Molecular dynamics simulation of channel-size dependence of the force around a liquid-vapor-solid contact line region

Molecular dynamics was used to evaluate the channel size dependence of force acting near a liquid-vapor-solid contact line. The shear stress distribution acting on the solid wall surface was calculated using the spatial distribution of the stress tensor to obtain the force acting near the contact line. The force, nondimensionalized by that acting at a region away from the contact line, is proportional to the ratio of the slip length to the channel size. The obtained equation also showed good agreement with the force obtained from the shape of the liquid-vapor interface. Moreover, the obtained equation was dependent on the channel size but independent on the channel size when the channel size was sufficiently large compared with the slip length. This result differs from the channel size dependence of the shear stress at the region distant from the liquid-vapor interface, indicating that the shear stress at the region away from the liquid-vapor interface is more important than the force owing to the surface tension in a nano-order channel.