Abstract
The effect of rough-wall/fluid interaction on flow in nanochannels is investigated by NEMD. Hydrophobic and hydrophilic surfaces are studied for walls with nearly atomic-size rectangular protrusions and cavities. Our NEMD simulations reveal that the number of liquid atoms temporarily trapped in the cavities is affected by the strength of the potential energy inside the cavities. Regions of low potential energy are possible trapping locations. Fluid atom localization is also affected by the hydrophilicity/hydrophobicity of the surface. Potential energy is greater between two successive hydrophilic protrusions, compared to hydrophobic ones. Moreover, groove size and wall wettability are factors that control effective slip length. Surface roughness and wall wettability have to be taken into account in the design of nanofluidic devices.
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Abbreviations
- F ext :
-
Magnitude of external driving force
- h :
-
Gap between channel walls
- K :
-
Spring constant
- k B :
-
Boltzman constant
- L x :
-
Length of the computational domain in the x-direction
- L y :
-
Length of the computational domain in the y-direction
- L z :
-
Length of the computational domain in the z-direction
- L s :
-
Slip length
- L s,eff :
-
Effective slip length
- m :
-
Atom mass
- N :
-
Number of atoms
- p :
-
Periodic roughness factor
- r eq :
-
Position of a wall atom on fcc lattice site
- r i :
-
Position vector of atom i
- r ij :
-
Distance vector between ith and jth atom
- T :
-
Temperature
- u(r ij ):
-
LJ potential of atom i with atom j
- V :
-
Volume of the computational domain (L x × L y × L z )
- ε :
-
Energy parameter in the LJ potential
- σ :
-
Length parameter in the LJ potential
- υ w :
-
Fluid velocity at the channel wall
- \( \left\langle {\upsilon_{\text{w}} } \right\rangle \) :
-
Average fluid velocity at the channel wall
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Sofos, F., Karakasidis, T.E. & Liakopoulos, A. Surface wettability effects on flow in rough wall nanochannels. Microfluid Nanofluid 12, 25–31 (2012). https://doi.org/10.1007/s10404-011-0845-y
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DOI: https://doi.org/10.1007/s10404-011-0845-y