An atomic model for water flows in a circular nanochannel.
Atomic models with various channel size for circular nanochannel. The radius of the channel varies from R = 10, 20, 30 Å.
Atomic models for circular nanochannels with surface roughness in the form of sinusoidal variation. The amplitudes of the sine function in Eq. (1) are (b) r = 0.1, (c) r = 0.2, and (d) r = 0.3.
Atomic models of nanochannels with various cross sectional shapes: (a) triangular (b) square, (c) kagome, (d) hexagonal, and (e) circular (oxygen (blue), hydrogen (green), wall (red)).
A schematic of TIP4P water model. Near the water molecule, there is a fictitious atom (M) added for the total charge balance.
The pair distributions of the water molecules (O-Wall) are different for (a) hydrophobic and (b) hydrophilic channel walls. (c) The waters in the hydrophilic wall show significant correlations with long range ordering.
Flow patterns of water molecules in the circular channels of different size. (a) The flow velocities are saturated to certain values after the interaction between the water molecule and wall atoms are balanced. (b) The average velocities are dependent to the radius of the channel. It is also shown that the threshold channel size is dependent on the applied force. (c) The average velocities are zeroes under certain threshold forces dependent on the channel size. Beyond the threshold forces, the velocities become proportional to the applied force due to the interfacial friction.
(a) Water flow patterns in the rough channels for r = 0.1, 0.2, 0.3. (b) The average velocities were obtained for various roughness (r = 0–0.3). It is shown that the flow is nearly stopped as the roughness increases, in this case, r ∼ 0.1.
(a) Averaged velocities of water molecules in various nanochannel shapes (f = 0.005, 0.01 Kcal/mol-Å) with same cross sectional areas (∼2826 Å2). (b) The average velocities appeared sensitive to the cross sectional shape as well as the applied force. The shape factors (filled squares) were plotted after the normalization by that of the circular shape.
Shape factors for various cross sectional shapes with same cross-sectional areas.
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