报告题目：Molecular hydrodynamics of the moving contact line

报告人：Prof. Qian Tiezheng (Hong Kong University of Science and Technology)

报告时间：第一讲：10月11日  3:00-5:00pm（周四下午）

             第二讲：10月12日  3:00-5:00pm（周五下午）

Abstract: 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. The recently discovered generalized Navier boundary condition (GNBC) offers an alternative to the no-slip boundary condition which can resolve the moving contact line conundrum.  We present a variational derivation of the GNBC through the principle of minimum energy dissipation (entropy production), as formulated by Onsager for small perturbations away from equilibrium. Through numerical implementation of a continuum hydrodynamic model, it is demonstrated that the GNBC can 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 talk will be organized as follows: (1) The no-slip boundary condition and the moving contact line problem, (2) The generalized Navier boundary condition from molecular dynamics simulations, (3) Implementation of the new slip boundary condition in a continuum hydrodynamic model, (4) Comparison of continuum and molecular dynamics results, (5) A variational derivation of the continuum model, for both the bulk equations and the boundary conditions, from Onsager's principle of least energy dissipation.

Biography:Tiezheng Qian received his PhD from Institute of Theoretical Physics of CAS in 1997. He joined the Mathematics Department of Hong Kong University of Science and Technology after years of postdoctoral studies in UC Berkeley, Case Western Reserve University, and Hong Kong University of Science and Technology.

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