粗糙表面上的移动接触线和动态接触角

A model to describe the motion of contact line and dynamic contact angle on rough solid surfaces was proposed. It was assumed that a precursor film exists ahead the apparent contact line (ACL) at small velocities of ACL or capillary numbers. The ACL moves on the wetted solid surface, rather than dry solid surface as expected in the conventional hydrodynamic theories. With introduction of the contact line characteristic parameter, λ′, describing the slipping degree of ACL on the precursor film, the relationship between the dynamic contact angle and the velocity of moving contact line were derived. The comparison of the experimental results with the model indicates the dimensionless characteristic parameter, λ, can describe very well the effect of the solid material and surface properties (roughness etc.) on dynamic wetting processes, and is independent of liquid properties. The difference of static contact angles measured by the dynamic measurement technique from static measurement technique was interpreted by this model and the previous hysteresis tension model.