Modeling of the dynamic wetting behavior in a capillary tube considering the macroscopic–microscopic contact angle relation and generalized Navier boundary condition

• A numerical wetting model was proposed using the GNBC and the Cox’s relation.
• The experimentally measured angle-velocity correlation is well reproduced.
• The wetting dynamics is described by combining micro-model and macro–micro-relations.

In this study, dynamic wetting phenomena in a capillary tube were studied by using numerical simulations based on the front-tracking method employing the generalized Navier boundary condition (GNBC) and by experimental measurements. For the GNBC, based on molecular dynamics simulations, the microscopic dynamic contact angle is estimated from the grid-scale contact angle using Cox’s macroscopic–microscopic relation. The experimentally measured correlation between the apparent dynamic contact angle and the moving velocity of the contact line is well reproduced by the present simulation technique considering Cox’s macroscopic–microscopic relation. Thus, we found that the dynamics of wetting are well described by combining molecular-scale behavior and macroscopic–microscopic relations.