Thermo-osmosis in silica nanochannels

Abstract

Thermo-osmosis is a coupled phenomenon describing the fluid flow induced by a thermal gradient. Recent studies on thermo-osmosis in clays and within the coupled thermal, hydraulic and mechanical analysis have revealed the importance of this physical processes in geo-energy and geo-environmental applications. This paper presents a series of molecular dynamics simulations of the interfacial water behaviour at the vicinity of silicate layers to quantify the nanochannel size effect on the thermo-osmotic coefficient and reveal some aspects of governing mechanisms of thermo-osmosis in nanoscale space. Our results show that the size effect emerges from the specific liquid structure controlled by the channel width. The overlapping and interfering boundary layers lead to the variations of thermo-osmotic response with the channel width. Our findings not only facilitate a basic knowledge of thermo-osmosis, but also contribute insights and methods to analyse a wider category of coupled heat and mass transfer problems in nanometric space.