nn6b00187_si_001.mpg (3.67 MB)
Commensurability Effects in Viscosity of Nanoconfined Water
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posted on 2016-02-22, 13:13 authored by Mehdi Neek-Amal, Francois M. Peeters, Irina
V. Grigorieva, Andre K. GeimThe
rate of water flow through hydrophobic nanocapillaries is greatly
enhanced as compared to that expected from macroscopic hydrodynamics.
This phenomenon is usually described in terms of a relatively large
slip length, which is in turn defined by such microscopic properties
as the friction between water and capillary surfaces and the viscosity
of water. We show that the viscosity of water and, therefore, its
flow rate are profoundly affected by the layered structure of confined
water if the capillary size becomes less than 2 nm. To this end, we
study the structure and dynamics of water confined between two parallel
graphene layers using equilibrium molecular dynamics simulations.
We find that the shear viscosity is not only greatly enhanced for
subnanometer capillaries, but also exhibits large oscillations that
originate from commensurability between the capillary size and the
size of water molecules. Such oscillating behavior of viscosity and,
consequently, the slip length should be taken into account in designing
and studying graphene-based and similar membranes for desalination
and filtration.
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exhibitCommensurability Effectsphenomenonoscillationcommensurability2 nmNanoconfined Waterflow rateViscositydynamics simulationsmembraneSuchmacroscopic hydrodynamicsequilibriumsubnanometer capillariesnanocapillariecapillary surfaceswater moleculescapillary sizewater flowfiltrationtermshear viscositylengthgraphene layersdesalination
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