Effect of patchwise slip on fluid flow

Research output: Contribution to journalArticle

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. < 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.

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Research areas and keywords

Subject classification (UKÄ) – MANDATORY

  • Theoretical Chemistry
  • Physical Chemistry

Keywords

  • Slip patch, Stick, COMSOL Multiphysics, Navier-Stokes equations
Original languageEnglish
Pages (from-to)341-347
JournalMicrofluidics and Nanofluidics
Volume17
Issue number2
Publication statusPublished - 2014
Publication categoryResearch
Peer-reviewedYes

Bibliographic note

The information about affiliations in this record was updated in December 2015. The record was previously connected to the following departments: Biophysical Chemistry (LTH) (011001011), Theoretical Chemistry (S) (011001039)