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Effect of patchwise slip on fluid flow

Pihl, Maria; Jönsson, Bengt LU and Skepö, Marie LU (2014) In Microfluidics and Nanofluidics 17(2). p.341-347
Abstract
In this paper, we show that large connected slip patches (hydrophobic patches) are a necessity to induce macroscopic slip effects of water flow in microchannels. For this purpose, the 2D fluid flow between a planar stationary surface with alternating stick and slip patches and a parallel planar surface moving with a constant relative velocity has been studied by computer simulations based on Navier-Stokes equations. A slip patch is defined as the slipping length in a 2D system or a slip area of the surface in a 3D system. The simulations reveal that the ratio (size of each slip patch)/(distance between the two parallel interfaces) has profound effect on the viscous stress on the moving surface when this ratio is around and above one.... (More)
In this paper, we show that large connected slip patches (hydrophobic patches) are a necessity to induce macroscopic slip effects of water flow in microchannels. For this purpose, the 2D fluid flow between a planar stationary surface with alternating stick and slip patches and a parallel planar surface moving with a constant relative velocity has been studied by computer simulations based on Navier-Stokes equations. A slip patch is defined as the slipping length in a 2D system or a slip area of the surface in a 3D system. The simulations reveal that the ratio (size of each slip patch)/(distance between the two parallel interfaces) has profound effect on the viscous stress on the moving surface when this ratio is around and above one. However, when the ratio is much below one, the effect of the slip patches are minor, even if the area fraction of slip patches are higher than 50 %. Obviously, the stick patches adjacent to the slip patches act as effective barriers, preventing the fluid velocity to increase near the surface with alternating stick and slip patches. The obtained results are scalable and applicable on all length scales, with an exception for narrow channels in the subnano regime, i.e. < 1 nm where specific effects as the atomistic composition and the nanostructure of the wall as well as the interactions between the wall and the water molecules have an effect. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
Slip patch, Stick, COMSOL Multiphysics, Navier-Stokes equations
in
Microfluidics and Nanofluidics
volume
17
issue
2
pages
341 - 347
publisher
Springer
external identifiers
  • wos:000339886000009
  • scopus:84904796541
ISSN
1613-4982
DOI
10.1007/s10404-013-1300-z
language
English
LU publication?
yes
id
ff2c237c-4807-46b2-af84-8a4717d1d6dd (old id 4667796)
date added to LUP
2014-09-25 10:01:17
date last changed
2017-01-01 04:09:44
@article{ff2c237c-4807-46b2-af84-8a4717d1d6dd,
  abstract     = {In this paper, we show that large connected slip patches (hydrophobic patches) are a necessity to induce macroscopic slip effects of water flow in microchannels. For this purpose, the 2D fluid flow between a planar stationary surface with alternating stick and slip patches and a parallel planar surface moving with a constant relative velocity has been studied by computer simulations based on Navier-Stokes equations. A slip patch is defined as the slipping length in a 2D system or a slip area of the surface in a 3D system. The simulations reveal that the ratio (size of each slip patch)/(distance between the two parallel interfaces) has profound effect on the viscous stress on the moving surface when this ratio is around and above one. However, when the ratio is much below one, the effect of the slip patches are minor, even if the area fraction of slip patches are higher than 50 %. Obviously, the stick patches adjacent to the slip patches act as effective barriers, preventing the fluid velocity to increase near the surface with alternating stick and slip patches. The obtained results are scalable and applicable on all length scales, with an exception for narrow channels in the subnano regime, i.e. &lt; 1 nm where specific effects as the atomistic composition and the nanostructure of the wall as well as the interactions between the wall and the water molecules have an effect.},
  author       = {Pihl, Maria and Jönsson, Bengt and Skepö, Marie},
  issn         = {1613-4982},
  keyword      = {Slip patch,Stick,COMSOL Multiphysics,Navier-Stokes equations},
  language     = {eng},
  number       = {2},
  pages        = {341--347},
  publisher    = {Springer},
  series       = {Microfluidics and Nanofluidics},
  title        = {Effect of patchwise slip on fluid flow},
  url          = {http://dx.doi.org/10.1007/s10404-013-1300-z},
  volume       = {17},
  year         = {2014},
}