Mixing characteristics and energy conversion in the coalescence process of the two droplets

In the case of fluid flow with a low Reynolds number, the internal fluid stratification can be easily observed after droplet coalescence, impeding rapid mixing of fluid. In this study, the capillary pressure difference is increased by adjusting the droplet size and the interfacial tension, so that a strong jet can be generated, resulting in a rapid mixing. Five distinct droplet mixing modes have been found. The phase diagram of the droplet mixing modes is obtained and the transition rule of the droplet mixing modes is established on this basis. A novel energy distribution model is employed to analyze the dependence between liquid bridge expansion and jet movement of two droplets. In addition, a criterion for evaluating the mixing efficiency of droplets is presented. The results presented in this paper provide a theoretical basis and practical guidance for realizing the efficient mixing of microfluids. (c) 2021 Elsevier Ltd. All rights reserved.

Automated summary

In this study, a strong jet is generated by increasing the capillary pressure difference through adjusting droplet size and interfacial tension, leading to rapid mixing in low Reynolds number fluid flow. Five distinct droplet mixing modes are identified, with a phase diagram and transition rule established. A novel energy distribution model is used to analyze the relationship between liquid bridge expansion and jet movement of two droplets, along with a criterion for evaluating droplet mixing efficiency. These findings offer a theoretical basis and practical guidance for efficient mixing of microfluids.