Research on the Design of Micromixer Based on Acoustic Streaming-Driven Sharp-Edge Structures.

This paper presents a three-dimensional, acoustic streaming-driven circular micromixer with sharp-edge structures and the coupling mechanism between acoustic streaming and background flow in biological systems. A piezoelectric transducer induces vibrations in the sharp-edge structures, generating a localized, intense acoustic field that produces a nonlinear acoustic streaming vortex at the tip. The disk-shaped mixing chamber design enhances acoustic field perturbation. This study incorporates the actual background flow field into the model to elucidate the strong interaction between acoustic streaming and steady-state flow. In the sharp-edge structural region, structural curvature induces local variations in acoustic amplitude, generating a non-zero mean Reynolds stress that significantly perturbs the background laminar flow, reduces flow stability, and substantially enhances mixing. The effects of displacement amplitude, Reynolds number, sharp-edge angle, and excitation frequency on the mixing efficiency are systematically investigated. Furthermore, the mixing performances of two different fluids, water and blood, are compared to elucidate the influence of fluid properties on mixing behavior. This mechanism provides theoretical support for microscale active mixing and offers novel insights for microfluidic device design.