Numerical investigation of acoustic streaming vortex and operating parameters in curved microchannel: driven by standing surface acoustic wave

The employment of ultrasonic fields to control particles has been received attention for its efficient role in harmless applications such as separation, sorting, and trapping. The capability of this technology in related applications is improved by better analyzing and visualizing the interfacing parameters. In this research, the operating parameters, including working frequency, phase difference, displacement amplitude, cross section, and microchannel material in a water-filled microchannel actuated by standing surface acoustic wave, are studied. Perturbation theory is employed to derive the first-order acoustic field and time-averaged second-order governing equations. Also, appropriate and lately introduced boundary conditions are precisely applied to capture the fluid flow and particle motion. Results show the half-wave resonance model in Pyrex wall can effectively sort particles in regions where Acoustic Streaming (AS) is not disruptive. The new design of the microchannel introduces a different pattern in polystyrene aggregation, which can be applied for further acoustic sorting and separation. Additionally, by increasing frequency in Pyrex, stronger streaming is inclined close to the walls which can be applied to mix sheath flows with the buffer flows in cell lysis application. Comparison of different cross sections for different material at different frequencies significantly help to find a trade-off between Acoustic Radiation Force (ARF) and AS. Operating parameters effect on the AS and ARF is visualized and compared to reveal each case potential for sorting, separation, trapping, and mixing application. This quantitative simulation will help researchers choose the appropriate material and correct resonance frequency for lateral biological applications.