CFD analysis of drop generation in cross-junction microchannel

Abstract

The development of microfluidic devices, which handle small volumes of fluids for mechanical, chemical and medical purposes, is accelerating. Drop microfluidics is a booming field. This study aimed to attain a better understanding of drop generation in a cross-junction device. Hence, the generation of drops in the cross-junction microchannel was numerically and two-dimensionally simulated. For this purpose, the open-source code of Gerris was implemented. Also, the effect of Ca and We number on the drop generation process was evaluated. The AMR technique is utilized to simulate drop motion. Six distinct regimes are identified, namely, long alternating (LA), short alternating (SA), alternating with different sizes (ADS), small drops (SD), jetting (J) and parallel (P). In combination with (LA and SA) regimes, the size of one drop is larger than the hydraulic diameter and the other is smaller. In the large alternating regime, the length of the drops decreases when Weber numbers increase and the drop generation frequency increases as the We number increases. In each transition from one regime to another, the pinch-off location suddenly increases, and then in each regime, with the increment of the We number, the location of drop breakage decreases.