DYNAMICS OF CONTACT LINE DEPINNING FROM A SINGLE DEFECT

We examine the motion of the contact line as it is depinned from a single defect. The main features of the time evolution are in agreement with the ''pinched cord'' model of de Gennes. In particular, the contact line shape is well described by a logarithmic form with width increasing linearly and maximum distortion decreasing logarithmically in time. The velocity characteristic of the width increase, however, is larger than expected. Evidence is presented that this is a consequence of the role played by the dynamic contact angle in real situations, which is not accounted for in the present theory.