Investigation of the Shapes, Velocity and Pressure Profiles of Gas Bubbles in Liquid Flowing in T-Junction Microchannels Via Simulations

The formation and control of gas bubbles in gas-liquid systems is an important problem for biomedical, optical, mechanical, chemical engineering and materials science discussions. Examining these systems in microchannels is important in terms of reflecting the problems of these disciplines to the problem. Important parameters affecting gas bubble formation are the viscosity of the liquid, the velocity of the liquid flowing in the microchannel, the inertia forces and the geometry of the microchannel. This project seeks to examine the prominent parameters of gas-liquid systems and the two-phase flows inside the microchannels where specifically flow regimes, bubble shape and pressure drop over the bubbles are investigated.

For this purpose, T-junction microchannel geometries in different dimensions were prepared using the open-source CFD software OpenFOAM in a simulation environment and the results are compared with the experimental data available in the literature and among themselves for verification purposes. The problem is solved in two-dimensions, where the dispersed phase is air, and the continuous phase is water. After verification with the literature, contraction and expansion in the microchannel geometry is simulated to observe the change in the shape of the air bubble. For a different investigation, pressure and velocity profiles at gas inlet and along the channel were examined. The comparisons with the literature were made and the pressure drop values in the simulation were successfully associated with the Hagen-Poiseuille law and Laplace pressure in the theory. The methods and results used in simulations are discussed.