Dependence between velocity slip and temperature jump in shear flows.

In this paper, we investigate the dependence of coupled velocity slip (quantified by the slip length) and temperature jump (quantified by the Kapitza length) on solid-liquid bonding strength and shear rate in shear flows. We find that the interfacial behaviors of nano-confined liquid are distinctly different in the weak and strong solid-liquid interaction regimes identified by a threshold of β = 2 (β being the proportional factor of solid-liquid bonding strength). In the weak solid-liquid interaction regime, the liquid molecules adjacent to the surface of the wall are randomly distributed and are free to slip. The variations of the slip and Kapitza lengths against solid-liquid bonding strength and shear rate are regular and monotonic. In the strong solid-liquid interaction regime, the liquid molecules in the vicinity of the wall are in multi-layered ordering and are largely restricted. The slip length becomes multivalued with increasing solid-liquid bonding strength and shear rate, while the Kapitza length seems insensitive to these two parameters. Furthermore, we find that (1) the temperature jump monotonically increases with velocity slip in the weak solid-liquid interaction regime, while it varies non-monotonically with a minimum value in the strong solid-liquid interaction regime; (2) the Kapitza length grows as a power function of the slip length in the weak solid-liquid interaction regime, while it keeps constant in the strong solid-liquid interaction regime.