COMPUTATIONAL FLUID DYNAMICS SIMULATION OF WATER-OIL TWO-PHASE SLUG FLOW IN MICROCHANNELS

摘要

Oil-water slug flow in microchannels is one of the basic problems of pore-scale seepage. In recent years, more computational fluid dynamics (CFD) simulations concerning two-phase flow in microchannels have been developed. However, few simulations have studied the flow resistance of oil slug in microchannels. In this study, a CFD method was used to simulate the movement of slug in oil-water two-phase flow in circular microchannels with diameters of 20 and 200 μm. The flow resistances of oil slugs were investigated at different contact angles. The effects of the length and speed of the movement of oil slugs on their flow resistances were analyzed. The simulation results indicate that the shape of the oil slug as well as the flow pattern are influenced by the oil contact angle, defined as the angle between the oil-water and oil-wall interfaces. A certain number of vortices appear in the front, back, and inside of an oil slug when the oil contact angle is 60°. However, few vortices arise at the back and front of an oil slug when the oil contact angle is 140°. If the oil contact angle is less than 30°, the microchannel wall is strongly lipophilic and the oil slug beomes an annular film.