[@chen1989]. Arguably, the easiest method to define the dynamic microscopic contact angle is to simply assume it is fixed and the same as the static contact angle [@eggers2004a]. Instead of a fixed dynamic contact angle, Molecular Kinetic Theory (MKT) [@blake1969; @blake2006] predicts a microscopic contact angle which changes with the contact line velocity. The Voinov-Tanner-Cox [@voinov1976; @tanner1979; @cox1986] law describes the relation between the apparent contact angle and the microscopic contact angle. This law is based on the assumption that it is possible to choose a length scale arbitrary close to the contact line. This makes it impossible to identify a characteristic length scale of the contact line geometry, and reduces its physics to a balance between capillary and viscous stresses [@kafka1979]. Using the lubrication approximation one can now derive the @voinov1976 equation for some specific asymptotic limits, and matching solutions of the Voinov equation with the mesoscopic hydrodynamic solution further away from the wall then gives the Cox-Tanner-Voinov law [@voinov1976; @tanner1979; @cox1986].

Although there are a lot of different models to describe contact lines, there is no consensus on what is the correct description of the physics. Many models have multiple fitting parameters which can be tuned to give 