Effects of surface profile on a boundary-driven acoustic streaming field

Abstract

Control of boundary-driven streaming in acoustofluidic systems is vital for various microfluidic applications either to generate it as a positive mechanism (e.g. microfluidic mixing, heat/mass transfer and fluid pumping) or suppressing it as an undesired disturbance (e.g. particle/cell focusing). It has been shown that two-dimensional (2D) and three-dimensional (3D) boundary-driven streaming can be solved from the limiting velocity method as long as the curvature of the surface is small compared to the viscous penetration depth. In this work, acoustic streaming fields in 2D rectangular enclosures that have structured textures, which do not satisfy this condition are numerically studied by full modelling of Reynolds stresses and the effects of surface profile amplitude on a boundary-driven acoustic streaming field are investigated. Specifically, a sine-wave shaped profile on a boundary parallel to the particle oscillations is considered, which is found to have large influences on both the magnitude of acoustic streaming velocities and streaming patterns