The a 1 parameter may readily be expressed via the parameter Consideration is given to the stationary motion of a capillary PΛin (9), a 1 Γ
2/3PΛ. Reference (5) provides a simplified meniscus of a wetting liquid over a solid at rather slow speeds contact angle relation relying upon the perturbation method when a precursor film moved by van der Waals forces exists. A and the assumption that a 1 has a small value. It is of interest transient region between (I) the meniscus motion with a dynamic to evaluate the effectiveness of this solution by comparing contact angle and (II) the slow-wetting regime is studied. The it to numerical analysis data.
dependence of the dynamic contact angle on the wetting velocity
As the asymptotic theory shows, the dynamic contact is derived. The phenomenon of zero contact angle at a nonzero angle a 0 exists when a 1 is small or PΛis great (PΛΣ· 1).
critical speed is demonstrated. The numerically obtained interrela-At low values (PΛΣΆ 1) we have slow wetting in which the tion between the contact angle and the velocity is compared to that provided by the asymptotic theory. The asymptotic equations precursor film starts from the equilibrium transient zone of for the meniscus contact angle is shown to be highly effective over the meniscus. The intermediate regime of wetting dynamics a wide range of nondimensional velocities. The meniscus contact (PΛΓ 1) is analyzed below. In this regime, the dependence angle existence criterion is refined. Dependence of the initial thickof the contact angle on the wetting rate must substantially ness of the precursor film on the speed is estimated. The conditions differ from that previously known (a 0 Γ Ca 1/3 ).
of the initial thickness, being in correspondence with the slow-
We would employ the previously known parabolic apwetting regime, are outlined.