Nanofluidics: Viscous Dissipation in Layered Liquid Films

Becker, Thomas; Mugele, Friedrich Gunther

doi:10.1103/physrevlett.91.166104

Cited by 107 publications

(124 citation statements)

References 29 publications

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“…More recent experiments have provided additional insights into this debate; several studies have found results consistent with the work of Klein and Kumacheva [13][14][15] while others have shown agreement with the conclusions of Granick 16,17 . Atomic force microscopy (AFM), with a much smaller contact area than SFB and SFA, has also been applied to study the confinement of organic fluids [18][19][20] .…”

Section: Introductionsupporting

confidence: 67%

Confined fluid and the fluid-solid transition: Evidence from absolute free energy calculations

et al. 2012

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The debate on whether an organic fluid nanoconfined by mica sheets will undergo a fluid-tosolid transition as the fluid film thickness is reduced below a critical value has lasted over two decades. Extensive experimental and simulation investigations have thus far left this question only partially addressed. In this work we adapt and apply absolute free energy calculations to analyze the phase behavior of a simple model for nanoconfined fluids, consisting of spherical Lennard-Jones (LJ) molecules confined between LJ solid walls, which we use in combination with grand canonical molecular dynamics simulations. Absolute Helmholtz free energy calculations of the simulated nanoconfined systems directly support the existence of order-disorder phase transition as a function of decreasing wall separation, providing results in close agreement with previous experiments and detailed atomistic simulations.

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Section: Introductionsupporting

confidence: 67%

Confined fluid and the fluid-solid transition: Evidence from absolute free energy calculations

et al. 2012

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“…The series of images presented on Fig. 3, which illustrates a transition from 5 to 4 layers, therefore shows a "squeeze-out front", as observed by Becker and Mugele (BM) [26].…”

Section: Outward Frontsmentioning

confidence: 69%

“…We now analyze in greater detail these results on squeeze-out front dynamics in order to (i) compare them quantitatively with those from BM [26], and (ii) check their consistency with the results obtained from the drainage experiments described in section III A.…”

Section: Outward Frontsmentioning

confidence: 99%

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Drainage of a nanoconfined simple fluid: Rate effects on squeeze-out dynamics

Bureau

Arvengas

2008

Phys. Rev. E

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We investigate the effect of loading rate on drainage in molecularly thin films of a simple fluid made of quasi-spherical molecules (octamethylcyclotetrasiloxane, OMCTS). We find that (i) rapidly confined OMCTS retains its tendency to organize into layers parallel to the confining surfaces, and (ii) flow resistance in such layered films can be described by bulklike viscous forces if one accounts for the existence of one monolayer immobilized on each surfaces. The latter result is fully consistent with the recent work of Becker and Mugele, who reached a similar conclusion by analyzing the dynamics of squeeze-out fronts in OMCTS [T. Becker and F. Mugele, Phys. Rev. Lett. 91 166104 (2003)]. Furthermore, we show that the confinement rate controls the nature of the thinning transitions: layer-by-layer expulsion of molecules in metastable, slowly confined films proceeds by a nucleation/growth mechanism, whereas deeply and rapidly quenched films are unstable and undergo thinning transitions akin to spinodal decomposition.

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“…While this behavior of the conservative forces is well understood and has also been reproduced for nanoscale contacts in early Atomic Force Microscopy (AFM) experiments [8], the dissipative behavior of nano-confined liquid films is heavily debated. In the SFA community, slightly different measurement techniques for nominally identical systems produced highly incompatible experimental results with interpretations ranging from confinement-induced solidification [9] or a glassy response [10] to bulk-like dynamics for liquid films of even just a few molecular layers thickness [11][12][13]. SFA measurements are limited to film thicknesses of integer numbers of molecular layers due to a mechanical (''jump-to-contact'') instability.…”

Section: Introductionmentioning

confidence: 99%

Can Confinement-Induced Variations in the Viscous Dissipation be Measured?

et al. 2012

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Liquids confined to molecular scales become anisotropic and often show pronounced self-organization such as layering. Although this effect is well accepted, it is still debated if confinement induces measurable changes of viscous friction. We use molecular dynamics to address this issue by simulating a Lennard-Jones liquid confined between a solid cylinder and an atomically smooth surface. The simulations reproduce the well-established variations of normal force, density, and diffusivity with the distance between wall and cylinder. We find high diffusivity and low density when the numbers of layers is in between integers. This observation seems to contradict most experimental results on the effective damping between atomic force microscope tips and substrates when interpreting them within continuum hydrodynamics used to connect liquid viscosity and diffusivity. This contradiction is resolved by directly extracting the damping that the tip experiences, which we achieve by using the fluctuationdissipation theorem; as in experiment, we find local minima in the damping near integer numbers of molecular layers and maxima in between. These variations correlate with distinct structural changes in the microscopic order of the fluid. We reconfirm that constitutive equations valid at macroscopic scales cannot be used to interpret confined liquids and finally conclude that viscous friction displays measurable, non-monotonic behavior with the degree of confinement.

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Nanofluidics: Viscous Dissipation in Layered Liquid Films

Cited by 107 publications

References 29 publications

Confined fluid and the fluid-solid transition: Evidence from absolute free energy calculations

Confined fluid and the fluid-solid transition: Evidence from absolute free energy calculations

Drainage of a nanoconfined simple fluid: Rate effects on squeeze-out dynamics

Can Confinement-Induced Variations in the Viscous Dissipation be Measured?

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