Turbulent plane Poiseuille-Couette flow as a model for fluid slip over superhydrophobic surfaces

摘要

In this study, plane Poiseuille-Couette flow is simulated as a model for specified streamwise slip on one of thenchannel walls. The relative velocity between the two walls is set to be 1, 2, and 4 in viscous wall units. This isnequivalent to the presence of a superhydrophobic surface at one of the channel walls that causes fluid to slip onnthe boundary. The results show that the streamwise slip forces turbulence in the near-wall region to tend towardsna limiting one-component state. This leads to the suppression of small scale turbulence and laminarization closento the wall and then to drag reduction. The selective weakening of the streamwise vorticity close the wall andnthe observed decrease of turbulence kinetic energy production can then be considered as a consequence of thisneffect. Changes in the coherent structures, including a decrease of sweep events and increase of ejection eventsnclose to the wall where slip occurs, are also observed.