numerical simulation of droplet formation in cross-shape microchannels using lattice boltzmann method

Wide range of important phenomena in fluid dynamics contains multiphase flows. In this way, simulation and study of two-phase flows are of great importance.Droplet formation in micro-channels is one of these topics which is of great interest within scientists. It is important to understand clearly the dynamic of dropletin multiphase systems from the point of formation to the transport process along the micro-channel. In this research, the lattice Boltzmann method (LBM) isemployed to simulate different mode of droplet formation in a cross-shape micro-channel. Indexfunction model which is a reliable and compromising model is used to track the interface between different phases. Accuracy of the model is examined by wellknownbasic analytical two-phase flows including Laplace law and relaxation of rectangular cylinder, and our results are in good agreement with analyticaloutcomes which certify our final results quality. In a cross-junction micro-channel second phase enter from the one of the channels and continuous phase enter thedomain from two channels cross to the basic stream of second phase. This interaction leads to droplet formation in channel. Different geometry and velocityratios lead to different result in formation. For study of different properties for fluids and different position offormation, the influence of different parameters on droplet formation is investigated with dimensionless numbers that determine the droplet formation in variousconditions. The capillary number which is the ratio between viscosity and surface tension is one of the most important dimensionless numbers in determination offluid flow characteristic in micro-channels. High dependence of dynamic of formation and its frequencyon capillary number is determined from results. Results in variety of conditions are analyzed and compared with each other and this comparison left important results.

Keywords:

lattice Boltzmann method , micro-channel , multiphase flow , index function model