Effects of wettability and interfacial nanobubbles on flow through structured nanochannels: an investigation of molecular dynamics

Abstract

Solid-fluid boundary conditions are strongly influenced by a number of factors, including the intrinsic properties of the solid/fluid materials, surface roughness, wettability, and the presence of interfacial nanobubbles (INBs). The interconnected nature of these factors means that they should be considered jointly. This paper employs molecular dynamics (MD) simulation in a series of studies aimed at elucidating the influence of wettability in boundary behaviour and the accumulation of interfacial gas. Specifically, we examined the relationship between effective slip length, the morphology of nanobubbles, and wettability. Two methods were employed for the promotion of hydrophobicity between two structured substrates with similar intrinsic contact angles. We also compared anisotropic and isotropic atomic arrangements in the form of graphite and Si(100), respectively. A physical method was employed to deal with variations in surface roughness, whereas a chemical method was used to adjust the wall-fluid interaction energy (ε wf ). We first compared the characteristic properties of wettability, including contact angle and fluid density within the cavity. We then investigated the means by which variations in solid-fluid interfacial wettability affect interfacial gas molecules. Our results reveal that the morphology of INB on a patterned substrate is determined by wettability as well as the methods employed for the promotion of hydrophobicity. The present study also illustrates the means by which the multiple effects of the atomic arrangement of solids, surface roughness, wettability and INB influence effective slip length.

Molecular Dynamics Study of Friction Reduction of Two-Phase Flows on Surfaces Using 3D Hierarchical Nanostructures

“…Yen et al 48 have simulated plane Poiseuille flow of a nanodroplet with/without Argon between two surfaces with nanostructures. The setup is shown in Figure 4a.…”

Analytical solution of micro-/nanoscale convective liquid flows in tubes and slits

“…In the literature, research has been focused on the effects of interfacial properties (Jabbarzadeh et al 1999;Barrat and Bocquet 1999;Cottin-Bizonne et al 2002;Koumoutsakos et al 2003;Cho et al 2004;Schmatko et al 2005;Voronov et al 2006Voronov et al , 2007Huang and Breuer 2007;Huang et al 2008;Sendner et al 2009;Sun et al 2012;Sofos et al 2013;Zhang and Chen 2014;Yen 2015;Yen and Soong 2016;Ramos-Alvarado et al 2016), shear rate (Jabbarzadeh et al 1999;Craig et al 2001;Choi et al 2003;Joseph and Tabeling 2005;Li et al 2014), and channel height (Cheng and Giordano 2002;Lichter et al 2007;Xu and Li 2007;Lee et al 2012) on slip length. The extensive literature survey shows that studies about the dependence of slip length on the surface and flow properties are widespread, and there is a consensus about the direct relationship between slip length, liquid/solid interaction energies, and shear rate.…”

Molecular Dynamics Study on Water Flow Behaviour inside Planar Nanochannel Using Different Temperature Control Strategies

“…In the MD simulations, the classical equations of motion for each atom/molecule of the molecular many-body system are numerically solved, while the intermolecular interactions are described by effective interaction potentials in order to obtain molecular trajectories, which can be used to obtain macroscopic properties of the system using statistical analysis methods [12]. Many of the MD simulations studies were performed to investigate the confinement wall roughness [13][14][15][16][17][18][19], various solid wettability and liquidsolid interaction type [5,10,[20][21][22][23][24][25][26][27][28][29][30][31][32][33][34], confinement size [5,29,[35][36][37], flow shear rate [24,38,39], and various confinement shape, and entrance/exit [40][41][42] effects on fluid behaviour in nanoconfinements. In recent years, much effort was also put to study flow behaviour in nanochannels with the presence of nanoparticles as the solid nanoparticles improve the thermal characteristics of fluids [15,[43][44][45][46][47]…”