Obnašanje segmentiranega dvofaznega toka tekočin v mikrofluidni napravi

Over the last decades, the Lattice Boltzmann method has been shown to be a powerful tool for numerical simulations of fluid dynamics systems, primarily because of its ability to capture macroscopic as well as microscopic behavior. The Lattice Boltzmann method has introduced an exceptional and innovative approach with interface monitoring of multiphase systems, which is why it is preferred option when dealing with segmented fluid flows. In this work, the aim was to research the parameters contributing to the segmentation of a two-phase liquid flow. Segmented flow regime is characterized by the formation of practically pure dispersed phase segments detectable in a continuous phase in a two-phase fluid flow. The model used for the segmented flow research performs on the fundamental principles of thermodynamics. The fluid flow is driven by differences in chemical potential, with inclusion of the independently manageable parameters representing diffusion coefficient, viscosity and surface tension. The experimental part of the thesis was carried out with undertaken code. The system was set into the two-dimensional square-shaped microchannel, with accordingly adjusted bounce-back and periodic boundary conditions. The system chosen for interpretation of the experiment was methyl diethylamine with water, whose activity coefficients were accordingly included using the three-suffix Margules equation. The first part of the experiment was carried out through the study of molar fraction distribution on ten cases. Each case stands for the set of parameters for diffusion coefficient and viscosity. For eight out of ten cases the results at equilibrium were within expectations. Among ten cases, two turned out to be inadequate for the certain model to simulate and were not included in the results and therefore were not discussed, while one showed turbulent flow tendencies and was chosen for further research. The second part was carried onto three cases, chosen based on the results of the first part. Those three cases were subjected to velocity profile and interface monitoring by adjusting surface tension parameter. Two out of three cases showed predicted behavior with surface energy increase, while the one that showed turbulent tendencies, proved to be under conditions which were unsuitable for development of stabile flow.