamics (SPH) model is
employed to simulate surface tension, contact angle, and dynamic wetting
effects. The wetting and dewetting phenomena are simulated in a capillary tube,
where the liquid particles are raised or withdrawn by a shifting substrate. The
SPH model is modified by introducing a newly-developed viscous force
formulation at liquid-solid interface to reproduce the rate-dependent behaviour
of moving contact line. Dynamic contact angle simulations with interfacial
viscous force are conducted to verify the effectiveness and accuracy of this
new formulation. In addition, the influence of interfacial viscous force with
different magnitude on contact angle dynamics is examined by empirical power
law correlations, and the derived constants suggest the dynamic contact angle
changes monotonically with interfacial viscous force. The simulation results
are consistent with the experimental observations and theoretical predictions,
implying that the interfacial viscous force can be associated with slip length
of flow and microscopic surface roughness. This work has demonstrated that the
modified SPH model can successfully account for the rate-dependent effects of
moving contact line, and can be used for realistic multiphase flow simulation
under dynamic conditions.
