Transport induced by a surface acoustic wave along a slab

Department of Physics, Northwest Normal University, Gansu, Lanzhou 730070, PR China

Corresponding author: chukh01@nwnu.edu.cn

Received: 7 April 2001
Revised: 21 January 2002
Accepted: 24 January 2002
Published online: 15 April 2002

Abstract

The transport of non-equilibrium gases in the flow regime of slightly rarefied gas dynamics within a plane channel bounded by two parallel slabs is addressed. Hydrodynamic derivation of the entrainment of rarefied gases induced by a surface acoustic wave (SAW) along the walls in a confined parallel-plane microchannel is conducted by considering the nonlinear coupling between the interface and the velocity-slip. Both no-slip and slip flow results are obtained with the former ones matched with the previous approach. The critical reflux values associated with the product of the second order pressure-gradient and the Reynolds number decrease as the Knudsen number increases from zero to 0.1. We found when the Reynolds number is larger the surface wave-modulation effect (due to the wave number) to the flow field is significant which represents the strong coupling between the boundary and the flow-inertia term. Meanwhile, the (perturbed) mean flow induced by SAW along the walls of a 2D microchannel is proportional to the square of the wave-amplitude ratio which has been qualitatively confirmed by previous approaches.