Numerical framework of particle separation via acoustic radiation force and acoustic streaming

This study presents a numerical framework for acoustofluidic particle separation, integrating acoustic radiation forces and streaming effects in a microfluidic system. Using perturbation theory, the governing equations are decomposed into steady flow, acoustic fields, and time-averaged streaming effects. A two-dimensional microchannel with a sharp wedge is modeled, showing that larger microparticles (1.5 μm radius) are trapped by the combined effects of acoustic radiation forces and streaming vortices, while smaller particles (0.7 μm radius) pass through the channel. Parametric analyses reveal that the separation efficiency is highly influenced by the wedge's inclination angle and the fluid inflow speed, providing tunable control over particle size selection. This framework, which employs finite element analysis, offers insights into optimizing acoustofluidic device performance for applications in biological, chemical, and medical fields that require efficient particle separation.