Moving contact line in immiscible flows: Resolution of a classical puzzle
Student No.:100
Time:Friday 16:30-17:30, 2017.11.17
Instructor:Ping Sheng  
Place:Lecture Hall, 3rd floor, Jin Chun Yuan West Bldg.
Starting Date:2017-11-17
Ending Date:2017-11-17

In immiscible two-phase flows, the contact line denotes the intersection of the fluid–fluid interface with the solid wall. When one fluid displaces the other, the contact line moves along the wall. A classical problem in continuum hydrodynamics is the incompatibility between the moving contact line and the no-slip boundary condition, as the latter leads to a non-integrable singularity. We present a variational derivation of the continuum boundary condition, based on the principle of minimum energy dissip-ation (entropy production), that is shown to resolve this classical conundrum. Through numerical implementation of the derived continuum hydrodynamic boundary condition for the immiscible flows, it is demonstrated that the continuum prediction can for the first time quantitatively reproduce the moving contact line slip velocity profiles obtained from molecular dynamics simulations. In particular, the transition from complete slip at the moving contact line to near-zero slip far away is shown to be governed by a power-law partial-slip regime, extending to mesoscopic length scales.  The prediction of the continuum model is also shown to be verified by experiments