Description of Dynamic Contact Angle on a Rough Solid Surface

An investigation was conducted to understand the contact line movement and associated contact angle phenomena. Contact line was supposed to move on a thin precursor film caused by molecular interaction between solid and liquid and asperity of solid surface. It is expected that contact line has a velocity and is subject to viscous stress on the film or geometrically on the solid surface. With the introduction of a characteristic parameter, λ′, the movement of contact line and contact angle phenomena were very well described in both physics and mathematics. The viscous shearing stress exerted by liquid on solid surface was derived, and the behavior of dynamic contact angle was recognized on rough solid surfaces. The analyses indicate that characteristic parameter, λ′, is dependent upon solid wall intrinsic property and mechanical performance, not liquid property. The comparison of theoretical predictions with available experimental data in open literature showed a quite good agreement with each other.