Behavior of mixing enhancement in microscale shock cylindrical bubble interaction

The investigation in the mixing characteristics of microscale shock cylindrical bubble interaction (SBI) provides a fundamental perspective into the microscale fuel injection. In present paper, the mixing performance of multi-scale SBI is numerically studied based on compressible Navier–Stokes equation. Starting from the bubble morphology, a scaling behavior of concentration distribution is exhibited in macroscale dynamics, whereas a superior capability of concentration decaying is observed in microscale cases. On the basis of mixedness evaluation, the mixing property of microscale bubbles is reinforced in the pre-interaction stage with notable viscous diffusion, and suppressed in the later evolution in the absence of vortex formation. Resorting to the Lagrangian coherent structure, a spatial coincidence between fluid stretching and mixing extent is visualized. The present study attempts to clarify the physical rationality of microscale injection strategies such as the atomization process and multiple micro-nozzles for mixing enhancement. Further efforts are devoted to physically modelling the competing mechanism of stirring effect (macroscale dynamics) and viscous diffusion (microscale dynamics) for optimal mixing performance.