Effects of acoustic resonance intensification on micromixing performance in a heart-shaped microreactor

To overcome the inherent mixing limitations dominated by laminar flow in microchannels, low-frequency and high-intensity acoustic resonance was introduced as an active external excitation to intensify the micromixing performance within a heart-shaped microreactor. Experimental investigations were systematically conducted using the Villermaux-Dushman parallel competitive reaction system. The micromixing efficiency was quantitatively characterized using the segregation index （X_S）, micromixing time （t_m）, and Damköhler number （Da）. The results demonstrate that the transient inertial forces and secondary flows induced by acoustic resonance effectively disrupt laminar stability, significantly enhancing chaotic advection and species blending across the entire flow field. Compared to non-vibrated conditions, the application of acoustic resonance decreased X_S by 11.3% to 84.5% and drastically reduced t_m from 1.94×10⁻⁴–7.27×10⁻⁴ s to 5.50×10⁻⁵–1.08×10⁻⁴ s. Under all intensified operating conditions, Da remained below 1 （reaching a minimum of 0.12）, indicating that the system transitions into a reaction-controlled regime, thereby eliminating the micromixing bottleneck. This acoustic resonance strategy efficiently matches the time scales of mixing and chemical reactions, providing a novel approach and robust data support for the process intensification and industrial application of microreactors.