Drop impact onto a dry surface: Role of the dynamic contact angle

We have developed a new algorithm for modeling the dynamic contact angle, in which the dynamic contact angle is a function of the instantaneous velocity of the contact line. It is emphasized that in general this velocity cannot be approximated by the velocity of any material point, even when the point is very close to the contact line. The algorithm was implemented into a two-phase flow model. The model, which is two-dimensional axisymmetric, uses the volume-of-fluid (VOF) method. The model was used to simulate the spreading of drops impacting a dry solid surface at low Weber numbers. The spread factor, the height of the drop and the dynamic contact angle obtained by the numerical simulations were compared with the experimental data. The numerical results agree well with the experimental data.