Abstract
A two-dimensional molecular dynamics model of the liquid flow inside rough nanochannels is developed to investigate the effect of a solid wall on the interface slip of liquid in nanochannels with a surface roughness constructed by rectangular protrusions. The liquid structure, velocity profile, and confined scale on the boundary slip in a rough nanochannel are investigated, and the comparison of those with a smooth nanochannel are presented. The influence of solid wall properties, including the solid wall density, wall-fluid coupling strength, roughness height and spacing, on the interfacial velocity slip are all analyzed and discussed. It is indicated that the rough surface induces a smaller magnitude of the density oscillations and extra energy losses compared with the smooth solid surface, which reduce the interfacial slip of liquid in a nanochannel. In addition, once the roughness spacing is very small, the near-surface liquid flow dominates the momentum transfer at the interface between liquid and solid wall, causing the role of both the corrugation of wall potential and wall-fluid coupling strength to be less obvious. In particular, the slip length increases with increasing confined scales and shows no dependence on the confined scale once the confined scale reaches a critical value. The critical confined scale for the rough channel is larger than that of the smooth scale.
Highlights
The microscale heat and mass transfer has recently been an attractive subject of both scientific investigations [1] and engineering applications, such as microfluidic preparation [2,3,4], biomedical detection [5,6], surface engineering [7], microelectronic cooling [8,9], microchemical production [10,11,12], micro-energy technology [13,14], micro-heat transfer devices [15,16], etc
It is significant to understand the role of the solid wall on the interface slip of liquid in rough nanochannels
Wan et al [41] studied the slip length of liquid flow through rough solid-liquid interfaces in a restrained space using perturbation expansion and the Dyadic Green function, and the results showed that the total slip length at a solid-liquid interface is proportional to the slip length arising from the chemical interaction
Summary
The microscale heat and mass transfer has recently been an attractive subject of both scientific investigations [1] and engineering applications, such as microfluidic preparation [2,3,4], biomedical detection [5,6], surface engineering [7], microelectronic cooling [8,9], microchemical production [10,11,12], micro-energy technology [13,14], micro-heat transfer devices [15,16], etc. At this scale, owing to the strong liquid-solid interaction inside a confined nanospace, the interface slip of liquid at the boundary is crucially affected by the solid wall properties of the channel [20]. It is significant to understand the role of the solid wall on the interface slip of liquid in rough nanochannels.
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