接触線の過渡運動時における動的接触角の決定機構

Abstract

Estimation of the contact angle on a moving contact line is one of the important factors for the prediction of the liquid surface geometry contacting with solid. In this study the dynamic contact angle on an accelerating vertical glass rod is investigated both experimentally and numerically to elucidate the effect of the acceleration of the contact line. The experiment was held by using ethylene-glycol and its aqueous solution as test fluid. The measured contact angle in the transient state clearly deviated from that for the steady state, depending on the acceleration of the rod. Numerical simulation shows that the acceleration and the gravity terms in the momentum equation, which are relatively remarkable in macroscopic scale, are not responsible for such deviation in the contact angle. Rather, the dependence of the microscopic contact angle on the acceleration, estimated with the viscous bending model, should be the primary factor on the deviation of the contact angle.