Numerical study of ultrasound-induced acoustic streamingin sharp-edge acoustofluidic micromixer

In recent years, acoustofluidic micromixers have been utilized to improve the mixing quality of themicrosystems. Hence, we present a numerical model to study the acoustic streaming flow generated inside themicromixer containing a Newtonian fluid, which this acoustofluidic approach demonstrates fast, effectivemixing in microfluidic systems. For the special case of sharp-edge acoustofluidic micromixer, we havesuccessfully validated our numerical method with experimental results in the literature. In this study, weinvestigate the influence of the sharp structure, the position of the tips, inlet velocity, tip angles and drivingfrequencies on the mixing performance. These parameters were determined by the mixing quality (σ) andconcentration profile at the outlet of the channel. It was found that various tip angles (α =۱۵°, ۳۰°, ۶۰°) have adirect influence on mixing quality (σ) and the optimal tip angle was found in ۶۰°. The effect of various numberof sharp edges and their positions as Case۱ and Case ۲ was investigated. It was concluded that lower inletvelocity increases the mixing. By optimizing the frequency, excellent mixing performance and fast mixing speedcan be achieved in a higher driving frequency (۱۰۰ kHz), also lower frequencies were investigated by three sharpedges to achieve an optimal configuration of acoustofluidic micromixer.